Are the Hypertrophic Adaptations to High and Low-Load Resistance Training Muscle Fiber Type Specific?

Grgić, Jozo; Schöenfeld, Brad J.

doi:10.3389/fphys.2018.00402

Cited by 46 publications

(49 citation statements)

References 29 publications

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“…It has been proposed that performing resistance exercise (RE) with heavier loads [greater than 60% one repetition maximum (1RM) strength] is required to elicit muscle hypertrophy and to recruit and result in hypertrophy of type II muscle fibres (Ratamess et al 2009;Grgic & Schoenfeld, 2018). By contrast, studies show that performing RE training with relatively lighter loads to task failure (i.e.…”

Section: Introductionmentioning

confidence: 99%

Muscle fibre activation is unaffected by load and repetition duration when resistance exercise is performed to task failure

Morton

Sonne

Zuniga

et al. 2019

The Journal of Physiology

104

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Performing resistance exercise with heavier loads is often proposed to be necessary for the recruitment of larger motor units and activation of type II muscle fibres, leading to type II fibre hypertrophy. Indirect measures [surface electromyography (EMG)] have been used to support this thesis, although we propose that lighter loads lifted to task failure (i.e. volitional fatigue) result in the similar activation of type II fibres. r In the present study, participants performed resistance exercise to task failure with heavier and lighter loads with both a normal and longer repetition duration (i.e. time under tension). r Type I and type II muscle fibre glycogen depletion was determined by neither load, nor repetition duration during resistance exercise performed to task failure. r Surface EMG amplitude was not related to muscle fibre glycogen depletion or anabolic signalling; however, muscle fibre glycogen depletion and anabolic signalling were related. r Performing resistance exercise to task failure, regardless of load lifted or repetition duration, necessitates the activation of type II muscle fibres.

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Section: Introductionmentioning

confidence: 99%

Muscle fibre activation is unaffected by load and repetition duration when resistance exercise is performed to task failure

Morton

Sonne

Zuniga

et al. 2019

The Journal of Physiology

104

View full text Add to dashboard Cite

show abstract

“…Resistance training and aging are two stressors which have profound consequences on skeletal muscle physiology. For instance, several studies have demonstrated that resistance training is capable of increasing type I and II muscle fiber cross sectional areas (fCSA), which, in turn, contributes to increased tissue mass and enhances force producing capability (reviewed in [2][3][4]). On the other hand, aging in the absence of resistance training has been associated with a decrease in type II fCSA, increased fibrosis, a loss in muscle mass, and a reduction in force producing capability (reviewed in [5]).…”

Section: Introductionmentioning

confidence: 99%

Skeletal Muscle Myofibrillar Protein Abundance Is Higher in Resistance-Trained Men, and Aging in the Absence of Training May Have an Opposite Effect

Vann

Roberson

Osburn

et al. 2020

Sports

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Resistance training generally increases skeletal muscle hypertrophy, whereas aging is associated with a loss in muscle mass. Interestingly, select studies suggest that aging, as well as resistance training, may lead to a reduction in the abundance of skeletal muscle myofibrillar (or contractile) protein (per mg tissue). Proteomic interrogations have also demonstrated that aging, as well as weeks to months of resistance training, lead to appreciable alterations in the muscle proteome. Given this evidence, the purpose of this small pilot study was to examine total myofibrillar as well as total sarcoplasmic protein concentrations (per mg wet muscle) from the vastus lateralis muscle of males who were younger and resistance-trained (denoted as YT, n = 6, 25 ± 4 years old, 10 ± 3 self-reported years of training), younger and untrained (denoted as YU, n = 6, 21 ± 1 years old), and older and untrained (denoted as OU, n = 6, 62 ± 8 years old). The relative abundances of actin and myosin heavy chain (per mg tissue) were also examined using SDS-PAGE and Coomassie staining, and shotgun proteomics was used to interrogate the abundances of individual sarcoplasmic and myofibrillar proteins between cohorts. Whole-body fat-free mass (YT > YU = OU), VL thickness (YT > YU = OU), and leg extensor peak torque (YT > YU = OU) differed between groups (p < 0.05). Total myofibrillar protein concentrations were greater in YT versus OU (p = 0.005), but were not different between YT versus YU (p = 0.325). The abundances of actin and myosin heavy chain were greater in YT versus YU (p < 0.05) and OU (p < 0.001). Total sarcoplasmic protein concentrations were not different between groups. While proteomics indicated that marginal differences existed for individual myofibrillar and sarcoplasmic proteins between YT versus other groups, age-related differences were more prominent for myofibrillar proteins (YT = YU > OU, p < 0.05: 7 proteins; OU > YT = YU, p < 0.05: 11 proteins) and sarcoplasmic proteins (YT = YU > OU, p < 0.05: 8 proteins; OU > YT&YU, p < 0.05: 29 proteins). In summary, our data suggest that modest (~9%) myofibrillar protein packing (on a per mg muscle basis) was evident in the YT group. This study also provides further evidence to suggest that notable skeletal muscle proteome differences exist between younger and older humans. However, given that our n-sizes are low, these results only provide a preliminary phenotyping of the reported protein and proteomic variables.

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“…In general, these studies have reported that acute anabolic signaling events do not differ between exercise modalities when lifts are performed to volitional fatigue. In addition, a review that analyzed 11 studies reported similar increases in mean fiber cross-sectional area (fCSA) and types I and II fCSA in response to months of higher versus lower-load resistance training (Grgic and Schoenfeld, 2018). However, the intramuscular protein adaptations that occur in response to each mode of training -specifically, changes in myofibrillar protein concentrations, sarcoplasmic protein concentrations, or muscle tissue percent fluid -have been vastly understudied.…”

Section: Introductionmentioning

confidence: 99%

Skeletal Muscle Protein Composition Adaptations to 10 Weeks of High-Load Resistance Training in Previously-Trained Males

et al. 2020

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While high-load resistance training increases muscle hypertrophy, the intramuscular protein responses to this form of training remains largely unknown. In the current study, recreationally resistance-trained college-aged males (N = 15; mean ± SD: 23 ± 3 years old, 6 ± 5 years training) performed full-body, low-volume, high-load [68-90% of one repetition maximum (1RM)] resistance training over 10 weeks. Back squat strength testing, body composition testing, and a vastus lateralis biopsy were performed before (PRE) and 72 h after the 10-week training program (POST). Fiber typespecific cross-sectional area (fCSA), myofibrillar protein concentrations, sarcoplasmic protein concentrations, myosin heavy chain and actin protein abundances, and muscle tissue percent fluid were analyzed. The abundances of individual sarcoplasmic proteins in 10 of the 15 participants were also assessed using proteomics. Significant increases (p < 0.05) in type II fCSA and back squat strength occurred with training, although whole-body fat-free mass paradoxically decreased (p = 0.026). No changes in sarcoplasmic protein concentrations or muscle tissue percent fluid were observed. Myosin heavy chain protein abundance trended downward (−2.9 ± 5.8%, p = 0.069) and actin protein abundance decreased (−3.2 ± 5.3%, p = 0.034) with training. Proteomics indicated only 13 sarcoplasmic proteins were altered with training (12 upregulated, 1 down-regulated, p < 0.05). Bioinformatics indicated no signaling pathways were affected, and proteins involved with metabolism (e.g., ATP-PCr, glycolysis, TCA cycle, or beta-oxidation) were not affected. These data comprehensively describe intramuscular protein adaptations that occur following 10 weeks of high-load resistance training. Although previous data from our laboratory suggests high-volume resistance training enhances the ATP-PCr and glycolytic pathways, we observed different changes in metabolism-related proteins in the current study with high-load training.

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Are the Hypertrophic Adaptations to High and Low-Load Resistance Training Muscle Fiber Type Specific?

Cited by 46 publications

References 29 publications

Muscle fibre activation is unaffected by load and repetition duration when resistance exercise is performed to task failure

Muscle fibre activation is unaffected by load and repetition duration when resistance exercise is performed to task failure

Skeletal Muscle Myofibrillar Protein Abundance Is Higher in Resistance-Trained Men, and Aging in the Absence of Training May Have an Opposite Effect

Skeletal Muscle Protein Composition Adaptations to 10 Weeks of High-Load Resistance Training in Previously-Trained Males

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