Kinesiology: international journal of fundamental and applied kinesiology, Jun 30, 2013
The purpose of this study was to investigate the effects of 30-second all-out sprint interval exe... more The purpose of this study was to investigate the effects of 30-second all-out sprint interval exercise (SIE) vs. moderate aerobic exercise (MA) on excess post-exercise oxygen consumption (EPOC). Six recreationallytrained males (age=23.3±1.4 yrs, weight=81.8±9.9 kg, height=180.8±6.3 cm) completed a sprint interval exercise session consisting of three repeated 30-second Wingate cycling tests separated by four minutes (duration ~11minutes) as well as a moderate aerobic exercise session consisting of 30-minute cycling at 60% heart rate reserve (HRR) in a random counterbalanced design. Baseline oxygen consumption (VO 2) was determined by an average VO 2 from the final five minutes of a 30-minute supine rest period prior to each trial. Following each protocol, VO 2 was measured for 30 minutes or until baseline measures were reached. EPOC was determined by subtracting baseline VO 2 from post-exercise VO 2 measurements. Energy expenditure (kJ) was determined by multiplying kJ per liter of oxygen by the average VO 2 during recovery. EPOC values were significantly higher in SIE (7.5±1.3 L) than MA (1.8±0.7 L). SIE produced a higher recovery caloric expenditure (156.9 kJ) compared to MA (41.0 kJ) and remained significantly elevated (p=.024) over resting levels during the entire recovery period (30 minutes) compared to MA (6 minutes, p=.003). The energy required to recover from three repeated maximal effort 30-second Wingate cycling tests was greater than 30 minutes of moderate aerobic exercise. Future studies should examine the chronic effects of maximal effort sprint training protocol on cardiovascular fitness and body composition.
Secreted protein acidic and rich in cysteine (SPARC) and musclin are myokines implicated in gluco... more Secreted protein acidic and rich in cysteine (SPARC) and musclin are myokines implicated in glucose uptake signaling. SPARC has been shown to increase expression of GLUT4 on myocytes, while musclin...
Medicine and Science in Sports and Exercise, May 1, 2014
• To examine the changes in performance, ultrasonography and biochemical markers of inflammation ... more • To examine the changes in performance, ultrasonography and biochemical markers of inflammation in response to a muscle damaging, lower-body workout in resistance trained individuals • To examine the effects of two different recovery modalities, NMES and CWI, on measures of performance, ultrasonography, and biochemical markers of inflammation following muscle damage in resistance trained individuals.
Medicine and Science in Sports and Exercise, May 1, 2017
David D. Church, Jay R. Hoffman, FACSM, Gerald T. Mangine, Adam R. Jajtner, Jeremy R. Townsend, A... more David D. Church, Jay R. Hoffman, FACSM, Gerald T. Mangine, Adam R. Jajtner, Jeremy R. Townsend, Adam M. Gonzalez, Kyle S. Beyer, Ran Wang, Carleigh H. Boone, Michael B. La Monica, Amelia A. Miramonti, Adam, J. Wells, David H. Fukuda, Jeffrey R. Stout, FACSM. University of Central Florida, Orlando, FL. Kennesaw State University, Kennesaw, GA. Kent State University, Kent, OH. Lipscomb University, Nashville, TN. Hofstra University, Hempstead, NY. University of Nebraska, Lincoln, NE. (Sponsor: Jay R. Hoffman, FACSM)
Medicine and Science in Sports and Exercise, May 1, 2015
CONCLUSIONS: Regulation of the GCr may be related to functional characteristics of the different ... more CONCLUSIONS: Regulation of the GCr may be related to functional characteristics of the different circulating leukocyte subtypes. The acute reduction in GCr expression in circulating basophils in response to a brief bout of exercise was observed after only 8 weeks of training. The training was successful as evidenced by a measurable increase in peak VO2. Perhaps repeated bouts of exercise led to a reduced leukocyte stress response manifest by reduced GCr on key leukocyte subtypes. The dampened immune response to stress might explain the growing number of studies demonstrating that exercise training improves asthma control.
Medicine and Science in Sports and Exercise, May 1, 2014
Resistance exercise induces strength gains prior to muscle hypertrophy. The mechanism for this ea... more Resistance exercise induces strength gains prior to muscle hypertrophy. The mechanism for this early strength gain is not well understood. Multiple studies regarding animal models have reported increased muscle fiber number and altered muscle fiber size following voluntary resistance exercise. These investigations lacked direct performance measurements and analyzed muscles only after the onset of muscle hypertrophy. Consequently, whether these morphological changes contribute to early strength gains is unknown. Our group developed a voluntary weight-lifting model for rats which measures performance and induces increased muscle mass after two months of training. PURPOSE: To characterize muscle morphology and performance after one month of volitional training -a time period with the potential to precede muscle hypertrophy. METHODS: Rats (8 per group) were exposed to squat-type lifts of a weighted (70g or 700g) ring 5 days per week. Sections of soleus (SOL), medial gastrocnemius (MG), lateral gastrocnemius (LG), plantaris (PL), and tibialis anterior (TA) muscles were analyzed by stereology. Two-way ANOVA was used for statistical analysis; significance was set at p < 0.05. RESULTS: Despite the absence of muscle hypertrophy, 700g load training induced significant effects compared with cage control conditions. Fiber number per unit area increased by 16% for SOL muscles (212 ± 7 vs. 183 ± 9 fibers/mm 2 , p = 0.03) and 23% for TA muscles (349 ± 11 vs. 283 ± 19 fibers/mm 2 , p = 0.01). Fiber number per section, evaluated for SOL muscles, increased by 18% (2749 ± 42 vs. 2324 ± 121 fibers/section, p < 0.05). These results were accompanied by decreases in muscle fiber area of 15% for SOL muscles (4449 ± 127 vs. 5234 ± 277 µm 2 , p = 0.03) and 21% for TA muscles (2787 ± 91 vs. 3510 ± 219 µm 2 , p = 0.01) -a finding consistent with muscle fiber splitting. No chronic degeneration/regeneration was observed excluding such phenomenon as a requirement for the morphologic changes. Peak lifting forces increased by 21% (12.4 ± 0.2 vs. 10.3 ± 0.5 N, p = 0.01) -possibly an outcome of adaptive remodeling at the neural, capillary, or connective tissue level during fiber splitting. CONCLUSION: These findings indicate that modulation of muscle fiber number should be considered as a potential mechanism for early exercise-induced strength gains.
The purpose of this study was to investigate the effects of30-second all-out sprint interval exer... more The purpose of this study was to investigate the effects of30-second all-out sprint interval exercise (SIE) vs. moderate aerobic exercise (MA) on excess post-exercise oxygen consumption (EPOC). Six recreationallytrained males (age=23 .3±1.4 yrs, weight=81.8±9.9 kg, height=180.8±6.3 cm) completed a sprint interval exercise session consisting of three repeated 30-second Wingate cycling tests separated by four minutes (duration-llminutes) as well as a moderate aerobic exercise session consisting of30-minute cycling at 60% heart rate reserve (HRR) in a random counterbalanced design. Baseline oxygen consumption (V0 2) was determined by an average V0 2 from the final five minutes of a 30-minute supine rest period prior to each trial. Following each protocol, V0 2 was measured for 30 minutes or until baseline measures were reached. EPOC was determined by subtracting baseline V0 2 from post-exercise V0 2 measurements. Energy expenditure (kJ) was determined by multiplying kJ per liter of oxygen by the average V0 2 during recovery. EPOC values were significantly higher in SIE (7.5±1.3 L) than MA (1.8±0.7 L). SIE produced a higher recovery caloric expenditure (156.9 kJ) compared to MA (41.0 kJ) and remained significantly elevated (p=.024) over resting levels during the entire recovery period (30 minutes) compared to MA (6 minutes, p=.003). The energy required to recover from three repeated maximal effort 30-second Wingate cycling tests was greater than 30 minutes of moderate aerobic exercise. Future studies should examine the chronic effects of maximal effort sprint training protocol on cardiovascular fitness and body composition.
Journal of Strength and Conditioning Research, 2017
Mangine, GT, Hoffman, JR, Gonzalez, AM, Townsend, JR, Wells, AJ, Jajtner, AR, Beyer, KS, Boone, C... more Mangine, GT, Hoffman, JR, Gonzalez, AM, Townsend, JR, Wells, AJ, Jajtner, AR, Beyer, KS, Boone, CH, Wang, R, Miramonti, AA, LaMonica, MB, Fukuda, DH, Witta, EL, Ratamess, NA, and Stout, JR. Exercise-induced hormone elevations are related to muscle growth. J Strength Cond Res 31(1): 45–53, 2017—Partial least squares regression structural equation modeling (PLS-SEM) was used to examine relationships between the endocrine response to resistance exercise and muscle hypertrophy in resistance-trained men. Pretesting (PRE) measures of muscle size (thickness and cross-sectional area) of the vastus lateralis and rectus femoris were collected in 26 resistance-trained men. Participants were randomly selected to complete a high-volume (VOL, n = 13, 10–12RM, 1-minute rest) or high-intensity (INT, n = 13, 3–5RM, 3-minute rest) resistance training program. Blood samples were collected at baseline, immediately postexercise, 30-minute, and 60-minute postexercise during weeks 1 (week 1) and 8 (week 8) of training. The hormonal responses (testosterone, growth hormone [22 kD], insulin-like growth factor-1, cortisol, and insulin) to each training session were evaluated using area-under-the-curve (AUC) analyses. Relationships between muscle size (PRE), AUC values (week 1 + week 8) for each hormone, and muscle size (POST) were assessed using a consistent PLS-SEM algorithm and tested for statistical significance (p ≤ 0.05) using a 1,000 samples consistent bootstrapping analysis. Group-wise comparisons for each relationship were assessed through independent t-tests. The model explained 73.4% (p &lt; 0.001) of variance in muscle size at POST. Significant pathways between testosterone and muscle size at PRE (p = 0.043) and muscle size at POST (p = 0.032) were observed. The ability to explain muscle size at POST improved when the model was analyzed by group (INT: R 2 = 0.882; VOL: R 2 = 0.987; p &lt; 0.001). No group differences in modal quality were found. Exercise-induced testosterone elevations, independent of the training programs used in this study, seem to be related to muscle growth.
Purpose This study evaluated the contributions of somatic maturity (years from estimated peak hei... more Purpose This study evaluated the contributions of somatic maturity (years from estimated peak height velocity) and training experience as developmental indicators of muscle morphology, biomechanical parameters, and bilateral asymmetries in youth judo athletes. Methods Twenty-six judo athletes aged 8-18 years (mean ± SD; age = 12.9 ± 2.6 years, maturity offset = -0.6 ± 2.2 years, training experience = 6.1 ± 2.9 years) completed anthropometric measurements, performance testing, and ultrasound evaluation of the vastus lateralis. Results Somatic maturity had the greatest relationship with handgrip performance (r 2 = 0.76-0.80; p < 0.01) and lower-body plyometric ability (r 2 = 0.23-0.72; p < 0.05). Somatic maturity and training experience accounted for 72% of the variance in hopping power. Bilateral asymmetries in average/peak force and 1-/2-s force-time integration during isometric handgrip increased with training experience (r 2 = 0.17-0.46 p < 0.05). Muscle morphology (r 2 = 0.29-0.75; p < 0.01) was best related to somatic maturity. Significant differences were found between child and adolescent judo athletes in force-time curve parameters, muscle morphology, and plyometric ability. Conclusions These results indicate that somatic maturity and training experience exert unique influences on muscle morphology, biomechanical parameters, and bilateral asymmetries in youth judo athletes.
Journal of Strength and Conditioning Research, May 1, 2016
Short-term unilateral resistance training results in cross education of strength without changes ... more Short-term unilateral resistance training results in cross education of strength without changes in muscle size, activation, or endocrine response. J Strength Cond Res 30(5): 1213-1223, 2016-The purpose of this study was to assess the cross education of strength and changes in the underlying mechanisms (muscle size, activation, and hormonal response) after a 4-week unilateral resistance training (URT) program. A group of 9 untrained men completed a 4-week URT program on the dominant leg (DOM), whereas cross education was measured in the nondominant leg (NON); and were compared with a control group (n = 8, CON). Unilateral isometric force (PKF), leg press (LP) and leg extension (LE) strength, muscle size (by ultrasonography) and activation (by electromyography) of the rectus femoris and vastus lateralis, and the hormonal response (testosterone, growth hormone, insulin, and insulinlike growth factor-1) were tested pretraining and posttraining. Group 3 time interactions were present for PKF, LP, LE, and muscle size in DOM and for LP in NON. In all interactions, the URT group improved significantly better than CON. There was a significant acute hormonal response to URT, but no chronic adaptation after the 4-week training program. Four weeks of URT resulted in an increase in strength and size of the trained musculature, and cross education of strength in the untrained musculature, which may occur without detectable changes in muscle size, activation, or the acute hormonal response.
Kinesiology: international journal of fundamental and applied kinesiology, Jun 30, 2013
The purpose of this study was to investigate the effects of 30-second all-out sprint interval exe... more The purpose of this study was to investigate the effects of 30-second all-out sprint interval exercise (SIE) vs. moderate aerobic exercise (MA) on excess post-exercise oxygen consumption (EPOC). Six recreationallytrained males (age=23.3±1.4 yrs, weight=81.8±9.9 kg, height=180.8±6.3 cm) completed a sprint interval exercise session consisting of three repeated 30-second Wingate cycling tests separated by four minutes (duration ~11minutes) as well as a moderate aerobic exercise session consisting of 30-minute cycling at 60% heart rate reserve (HRR) in a random counterbalanced design. Baseline oxygen consumption (VO 2) was determined by an average VO 2 from the final five minutes of a 30-minute supine rest period prior to each trial. Following each protocol, VO 2 was measured for 30 minutes or until baseline measures were reached. EPOC was determined by subtracting baseline VO 2 from post-exercise VO 2 measurements. Energy expenditure (kJ) was determined by multiplying kJ per liter of oxygen by the average VO 2 during recovery. EPOC values were significantly higher in SIE (7.5±1.3 L) than MA (1.8±0.7 L). SIE produced a higher recovery caloric expenditure (156.9 kJ) compared to MA (41.0 kJ) and remained significantly elevated (p=.024) over resting levels during the entire recovery period (30 minutes) compared to MA (6 minutes, p=.003). The energy required to recover from three repeated maximal effort 30-second Wingate cycling tests was greater than 30 minutes of moderate aerobic exercise. Future studies should examine the chronic effects of maximal effort sprint training protocol on cardiovascular fitness and body composition.
Secreted protein acidic and rich in cysteine (SPARC) and musclin are myokines implicated in gluco... more Secreted protein acidic and rich in cysteine (SPARC) and musclin are myokines implicated in glucose uptake signaling. SPARC has been shown to increase expression of GLUT4 on myocytes, while musclin...
Medicine and Science in Sports and Exercise, May 1, 2014
• To examine the changes in performance, ultrasonography and biochemical markers of inflammation ... more • To examine the changes in performance, ultrasonography and biochemical markers of inflammation in response to a muscle damaging, lower-body workout in resistance trained individuals • To examine the effects of two different recovery modalities, NMES and CWI, on measures of performance, ultrasonography, and biochemical markers of inflammation following muscle damage in resistance trained individuals.
Medicine and Science in Sports and Exercise, May 1, 2017
David D. Church, Jay R. Hoffman, FACSM, Gerald T. Mangine, Adam R. Jajtner, Jeremy R. Townsend, A... more David D. Church, Jay R. Hoffman, FACSM, Gerald T. Mangine, Adam R. Jajtner, Jeremy R. Townsend, Adam M. Gonzalez, Kyle S. Beyer, Ran Wang, Carleigh H. Boone, Michael B. La Monica, Amelia A. Miramonti, Adam, J. Wells, David H. Fukuda, Jeffrey R. Stout, FACSM. University of Central Florida, Orlando, FL. Kennesaw State University, Kennesaw, GA. Kent State University, Kent, OH. Lipscomb University, Nashville, TN. Hofstra University, Hempstead, NY. University of Nebraska, Lincoln, NE. (Sponsor: Jay R. Hoffman, FACSM)
Medicine and Science in Sports and Exercise, May 1, 2015
CONCLUSIONS: Regulation of the GCr may be related to functional characteristics of the different ... more CONCLUSIONS: Regulation of the GCr may be related to functional characteristics of the different circulating leukocyte subtypes. The acute reduction in GCr expression in circulating basophils in response to a brief bout of exercise was observed after only 8 weeks of training. The training was successful as evidenced by a measurable increase in peak VO2. Perhaps repeated bouts of exercise led to a reduced leukocyte stress response manifest by reduced GCr on key leukocyte subtypes. The dampened immune response to stress might explain the growing number of studies demonstrating that exercise training improves asthma control.
Medicine and Science in Sports and Exercise, May 1, 2014
Resistance exercise induces strength gains prior to muscle hypertrophy. The mechanism for this ea... more Resistance exercise induces strength gains prior to muscle hypertrophy. The mechanism for this early strength gain is not well understood. Multiple studies regarding animal models have reported increased muscle fiber number and altered muscle fiber size following voluntary resistance exercise. These investigations lacked direct performance measurements and analyzed muscles only after the onset of muscle hypertrophy. Consequently, whether these morphological changes contribute to early strength gains is unknown. Our group developed a voluntary weight-lifting model for rats which measures performance and induces increased muscle mass after two months of training. PURPOSE: To characterize muscle morphology and performance after one month of volitional training -a time period with the potential to precede muscle hypertrophy. METHODS: Rats (8 per group) were exposed to squat-type lifts of a weighted (70g or 700g) ring 5 days per week. Sections of soleus (SOL), medial gastrocnemius (MG), lateral gastrocnemius (LG), plantaris (PL), and tibialis anterior (TA) muscles were analyzed by stereology. Two-way ANOVA was used for statistical analysis; significance was set at p < 0.05. RESULTS: Despite the absence of muscle hypertrophy, 700g load training induced significant effects compared with cage control conditions. Fiber number per unit area increased by 16% for SOL muscles (212 ± 7 vs. 183 ± 9 fibers/mm 2 , p = 0.03) and 23% for TA muscles (349 ± 11 vs. 283 ± 19 fibers/mm 2 , p = 0.01). Fiber number per section, evaluated for SOL muscles, increased by 18% (2749 ± 42 vs. 2324 ± 121 fibers/section, p < 0.05). These results were accompanied by decreases in muscle fiber area of 15% for SOL muscles (4449 ± 127 vs. 5234 ± 277 µm 2 , p = 0.03) and 21% for TA muscles (2787 ± 91 vs. 3510 ± 219 µm 2 , p = 0.01) -a finding consistent with muscle fiber splitting. No chronic degeneration/regeneration was observed excluding such phenomenon as a requirement for the morphologic changes. Peak lifting forces increased by 21% (12.4 ± 0.2 vs. 10.3 ± 0.5 N, p = 0.01) -possibly an outcome of adaptive remodeling at the neural, capillary, or connective tissue level during fiber splitting. CONCLUSION: These findings indicate that modulation of muscle fiber number should be considered as a potential mechanism for early exercise-induced strength gains.
The purpose of this study was to investigate the effects of30-second all-out sprint interval exer... more The purpose of this study was to investigate the effects of30-second all-out sprint interval exercise (SIE) vs. moderate aerobic exercise (MA) on excess post-exercise oxygen consumption (EPOC). Six recreationallytrained males (age=23 .3±1.4 yrs, weight=81.8±9.9 kg, height=180.8±6.3 cm) completed a sprint interval exercise session consisting of three repeated 30-second Wingate cycling tests separated by four minutes (duration-llminutes) as well as a moderate aerobic exercise session consisting of30-minute cycling at 60% heart rate reserve (HRR) in a random counterbalanced design. Baseline oxygen consumption (V0 2) was determined by an average V0 2 from the final five minutes of a 30-minute supine rest period prior to each trial. Following each protocol, V0 2 was measured for 30 minutes or until baseline measures were reached. EPOC was determined by subtracting baseline V0 2 from post-exercise V0 2 measurements. Energy expenditure (kJ) was determined by multiplying kJ per liter of oxygen by the average V0 2 during recovery. EPOC values were significantly higher in SIE (7.5±1.3 L) than MA (1.8±0.7 L). SIE produced a higher recovery caloric expenditure (156.9 kJ) compared to MA (41.0 kJ) and remained significantly elevated (p=.024) over resting levels during the entire recovery period (30 minutes) compared to MA (6 minutes, p=.003). The energy required to recover from three repeated maximal effort 30-second Wingate cycling tests was greater than 30 minutes of moderate aerobic exercise. Future studies should examine the chronic effects of maximal effort sprint training protocol on cardiovascular fitness and body composition.
Journal of Strength and Conditioning Research, 2017
Mangine, GT, Hoffman, JR, Gonzalez, AM, Townsend, JR, Wells, AJ, Jajtner, AR, Beyer, KS, Boone, C... more Mangine, GT, Hoffman, JR, Gonzalez, AM, Townsend, JR, Wells, AJ, Jajtner, AR, Beyer, KS, Boone, CH, Wang, R, Miramonti, AA, LaMonica, MB, Fukuda, DH, Witta, EL, Ratamess, NA, and Stout, JR. Exercise-induced hormone elevations are related to muscle growth. J Strength Cond Res 31(1): 45–53, 2017—Partial least squares regression structural equation modeling (PLS-SEM) was used to examine relationships between the endocrine response to resistance exercise and muscle hypertrophy in resistance-trained men. Pretesting (PRE) measures of muscle size (thickness and cross-sectional area) of the vastus lateralis and rectus femoris were collected in 26 resistance-trained men. Participants were randomly selected to complete a high-volume (VOL, n = 13, 10–12RM, 1-minute rest) or high-intensity (INT, n = 13, 3–5RM, 3-minute rest) resistance training program. Blood samples were collected at baseline, immediately postexercise, 30-minute, and 60-minute postexercise during weeks 1 (week 1) and 8 (week 8) of training. The hormonal responses (testosterone, growth hormone [22 kD], insulin-like growth factor-1, cortisol, and insulin) to each training session were evaluated using area-under-the-curve (AUC) analyses. Relationships between muscle size (PRE), AUC values (week 1 + week 8) for each hormone, and muscle size (POST) were assessed using a consistent PLS-SEM algorithm and tested for statistical significance (p ≤ 0.05) using a 1,000 samples consistent bootstrapping analysis. Group-wise comparisons for each relationship were assessed through independent t-tests. The model explained 73.4% (p &lt; 0.001) of variance in muscle size at POST. Significant pathways between testosterone and muscle size at PRE (p = 0.043) and muscle size at POST (p = 0.032) were observed. The ability to explain muscle size at POST improved when the model was analyzed by group (INT: R 2 = 0.882; VOL: R 2 = 0.987; p &lt; 0.001). No group differences in modal quality were found. Exercise-induced testosterone elevations, independent of the training programs used in this study, seem to be related to muscle growth.
Purpose This study evaluated the contributions of somatic maturity (years from estimated peak hei... more Purpose This study evaluated the contributions of somatic maturity (years from estimated peak height velocity) and training experience as developmental indicators of muscle morphology, biomechanical parameters, and bilateral asymmetries in youth judo athletes. Methods Twenty-six judo athletes aged 8-18 years (mean ± SD; age = 12.9 ± 2.6 years, maturity offset = -0.6 ± 2.2 years, training experience = 6.1 ± 2.9 years) completed anthropometric measurements, performance testing, and ultrasound evaluation of the vastus lateralis. Results Somatic maturity had the greatest relationship with handgrip performance (r 2 = 0.76-0.80; p < 0.01) and lower-body plyometric ability (r 2 = 0.23-0.72; p < 0.05). Somatic maturity and training experience accounted for 72% of the variance in hopping power. Bilateral asymmetries in average/peak force and 1-/2-s force-time integration during isometric handgrip increased with training experience (r 2 = 0.17-0.46 p < 0.05). Muscle morphology (r 2 = 0.29-0.75; p < 0.01) was best related to somatic maturity. Significant differences were found between child and adolescent judo athletes in force-time curve parameters, muscle morphology, and plyometric ability. Conclusions These results indicate that somatic maturity and training experience exert unique influences on muscle morphology, biomechanical parameters, and bilateral asymmetries in youth judo athletes.
Journal of Strength and Conditioning Research, May 1, 2016
Short-term unilateral resistance training results in cross education of strength without changes ... more Short-term unilateral resistance training results in cross education of strength without changes in muscle size, activation, or endocrine response. J Strength Cond Res 30(5): 1213-1223, 2016-The purpose of this study was to assess the cross education of strength and changes in the underlying mechanisms (muscle size, activation, and hormonal response) after a 4-week unilateral resistance training (URT) program. A group of 9 untrained men completed a 4-week URT program on the dominant leg (DOM), whereas cross education was measured in the nondominant leg (NON); and were compared with a control group (n = 8, CON). Unilateral isometric force (PKF), leg press (LP) and leg extension (LE) strength, muscle size (by ultrasonography) and activation (by electromyography) of the rectus femoris and vastus lateralis, and the hormonal response (testosterone, growth hormone, insulin, and insulinlike growth factor-1) were tested pretraining and posttraining. Group 3 time interactions were present for PKF, LP, LE, and muscle size in DOM and for LP in NON. In all interactions, the URT group improved significantly better than CON. There was a significant acute hormonal response to URT, but no chronic adaptation after the 4-week training program. Four weeks of URT resulted in an increase in strength and size of the trained musculature, and cross education of strength in the untrained musculature, which may occur without detectable changes in muscle size, activation, or the acute hormonal response.
Uploads
Papers by Jeffrey Stout