Fraysse, B., C. Guillet, C. Huchet-Cadiou, D. Conte Camerino, H. Gascan, and C. Lé oty. Ciliary n... more Fraysse, B., C. Guillet, C. Huchet-Cadiou, D. Conte Camerino, H. Gascan, and C. Lé oty. Ciliary neurotrophic factor prevents unweighting-induced functional changes in rat soleus muscle. J Appl Physiol 88: [1623][1624][1625][1626][1627][1628][1629][1630] 2000.-The purpose of the present work was to see whether changes in rat soleus characteristics due to 3 wk of hindlimb suspension could be modified by ciliary neurotrophic factor (CNTF) treatment. Throughout the tail suspension period, the cytokine was delivered by means of an osmotic pump (flow rate 16 µg·kg Ϫ1 ·h Ϫ1 ) implanted under the hindlimb skin. In contrast to extensor digitorum longus, CNTF treatment was able to reduce unweighting-induced atrophy in the soleus. Twitch and 146 mM potassium (K) tensions, measured in small bundles of unloaded soleus, decreased by 48 and 40%, respectively. Moreover, the time to peak tension and the time constant of relaxation of the twitch were 48 and 54% faster, respectively, in unloaded soleus than in normal muscle. On the contrary, twitch and 146 mM K contracture generated in CNTF-treated unloaded and normal soleus were not different. CNTF receptor-␣ mRNA expression increased in extensor digitorum longus and soleus unloaded nontreated muscles but was similar in CNTF-treated unloaded muscles. The present results demonstrate that exogenously provided CNTF could prevent functional changes occurring in soleus innervated muscle subject to unweighting. ciliary neurotrophic factor receptor-␣; mammalian skeletal muscle; hindlimb unweighting
Altitude exposure and exercise elicit oxidative stress in blood; however, exercise recovery at 50... more Altitude exposure and exercise elicit oxidative stress in blood; however, exercise recovery at 5000 m attenuates oxidative stress. The purpose was to determine the altitude threshold at which blood oxidative stress is blunted during exercise recovery. Twelve males 18-28 years performed four-cycle ergometry bouts (60 min, 70% VO2max, at 975 m). In a randomised counterbalanced crossover design, participants recovered 6 h at 0, 1667, 3333 and 5000 m in a normobaric hypoxia chamber (recovery altitudes were simulated by using a computerised system in an environmental chamber by lowering the partial pressure of oxygen to match that of the respective altitude). Oxygen saturation was monitored throughout exercise recovery. Blood samples obtained pre-, post-, 1 h post- and 5 h post-exercise were assayed for ferric-reducing antioxidant plasma, Trolox equivalent antioxidant capacity, uric acid, lipid hydroperoxides and protein carbonyls. Muscle biopsies obtained pre and 6 h were analysed by real-time polymerase chain reaction to quantify expression of hemeoxgenase 1, superoxide dismutase 2 and nuclear factor (euthyroid-derived 2)-like factor. Pulse oximetry data were similar during exercise, but decreased for the three highest recovery elevations (0 m = 0%, 1667 m = -3%; 3333 m = -7%; 5000 m = -17%). A time-dependent oxidative stress occurred following exercise for all variables, but the two highest recovery altitudes partially attenuated the lipid hydroperoxide response (0 m = +135%, 1667 m = +251%, 3333 m = +99%; 5000 m = +108%). Data may indicate an altitude threshold between 1667 and 3333 m, above which the oxidative stress response is blunted during exercise recovery.
The purpose of this study was to compare glucose and insulin responses during an oral glucose tol... more The purpose of this study was to compare glucose and insulin responses during an oral glucose tolerance test (OGTT) in cold (C), neutral (N), and hot (H) environments. Eleven males completed three 4-hour climate-controlled OGTT trials (C, 7.2°C; N, 22°C; and H, 43°C). Participants remained semireclined for 60 minutes before ingesting a 1.8 g/kg glucose beverage. Skin and rectal core temperatures were continuously monitored. Blood was collected just before glucose ingestion (time 0) and at 15, 30, 60, 90, 120, and 180 minutes, and analyzed for serum glucose, insulin, hematocrit, and hemoglobin. Expired gases were collected upon entering the chamber (-60 minutes), before glucose ingestion (0 minutes), and at 60, 120, and 180 minutes to determine Vo2 and respiratory exchange ratio. Rectal core temperature was greater in the H condition compared with both C and N (P < .001). Rectal core temperature was not different between C and N, whereas skin temperature was different across all trials (H greater than N greater than C). The Vo2 was greater in C than in both H and N during all time points. Carbohydrate oxidation was greater in C compared with H and N (P < 0.001). Glucose was higher during H compared with C and N (P ≤ 0.002). Glucose was elevated in C compared with N. Insulin was higher in H compared with C (P = 0.009). Area under the curve for serum glucose was greater in H compared with C and N (P ≤ 0.001); however, there was no significant difference in area under the curve for insulin. These data indicate that after an OGTT, glucose and insulin are elevated in a hot environment.
International journal of sports physiology and performance, 2010
The purpose of this study was to determine the metabolic profile during the 2006 Ironman World Ch... more The purpose of this study was to determine the metabolic profile during the 2006 Ironman World Championship in Kailua-Kona, Hawaii. One recreational male triathlete completed the race in 10:40:16. Before the race, linear regression models were established from both laboratory and field measures to estimate energy expenditure and substrate utilization. The subject was provided with an oral dose of ²H2(18)O approximately 64 h before the race to calculate total energy expenditure (TEE) and water turnover with the doubly labeled water (DLW) technique. Body weight, blood sodium and hematocrit, and muscle glycogen (via muscle biopsy) were analyzed pre-and postrace. The TEE from DLW and indirect calorimetry was similar: 37.3 MJ (8,926 kcal) and 37.8 MJ (9,029 kcal), respectively. Total body water turnover was 16.6 L, and body weight decreased 5.9 kg. Hematocrit increased from 46 to 51% PCV. Muscle glycogen decreased from 152 to 48 mmoL/kg wet weight pre- to postrace. These data demonstrate...
This study investigated the effects of hot (H) and room temperature (RT) recovery environments on... more This study investigated the effects of hot (H) and room temperature (RT) recovery environments on glycogen resynthesis. Nine male participants completed two trials, cycling for 1 h in a temperature-controlled chamber (32.6 degrees C), followed by 4 h of recovery at 32.6 degrees C (H) or 22.2 degrees C (RT). Rectal temperature was continuously recorded. A carbohydrate beverage (1.8 g/kg bodyweight) was supplied at 0 and 2 h post-exercise. Muscle biopsies were taken immediately, 2 h, and 4 h post-exercise for glycogen analysis. Blood samples were taken at 30, 60, 120, 150, 180, and 240 min into recovery for glucose and insulin analysis. Expired gas was collected at 105 min and 225 min into recovery to calculate whole body carbohydrate oxidation. Average core temperature, whole body carbohydrate oxidation, and serum glucose at 120, 150, 180 and 240 min was higher in H compared to RT (p<0.05). Muscle glycogen was higher in RT vs. H at 4 h (105+/-28 vs. 88+/-24 mmolxkg (-1) wet weight...
The purpose of this study was to determine the effects of a recovery beverage immediately after e... more The purpose of this study was to determine the effects of a recovery beverage immediately after exercise on rates of muscle glycogen resynthesis in response to road cycling when nutritional supplementation was supplied during exercise and a solid meal was served two hours after exercise. Eight trained male cyclists, (25+/-4 years, 69.3+/-5.2 kg, VO2 peak=4.5+/-0.4 L.min(-1)) performed two 62 km outdoor training rides in a double-blind, randomized cross-over experiment. Subjects received a food bar and a commercial sport drink during each ride. A recovery beverage (40 g CHO+20 g PRO) or a placebo (PL) was administered 30 min post-exercise. At 2 h post-exercise, a solid meal was provided for both trials. There was no difference between trials at any time point for glycogen (140+/-9, 56+/-8, and 70+/-8 mmol.kg(-1)wet wt.(-1).hr.(-1) for pre, post, and 4 h post, respectively). The addition of a supplemental recovery beverage ingested soon after exercise did not significantly increase th...
Journal of applied physiology (Bethesda, Md. : 1985), 2006
The purpose of this study was to investigate mRNA expression of several key skeletal muscle myoge... more The purpose of this study was to investigate mRNA expression of several key skeletal muscle myogenic controllers; myogenic differentiation factor (MyoD), muscle regulatory factor 4 (MRF4), myogenic factor 5 (Myf5), myogenin, myostatin, and myocyte enhancer factor 2 (MEF2) at rest and 4 h after a single bout of resistance exercise (RE) in young and old women. Eight young women (YW; 23 +/- 2 yr, 67 +/- 5 kg) and six old women (OW; 85 +/- 1 yr, 67 +/- 4 kg) performed 3 sets of 10 repetitions of bilateral knee extensions at 70% of one repetition maximum. Muscle biopsies were taken from the vastus lateralis before and 4 h after RE. Using real-time RT PCR, mRNA from the muscle samples was amplified and normalized to GAPDH. At rest, OW expressed higher (P < 0.05) levels of MyoD, MRF4, Myf5, myogenin, and myostatin compared with YW. In response to RE, there was a main time effect (P < 0.05) for the YW and OW combined in the upregulation of MyoD (2.0-fold) and MRF4 (1.4-fold) and in th...
International Journal of Sport Nutrition and Exercise Metabolism, 2014
Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude ind... more Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude independently elicit redox perturbations, the study purpose was to examine hypoxic and normoxic steady-state exercise on blood oxidative stress. Active males (n = 11) completed graded cycle ergometry in normoxic (975 m) and hypoxic (3,000 m) simulated environments before programing subsequent matched intensity or workload steady-state trials. In a randomized counterbalanced crossover design, participants completed three 60-min exercise bouts to investigate the effects of hypoxia and exercise intensity on blood oxidative stress. Exercise conditions were paired as such; 60% normoxic VO(2)peak performed in a normoxic environment (normoxic intensity-normoxic environment, NI-NE), 60% hypoxic VO(2)peak performed in a normoxic environment (HI-NE), and 60% hypoxic VO(2)peak performed in a hypoxic environment (HI-HE). Blood plasma samples drawn pre (Pre), 0 (Post), 2 (2HR) and 4 (4HR) hr post exercise were analyzed for oxidative stress biomarkers including ferric reducing ability of plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), lipid hydroperoxides (LOOH) and protein carbonyls (PCs). Repeated-measures ANOVA were performed, a priori significance of p ≤ .05. Oxygen saturation during the HI-HE trial was lower than NI-NE and HI-NE (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). A Time × Trial interaction was present for LOOH (p = .013). In the HI-HE trial, LOOH were elevated for all time points post while PC (time; p = .001) decreased post exercise. As evidenced by the decrease in absolute workload during hypoxic VO(2)peak and LOOH increased during HI-HE versus normoxic exercise of equal absolute (HI-NE) and relative (NI-NE) intensities. Results suggest acute hypoxia elicits work decrements associated with post exercise oxidative stress.
Background. Skeletal muscle atrophy in rodents is associated with increased gene expression of pr... more Background. Skeletal muscle atrophy in rodents is associated with increased gene expression of proteolytic markers muscle-RING-finger protein 1 (MuRF-1) and atrogin-1. In humans with age-related muscle atrophy, known as sarcopenia, little is known about these key proteolytic biomarkers. Therefore, the purpose of this investigation was 2-fold: (i) measure messenger RNA (mRNA) expression of proteolytic genes MuRF-1, atrogin-1, forkhead box (FOXO)3A,
Objective.-The purpose of this project was to determine the effects of wildfire suppression on mu... more Objective.-The purpose of this project was to determine the effects of wildfire suppression on muscle glycogen utilization in wildland firefighters (WLFFs).
Objective.-The purpose of this study was to compare the effects of a water ϩ electrolyte solution... more Objective.-The purpose of this study was to compare the effects of a water ϩ electrolyte solution versus plain water on changes in drinking behaviors, hydration status, and body temperatures during wildfire suppression.
PURPOSE: The purpose of this study was to compare total energy expenditure (TEE) via the doubly l... more PURPOSE: The purpose of this study was to compare total energy expenditure (TEE) via the doubly labeled water (DLW) method to developed regression equations, determine muscle glycogen use, and hydration changes during the Ironman World Championship triathlon. ...
The aim of the present investigation was to examine the response of 80 plasma inflammatory analyt... more The aim of the present investigation was to examine the response of 80 plasma inflammatory analytes during five days of exercise in a hot (38 1C, 40% relative humidity) environment. 15 male participants (25 7 4yrs, 54 76 ml kg À 1 min À 1 VO 2 max), with no heat exposure within the previous 3 weeks, were asked to cycle in a hot environment at 70% of their VO 2 max workload until their terminal temperature was obtained, for 5 consecutive days. Terminal temperature was determined as the core temperature at volitional exhaustion or a core temperature of 39.5 1C, whichever came first. Blood samples were collected pre-and post-exercise on day 1 and day 5. Pre-trial urine specific gravity and body weight was not different on day 1 and day 5. Exercise time and heart rate at terminal temperature did not change during the five days. Of the 52 plasma analytes that increased in concentration on day 1, only 30 demonstrated increased concentrations at terminal temperature on day 5. Resting concentrations of 18, both pro-(IL-12p40, IL-15) and anti-inflammatory (IL-1ra, IL-10, IL-13) analytes were elevated on day 5 compared to day 1. We conclude that individuals completing consecutive days of exercise in the heat, but not definitively attaining heat acclimation, have increased resting levels of many inflammatory analytes associated with heat illness, but also demonstrate a reduced inflammatory response to a subsequent bout of exercise in the heat.
Fraysse, B., C. Guillet, C. Huchet-Cadiou, D. Conte Camerino, H. Gascan, and C. Lé oty. Ciliary n... more Fraysse, B., C. Guillet, C. Huchet-Cadiou, D. Conte Camerino, H. Gascan, and C. Lé oty. Ciliary neurotrophic factor prevents unweighting-induced functional changes in rat soleus muscle. J Appl Physiol 88: [1623][1624][1625][1626][1627][1628][1629][1630] 2000.-The purpose of the present work was to see whether changes in rat soleus characteristics due to 3 wk of hindlimb suspension could be modified by ciliary neurotrophic factor (CNTF) treatment. Throughout the tail suspension period, the cytokine was delivered by means of an osmotic pump (flow rate 16 µg·kg Ϫ1 ·h Ϫ1 ) implanted under the hindlimb skin. In contrast to extensor digitorum longus, CNTF treatment was able to reduce unweighting-induced atrophy in the soleus. Twitch and 146 mM potassium (K) tensions, measured in small bundles of unloaded soleus, decreased by 48 and 40%, respectively. Moreover, the time to peak tension and the time constant of relaxation of the twitch were 48 and 54% faster, respectively, in unloaded soleus than in normal muscle. On the contrary, twitch and 146 mM K contracture generated in CNTF-treated unloaded and normal soleus were not different. CNTF receptor-␣ mRNA expression increased in extensor digitorum longus and soleus unloaded nontreated muscles but was similar in CNTF-treated unloaded muscles. The present results demonstrate that exogenously provided CNTF could prevent functional changes occurring in soleus innervated muscle subject to unweighting. ciliary neurotrophic factor receptor-␣; mammalian skeletal muscle; hindlimb unweighting
Altitude exposure and exercise elicit oxidative stress in blood; however, exercise recovery at 50... more Altitude exposure and exercise elicit oxidative stress in blood; however, exercise recovery at 5000 m attenuates oxidative stress. The purpose was to determine the altitude threshold at which blood oxidative stress is blunted during exercise recovery. Twelve males 18-28 years performed four-cycle ergometry bouts (60 min, 70% VO2max, at 975 m). In a randomised counterbalanced crossover design, participants recovered 6 h at 0, 1667, 3333 and 5000 m in a normobaric hypoxia chamber (recovery altitudes were simulated by using a computerised system in an environmental chamber by lowering the partial pressure of oxygen to match that of the respective altitude). Oxygen saturation was monitored throughout exercise recovery. Blood samples obtained pre-, post-, 1 h post- and 5 h post-exercise were assayed for ferric-reducing antioxidant plasma, Trolox equivalent antioxidant capacity, uric acid, lipid hydroperoxides and protein carbonyls. Muscle biopsies obtained pre and 6 h were analysed by real-time polymerase chain reaction to quantify expression of hemeoxgenase 1, superoxide dismutase 2 and nuclear factor (euthyroid-derived 2)-like factor. Pulse oximetry data were similar during exercise, but decreased for the three highest recovery elevations (0 m = 0%, 1667 m = -3%; 3333 m = -7%; 5000 m = -17%). A time-dependent oxidative stress occurred following exercise for all variables, but the two highest recovery altitudes partially attenuated the lipid hydroperoxide response (0 m = +135%, 1667 m = +251%, 3333 m = +99%; 5000 m = +108%). Data may indicate an altitude threshold between 1667 and 3333 m, above which the oxidative stress response is blunted during exercise recovery.
The purpose of this study was to compare glucose and insulin responses during an oral glucose tol... more The purpose of this study was to compare glucose and insulin responses during an oral glucose tolerance test (OGTT) in cold (C), neutral (N), and hot (H) environments. Eleven males completed three 4-hour climate-controlled OGTT trials (C, 7.2°C; N, 22°C; and H, 43°C). Participants remained semireclined for 60 minutes before ingesting a 1.8 g/kg glucose beverage. Skin and rectal core temperatures were continuously monitored. Blood was collected just before glucose ingestion (time 0) and at 15, 30, 60, 90, 120, and 180 minutes, and analyzed for serum glucose, insulin, hematocrit, and hemoglobin. Expired gases were collected upon entering the chamber (-60 minutes), before glucose ingestion (0 minutes), and at 60, 120, and 180 minutes to determine Vo2 and respiratory exchange ratio. Rectal core temperature was greater in the H condition compared with both C and N (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001). Rectal core temperature was not different between C and N, whereas skin temperature was different across all trials (H greater than N greater than C). The Vo2 was greater in C than in both H and N during all time points. Carbohydrate oxidation was greater in C compared with H and N (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Glucose was higher during H compared with C and N (P ≤ 0.002). Glucose was elevated in C compared with N. Insulin was higher in H compared with C (P = 0.009). Area under the curve for serum glucose was greater in H compared with C and N (P ≤ 0.001); however, there was no significant difference in area under the curve for insulin. These data indicate that after an OGTT, glucose and insulin are elevated in a hot environment.
International journal of sports physiology and performance, 2010
The purpose of this study was to determine the metabolic profile during the 2006 Ironman World Ch... more The purpose of this study was to determine the metabolic profile during the 2006 Ironman World Championship in Kailua-Kona, Hawaii. One recreational male triathlete completed the race in 10:40:16. Before the race, linear regression models were established from both laboratory and field measures to estimate energy expenditure and substrate utilization. The subject was provided with an oral dose of ²H2(18)O approximately 64 h before the race to calculate total energy expenditure (TEE) and water turnover with the doubly labeled water (DLW) technique. Body weight, blood sodium and hematocrit, and muscle glycogen (via muscle biopsy) were analyzed pre-and postrace. The TEE from DLW and indirect calorimetry was similar: 37.3 MJ (8,926 kcal) and 37.8 MJ (9,029 kcal), respectively. Total body water turnover was 16.6 L, and body weight decreased 5.9 kg. Hematocrit increased from 46 to 51% PCV. Muscle glycogen decreased from 152 to 48 mmoL/kg wet weight pre- to postrace. These data demonstrate...
This study investigated the effects of hot (H) and room temperature (RT) recovery environments on... more This study investigated the effects of hot (H) and room temperature (RT) recovery environments on glycogen resynthesis. Nine male participants completed two trials, cycling for 1 h in a temperature-controlled chamber (32.6 degrees C), followed by 4 h of recovery at 32.6 degrees C (H) or 22.2 degrees C (RT). Rectal temperature was continuously recorded. A carbohydrate beverage (1.8 g/kg bodyweight) was supplied at 0 and 2 h post-exercise. Muscle biopsies were taken immediately, 2 h, and 4 h post-exercise for glycogen analysis. Blood samples were taken at 30, 60, 120, 150, 180, and 240 min into recovery for glucose and insulin analysis. Expired gas was collected at 105 min and 225 min into recovery to calculate whole body carbohydrate oxidation. Average core temperature, whole body carbohydrate oxidation, and serum glucose at 120, 150, 180 and 240 min was higher in H compared to RT (p<0.05). Muscle glycogen was higher in RT vs. H at 4 h (105+/-28 vs. 88+/-24 mmolxkg (-1) wet weight...
The purpose of this study was to determine the effects of a recovery beverage immediately after e... more The purpose of this study was to determine the effects of a recovery beverage immediately after exercise on rates of muscle glycogen resynthesis in response to road cycling when nutritional supplementation was supplied during exercise and a solid meal was served two hours after exercise. Eight trained male cyclists, (25+/-4 years, 69.3+/-5.2 kg, VO2 peak=4.5+/-0.4 L.min(-1)) performed two 62 km outdoor training rides in a double-blind, randomized cross-over experiment. Subjects received a food bar and a commercial sport drink during each ride. A recovery beverage (40 g CHO+20 g PRO) or a placebo (PL) was administered 30 min post-exercise. At 2 h post-exercise, a solid meal was provided for both trials. There was no difference between trials at any time point for glycogen (140+/-9, 56+/-8, and 70+/-8 mmol.kg(-1)wet wt.(-1).hr.(-1) for pre, post, and 4 h post, respectively). The addition of a supplemental recovery beverage ingested soon after exercise did not significantly increase th...
Journal of applied physiology (Bethesda, Md. : 1985), 2006
The purpose of this study was to investigate mRNA expression of several key skeletal muscle myoge... more The purpose of this study was to investigate mRNA expression of several key skeletal muscle myogenic controllers; myogenic differentiation factor (MyoD), muscle regulatory factor 4 (MRF4), myogenic factor 5 (Myf5), myogenin, myostatin, and myocyte enhancer factor 2 (MEF2) at rest and 4 h after a single bout of resistance exercise (RE) in young and old women. Eight young women (YW; 23 +/- 2 yr, 67 +/- 5 kg) and six old women (OW; 85 +/- 1 yr, 67 +/- 4 kg) performed 3 sets of 10 repetitions of bilateral knee extensions at 70% of one repetition maximum. Muscle biopsies were taken from the vastus lateralis before and 4 h after RE. Using real-time RT PCR, mRNA from the muscle samples was amplified and normalized to GAPDH. At rest, OW expressed higher (P < 0.05) levels of MyoD, MRF4, Myf5, myogenin, and myostatin compared with YW. In response to RE, there was a main time effect (P < 0.05) for the YW and OW combined in the upregulation of MyoD (2.0-fold) and MRF4 (1.4-fold) and in th...
International Journal of Sport Nutrition and Exercise Metabolism, 2014
Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude ind... more Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude independently elicit redox perturbations, the study purpose was to examine hypoxic and normoxic steady-state exercise on blood oxidative stress. Active males (n = 11) completed graded cycle ergometry in normoxic (975 m) and hypoxic (3,000 m) simulated environments before programing subsequent matched intensity or workload steady-state trials. In a randomized counterbalanced crossover design, participants completed three 60-min exercise bouts to investigate the effects of hypoxia and exercise intensity on blood oxidative stress. Exercise conditions were paired as such; 60% normoxic VO(2)peak performed in a normoxic environment (normoxic intensity-normoxic environment, NI-NE), 60% hypoxic VO(2)peak performed in a normoxic environment (HI-NE), and 60% hypoxic VO(2)peak performed in a hypoxic environment (HI-HE). Blood plasma samples drawn pre (Pre), 0 (Post), 2 (2HR) and 4 (4HR) hr post exercise were analyzed for oxidative stress biomarkers including ferric reducing ability of plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), lipid hydroperoxides (LOOH) and protein carbonyls (PCs). Repeated-measures ANOVA were performed, a priori significance of p ≤ .05. Oxygen saturation during the HI-HE trial was lower than NI-NE and HI-NE (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). A Time × Trial interaction was present for LOOH (p = .013). In the HI-HE trial, LOOH were elevated for all time points post while PC (time; p = .001) decreased post exercise. As evidenced by the decrease in absolute workload during hypoxic VO(2)peak and LOOH increased during HI-HE versus normoxic exercise of equal absolute (HI-NE) and relative (NI-NE) intensities. Results suggest acute hypoxia elicits work decrements associated with post exercise oxidative stress.
Background. Skeletal muscle atrophy in rodents is associated with increased gene expression of pr... more Background. Skeletal muscle atrophy in rodents is associated with increased gene expression of proteolytic markers muscle-RING-finger protein 1 (MuRF-1) and atrogin-1. In humans with age-related muscle atrophy, known as sarcopenia, little is known about these key proteolytic biomarkers. Therefore, the purpose of this investigation was 2-fold: (i) measure messenger RNA (mRNA) expression of proteolytic genes MuRF-1, atrogin-1, forkhead box (FOXO)3A,
Objective.-The purpose of this project was to determine the effects of wildfire suppression on mu... more Objective.-The purpose of this project was to determine the effects of wildfire suppression on muscle glycogen utilization in wildland firefighters (WLFFs).
Objective.-The purpose of this study was to compare the effects of a water ϩ electrolyte solution... more Objective.-The purpose of this study was to compare the effects of a water ϩ electrolyte solution versus plain water on changes in drinking behaviors, hydration status, and body temperatures during wildfire suppression.
PURPOSE: The purpose of this study was to compare total energy expenditure (TEE) via the doubly l... more PURPOSE: The purpose of this study was to compare total energy expenditure (TEE) via the doubly labeled water (DLW) method to developed regression equations, determine muscle glycogen use, and hydration changes during the Ironman World Championship triathlon. ...
The aim of the present investigation was to examine the response of 80 plasma inflammatory analyt... more The aim of the present investigation was to examine the response of 80 plasma inflammatory analytes during five days of exercise in a hot (38 1C, 40% relative humidity) environment. 15 male participants (25 7 4yrs, 54 76 ml kg À 1 min À 1 VO 2 max), with no heat exposure within the previous 3 weeks, were asked to cycle in a hot environment at 70% of their VO 2 max workload until their terminal temperature was obtained, for 5 consecutive days. Terminal temperature was determined as the core temperature at volitional exhaustion or a core temperature of 39.5 1C, whichever came first. Blood samples were collected pre-and post-exercise on day 1 and day 5. Pre-trial urine specific gravity and body weight was not different on day 1 and day 5. Exercise time and heart rate at terminal temperature did not change during the five days. Of the 52 plasma analytes that increased in concentration on day 1, only 30 demonstrated increased concentrations at terminal temperature on day 5. Resting concentrations of 18, both pro-(IL-12p40, IL-15) and anti-inflammatory (IL-1ra, IL-10, IL-13) analytes were elevated on day 5 compared to day 1. We conclude that individuals completing consecutive days of exercise in the heat, but not definitively attaining heat acclimation, have increased resting levels of many inflammatory analytes associated with heat illness, but also demonstrate a reduced inflammatory response to a subsequent bout of exercise in the heat.
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Papers by Dustin Slivka