The Effects of Endurance, Strength, and Power Training on Muscle Fiber Type Shifting

Wilson, Jacob M.; Loenneke, Jeremy P.; Jo, Edward; Wilson, Gabriel J.; Zourdos, Michael C.; Kim, Jeong‐Su

doi:10.1519/jsc.0b013e318234eb6f

Cited by 225 publications

(206 citation statements)

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“…Although the genetic basis of skeletal muscle MHC isoform specification is an active area of research (e.g., ref. 16), the magnitude of the chimpanzeehuman contrast in MHC I fibers appears to exceed the more modest shifts that may be induced through intense athletic training (∼10-15%) (17,18). Furthermore, characterization of fiber-type distributions in the muscles of lemurs, galagos, and macaques suggests that a predominance of MHC II (IIa + IId) isoforms (i.e., fast fibers) is common among primates, as well as other terrestrial mammals (SI Appendix, SI Methods and Table S5).…”

Section: Resultsmentioning

confidence: 96%

Chimpanzee super strength and human skeletal muscle evolution

O’Neill

Umberger

Holowka

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Since at least the 1920s, it has been reported that common chimpanzees (Pan troglodytes) differ from humans in being capable of exceptional feats of "super strength," both in the wild and in captive environments. A mix of anecdotal and more controlled studies provides some support for this view; however, a critical review of available data suggests that chimpanzee mass-specific muscular performance is a more modest 1.5 times greater than humans on average. Hypotheses for the muscular basis of this performance differential have included greater isometric force-generating capabilities, faster maximum shortening velocities, and/or a difference in myosin heavy chain (MHC) isoform content in chimpanzee relative to human skeletal muscle. Here, we show that chimpanzee muscle is similar to human muscle in its single-fiber contractile properties, but exhibits a much higher fraction of MHC II isoforms. Unlike humans, chimpanzee muscle is composed of ∼67% fast-twitch fibers (MHC IIa+IId). Computer simulations of species-specific whole-muscle models indicate that maximum dynamic force and power output is 1.35 times higher in a chimpanzee muscle than a human muscle of similar size. Thus, the superior mass-specific muscular performance of chimpanzees does not stem from differences in isometric force-generating capabilities or maximum shortening velocities-as has long been suggested-but rather is due in part to differences in MHC isoform content and fiber length. We propose that the hominin lineage experienced a decline in maximum dynamic force and power output during the past 7-8 million years in response to selection for repetitive, low-cost contractile behavior.chimpanzee | human | muscle | myosin heavy chain | muscle modeling M odern humans-with some exceptions-are often characterized as a weak and unathletic species compared with our closest living relatives, the chimpanzees. Whereas chimpanzees are proficient tree climbers and arborealists (1), our hominin ancestors gave up a reliance on the forest canopy after the emergence of the genus Homo (2). Subsequent evolution in brain size (3) and cognition as well as advancements in tools and other material culture (4, 5) have reduced our strict dependence on muscular strength for survival and fitness.Since at least the 1920s, both anecdotal reports and more controlled experiments have indicated that the strength of a chimpanzee can exceed that of a human (6-12). This has led to the now long-standing proposal that chimpanzees are "super strong" compared with humans. A critical review of experiments (i.e., pulling and jumping tasks) carried out between 1923 and 2014 suggests that chimpanzee mass-specific muscular performance consistently exceeds that of humans, with a differential of about 1.5 times, on average (SI Appendix, SI Discussion). Hypotheses for the muscular basis of the chimpanzee-human performance differential have included higher isometric force-producing capabilities (6-8, 11), faster maximum shortening velocities (7, 11), and/or a different distribution of myosin ...

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Section: Resultsmentioning

confidence: 96%

Chimpanzee super strength and human skeletal muscle evolution

O’Neill

Umberger

Holowka

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…28 However, given that we used maximum isokinetic torque to compute asymmetries between limbs, it seems highly plausible that interlimb morphologic differences in isokinetic torque were being regulated by a shift in muscle phenotype from fast-twitch to slow-twitch fibers in the involved limb. 28,29 Notably, this shift in muscle phenotype has been shown to have a debilitating effect on athletes' performance, 28,47 and alterations in the torque-velocity relationship were present before ACLR and at 3 and 6 months postsurgery. 24 Our observations suggest that alterations in muscle phenotype may be an important underlying morphologic factor that likely contributed to interlimb asymmetry in patients with ACLR.…”

Section: Isokinetic Interlimb Asymmetriesmentioning

confidence: 99%

Contribution of Neuromuscular Factors to Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Johnson¹,

Palmieri-Smith

Lepley

2018

Journal of Athletic Training

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Context: To quantify quadriceps weakness after anterior cruciate ligament reconstruction (ACLR), researchers have often analyzed only peak torque. However, analyzing other characteristics of the waveform, such as the rate of torque development (RTD), time to peak torque (TTP), and central activation ratio (CAR), can lend insight into the underlying neuromuscular factors that regulate torque development.Objective: To determine if interlimb neuromuscular asymmetry was present in patients with ACLR at the time of clearance to return to activity.Design: Cross-sectional study. Conclusions: Interlimb asymmetries at return to activity after ACLR appeared to be regulated by several underlying neuromuscular factors. We theorize that interlimb asymmetries in isometric and isokinetic quadriceps strength were associated with changes in muscle architecture. Reduced CAR, TTP, and RTD were also present, indicating a loss of motor-unit recruitment or decrease in firing rate.

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“…The muscle also consists of 28.2% type Ι muscle fibers, which are slow-twitch fibers suited for aerobic exercise related to muscle endurance [19,20].…”

Section: Effectiveness Of Trainingmentioning

confidence: 99%

Study of training for improving lip incompetence

et al. 2016

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Abstract:Purpose: We have been using myofunctional therapy in orthodontic treatment to improve orofacial disorders. Our previous study showed that lip training increased orbicularis oris muscle strength and endurance. The aim of this study was to determine the effectiveness of hypoxic lip training for improving lip incompetence.Subjects & Methods: Twenty healthy subjects (10 males and 10 females, 23.6 ± 2.3 years old) with lip incompetence participated in this study. We recorded the sealed lip ratio calculated by using the formula "(lip-sealing time / total recorded time) × 100" during relaxation (listening to soothing music) and during concentration (performing a mathematical calculation). Then the subjects performed a standardized hypoxic lip training (5 repetitive contractions with 80% of maximum tensile strength of the orbicularis oris muscle) with a traction plate. Training was repeated daily for 4 weeks. To estimate training effects, the sealed lip ratios during relaxation and concentration were recorded before training (T1), at 2 weeks (T2) and 4 weeks (T3) after the start of training, and at 4 weeks (T4) and 8 weeks (T5) after the end of training.Results: The sealed lip ratios in both the relaxation and concentration conditions significantly (P < 0.003 after Bonferroni correction) increased during the training period. Although the sealed lip ratios slightly decreased during the post-training period, they were not significantly different from those at T3.Conclusions: Hypoxic lip training increases the sealed lip ratio and is thus effective for improving lip incompetence. Sealed lip ratios were maintained after 8 weeks of training.

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The Effects of Endurance, Strength, and Power Training on Muscle Fiber Type Shifting

Cited by 225 publications

References 50 publications

Chimpanzee super strength and human skeletal muscle evolution

Chimpanzee super strength and human skeletal muscle evolution

Contribution of Neuromuscular Factors to Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Study of training for improving lip incompetence

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