Commentaries on Viewpoint: Physiology and fast marathons

J Appl Physiol 128: 1069–1085, 2020; doi:10.1152/japplphysiol.00167.2020. VIEWPOINT Commentaries on Viewpoint: Physiology and fast marathons COMMENTARY ON VIEWPOINT: PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: An essential addition to the Viewpoint of Joyner et al. (3) is to consider how the pacing strategies of word record (WR) holders have changed in the last decades (1). As such, from 1967 to 1988, athletes used to start off faster than the goal speed needed to break the WR, and due to these unsustainable initial speeds, they displayed significant speed losses in the second half of the race. However, since 1988, it seems that the pacing strategy has moved from a positive to a negative profile, with athletes speeding up from the 25th km to the finish line (1). The trend toward smaller pace variations between 5-km sections in recent WRs also suggests that a more stable pacing, with an average speed almost equal for the whole race, may be the pacing goal for future WR seekers. One way of ensuring such a stable pace is a careful selection of the course profile. For example, for the “Breaking2” attempt, Nike looked for a course as flat as possible (Monza, Italy), and in the subsequent Ineos 1:59 Challenge, Kipchoge ran on a flat course with only 2.4 m of elevation change. Within the conventional WR eligible races, Berlin, one of the most likely candidates in terms of potential venues for future WR attempts (2), is relatively flat (starts at an elevation of 38 m above sea level and never exceeds 53 m), and has a net downhill profile over the final 15 km. REFERENCES 1. Díaz JJ, Fernández-Ozcorta EJ, Santos-Concejero J. The influence of pacing strategy on marathon world records. Eur J Sport Sci 18: 781–786, 2018. doi:10.1080/17461391.2018.1450899. 2. Díaz JJ, Renfree A, Fernández-Ozcorta EJ, Torres M, Santos-Concejero J. Pacing and performance in the 6 world marathon majors. Front Sports Act Living 1: 54, 2019. doi:10.3389/fspor.2019.00054. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. Jordan Santos-Concejero1 Fernando González-Mohíno2,3 José María González-Ravé2 1 Department of Physical Education and Sport, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain; 2 University of Castilla-La Mancha, Sport Training Lab, Toledo, Spain; and 3 Facultad de Lenguas y Educación, Universidad Nebrija, Madrid, Spain BETTER ENGAGEMENT DURING FAST MARATHONS TO THE EDITOR: We would like to comment on the Viewpoint by Joyner et al. (3). Research has outlined that elite marathon runners possess excellent running economy among other wellknown physiological and biomechanical determinants (2). Not only is whole body dynamic exercise metabolically costly, but neural processing effort, requiring the brain’s limited metabolic resources, continually occurs during prolonged exercise (4), notably for self-paced exercise like running a marathon. Under the umbrella of energy saving, executive functioning capacity resting on goal-oriented behavior may also explain http://www.jap.org differences in endurance performance even at top levels. First, executive function may be predictive of endurance performance (1): faster runners would have better inhibitory control, not only over motor responses but also over interfering, distracting information. Further, the elite athletes through deliberate practice over the years may have developed the ability to execute their patterns free of much frontal cortex participation. Neuroimaging studies corroborate this idea, as prefrontal cortex activity is seen to decrease in elite Kenyan runners (5). Second, effective pacing involving cognitive control and decision-making process is crucial to endurance performance. As highlighted (2), optimal pacing was an important factor in the exhibition event to break the 2-h barrier. Given that marathon might be seen as an effortful cognitive task that places high demands on several brain areas related to emotional, motivational, interoception, and executive processing, pacing assistance would be valuable in reaching an automatic mode to divert resources effortlessly and when needed. Thus, we can assume that this strategic conservation of mental effort resources through pacing aid may lead to hypofrontality phenomenon (4) and the so-called neural efficiency. REFERENCES 1. Cona G, Cavazzana A, Paoli A, Marcolin G, Grainer A, Bisiacchi PS. It’s a matter of mind! Cognitive functioning predicts the athletic performance in ultra-marathon runners. PLoS One 10: e0132943, 2015. doi:10. 1371/journal.pone.0132943. 2. Joyner MJ, Coyle EF. Endurance exercise performance: the physiology of champions. J Physiol 586: 35–44, 2008. doi:10.1113/jphysiol.2007.143834. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Radel R, Brisswalter J, Perrey S. Saving mental effort to maintain physical effort: a shift of activity within the prefrontal cortex in anticipation of prolonged exercise. Cogn Affect Behav Neurosci 17: 305–314, 2017. doi:10.3758/s13415-016-0480-x. 5. Santos-Concejero J, Billaut F, Grobler L, Oliván J, Noakes TD, Tucker R. Brain oxygenation declines in elite Kenyan runners during a maximal interval training session. Eur J Appl Physiol 117: 1017–1024, 2017. doi:10.1007/s00421-017-3590-4. Stephane Perrey EuroMov Digital Health in Motion, University of Montpellier, IMT Mines Ales, Montpellier, France PHYSIOLOGY AND FAST MARATHONS: “THE PROPULSIVE AND MUSCULAR EFFICIENCY,” KEYSTONES OF RUNNING PERFORMANCE TO THE EDITOR: Joyner et al. (5) in their Viewpoint left no stone unturned in their search for determinants of Kipchoge’s world record. However, they poorly defined the “mechanical efficiency,” which should be clarified since it is a key parameter of running performance. The minimum, inevitable, work that Kipchoge et al. did to cross the finish line is given by the external frictional drag times the 42.195 km. The overall efficiency can thus be expressed as the ratio between this minimum work and the chemical energy transformed by the muscles (2). It can be also defined as the product of the “muscular efficiency,” indicating 8750-7587/20 Copyright © 2020 the American Physiological Society Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1069 1070 the ability to transform chemical energy into muscle work, and the “propulsive efficiency,” indicating the ability to utilize the muscle work to move the body against the wind resistance. While Kipchoge’s recent performance may be partly explained by lower drag due to his body shape and drafting, the recent improvements of running performances are certainly closely related to an enhancement of muscular efficiency. For instance, trained subjects can exploit better the dynamic coupling between segments to save mechanical energy than untrained (1). Additionally, smaller muscle-tendons (and shoes!) hysteresis in athletes (3) reduces the imbalance between energy dissipation and generation, a major determinant of the running cost (4). Scientific contributions on fatigue resistance, muscle strengthening, and training intensity have potentially led to biochemical and neuromechanical adaptations, improving efficiency. Even a small enhancement of the role played by elasticity may especially impact long-distance performances, by reducing muscular fatigue over a huge number of steps. REFERENCES 1. Bianchi L, Angelini D, Lacquaniti F. Individual characteristics of human walking mechanics. Pflugers Arch 436: 343–356, 1998. doi:10.1007/ s004240050642. 2. Cavagna GA. Symmetry and asymmetry in bouncing gaits. Symmetry (Basel) 2: 1270 –1321, 2010. doi:10.3390/sym2031270. 3. da Rosa RG, Oliveira HB, Gomeñuka NA, Masiero MPB, da Silva ES, Zanardi APJ, de Carvalho AR, Schons P, Peyré-Tartaruga LA. Landing-takeoff asymmetries applied to running mechanics: a new perspective for performance. Front Physiol 10: 415, 2019. doi:10.3389/fphys.2019. 00415. 4. Dewolf AH, Willems PA. Running on a slope: A collision-based analysis to assess the optimal slope. J Biomech 83: 298 –304, 2019. doi:10.1016/j. jbiomech.2018.12.024. 5. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. Arthur H. Dewolf Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, Rome, Italy NEUROMUSCULAR FUNCTION: THE POWER BEHIND FAST MARATHONS TO THE EDITOR: I appreciate the physiologically informed discussion presented in the Viewpoint by Joyner et al. (3), highlighting the potential mechanisms underpinning the recent marathon performances by Eliud Kipchoge and Brigid Kosgei. The authors note that at the elite level maximal oxygen uptake of endurance athletes is likely similar to that which was reported in the 1960s (4); therefore, other factors beyond improved cardiac output and arteriovenous oxygen difference must be considered. Taken together with the lack of data demonstrating higher lactate thresholds in elite runners compared with the 1960s, it is most plausible that Kipchoge and Kosgei achieved greater improvements in running economy (RE). Although the authors provide a biomechanical perspective for differences in RE, I believe the potential trainingrelated neuromuscular adaptations (e.g., force, velocity, and power) and the subsequent effect on RE have been underappreciated in this discussion. For example, Kipchoge regularly performs tempo runs consisting of interspersed high-speed sprinting and jogging (3). Explosive exercise training of this nature has been shown to improve neuromuscular characteristics and RE (1, 2) in ab- sence of changes in maximal oxygen capacity (1). This may be due to increased muscle stiffness or motor unit coordination and/or recruitment resulting in 1) greater storage and utilization of elastic energy, 2) reduced ground contact time, and 3) reduced energy expenditure (1, 2). Collectively, these neuromuscular adaptations would allow endurance runners to run at a greater relative peak power output and/or reduce rate of muscle fatigue (1, 2, 5). Thus, it is pertinent that differences in neuromuscular attributes are considered in this discussion. REFERENCES 1. Barnes KR, Kilding AE. Strategies to improve running economy. Sports Med 45: 37–56, 2015. doi:10.1007/s40279-014-0246-y. 2. Denadai BS, de Aguiar RA, de Lima LCR, Greco CC, Caputo F. Explosive training and heavy weight training are effective for improving running economy in endurance athletes: a systematic review and metaanalysis. Sports Med 47: 545–554, 2017. doi:10.1007/s40279-016-0604-z. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Pollock ML. Submaximal and maximal working capacity of elite distance runners. Part I: Cardiorespiratory aspects. Ann N Y Acad Sci 301: 310 –322, 1977. doi:10.1111/j.1749-6632.1977.tb38209.x. 5. Weston AR, Mbambo Z, Myburgh KH. Running economy of African and Caucasian distance runners. Med Sci Sports Exerc 32: 1130 –1134, 2000. doi:10.1097/00005768-200006000-00015. Brandon A. Yates1,2 Department of Kinesiology, Indiana University-Purdue University of Indianapolis, Indianapolis, Indiana; and 2 Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana 1 TIME-DEPENDENT PHYSIOLOGICAL CHANGES—THE MISSING PIECE OF THE MARATHON PUZZLE? TO THE EDITOR: While the Viewpoint by Joyner et al. (3) superbly summarizes key factors underlying marathon running physiology and potential reasons for recent records surge, the inherently dynamic physiological nature of marathon running might have been understated. To comprehensively interpret marathon performance, one also needs to consider the timedependent physiological alterations during both the actual marathon run and the preceding training. In particular, the average elite marathon running velocities can be explained by regression calculations using “static” values of maximal oxygen uptake, lactate threshold (LT) and running economy (RE) (2). However, given the dynamic nature of long-distance running, the contribution of these determinants to subsequent physiological responses and actual running performance significantly varies and cannot be precisely predicted by static values modeling. The variation can relate to both the relative contribution/importance of each factor and the duration-related dynamic differences. Indeed, LT can be altered due to potential glycogen-depletion-related reduction in lactate production while RE is known to decrease as a function of running duration (4). Training also represents a complex dynamical system comprised of numerous fluctuating determinants (i.e., intensity/duration/frequency, hypoxic/heat training, tapering) further complicated by the distinct individual (5) and daily (1) variability in training-induced responses. It, thus, seems crucial to constantly monitor the corresponding training-related physiological fluctuations. Given our currently scarce understanding, further exploration of time-dependent dynamics of physiological determinants during both the marathon running and J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1071 training seems warranted. It will provide important insight into the often omitted “dynamic” aspect of the marathon performance puzzle and, ultimately, limits of marathon running. REFERENCES 1. Cappaert TA. Time of day effect on athletic performance: an update. J Strength Cond Res 13: 412–421, 1999. doi:10.1519/00124278-19991100000019. 2. Joyner MJ. Modeling: optimal marathon performance on the basis of physiological factors. J Appl Physiol (1985) 70: 683–687, 1991. doi:10. 1152/jappl.1991.70.2.683. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Lazzer S, Salvadego D, Rejc E, Buglione A, Antonutto G, di Prampero PE. The energetics of ultra-endurance running. Eur J Appl Physiol 112: 1709 –1715, 2012. doi:10.1007/s00421-011-2120-z. 5. Ross R, Goodpaster BH, Koch LG, Sarzynski MA, Kohrt WM, Johannsen NM, Skinner JS, Castro A, Irving BA, Noland RC, Sparks LM, Spielmann G, Day AG, Pitsch W, Hopkins WG, Bouchard C. Precision exercise medicine: understanding exercise response variability. Br J Sports Med 53: 1141–1153, 2019. doi:10.1136/bjsports-2018-100328. Ušaj Anton1 Debevec Tadej1,2 1 Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia; and 2 Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia FAST MARATHON PHYSIOLOGY: THE ROLE OF CARDIAC TROPONINS TO THE EDITOR: Marathons are a showcase of exquisite physical prowess as well as a remarkable opportunity for physiological discovery. Joyner et al. (1) in their Viewpoint “Physiology and fast marathons” analyze the factors that have led to the recent improvements in the marathon and 1,500-m run world records. They conclude that reductions in time come from the interplay between biological ability, intensive training programs, and modern techniques such as drafting and pacing. Moreover, better shoes, optimized tracks, and carbohydrate feeding could have also played a role by increasing running efficiency. Parallel to these advances, there is a strong body of evidence suggesting that cardiac troponin (cTn) levels rise as a consequence of running a marathon, specially in young male runners (2, 3). Troponin, a heterotrimeric protein complex that regulates muscle contraction, is a valuable biomarker in cardiology, used to define acute myocardial infarction or AMI (4). However, the prognostic significance of cTn elevation in the setting of a marathon is controversial (5). From a physiological viewpoint and returning to the topic of marathons, it would be interesting to evaluate if the magnitude of troponin rise is altered with the presence or absence of the novel running techniques (i.e., drifting, pacing, specialized shoes, improved tracks, and carbohydrate feeding). This is a unique opportunity to study the release of cTn triggered by exercise and could inform whether the release of troponins is a modifiable phenomenon. Thus marathons are more than ever a valuable method for the advancement of cardiovascular research and could potentially provide the much-needed answers for the clinical dilemma around cardiac troponins and endurance running. REFERENCES 1. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 2. Kong Z, Nie J, Lin H, George K, Zhao G, Zhang H, Tong TK, Shi Q. Sex differences in release of cardiac troponin T after endurance exercise. Biomarkers 22: 345–350, 2017. doi:10.1080/1354750X.2016.1265007. 3. Tian Y, Nie J, Huang C, George KP. The kinetics of highly sensitive cardiac troponin T release after prolonged treadmill exercise in adolescent and adult athletes. J Appl Physiol (1985) 113: 418 –425, 2012. doi:10.1152/ japplphysiol.00247.2012. 4. Thygesen K, Alpert JS, Jaffe AS, Chaitman BR, Bax JJ, Morrow DA, White HD; Executive Group on Behalf of the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Foundation (WHF) Task Force for the Universal Definition of Myocardial Infarction. Fourth universal definition of myocardial infarction (2018). Eur Heart J 40: 237–269, 2019. doi:10.1093/eurheartj/ehy462. 5. Vilela EM, Bastos JCC, Rodrigues RP, Nunes JPL. High-sensitivity troponin after running–a systematic review. Neth J Med 72: 5–9, 2014. José Manuel González-Rayas1 Ana Lilia Rayas-Gómez2 José Manuel González-Yáñez2 1 School of Medicine and Health Sciences, Monterrey Institute of Technology and Higher Education, Monterrey, México; and 2 Hospital San José de Querétaro, Querétaro, México PREDICTING FAST MARATHON PERFORMANCES WITH ADVANCING AGE TO THE EDITOR: Over the last three decades, the improvement in the marathon world record (WR) has been ~4 –5% for elite runners (1). During the same time period, marathon performances of the best master runners have improved at a much greater rate, especially for the older age groups (⬎ 60 yr old) (2, 3). When changes in marathon world record performances are considered with advancing age, the decline in performance is ~10% per decade. For example, the marathon WR for a 60-yr-old male is 02:36:30, which represents a running velocity 22% slower than that of the world’s fastest time, set by Eliud Kipchoge (age 34 yr old). However, this trend of agerelated decline in marathon performance is based on WRs that belong to different runners and thus induces bias in the analysis. Previous studies showed that the age-related decline could be limited to 5–7% per decade at least until 60 yr of age for the same well-trained individual (4). Imagine therefore that Kipchoge remains competitive until 60 yr old. If so, we could predict a 6% decline in velocity per decade which would result in a marathon time of 02:18:15 at 60 yr old i.e., 18 min faster than the current WR for a 60-yr-old. This simulation suggests that marathon WRs in master categories will probably continue to improve in the future if ex-elite runners preserve their motivation to compete as they age. These super master runners will therefore offer valuable information about how lifelong endurance exercise can counteract the age-related decline in integrative physiological function (3, 5). REFERENCES 1. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 2. Lepers R, Cattagni T. Do older athletes reach limits in their performance during marathon running? Age (Dordr) 34: 773–781, 2012. doi:10.1007/ s11357-011-9271-z. 3. Lepers R, Stapley PJ. Master athletes are extending the limits of human endurance. Front Physiol 12: 613, 2016. doi:10.3389/fphys.2016.00613. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1072 4. Lepers R, Bontemps B, Louis J. Physiological profile of a 59-year-old male world record holder marathoner. Med Sci Sports Exerc 52: 623–626, 2020. doi:10.1249/MSS.0000000000002181. 5. Valenzuela PL, Maffiuletti NA, Joyner MJ, Lucia A, Lepers R. Lifelong endurance exercise as a countermeasure against age-related V̇O2max decline: physiological overview and insights from masters athletes. Sports Med 50: 703–716, 2020. doi:10.1007/s40279-019-01252-0. X Romuald Lepers1 Paul Stapley2 Julien Louis3 1 INSERM UMR1093-CAPS, UFR des Sciences du Sport, Université Bourgogne Franche-Comté, Dijon, France; 2 Neural Control of Movement Laboratory, School of Medicine, Faculty of Science, Medicine and Health, Illawarra Health and Medical Research Institute, University of Wollongong, New South Wales, Australia; and 3 Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom PHYSIOLOGY AND FAST MARATHONS—FUTURE IMPROVEMENTS THROUGH BRAIN STIMULATION? TO THE EDITOR: In their Viewpoint, Joyner et al. (1) describe the physiological underpinnings of maximal oxygen consumption (V̇O2max), lactate threshold, and running economy in light of the recent improvements in marathon world records. Rightfully, the authors point to advancements in footwear design and even the psychological benefits of pacing when reviewing determinants of running economy. While adequate, it is apparent that most recent improvements in running economy are of peripheral or environmental origin, potentially approaching a point of diminishing returns apart from further technological progression. Although less work exploited central nervous system (CNS) circuitry, central fatigue (CF) is known to influence endurance performance (3), suggesting a putative role for the CNS in marathon outcomes. Transcranial magnetic stimulation (TMS) and the more portable direct-current stimulation (tDCS) (2) are two noninvasive brain stimulation techniques that can alter corticospinal excitability, and thus provide a theoretical alternative to reduce the energetic cost of running. As the performance-enhancing benefits of tDCS/rTMS remain inconclusive, better targeting strategies and repeated, instead of single-session, studies are needed. Although consecutive sessions of brain stimulation warrant careful monitoring, refined stimulation parameters and insight from neuroimaging modalities, such as positron emission tomography (PET) using the glucose analog fluorodeoxyglucose, could provide intriguing information about whole body energetic costs (i.e., glucose uptake of brain and active skeletal muscle) during running (4). If brain stimulation effectively modulates supplementary motor area-, dorsolateral prefrontal-, or primary motor cortex activity, similar improvements in perceived effort (5) as during pacing are plausible, presenting a framework for future endurance performance improvements. REFERENCES 1. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 2. Machado DGDS, Unal G, Andrade SM, Moreira A, Altimari LR, Brunoni AR, Perrey S, Mauger AR, Bikson M, Okano AH. Effect of transcranial direct current stimulation on exercise performance: A systematic review and meta-analysis. Brain Stimul 12: 593–605, 2019. doi:10. 1016/j.brs.2018.12.227. 3. Millet GY, Lepers R. Alterations of neuromuscular function after prolonged running, cycling and skiing exercises. Sports Med 34: 105–116, 2004. doi:10.2165/00007256-200434020-00004. 4. Rudroff T, Kindred JH, Kalliokoski KK. [18F]-FDG positron emission tomography–an established clinical tool opening a new window into exercise physiology. J Appl Physiol (1985) 118: 1181–1190, 2015. doi:10.1152/ japplphysiol.01070.2014. 5. Zénon A, Sidibé M, Olivier E. Disrupting the supplementary motor area makes physical effort appear less effortful. J Neurosci 35: 8737–8744, 2015. doi:10.1523/JNEUROSCI.3789-14.2015. Felix Proessl Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania IS PHYSIOLOGY OF FAST MARATHONS THE SAME FOR ALL AGE GROUPS? TO THE EDITOR: In their Viewpoint, Joyner and colleagues (1) provided a comprehensive overview of the physiological basis of fast marathon focusing on the physiology of the fastest runners independently of age. Considering the age of peak performance in marathon and the increased number of master runners participating in marathon races during the last decades (4), the physiological mechanisms reported by Joyner et al. (1) should be verified in master runners, i.e., those older than 40 yr old (2). It was acknowledged that physiological characteristics related to race time (maximal oxygen uptake, anaerobic threshold, and running economy) declined with age (2). Nevertheless, the older fast age groups— despite their slower race time compared with younger fast age groups—paced similarly as their younger counterparts (3). The ability of fast master runners to pace similarly as fast younger runners might be attributed to nonphysiological aspects. For instance, fast master runners might be considered as more “selected” runners compared with their younger counterparts considering the decreasing rates of participation in marathon races with age (3, 4). In addition, fast master runners accumulated a long sport experience, e.g., number of finished marathon races and training volume, which might offset the decline of physiological characteristics with age. Nowadays, master marathon runners compete at a high level, and considering their specific characteristics and increasing number, future research should examine the physiological characteristics of fast master marathon runners. REFERENCES 1. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 2. Lepers R, Stapley PJ. Master athletes are extending the limits of human endurance. Front Physiol 12: 613, 2016. doi:10.3389/fphys.2016.00613. 3. Nikolaidis PT, Knechtle B. Do fast older runners pace differently from fast younger runners in the “New York City Marathon”? J Strength Cond Res 33: 3423–3430, 2019. doi:10.1519/JSC.0000000000002159. 4. Nikolaidis PT, Rosemann T, Knechtle B. Sex differences in the age of peak marathon race time. Chin J Physiol 61: 85–91, 2018. doi:10.4077/ CJP.2018.BAG535. P. T. Nikolaidis1 B. Knechtle2 1 School of Health and Caring Sciences, University of West Attica, Athens, Greece; and 2 Institute of Primary Care, University of Zurich, Zurich, Switzerland J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1073 PHYSIOLOGY AND FAST MARATHONS: AN INTEGRATIVE APPROACH TO THE EDITOR: Joyner et al. (4) have presented an elegant discussion on the physiological factors that may have contributed to the improvement in marathon performance in recent years. The authors outlined classic physiological traits associated with endurance performance, such as the maximum oxygen consumption (V̇O2max), lactate threshold, and running economy [RE (4)]. Unfortunately, there are multiple combinations by which these aforementioned physiological traits result in a similar marathon performance [e.g., a modest V̇O2max and outstanding RE (4)]. A better approach to understand the physiology of fast marathons may be derived from the maximal intensity at which a steady state can be achieved. The relationship between speed and the duration until task failure is hyperbolic, and its asymptote termed critical speed (CS). Jones et al. (2) argued that CS is the “gold standard” to determine the maximal metabolic steady state. Furthermore, CS seems to be an excellent predictor of endurance performance (5). Indeed, Jones and Vanhatalo (3) reported that a group of elite athletes, on average, completed their fastest marathon at ~96% of their CS. Critical power, the cycling analog of CS, has been shown to decline with prolonged exercise (1), which may explain the fractional utilization of CS in the marathon. Further research should investigate whether data from elite athletes (3) are applicable to other populations (e.g., recreational athletes). In summary, marathon performance requires steady-state exercise, and CS has been proposed as the “gold standard” to assess maximal metabolic steady state. Therefore, CS offers an integrative approach of the physiological factors underpinning marathon performance. REFERENCES 1. Clark IE, Vanhatalo A, Bailey SJ, Wylie LJ, Kirby BS, Wilkins BW, Jones AM. Effects of two hours of heavy-intensity exercise on the powerduration relationship. Med Sci Sports Exerc 50: 1658 –1668, 2018. doi:10. 1249/MSS.0000000000001601. 2. Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A. The maximal metabolic steady state: redefining the ‘gold standard’. Physiol Rep 7: e14098, 2019. doi:10.14814/phy2.14098. 3. Jones AM, Vanhatalo A. The “critical power” concept: Applications to sports performance with a focus on intermittent high-intensity exercise. Sports Med 47, Suppl 1: 65–78, 2017. doi:10.1007/s40279-017-0688-0. 4. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 5. Muniz-Pumares D, Karsten B, Triska C, Glaister M. Methodological approaches and related challenges associated with the determination of critical power and curvature constant. J Strength Cond Res 33: 584 –596, 2019. doi:10.1519/JSC.0000000000002977. X D. Muniz-Pumares B. Hunter L. Bottoms Department of Psychology and Sport Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom PHYSIOLOGY AND FAST MARATHONS: LESSONS FROM MASTERS ATHLETES TO THE EDITOR: In their Viewpoint, Joyner et al. (2) proposed that a convergence of factors (physiology, training, technology, and logistics) may explain the recent swift improvement in marathon times. While we agree on the importance of these factors and we acknowledge previous research in elite mara- thon runners, we believe that masters athletes can add to the discussion for reaching fast marathons. The analysis of recent exceptional performances in masters runners (2:27:52 and 2:54:23 at 59 and 70 yr of age, respectively) reveals a common characteristic among these athletes, which is a very high fraction (91–93%) of V̇O2max at marathon pace (4, 5). In comparison, elite runners generally sustain 80 – 85% V̇O2max on the marathon with a quite similar running economy (1, 2). These data show new limits to human physiological capacities during endurance exercise and raise questions about the determinants of performance in the marathon. We may first wonder if the best marathon runners could sustain ⬎90% V̇O2max on the marathon, and by how much the current record could be improved. We may also wonder if the higher fractional utilization of V̇O2max observed in masters could derive from the reduction of V̇O2max with aging or could result from specific long-term training adaptation. Finally, it reopens the debate about the optimization of training for the marathon; should the fractional utilization of V̇O2max become a priority with advancing age? Within this context, masters athletes require the continued attention of exercise physiologists, and a better knowledge of their training practices could be valuable for improving performance after 40 yr of age (3). REFERENCES 1. Billat VL, Demarle A, Slawinski J, Paiva M, Koralsztein JP. Physical and training characteristics of top-class marathon runners. Med Sci Sports Exerc 33: 2089 –2097, 2001. doi:10.1097/00005768-200112000-00018. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Lepers R, Stapley PJ. Master athletes are extending the limits of human endurance. Front Physiol 12: 613, 2016. doi:10.3389/fphys.2016.00613. 4. Louis JB, Bontemps B, Lepers R. Analysis of the world record time for combined father and son marathon. J Appl Physiol (1985) 128: 440 –444, 2020. doi:10.1152/japplphysiol.00819.2019. 5. Robinson AT, Watso JC, Babcock MC, Joyner MJ, Farquhar WB. Record-breaking performance in a 70-year-old marathoner. N Engl J Med 380: 1485–1486, 2019. doi:10.1056/NEJMc1900771. X Julien Louis1 Bastien Bontemps2 Romuald Lepers3 1 Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; 2 Unité de recherche Impact de l’Activité Physique sur la Santé (UR IAPS Number 201723207F), University of Toulon, Toulon, France; and 3 INSERM UMR1093, CAPS, Faculty of Sport Sciences, University of Bourgogne Franche-Comté, Dijon, France MARATHON RECORD BREAKERS: IS IT IN THE GENES? TO THE EDITOR: As discussed in the Viewpoint by Joyner et al. (2), the combination of outstanding values in major physiological determinants of marathon performance, along with the latest technological advances, has contributed to the recent progression in marathon world records. Interestingly, most of the best marathon times have been obtained by Kenyan or Ethiopian runners, which reinforces the common believe that these athletes might also have the right genetic pool. However, limited evidence is currently available on the influence that genetics exert on athletic performance (1), which may be due to the multifactorial nature of the latter. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1074 A recent systematic review including 10,442 participants, of whom 2,984 were elite marathoners, identified 16 singlenucleotide polymorphisms associated with marathon performance (3). There is, however, a lack of replication studies of most of these genes, and thus it is not possible to identify yet the optimum genotype for endurance running performance (1, 3). Further, about half of world-class endurance athletes do not possess the supposedly “optimum” genetic pool (5), which suggests that having the right genetics might favor but not determine the odds of achieving elite-level performance, possibly due to the key influence of epigenetics. Although genetics are commonly considered an important factor to break the 2-h marathon barrier, we still do not possess any genetic tool to identify those runners with greater chances of achieving this feat (4). Future multicenter research involving whole genome sequencing, especially in top level marathoners, is needed to identify the performance-enhancing polymorphisms that would allow athletes to break the limits of human performance. REFERENCES (RE) and performance (1). This is particularly important for highly trained distance runners, who possess similar maximal oxygen uptake values, but display considerable variation in how much oxygen it costs to run at a given speed (2). Given the small margins of improvement that are possible using conventional running training methods at the elite level, we contend that an appropriately designed and periodized routine of strength training is likely to offer a potent stimulus to the neuromuscular system that enhances RE and marathon performance. The mechanisms that underpin an improvement in RE following a period of strength training remain to be fully elucidated. It has previously been shown that greater muscular strength endurance confers a fatigue-resistant effect resulting in smaller decrements to RE following intensive running (3). Although further work is required to confirm whether a relationship exists between strength qualities and deteriorations in RE during prolonged running, we speculate that improvements in marathon running performance are possible via this mechanism. REFERENCES 1. Ahmetov II, Egorova ES, Gabdrakhmanova LJ, Fedotovskaya ON. Genes and athletic performance: an update. Med Sport Sci 61: 41–54, 2016. doi:10.1159/000445240. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Moir HJ, Kemp R, Folkerts D, Spendiff O, Pavlidis C, Opara E. Genes and elite marathon running performance: a systematic review. J Sports Sci Med 18: 559 –568, 2019. 4. Pickering C, Kiely J, Grgic J, Lucia A, Del Coso J. Can genetic testing identify talent for sport? Genes (Basel) 10: 972, 2019. doi:10.3390/ genes10120972. 5. Ruiz JR, Gómez-Gallego F, Santiago C, González-Freire M, Verde Z, Foster C, Lucia A. Is there an optimum endurance polygenic profile? J Physiol 587: 1527–1534, 2009. doi:10.1113/jphysiol.2008.166645. 1,2 Pedro L. Valenzuela Daniel Boullosa3,4 Juan Del Coso5 1 Department of Systems Biology, University of Alcalá, Madrid, Spain; 2 Department of Sport and Health, Spanish Agency for Health Protection in Sport (AEPSAD), Madrid, Spain; 3 INISA, Federal University of Mato Grosso do Sul, Campo Grande, Brazil; 4 College of Healthcare Sciences, James Cook University, Townsville, Australia; and 5 Centre for Sport Studies, Rey Juan Carlos University, Fuenlabrada, Spain STRENGTH TRAINING AS AN ERGOGENIC TOOL TO ENHANCE RUNNING ECONOMY AND ELITE MARATHON RUNNING PERFORMANCE TO THE EDITOR: The Viewpoint by Joyner and colleagues (4) provides an eloquent summary of the physiological characteristics required for elite marathon running. Practically, the training insights of the world’s best marathon runner are also useful for applied practitioners in helping to understand the preparation required to reach this level. Although we appreciate that the focus of the section entitled “TRAINING” in Joyner and colleagues (4) was intended to be running-related, we feel it is important to highlight the value of strength training as a strategy to enhance running economy 1. Blagrove RC, Howatson G, Hayes PR. Effects of strength training on the physiological determinants of middle- and long-distance running performance: a systematic review. Sports Med 48: 1117–1149, 2018. doi:10.1007/ s40279-017-0835-7. 2. Conley DL, Krahenbuhl GS. Running economy and distance running performance of highly trained athletes. Med Sci Sports Exerc 12: 357–360, 1980. doi:10.1249/00005768-198025000-00010. 3. Hayes PR, French DN, Thomas K. The effect of muscular endurance on running economy. J Strength Cond Res 25: 2464 –2469, 2011. doi:10.1519/ JSC.0b013e3181fb4284. 4. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. Richard C. Blagrove1 Philip R. Hayes2 1 School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, United Kingdom; and 2 Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne, United Kingdom IS ALTITUDE TRAINING ONE OF THE KEY FACTORS IN FAST MARATHONS? TO THE EDITOR: In a recent Viewpoint, Joyner et al. (2) discussed the main factors responsible for the larger performance enhancement in marathon (4 –5%) than for the 1,500-m run (1–2%) over the last 30 years. Their section on TRAINING (2) reports some interesting novel data with historical comparison. In our view, the most important difference between the current training methods and those of the 1950s is the importance of altitude training. To our knowledge (4), most—if not all— elite marathon runners used altitude training. The diversity of these methods has been enlarged in the last 10 years (4). The total volume of training spent in altitude has been increased in many endurance sports over the last 30 years (1), and Joyner et al. (2) reported that “Kipchoge often trains in excess of 200 km/wk at high altitude.” In fact, altitude training is now integrated into the winter preparation program (1) and not only used as a precompetition peaking strategy, as 20 –30 years ago (1). Among the beneficial effects of this “extended” altitude train- J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1075 ing, an enhanced running economy has been shown (5). Since this latter represents one of the main determinants of endurance exercise performance in elite (2) and master marathon runners (3), altitude training may be directly (increased hemoglobin mass) or indirectly (improved running economy) considered as one of the training key factors in fast marathons. REFERENCES 1. Fiskerstrand A, Seiler KS. Training and performance characteristics among Norwegian international rowers 1970-2001. Scand J Med Sci Sports 14: 303–310, 2004. doi:10.1046/j.1600-0838.2003.370.x. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Malatesta D, Millet GP. More on the record-breaking performance in a 70-year-old marathoner. N Engl J Med 381: 293–294, 2019. doi:10.1056/ NEJMc1906513. 4. Millet GP, Brocherie F. Hypoxic training is beneficial in elite athletes. Med Sci Sports Exerc 52: 515–518, 2020. doi:10.1249/MSS.0000000000002142. 5. Schmitt L, Millet G, Robach P, Nicolet G, Brugniaux JV, Fouillot JP, Richalet JP. Influence of “living high-training low” on aerobic performance and economy of work in elite athletes. Eur J Appl Physiol 97: 627–636, 2006. doi:10.1007/s00421-006-0228-3. Gregoire P. Millet Davide Malatesta Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland CRITICAL SPEED: A GOOD ALTERNATIVE FOR TRAINING PRESCRIPTION, PERFORMANCE PREDICTION, AND TRAINING QUANTIFICATION IN MARATHON RUNNERS TO THE EDITOR: The main determinants of performance during the marathon are 1) maximal oxygen uptake (V̇O2max), 2) ability to sustain high percentages of V̇O2max during long periods of time, and 3) running economy (RE) (3). The fractional use of V̇O2max is related to the ability to sustain high workloads before lactate begins to accumulate in the blood, i.e., the so-called lactate threshold (LT) (3). Another important concept is the critical speed (CS) considered the boundary between fatigue and performance during endurance exercises (4). Typically, LT occurs at 75–90% V̇O2max (1) while CS occurs at higher absolute and relative intensities (2). Thus, physiologically, LT demarcates the transition between moderate- and heavy-intensity domains while CS demarcates the transition between heavy- and severe-intensity domains (1). Consequently, workloads above CS promote an increase in oxygen consumption, blood lactate accumulation, and a worsening in RE, causing a decrease in performance. In a literature review, Jones and Vanhatalo (2) showed that elite long-distance runners complete the marathon distance, on average, at 96 ⫾ 2% of their CS. In this way, considering that currently, CS is the main landmark for separating the physiological limit at which physiological homeostasis can be maintained during prolonged exercises (1), we believe that CS can be an attractive tool to guide the prescription of training intensity, as well as the race-pace strategy for the marathon. Furthermore, future studies should verify CS as a method to quantify the training intensity distribution, similar to other studies that used blood lactate accumulation as a reference (5). REFERENCES 1. Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A. The maximal metabolic steady state: redefining the “gold standard”. Physiol Rep 7: e14098, 2019. doi:10.14814/phy2.14098. 2. Jones AM, Vanhatalo A. The “critical power” concept: applications to sports performance with a focus on intermittent high-intensity exercise. Sports Med 47, Suppl 1: 65–78, 2017. doi:10.1007/s40279-017-0688-0. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical power: an important fatigue threshold in exercise physiology. Med Sci Sports Exerc 48: 2320 –2334, 2016. doi:10.1249/MSS.0000000000000939. 5. Seiler KS, Kjerland GØ. Quantifying training intensity distribution in elite endurance athletes: is there evidence for an “optimal” distribution? Scand J Med Sci Sports 16: 49 –56, 2006. doi:10.1111/j.1600-0838.2004.00418.x. Yuri de Almeida Costa Campos1,2 Miller Pereira Guimarães1,3 Jeferson Macedo Vianna2 Sandro Fernandes da Silva1,4 1 Study Group and Research in Neuromuscular Responses, University of Lavras, Brazil; 2 Postgraduate Program of the Faculty of Physical Education and Sports of the University of Juiz de Fora, Brazil; 3 Study Group and Research in Exercise Physiology, Federal University of São Paulo, Santos, Brazil; and 4 Postgraduate Program in Nutrition and Health, University of Lavras, Brazil PHYSIOLOGY AND FAST MARATHONS: CURRENTLY, CAN TECHNOLOGY BE CONSIDERED THE MAIN VARIABLE OF THIS PERFORMANCE? TO THE EDITOR: We would like to comment on the recent Viewpoint by Joyner et al. (2). Recently, the search for breaking two hours in the men’s marathon has increased the discussion of what to do to achieve this goal (1–3). Determination and prediction factors of endurance performance such as maximal oxygen consumption (V̇O2max), velocity corresponding to V̇O2max sustained for the maximal time, running economy, and anaerobic threshold are elucidated by the literature (2). As much as the combination of neural (4), metabolic, and mechanical mechanisms (5) are the main adaptations for performance, technology must also be added in this process. The evolution of running shoes and their relationship with performance are based mainly on sports biomechanics. Models that combine high midsoles, rigid carbon fiber plates, and low weight have been used even by athletes sponsored by other sports brands. Foams are highly compliant and resilient, cushioning, storing and returning energy in mechanical response. Carbon plates, on the other hand, can increase longitudinal flexural stiffness (1), providing modifications in the lever systems and consequently a possible improvement of the stretch-shortening cycle. For these reasons, World Athletics banned the use of a shoes prototype that had already been used in street competitions, further increasing the possible mechanisms related to shoes technology. Thus, in the current scenario, can technology be considered the main variable in fast marathons? We suggest vigorous discussions and studies on the topic. REFERENCES 1. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1076 3. Joyner MJ, Ruiz JR, Lucia A. The two-hour marathon: who and when? J Appl Physiol (1985) 110: 275–277, 2011. doi:10.1152/japplphysiol.00563. 2010. 4. Schumann M, Rønnestad BR. Concurrent Aerobic and Strength Training. New York, NY: Springer Berlin Heidelberg, 2018. 5. Skovgaard C, Almquist NW, Bangsbo J. The effect of repeated periods of speed endurance training on performance, running economy, and muscle adaptations. Scand J Med Sci Sports 28: 381–390, 2018. doi:10.1111/sms. 12916. Miller Pereira Guimarães1,2,3,4,5 Yuri de Almeida Costa Campos1,6 Paulo Henrique Silva Marques de Azevedo2,3 Sandro Fernandes da Silva1,7 1 Study Group and Research in Neuromuscular Responses, University of Lavras, Lavras, Brazil; 2 Study Group and Research in Exercise Physiology, Federal University of São Paulo, Santos, Brazil; 3 Postgraduate Program in Human Movement Sciences and Rehabilitation, Federal University of São Paulo, Santos, SP, Brazil; 4 Presbyterian College Gammon, Lavras, Brazil; 5 Mineiro Center for Higher Education, Campo Belo, Brazil; 6 Postgraduate Program of the Faculty of Physical Education and Sports of the University of Juiz de Fora, Juiz de Fora, Brazil; and 7 Postgraduate Program in Nutrition and Health, University of Lavras, Lavras, Brazil POPULARITY PRESERVES PHYSIOLOGY TO THE EDITOR: In their Viewoint, Joyner et al. (2) explain the recent advancement of the marathon world record by acknowledging the synergistic influence of training advancements, technology, nutrition, and optimal physiology. Omitted from the discussion, however, is the recent popularization of the marathon. The rising popularity of the marathon represents increased opportunity to race, to win, and to make running a financially viable occupation. As a result, the draw of the marathon has increased, and more runners have devoted their efforts towards this distance (3). Popularization of the marathon would also cause some top athletes to migrate from the track to pursue the luster of the roads. That this has occurred is perhaps most intriguing when one remembers that Eliud Kipchoge was once a 5,000-m track world champion. Additionally, the newfound opportunity afforded by the popularity of the marathon has undoubtedly prolonged the running careers of a number of athletes who otherwise may have retired following successful stints on the track. Some highly trained, aging athletes can maintain V̇O2max, lactate threshold, and running economy into their mid to late 30s (1), and the marathon has benefited from having runners continue to compete during these years. For example, world leading times have come from 35-yr-old Haile Gebrselassie (2:03:59), 37-yr-old Kenenisa Bekele (2:01:41), and even 34-yr-old Eliud Kipchoge (1:59: 40). In conclusion, the rising popularity of the marathon has attracted a greater talent pool and has preserved the career of top-tier athletes whose elite physiology remains conducive to world class performance. REFERENCES 1. Joyner MJ. Physiological limiting factors and distance running: influence of gender and age on record performances. Exerc Sport Sci Rev 21: 103–134, 1993. doi:10.1249/00003677-199301000-00004. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793. 2019. 3. Vitti A, Nikolaidis PT, Villiger E, Onywera V, Knechtle B. The “New York City Marathon”: participation and performance trends of 1.2M runners during half-century. Res Sports Med 28: 121–137, 2020. doi:10.1080/ 15438627.2019.1586705. Hunter L. Paris Margaret A. Leist Mast T. Lige William Malysa Alicia S. Oumsang Erin C. Sinai Department of Sports Medicine, Exercise Physiology Laboratory, Pepperdine University, Malibu, California PHYSIOLOGY AND FAST MARATHONS: THE IMPORTANCE OF CEREBRAL DEMAND AND OXYGENATION TO THE EDITOR: With interest we read the Viewpoint by Joyner et al. (2) addressing the physiology of fast marathons. In addition to the prerequisite of a high V̇O2max, the ability to sustain a high % of V̇O2max, and excellent running economy (2), we consider a role for cerebral oxygenation. A reduction in cerebral oxygenation has been implicated in the development of central fatigue as a limitation for exercise performance (4). Among elite Kenyan (Kalenjin) runners (mean half-marathon time 62.2 ⫾ 1.0 min), the top performers in a 5-km trial are those who best maintain their cerebral oxygenation (3). Although a reduced ventilatory drive during exercise would attenuate reduction in PaCO2 and in turn cerebral blood flow and oxygenation, Hansen et al. (1) found, by clamping PETCO2 during high-intensity exercise (~90% V̇O2max), that despite preventing the hyperventilation-induced reduction in PaCO2 and the concomitant decrease in cerebral flow velocity, cerebral oxygenation was reduced at exhaustion. We take reduction in cerebral oxygenation to indicate that during maximal exercise the cerebral demand exceeds the O2 delivery even under conditions of maintained cerebral blood flow (1), suggesting that not only O2 delivery but also the magnitude of cerebral O2 demand is important for exercise tolerance. It may be that Kenyan runners due to both excellent genetically endowed mechanical efficiency (2) and training (5) are better in attenuating the cerebral O2 demand for running and thus maintain cerebral oxygenation that contributes to the astonishing middle- and long-distance performances in this population (2). REFERENCES 1. Hansen RK, Nielsen PS, Schelske MW, Secher NH, Volianitis S. CO2 supplementation dissociates cerebral oxygenation and middle cerebral artery blood velocity during maximal cycling. Scand J Med Sci Sports 30: 399 –407, 2020. doi:10.1111/sms.13582. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Santos-Concejero J, Billaut F, Grobler L, Oliván J, Noakes TD, Tucker R. Brain oxygenation declines in elite Kenyan runners during a maximal interval training session. Eur J Appl Physiol 117: 1017–1024, 2017. doi:10.1007/s00421-017-3590-4. 4. Secher NH, Seifert T, Van Lieshout JJ. Cerebral blood flow and metabolism during exercise: implications for fatigue. J Appl Physiol 104: 306 – 314, 2008. doi:10.1152/japplphysiol.00853.2007. 5. Seifert T, Rasmussen P, Brassard P, Homann PH, Wissenberg M, Nordby P, Stallknecht B, Secher NH, Nielsen HB. Cerebral oxygenation and metabolism during exercise following three months of endurance J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1077 training in healthy overweight males. Am J Physiol Regul Integr Comp Physiol 297: R867–R876, 2009. doi:10.1152/ajpregu.00277.2009. Rasmus K. Hansen1 Niels H. Secher2 Stefanos Volianitis3 1 Department of Health Science and Technology, Sport Sciences–Performance and Technology, Aalborg University, Aalborg, Denmark; 2 Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark; and 3 The Copenhagen Muscle Research, Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark INTERPERSONAL SYNCHRONIZATION IN PACING STRATEGIES AND LOCOMOTOR-RESPIRATORY AND CARDIAC COUPLING AS POTENTIAL FACTORS INFLUENCING MARATHON RUNNING PERFORMANCE TO THE EDITOR: The physiological mechanisms determining endurance exercise performance have been studied mainly regarding various organismic subsystems and influencing factors. We want to emphasize that endurance performance is multifactorial and has to be considered holistically regarding interactions between the organism and the environment. In their Viewpoint, Joyner et al. (3) offer physiologically informed discussion about why marathon times have fallen so dramatically in the last decade. We would like to add a new aspect to the discussion that will address the increased implementation of pacing groups with multiple pacers in the majority of international marathon races and the influence of interpersonal synchronization on the running rhythm. Drafting behind another runner during a marathon provides substantial metabolic benefits (2), and besides running at a steady pace and drafting, running in a group can have additional effects. It has been shown that synchronization occurs preferably during side-by-side running (4) and that interpersonal synchronization can optimize running economy and performance (1). Furthermore, synchronization in step frequency comes along with additional synchronization of other physiological parameters such as breathing frequency, stated as locomotor-respiratory coupling and could have benefits for the entrainment between cardiac and locomotor rhythms (5). For interpersonal synchronization to occur, similar leg length, stride length, and step frequencies between two or a group of runners are prerequisite (4).Taking advantage of spontaneous interpersonal movement synchronization might be an important factor when optimizing pacing strategies. Further research is necessary to provide recommendations for specific pacing strategies to take advantage of interpersonal synchronization to enhance endurance performance. REFERENCES 1. Bood RJ, Nijssen M, van der Kamp J, Roerdink M. The power of auditory-motor synchronization in sports: enhancing running performance by coupling cadence with the right beats. PLoS One 8: e70758, 2013. doi:10.1371/journal.pone.0070758. 2. Hoogkamer W, Kram R, Arellano CJ. How biomechanical improvements in running economy could break the 2-hour marathon barrier. Sports Med 47: 1739 –1750, 2017. doi:10.1007/s40279-017-0708-0. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Nessler JA, Gilliland SJ. Interpersonal synchronization during side by side treadmill walking is influenced by leg length differential and altered sensory feedback. Hum Mov Sci 28: 772–785, 2009. doi:10.1016/j.humov.2009.04. 007. 5. Niizeki K, Kawahara K, Miyamoto Y. Interaction among cardiac, respiratory, and locomotor rhythms during cardiolocomotor synchronization. J Appl Physiol (1985) 75: 1815–1821, 1993. doi:10.1152/jappl.1993.75.4. 1815. Laura Hottenrott1 Kuno Hottenrott2 Thomas Gronwald3 1 Faculty of Sport Science, Ruhr-University, Bochum, Germany; 2 Institute of Sports Science. Martin Luther University of Halle-Wittenberg, Halle, Germany; and 3 Department of Performance, Neuroscience, Therapy and Health. Medical School Hamburg, Hamburg, Germany PHYSIOLOGY AND FAST MARATHONS: THE ROLE OF BIOLOGICAL AGE TO THE EDITOR: Biological age is a key factor contributing to fast marathon performance; however, the optimal age is unknown. At the time of their respective world record performances, Eluid Kipchoge was 33.8 yr old whereas Brigid Kosgei was only 25.6 yr old. As presented by Joyner and colleagues (3) in their Viewpoint, determinants of marathon performance include V̇O2max, “lactate threshold,” and running economy. Although V̇O2max declines on average by 1% per year after ~25 yr of age (1), this decline can be blunted among elite athletes who maintain high levels of training (5). Potential age-related declines in “lactate threshold” are likely secondary to reductions in V̇O2max (4); thus, the optimal age for marathon performance is primarily a trade-off between V̇O2max and running economy. Laboratory data from Paula Radcliffe, the previous world record holder for the women’s marathon, demonstrate a 15% improvement in running economy and no change in V̇O2max from age 18 until 29 yr when she set the marathon world record (2). Together, these laboratory and performance data suggest there is a broad range of optimal age for marathon performance over nearly one decade of life, influenced by an age-dependent trade-off between V̇O2max and running economy. Although personal best performances by Kipchoge and Kosgei have incrementally improved, likely reflecting progressive improvements in running economy, how much longer will these recordsetting athletes maintain an optimal physiology to perform fast marathons? The approximately decade-long optimal age for fast marathon performances may be dwindling for Kipchoge and just beginning for Kosgei. REFERENCES 1. Heath GW, Hagberg JM, Ehsani AA, Holloszy JO. A physiological comparison of young and older endurance athletes. J Appl Physiol 51: 634 –640, 1981. doi:10.1152/jappl.1981.51.3.634. 2. Jones AM. The physiology of the world record holder for the women’s marathon. Int J Sports Sci Coaching 1: 101–116, 2006. doi:10.1260/ 174795406777641258. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Tanaka H, Seals DR. Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms. J Physiol 586: 55–63, 2008. doi:10.1113/jphysiol.2007.141879. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1078 5. Trappe SW, Costill DL, Vukovich MD, Jones J, Melham T. Aging among elite distance runners: a 22-yr longitudinal study. J Appl Physiol (1985) 80: 285–290, 1996. doi:10.1152/jappl.1996.80.1.285. Jonathon W. Senefeld Mayo Clinic, Rochester, Minnesota COMMENTARY ON VIEWPOINT: PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: Joyner et al. (3) in their Viewpoint raised a relevant discussion regarding elite marathoners’ main performance determinants. Notwithstanding its solid background, some methodological and conceptual questions may arise. We agree on identification of the lactate threshold (LT) and running economy (RE) as the most decisive physiological variables to paramount marathon performances. However, LT hardly represents the ability to sustain high intensities before lactate starts to accumulate in blood (3) or the metabolic rate above which lactate first rises above baseline during incremental exercise (1–2 mmol/L) (1), but the ability to exercise as fast as possible without losing body homeostasis. Running fast for long periods without increasing significantly muscular acidosis does not mean that lactatemia could not rise, as well established in the maximal lactate steady state methodology (2). Thus, the LT might not happen at 80 – 85% of V̇O2max but higher particularly in elite athletes with a very well-developed aerobic capacity [as hypothesized by Joyner et al. (3) and observed by us for high level runners, cyclists, rowers, and swimmers]. Second, we consider that not only submaximal intensities should be used when assessing RE (3), but also all the steps of an incremental protocol to exhaustion should be included. Furthermore, both aerobic and anaerobic contributions should be considered. In fact, if a step protocol is interrupted before the last steps and only V̇O2 values are computed, RE could be overestimated (5). Last, we find it misleading to consider LT and RE as exclusively physiological markers since exercise metabolic effects are closely dependent on biomechanical/coordinative patterns (4). REFERENCES 1. Davison RR, Van Someren KA, Jones AM. Physiological monitoring of the Olympic athlete. J Sports Sci 27: 1433–1442, 2009. doi:10.1080/ 02640410903045337. 2. Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A. The maximal metabolic steady state: redefining the ‘gold standard’. Physiol Rep 7: e14098, 2019. doi:10.14814/phy2.14098. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Wakeling JM, Blake OM, Chan HK. Muscle coordination is key to the power output and mechanical efficiency of limb movements. J Exp Biol 213: 487–492, 2010. doi:10.1242/jeb.036236. 5. Zamparo P, Cortesi M, Gatta G. The energy cost of swimming and its determinants. Eur J Appl Physiol 120: 41–66, 2020. doi:10.1007/s00421019-04270-y. 1,2 Ricardo J. Fernandes João Paulo Vilas-Boas1,2 1 Centre of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal; and 2 Porto Biomechanics Laboratory, University of Porto, Porto, Portugal LONG DISTANCE CAPACITIES OF AMERINDIANS TO THE EDITOR: Joyner et al. (4) analyze the main factors contributing to the improvement in marathon races emphasizing V̇O2max, lactate threshold, and running economy (RE). We consider it important to foreground the role of high altitude. There is evidence that four weeks of training periods at simulated 2,000 –3,100 m can decrease the V̇O2 for a given velocity (5). Also, there are interesting investigations not only in African but also in Amerindian athletes. The latter living between 2,000 m and more than 4,000 m of altitude are not such good marathon runners as East-Africans, but successful on longer distances. Interestingly they do not train only on mountain planes but also on steep ascents. The last Tour de France winner Egan Bernal living near Bogotá/Colombia may climb from 500 m to 3,000 m during one training unit (2). Similarly, the Tarahumara tribe in Northern Mexico live and train alternately between 800 and 2,400 m of altitude. They usually do not win Marathon races but are excellent runners on mountainous distances between 60 and 700 km. Unfortunately, only a few investigations on the physiological basis have been performed (e.g., 1, 3). The body shape with long slender legs is similar to that of Kenyans; together with light sandals and a stiff foot arch, this helps to save energy. Running downhill (usually half of the distances in Tarahumara competitions) costs very little energy. The main causes for the successful distance running in both Kenyans and Tarahumara are therefore probably physique and conditioning beginning already in early childhood. REFERENCES 1. Balke B, Snow C. Anthropological and physiological observations on Tarahumara endurance runners. Am J Phys Anthropol 23: 293–301, 1965. doi:10.1002/ajpa.1330230317. 2. Böning D. The Colombian Tour de France winner Egan Bernal – physiological background. German J Sports Med 70: 195–196, 2019. doi:10.5960/ dzsm.2019.397. 3. Christensen DL, Espino D, Infante-Ramírez R, Cervantes-Borunda MS, Hernández-Torres RP, Rivera-Cisneros AE, Castillo D, Westgate K, Terzic D, Brage S, Hassager C, Goetze JP, Kjaergaard J. Transient cardiac dysfunction but elevated cardiac and kidney biomarkers 24 h following an ultra-distance running event in Mexican Tarahumara. Extrem Physiol Med 6: 3, 2017. doi:10.1186/s13728-017-0057-5. 4. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 5. Saunders PU, Telford RD, Pyne DB, Cunningham RB, Gore CJ, Hahn AG, Hawley JA. Improved running economy in elite runners after 20 days of simulated moderate-altitude exposure. J Appl Physiol (1985) 96: 931– 937, 2004. doi:10.1152/japplphysiol.00725.2003. Alain Riveros-Rivera1,2 Dieter Böning1 1 Institute of Physiology, Charité - Universitätsmedizin Berlin, Berlin, Germany; and 2 Department of Physiological Sciences. Pontificia Universidad Javeriana, Bogotá, Colombia COMMENTARY OF VIEWPOINT: PHYSIOLOGY OF FAST MARATHONS TO THE EDITOR: The recent Viewpoint by Joyner et al. (2) provides an excellent take on the converging factors that led to recent men’s and women’s marathon world records set by Eliud Kipchoge and Brigid Kosgei, respectively. However, there may be an additional performance-related factor yet to converge— age. Eliud Kipchoge was just shy of 35 yr old J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1079 when he broke the 2-h mark during an exhibition marathon in 2019. This is ~4 – 8 yr older than the age most elite male marathoners achieve personal best performances (1, 3, 4). Conversely, Brigid Kosgei was only 25 yr old during her record run in the 2019 Chicago Marathon, ~2– 4 yr younger than the reported age for peak performance in high-level female marathoners (1, 3). These results call into question whether 1) there is a narrow, universal age for peak marathon performance; and 2) if so, is it older or younger than currently reported peak performance ages? If younger athletes are best suited to the marathon, then future records may be set by those, like Kosgei, who debut at a young age. Or perhaps performance will converge around an older age as Kipchoge demonstrates that years of intensive training can lead to fitness gains at relatively older ages. Therefore, it will be interesting to see whether record-setting marathons continue to occur across a wide age range or if age converges and the marathon begins to be dominated by athletes of a specific age (older or younger) that differs from the reported age of peak performance. REFERENCES 1. Berthelot G, Len S, Hellard P, Tafflet M, Guillaume M, Vollmer J-C, Gager B, Quinquis L, Marc A, Toussaint J-F. Exponential growth combined with exponential decline explains lifetime performance evolution in individual and human species. Age (Dordr) 34: 1001–1009, 2012. doi:10.1007/s11357-011-9274-9. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Lara B, Salinero JJ, Del Coso J. The relationship between age and running time in elite marathoners is U-shaped. Age (Dordr) 36: 1003–1008, 2014. doi:10.1007/s11357-013-9614-z. 4. Noble TJ, Chapman RF. Marathon Specialization in Elites: A Head Start for Africans. Int J Sports Physiol Perform 13: 102–106, 2018. doi:10.1123/ ijspp.2017-0069. Daniel H. Craighead Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado COMMENTARY ON VIEWPOINT: PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: The Viewpoint by Joyner and colleagues (4) is timely with the recent marathon world records. Properly measuring the key physiological determinate running economy (RE) in a laboratory setting deserves commentary. First, it is now understood that the relationship between V̇O2 and velocity is not linear but curvilinear. Importantly, this means when RE is expressed as a cost-of-transport (COT) or the amount of oxygen or energy required to run a given distance (ml O2·kg⫺1·km⫺1), COT is U-shaped across velocity (1). Because RE is not constant across velocity, RE should be evaluated at a velocity near “lactate threshold” to understand marathon performance. Second, the practice of measuring RE at one particular incline (e.g., 1%) to simulate air resistance during treadmill running (3) has shortcomings. Aerodynamic force increases with running velocity. Thus, a single incline is only accurate for one running velocity. Furthermore, during running, the leg muscles and tendons function in series to store and return mechanical energy similar to springs. Treadmill inclines change the biomechanical determinants of energy return which influences RE (5). Air resistance should be considered only when trying to understand performance by accounting for the athlete’s exposed surface area and running velocity. Last, treadmill decks vary considerably in stiffness. More compliant surfaces increase leg stiffness, resulting in greater energy return which reduces the metabolic cost of running (2). Compliant treadmills in series with compliant running shoes can misinform the effects of RE during overground performance. Using stiff treadmills is obligatory to understand how technological advancements influence RE and performance. REFERENCES 1. Batliner ME, Kipp S, Grabowski AM, Kram R, Byrnes WC. Does metabolic rate increase linearly with running speed in all distance runners? Sports Med Int Open 2: E1–E8, 2017. doi:10.1055/s-0043-122068. 2. Kerdok AE, Biewener AA, McMahon TA, Weyand PG, Herr HM. Energetics and mechanics of human running on surfaces of different stiffnesses. J Appl Physiol (1985) 92: 469 –478, 2002. doi:10.1152/ japplphysiol.01164.2000. 3. Jones AM, Doust JH. A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. J Sports Sci 14: 321–327, 1996. doi:10. 1080/02640419608727717. 4. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 5. Snyder KL, Kram R, Gottschall JS. The role of elastic energy storage and recovery in downhill and uphill running. J Exp Biol 215: 2283–2287, 2012. doi:10.1242/jeb.066332. Shalaya Kipp School of Kinesiology, University of British Columbia, Vancouver, BC, Canada COMMENTARY ON VIEWPOINT: PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: Joyner et al. (3) posited that improvements in running economy (RE) have facilitated the recent rapid progression in marathon world records (WR). Here, I consider if improvements in RE can account for the historical progression in marathon times. RE (ml O2·kg⫺1·km⫺1) increases at faster running speeds but fair comparisons between measurements made at different speeds are possible if RE is converted based on Kipp et al. (4) to a standard speed (i.e., 16 km/h). In 1930 (WR 2:29:01.8), Dill et al. (1) determined that Clarence DeMar (2:34:48 marathoner and 7-time Boston marathon winner) had gross RE of 182 ml O2·kg⫺1·km⫺1 at 11.28 km/h which, converted to 16 km/h, equates to ~193 ml O2·kg⫺1·km⫺1. In 2006 (WR 2:04:55), Lucia et al. (5) discovered that Zersenay Tadese (2:08:46 marathoner) had unprecedented RE, averaging 153 ml O2·kg⫺1·km⫺1 while running at 17–21 km/h up a 1% inclined treadmill which, converted to level running at 16 km/h, is ~142 ml O2·kg⫺1·km⫺1. In 2018 (WR 2:02:57), Hoogkamer et al. (2) found that exceptional new racing shoes facilitated an average RE of 181 ml O2·kg⫺1·km⫺1 at 16 km/h in sub-elite runners, many of whom had run marathons faster than DeMar’s best. Over the past 90 years, the marathon WR has decreased ~19% and RE of elite runners by ~26%. RE values that were once rare are now commonplace. In 2020 (WR 2:01:39), I anxiously await public disclosure of RE and other physiological data for the athletes who have recently run record times wearing exceptional shoes. REFERENCES 1. Dill DB, Talbott JH, Edwards HT. Studies in muscular activity: VI. Response of several individuals to a fixed task. J Physiol 69: 267–305, 1930. doi:10.1113/jphysiol.1930.sp002649. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1080 2. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Kipp S, Grabowski AM, Kram R. What determines the metabolic cost of human running across a wide range of velocities? J Exp Biol 221: jeb184218, 2018. doi:10.1242/jeb.184218. 5. Lucia A, Esteve-Lanao J, Oliván J, Gómez-Gallego F, San Juan AF, Santiago C, Pérez M, Chamorro-Viña C, Foster C. Physiological characteristics of the best Eritrean runners-exceptional running economy. Appl Physiol Nutr Metab 31: 530 –540, 2006. doi:10.1139/h06-029. Rodger Kram1 1 Department of Integrative Physiology, University of Colorado, Boulder, Colorado 4. Sperlich B, Holmberg HC. The Responses of Elite Athletes to Exercise: An All-Day, 24-h Integrative View Is Required! Front Physiol 8: 564, 2017. doi:10.3389/fphys.2017.00564. Christoph Zinner1 Billy Sperlich2 1 Department of Sport, University of Applied Sciences for Police and Administration of Hesse, Wiesbaden, Germany; and 2 Integrative and Experimental Exercise Science, University of Würzburg, Germany PHYSIOLOGY AND FAST MARATHONS: MORE DETAILED CHARACTERIZATION OF TRAINING AND CAREFUL MONITORING ARE NECESSARY TO IMPROVE OUR UNDERSTANDING OF LONG-TERM ADAPTATIONS TO THE EDITOR: First, we would like to commend the authors of the Viewpoint (2) for publishing this comprehensive summary of important factors for running fast marathons and the intent to advance this area of research. Despite the recent performances achieved by elite runners, we believe age-group runners should receive similar research attention, since age-groupers of both sexes achieve remarkably fast marathon results with less financial and/or infrastructural support. In contrast to the few elite runners running ⬍2:05 h, the growing number of subelite runners in numerous marathon events represents a very interesting population to study the mechanisms and processes of breaking personal performance boundaries such as “sub 3” or “sub 4.” Joyner et al. (2) offer a “physiologically informed discussion about why marathon times have fallen so dramatically recently” building on evidence of the last years. Unfortunately, few analyses about the annual rate of increase in marathon performance of sub-elite runners are available. In this regard only few analyses about the performance declines in (fe)male age-group winners exist (3). Besides the physiological foundations and training, the influence of data-guided training prescription with new technology [e.g., wearable sensors with “intelligent” biofeedback (1)], running equipment, and logistics are of great interest for recreational runners. Subelite runners often behave as elite runners, but do not have the time or efficient infrastructure for, e.g., recovery and medical treatments. Therefore, we believe it is essential to understand subelite athletes’ responses of both sexes to exercise (4) to identify personalized strategies to achieve individual fast marathons. TO THE EDITOR: First, we would like to commend the authors of the Viewpoint (2) for this comprehensive summary of factors of importance for running fast marathons. Then, we would like to comment on their discussion of fast marathon physiology (2). We follow closely the debate concerning 1) footwear designed to improve marathon performance; and 2) nonofficial optimization of the course arrangement, ambient conditions, including headwind, individualized starting times, possibilities for hydration, pacing, etc., that influence running performance. Although marathon performance has improved more than middle-distance running (4 –5% versus 1–2%), does this reflect optimization of such factors and/or improvements in long-term preparation for fast marathons during the last 30 years? Descriptions of long-, middle- and short-term preparation by current elite marathon runners (1, 2) lack comprehensive analysis of macro- and mesocycles of exercise intensity, volume, frequency, and sequence and individual monitoring and control of internal and external loads. Our understanding, in particular, of the distribution of training intensity (5) and technology-assisted monitoring among elite athletes has improved (3), and researchers should describe in detail the preparation for and monitoring of fast marathons. This will advance our knowledge concerning intra-individual variations in the fundamental determinants of fast marathons (i.e., maximal oxygen uptake, running economy, etc.). This reporting should provide a holistic overview (4) of the distribution of training intensity and volume, frequency of sessions, recovery procedures, the type and characteristics of strength training, environmental conditions (heat and altitude) and potential nutritional strategies associated with the different macro- and mesocycles and tapering utilized by elite male and female marathon runners. REFERENCES REFERENCES 1. Düking P, Achtzehn S, Holmberg HC, Sperlich B. Integrated framework of load monitoring by a combination of smartphone applications, wearables and point-of-care testing provides feedback that allows individual responsive adjustments to activities of daily living. Sensors (Basel) 18: 1632, 2018. doi:10.3390/s18051632. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Leyk D, Rüther T, Wunderlich M, Sievert A, Essfeld D, Witzki A, Erley O, Küchmeister G, Piekarski C, Löllgen H. Physical performance in middle age and old age: good news for our sedentary and aging society. Dtsch Arztebl Int 107: 809 –816, 2010. 1. Jones AM. The physiology of the world record holder for the women’s marathon. Int J Sports Sci Coaching 1: 101–116, 2006. doi:10.1260/ 174795406777641258. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Sperlich B, Aminian K, Düking P, Holmberg HC. Editorial: wearable sensor technology for monitoring training load and health in the athletic population. Front Physiol 10: 1520, 2020. doi:10.3389/fphys.2019.01520. 4. Sperlich B, Holmberg HC. The responses of elite athletes to exercise: an all-day, 24-h integrative view is required! Front Physiol 8: 564, 2017. doi:10.3389/fphys.2017.00564. AGE GROUPERS ALSO RUN FAST MARATHONS! J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1081 5. Stöggl TL, Sperlich B. Editorial: training intensity, volume and recovery distribution among elite and recreational endurance athletes. Front Physiol 10: 592, 2019. doi:10.3389/fphys.2019.00592. Billy Sperlich1 Hans-Christer Holmberg2,3,4 1 Integrative and Experimental Exercise Science, Institute for Sport Sciences, University of Würzburg, Würzburg, Germany; 2 Department of Health Sciences, Mid Sweden University, Östersund, Sweden; 3 Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, Stockholm, Sweden; and 4 School of Kinesiology, University of British Columbia, Vancouver, Canada RECENT IMPROVEMENTS IN MARATHON TIMES ARE NOT PHYSIOLOGICAL TO THE EDITOR: October 2019 saw Eliud Kipchoge run the marathon distance unofficially in under 2 h, and Brigid Kosgei break Paula Radcliffe’s 16 yr-old marathon record both in carbon fiber plate (CFP) shoes. Current men’s and women’s world records in the half- and full-marathon have all been broken by Nike athletes in CFP shoes, raising concerns that the introduction of this technology leads to a distinct nonphysiological advantage to Nike-sponsored athletes. For example, Javier Guerra chose to break his Adidas contract to use a Nike CFP shoe and qualified for Tokyo 2020. Laboratory studies have shown improved running economy (RE) with CFP shoes (3). Unpublished data from our laboratory shows a 2.3% improvement in a female runner wearing CFP shoes during three 10-km trials (39:08 ⫾ 00:29 min:s) compared with three 10-km trials wearing her preferred nonCFP shoes (40:03 ⫾ 00:20 min:s). In another unpublished study from our laboratory, we tested an East African athlete (a current World Record holder) running on a treadmill at 21 km/h, and a CFP shoe elicited a 2.6% improvement in RE compared with his preferred non-CFP shoe. The recently released Nike Alphafly shoe has been suggested to improve RE by more than 5% and potentially, the men’s marathon by 5:30 (min:s) (4), which is comparable to the performance benefit of doping with erythropoietin (1, 2). Recent improvements in marathon world records are not physiological as implied in the Viewpoint of Joyner et al. (5) but rather technological. Current rules are therefore no longer fit for purpose, requiring revision to safeguard the integrity of sport. REFERENCES 1. Durussel J, Daskalaki E, Anderson M, Chatterji T, Haile D, Padmanabhan N, Patel RK, McClure JD, Pitsiladis YP. Haemoglobin mass and running time trial performance after recombinant human erythropoietin administration in trained men. PLoS One 8: e56151, 2013. doi:10.1371/ journal.pone.0056151. 2. Haile DW, Durussel J, Mekonen W, Ongaro N, Anjila E, Mooses M, Daskalaki E, Mooses K, McClure JD, Sutehall S, Pitsiladis YP. Effects of EPO on Blood Parameters and Running Performance in Kenyan Athletes. Med Sci Sports Exerc 51: 299 –307, 2019. doi:10.1249/MSS. 0000000000001777. 3. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 4. Joyner MJ. Modeling: optimal marathon performance on the basis of physiological factors. J Appl Physiol (1985) 70: 683–687, 1991. doi:10. 1152/jappl.1991.70.2.683. 5. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. Borja Muniz-Pardos1 Shaun Sutehall2 Konstantinos Angeloudis3 Fergus M. Guppy4 Andrew Bosch2 Yannis Pitsiladis3,5 1 GENUD (Growth, Exercise, Nutrition and Development) research group, University of Zaragoza, Zaragoza, Spain; 2 Division of Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa; 3 Collaborating Centre of Sports Medicine, University of Brighton, Eastbourne, United Kingdom; 4 Centre for Stress and Age-related Disease, School of Pharmacy and Biomolecular Sciences (PaBS), University of Brighton, Brighton, United Kingdom; and 5 International Federation of Sports Medicine (FIMS), Lausanne, Switzerland COMMENTARY ON VIEWPOINT: PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: In the recent Viewpoint of Joyner et al. (3), the authors showed evidence and hypothesized several mechanisms associated with fast marathons. Of note, Joyner et al. (3) stated that much of the success of the current men and women marathon world record holders is related to running economy (RE). Further, Joyner et al. (3) stated that it is unclear how trainable RE is; however, it has been shown that RE could be improved after plyometric jump training (PJT), a common training method among athletes, and since the 2000 scientific publications on PJT have increased 25-fold compared with any previous period, including studies with endurance runners (4). Indeed, PJT has demonstrated a significant improvement of RE and time-trial performance in recreational runners (1). Of note, in the aforementioned study (1), PJT was demonstrated to be of value for endurance athletes performing after an acute exposure to high altitude. One mechanism associated with improved RE may be related to the neural control of the lower-limb muscle and their mechanical properties, including enhanced lower-limb reactivity (e.g., reduced foot contact time while running) and foot-arch stiffness (2). Therefore, although we agree with Joyner et al. (3) that RE is key for successful marathon runners, evidence shows that adequate training methods, such as PJT, could be of value to improve RE, and, therefore, running times. In summary, in recent years, the improvements of performance in marathoners noted by Joyner et al. (3) may be related to improved training methods (i.e., PJT), leading toward improvements in RE, probably associated with enhanced lower-limb reactivity and stiffness, and thus better running times (2, 5). REFERENCES 1. Andrade DC, Beltrán AR, Labarca-Valenzuela C, Manzo-Botarelli O, Trujillo E, Otero-Farias P, Álvarez C, Garcia-Hermoso A, Toledo C, Del Rio R, Silva-Urra J, Ramírez-Campillo R. Effects of Plyometric Training on Explosive and Endurance Performance at Sea Level and at High Altitude. Front Physiol 9: 1415, 2018. doi:10.3389/fphys.2018.01415. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1082 2. García-Pinillos F, Lago-Fuentes C, Latorre-Román PA, PantojaVallejo A, Ramirez-Campillo R. Jump-rope training: Improved 3-km time-trial performance in endurance runners via enhanced lower-limb reactivity and foot-arch stiffness. Int J Sports Physiol Perform 1–7, 2020. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Ramirez-Campillo R, Álvarez C, García-Hermoso A, Ramírez-Vélez R, Gentil P, Asadi A, Chaabene H, Moran J, Meylan C, García-deAlcaraz A, Sanchez-Sanchez J, Nakamura FY, Granacher U, Kraemer W, Izquierdo M. Methodological characteristics and future directions for plyometric jump training research: A scoping review. Sports Med 48: 1059 –1081, 2018. doi:10.1007/s40279-018-0870-z. 5. Ramírez-Campillo R, Alvarez C, Henríquez-Olguín C, Baez EB, Martínez C, Andrade DC, Izquierdo M. Effects of plyometric training on endurance and explosive strength performance in competitive middle- and long-distance runners. J Strength Cond Res 28: 97–104, 2014. doi:10.1519/ JSC.0b013e3182a1f44c. David C. Andrade1,2 Rodrigo Del Rio2,3 Rodrigo Ramirez-Campillo1,4 1 Centro de Investigación en Fisiología del Ejercicio, Facultad de Ciencias, Universidad Mayor, Santiago, Chile; 2 Laboratory of Cardiorespiratory Control, Department of Physiology and Centro de Envejecimiento y Regeneración (CARE), Pontificia Universidad Católica de Chile, Santiago, Chile; 3 Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile; and 4 Human Performance Laboratory, Quality of Life and Wellness Research Group. Department of Physical Activity Sciences. Universidad de Los Lagos. Osorno, Chile standing and manipulation of brain physiology may give an extra push to elite marathoners to continue improving their marks. REFERENCES 1. Angius L, Santarnecchi E, Pascual-Leone A, Marcora SM. Transcranial direct current stimulation over the left dorsolateral prefrontal cortex improves inhibitory control and endurance performance in healthy individuals. Neuroscience 419: 34 –45, 2019. doi:10.1016/j.neuroscience.2019.08.052. 2. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 3. Martin K, Staiano W, Menaspà P, Hennessey T, Marcora S, Keegan R, Thompson KG, Martin D, Halson S, Rattray B. Superior inhibitory control and resistance to mental fatigue in professional road cyclists. PLoS One 11: e0159907, 2016. doi:10.1371/journal.pone.0159907. 4. Pageaux B. Perception of effort in Exercise Science: Definition, measurement and perspectives. Eur J Sport Sci 16: 885–894, 2016. doi:10.1080/ 17461391.2016.1188992. 5. Sabino-Carvalho JL, Lopes TR, Obeid-Freitas T, Ferreira TN, Succi JE, Silva AC, Silva BM. Effect of ischemic preconditioning on endurance performance does not surpass placebo. Med Sci Sports Exerc 49: 124 –132, 2017. doi:10.1249/MSS.0000000000001088. Thiago Ribeiro Lopes1,2,3,4 Bruno Moreira Silva2,4 1 Graduate Program in Translational Medicine, Federal University of São Paulo, SP, Brazil; 2 Laboratory of Exercise Physiology, Olympic Center of Training and Research, São Paulo, SP, Brazil; 3 São Paulo Association for Medicine Development, São Paulo, SP, Brazil; and 4 Department of Physiology, Federal University of São Paulo, São Paulo, SP, Brazil BRAIN PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: Accumulating evidence indicates that the brain can play a role to determine endurance performance, in addition to the classical aerobic parameters that are discussed in Joyner et al. (2). For instance, induction of positive expectations regarding an intervention can improve endurance performance of well-trained runners without modifying maximal oxygen consumption, lactate threshold, and running economy (5). Moreover, application of transcranial direct current stimulation on the left dorsolateral prefrontal cortex enhanced Stroop task performance (i.e., a measure of inhibitory control) at rest, as well as reduced perceived effort and improved endurance performance in healthy individuals (1). Such findings are possibly explained by a complex brain regulation of endurance performance. Signals derived from the brain itself (e.g., corollary discharges) and the periphery (e.g., muscle afferents) are involved in the formation of exercise-related sensations (e.g., pain, dyspnea, thermal discomfort, perceived effort) (4). Thus, the ability to cope with such sensations, which is known as inhibitory control, likely contributes to determine endurance performance. In this sense, professional cyclists have been shown to present better inhibitory control at rest as compared with recreational cyclist (3). However, few studies have investigated the brain regulation of endurance performance in elite athletes. Therefore, many questions remain unanswered. For example, does inhibitory control during exercise indeed play a role in performance regulation? Do African runners present better inhibitory control than other runners? Is it possible to improve elite runners’ inhibitory control to further improve performance? Thus, better under- COMMENTARY ON VIEWPOINT: PHYSIOLOGY AND FAST MARATHONS TO THE EDITOR: With great interest I read the recent Viewpoint by Joyner and colleagues (3). From a sociological perspective, the general disdain for Eliud Kipchoge’s efforts to break, and actually breaking, the 2 h barrier is unwarranted. Indeed, it seems governing bodies, and the rules they impose, are a “moving goal post” dependent upon the technology du jour. Physiologically, potent aerobic prowess, expressed as a high maximal oxygen consumption (V̇O2max), is the foundation for such sub-2 h performance (3). As human aerobic capacity seems to have plateaued, increasingly it is other factors such as running economy, nutrition (2), and sports science that are likely the premier targets. The physiological underpinnings of such great running economy have yet to be elucidated, although factors such as skeletal muscle expression of sarco(endo)plasmic reticulum Ca2⫹-ATPase (SERCA) and isoform (1), or changes in musculotendinous stiffening (5), are potential candidates. Although altitude is mentioned in the context of V̇O2max, it is also interesting to note that altitude exposure can also influence running economy (4), perhaps mediated at least in part through SERCA expression. Although in a discussion of a viewpoint in physiology it is perhaps heretical to evoke psychology, nonetheless the role of factors such as analytical ability, resiliency, self-confidence, and vast ability to adequately cope with pressure cannot be understated in producing such high levels of human performance. Although genetics is unlikely to reveal a singular explanation (3), epigenetics, integrative physiology, and transdisciplinary approaches may pro- J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1083 vide a unifying hypothesis for such human running performance. REFERENCES 1. Bueno CR Jr, Ferreira JC, Pereira MG, Bacurau AV, Brum PC. Aerobic exercise training improves skeletal muscle function and Ca2⫹ handling-related protein expression in sympathetic hyperactivity-induced heart failure. J Appl Physiol (1985) 109: 702–709, 2010. doi:10.1152/ japplphysiol.00281.2010. 2. Jeukendrup AE. Nutrition for endurance sports: marathon, triathlon, and road cycling. J Sports Sci 29, Suppl 1: S91–S99, 2011. doi:10.1080/ 02640414.2011.610348. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Saunders PU, Telford RD, Pyne DB, Cunningham RB, Gore CJ, Hahn AG, Hawley JA. Improved running economy in elite runners after 20 days of simulated moderate-altitude exposure. J Appl Physiol (1985) 96: 931– 937, 2004. doi:10.1152/japplphysiol.00725.2003. 5. Spurrs RW, Murphy AJ, Watsford ML. The effect of plyometric training on distance running performance. Eur J Appl Physiol 89: 1–7, 2003. doi:10.1007/s00421-002-0741-y. Stephen J. Ives Associate Professor Health and Human Physiological Sciences, Skidmore College NOW AFOOT: ENGINEERED RUNNING ECONOMY TO THE EDITOR: Drs. Joyner, Hunter, Lucia, and Jones deserve commendation for their timely, concise consideration of endurance running performance in terms of bodily energy supply and demand (3). Supply limits are imposed by the maximal rates at which oxygen is converted into chemical energy (O2/time). Demand is set by how economically the running muscles convert the energy available into speed (O2/distance). As they note, the supply limits of current and former marathon champions seem similar. Rather, racing records have fallen markedly since 2016 because innovative shoe technology has reduced the energy demands of running. The critical advance has been incorporating lightweight, compliant materials with superior energy return (1). The conspicuously thick, yet light midsoles of the new shoes appear to economize running as tuned tracks have (4, 5). Both allow the substrate beneath the runner to yield after touchdown before recoiling to elevate the body later in the step. Satisfying relatively more of the step-cycle lift requirements via passive, elastic recoil requires relatively less of energy burning muscles. Consequently, early models (1) reduced the energy demands of treadmill running by 4.0%, translating into 3.5% faster estimated racing velocities, and ⬎4-min reductions in marathon times, per both Hoogkamer et al. and Joyner’s analyses (2). Undoubtedly, the newer, thicker models reduce energy demands and marathon race times by greater margins. The agreement between scientific evidence and recent racetime reductions marks a technological watershed for endurance running. Performances set largely by physical capabilities in the past are now dependent on athlete-equipment interactions. REFERENCES 1. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 2. Joyner MJ. Modeling: optimal marathon performance on the basis of physiological factors. J Appl Physiol (1985) 70: 683–687, 1991. doi:10. 1152/jappl.1991.70.2.683. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793. 2019. 4. Kerdok AE, Biewener AA, McMahon TA, Weyand PG, Herr HM. Energetics and mechanics of human running on surfaces of different stiffnesses. J Appl Physiol (1985) 92: 469 –478, 2002. doi:10.1152/ japplphysiol.01164.2000. 5. McMahon TA, Greene PR. Fast running tracks. Sci Am 239: 148 –163, 1978. doi:10.1038/scientificamerican1278-148. Peter G. Weyand Southern Methodist University, Locomotor Performance Laboratory, Department of Applied Physiology and Wellness, Dallas, TX 75205 PSYCHOPHYSIOLOGY OF FAST MARATHONS TO THE EDITOR: Joyner et al. (1) proposed a physiologically founded perspective arguing that V̇O2max, lactate threshold (LT), and running economy (and training specificities and technology) likely explain why marathon time has largely fallen recently. We propose a more psychophysiologically oriented discussion, as the prefrontal cortex (PFC) plays a role in the exercise capacity regulation (2– 4) when integrating afferents from the periphery into emotionally relevant messages such as pleasure/displeasure (3). In addition to connections to premotor cortex areas to regulate the motor output, the PFC is further connected to amygdala and takes part in body interoceptive representations of a variety of physiological conditions. The PFC inhibits the amygdalamediated negative sensations; thus a decline in PFC oxygenation (i.e., deactivation) may reveal an impaired capacity to deal with aversive sensations during exercise (2, 3). In this regard, PFC oxygenation declines from LT intensities, even to baseline levels (2), so that a PFC deoxygenation from the LT can suggest a pleasure/displeasure turn point indicating a closeness to exercise disengagement and exhaustion (5). In contrast to recreational athletes with V̇O2max ~57.5 ml·kg⫺1·min⫺1 (2), elite Kenyan runners with V̇O2max ~71.9 ml·kg⫺1·min⫺1 (4) showed no decline in PFC oxygenation (after an initial increase) during maximal selfpaced exercise. In theory, the preserved PFC oxygenation allowed them to perform maximally, having a greater resilience to tolerate aversive sensations. Romantically, this may have allowed them to exercise resisting a “dream-to-nightmare turn point”. Surprisingly, were the “showcase” runners of the marathon records Kenyan? The understanding of elite athletes may require a psychophysiological model. REFERENCES 1. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 2. Pires FO, Dos Anjos CA, Covolan RJM, Pinheiro FA, St Clair Gibson A, Noakes TD, Magalhães FH, Ugrinowitsch C. Cerebral regulation in different maximal aerobic exercise modes. Front Physiol 7: 253, 2016. doi:10.3389/fphys.2016.00253. 3. Robertson CV, Marino FE. A role for the prefrontal cortex in exercise tolerance and termination. J Appl Physiol (1985) 120: 464 –466, 2016. doi:10.1152/japplphysiol.00363.2015. 4. Santos-Concejero J, Billaut F, Grobler L, Oliván J, Noakes TD, Tucker R. Maintained cerebral oxygenation during maximal self-paced exercise in elite Kenyan runners. J Appl Physiol (1985) 118: 156 –162, 2015. doi:10. 1152/japplphysiol.00909.2014. J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1084 5. Vasconcelos G, Canestri R, Prado RCR, Brietzke C, Franco-Alvarenga P, Santos TM, Pires FO. A comprehensive integrative perspective of the anaerobic threshold engine. Physiol Behav 210: 112435, 2019. doi:10.1016/ j.physbeh.2019.01.019. Cayque Brietzke1,2 Paulo Estevão Franco-Alvarenga1,2 Tony Meireles dos Santos1 Flávio Oliveira Pires1,2 1 Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, Brazil; and 2 Human Movement Science and Rehabilitation Program, Federal University of São Paulo, Santos, Brazil RUNNING ECONOMY UNDER THE MICROSCOPE TO THE EDITOR: We read with great interest the Viewpoint proposed by Joyner et al. (3) and would like to comment on the potential factors that may influence running economy and may have led to the recent improvements in marathon performance. First, it is striking that despite its importance in determining running economy, mitochondrial efficiency (P/O) ratio is unknown in elite athletes. Some reports suggest that mitochondrial efficiency can be improved to a greater extent by training twice per day versus once per day (1). Indeed, elite marathon runners often train twice or even thrice daily. Second, single muscle fiber size and contractile function (strength, speed, and power) can be improved with strength or plyometric training (5), which has gained popularity among athletes. Specifically, muscle fiber distribution, myosin heavy chain composition, and titin isoforms have been linked to running economy (4). In addition, it is likely that an interaction exists between muscle-tendon contractile properties, and the improvements in running economy from modern running shoes (2). It is apparent that variability exists in the metabolic benefits that can be obtained by using these modern marathon racing shoes (2), but it is not known how much more economical these shoes are for Kipchoge and Kosgei, specifically. Future research would need to determine whether those benefits are reduced or amplified in individual elite athletes due to specific contractile properties or modifications of lower limb biomechanics. REFERENCES 1. Ghiarone T, Andrade-Souza VA, Learsi SK, Tomazini F, Ataide-Silva T, Sansonio A, Fernandes MP, Saraiva KL, Figueiredo RCBQ, Tourneur Y, Kuang J, Lima-Silva AE, Bishop DJ. Twice-a-day training improves mitochondrial efficiency, but not mitochondrial biogenesis, compared with once-daily training. J Appl Physiol (1985) 127: 713–725, 2019. doi:10.1152/japplphysiol.00060.2019. 2. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Kyrolainen H, Kivela R, Koskinen S, McBride J, Andersen JL, Takala T, Sipila S, Komi PV. Interrelationships between muscle structure, muscle strength, and running economy. Med Sci Sports Exerc 35: 45–49, 2003. doi:10.1097/00005768-200301000-00008. 5. Pellegrino J, Ruby BC, Dumke CL. Effect of plyometrics on the energy cost of running and MHC and titin isoforms. Med Sci Sports Exerc 48: 49 –56, 2016. doi:10.1249/MSS.0000000000000747. Gwenael Layec Wouter Hoogkamer Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts; and Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts PHYSIOLOGY AND FAST MARATHONS: IT’S ABOUT TIME! TO THE EDITOR: The Viewpoint by Joyner and colleagues (4) on the physiology of fast marathons comes at a timely crossroads in athletics. The authors discuss the physiological limitations pertaining to two of the primary aerobic performance outcome factors, V̇O2max and lactate threshold. While athletes like Eliud Kipchoge and Brigid Kosgei are arguably near the limits of these physiological parameters, the athletic world has been remarkably naïve regarding technological considerations to improve running economy (RE), until very recently. Improvements in RE via footwear have been claimed by athletic companies for quite some time. In 1980, claims of 2.85% improvement in RE were demonstrated with an air cushion in the midsole of marathon shoes versus still-utilized ethylenevinyl acetate (EVA) foams (2). The minimalist footwear trend also distracted the running media, which were hypersensitized to data supporting the improvement of RE with reductions in shoe mass (1). Eventually, the ergogenic effects of cushioning outweighed the once-prevailing thoughts (5), and the search for novel lightweight foams with high rebound had begun. With new applications of polyether block amide (PEBA) foam with carbon fiber plates reported to exhibit resilience of up to 87% (3), it was only a matter of time before athletic performances caught up to the polymer science. Still, there remains a gap in the true effect of high-cushion, high-energy return marathon shoes. Studies typically measure running economy in shortduration circumstances; while these data are useful, it may underestimate the true improvements in running economy over the late stages of the marathon distance. REFERENCES 1. Frederick EC. Physiological and ergonomics factors in running shoe design. Appl Ergon 15: 281–287, 1984. doi:10.1016/0003-6870(84) 90199-6. 2. Frederick EC, Howley ET, Powers SK. Lower O2 cost while running in air-cushion type shoe. Med Sci Sports Exerc 12: 81–82, 1980. 3. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 4. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 5. Tung KD, Franz JR, Kram R. A test of the metabolic cost of cushioning hypothesis during unshod and shod running. Med Sci Sports Exerc 46: 324 –329, 2014. doi:10.1249/MSS.0b013e3182a63b81. Christopher S. Balestrini Department of Anatomy and Cell Biology, Western University, London, Ontario, Canada J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021. 1085 TECHNOLOGICAL AND STRATEGIC INFLUENCES ON RUNNING ECONOMY ACCOUNT FOR THE OUTSIZED IMPROVEMENT IN MARATHON RECORD TIMES TO THE EDITOR: Joyner et al. (3) suggest improvements in running economy (RE) as the most likely physiological mechanism behind the rapid improvement in marathon world records compared with other endurance disciplines. Interestingly, removing the recent record performances from Kipchoge and Kosgei brings the men’s and women’s marathon record improvement to 3.06% and 4.03%, respectively, since 1989 — more in line with the 5-km and 10-km record improvements. Thus, it appears that recent technological and strategic advances in two marathon-specific factors specifically affecting RE—shoes and drafting— can account for most, if not all, of the relatively larger marathon improvement. In 2017, Nike developed a shoe with a carbon-fiber plate in the midsole that enhances compliance and returns more mechanical energy with each step. Hoogkamer et al. (1) demonstrated the shoes improve RE by ~4% in the laboratory, translating to a 2–3% improvement in marathon performance time (2). Although the shoes have less of a benefit with wind resistance, much is mitigated by wind-blocking pacers running in a flying-V formation at modern marathon competitions. Running just 1 m behind another runner can reduce air resistance by up to 93%, which at a speed of 6 m/s (close to Kipchoge’s average speed of 5.78 m/s) can boost RE by up to 6% (4). These interventions together would be far above the smallest worthwhile change in RE of 2.2–2.6% (5). Consider- ing Kipchoge and Kosgei’s record times were a respective 1.06% and 1.00% improvement from the previous records, it is quite plausible the shoes and drafting made majority contributions. REFERENCES 1. Hoogkamer W, Kipp S, Frank JH, Farina EM, Luo G, Kram R. A comparison of the energetic cost of running in marathon racing shoes. Sports Med 48: 1009 –1019, 2018. [An Erratum for this article appears in Sports Med 48: 1521–1522, 2018.] doi:10.1007/s40279-017-0811-2. 2. Hoogkamer W, Kipp S, Spiering BA, Kram R. Altered running economy directly translates to altered distance-running performance. Med Sci Sports Exerc 48: 2175–2180, 2016. doi:10.1249/MSS.0000000000001012. 3. Joyner MJ, Hunter SK, Lucia A, Jones AM. Physiology and fast marathons. J Appl Physiol (1985). doi:10.1152/japplphysiol.00793.2019. 4. Pugh LGCE. The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal or vertical forces. J Physiol 213: 255–276, 1971. doi:10.1113/jphysiol.1971.sp009381. 5. Saunders PU, Pyne DB, Telford RD, Hawley JA. Reliability and variability of running economy in elite distance runners. Med Sci Sports Exerc 36: 1972–1976, 2004. doi:10.1249/01.MSS.0000145468.17329.9F. Curtis S. Goss1 Mikaela C. Gabler1 Albaro Escalera1 Shane A. Bielko1 Robert F. Chapman1 1 Human Performance Laboratory, Department of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana J Appl Physiol • doi:10.1152/japplphysiol.00167.2020 • www.jap.org Downloaded from journals.physiology.org/journal/jappl (054.234.110.166) on September 1, 2021.