Genetic determinism of fiber type proportion in human skeletal muscle

This brief review attempts to summarize a number of studies on the delineation, development, and distribution of human skeletal muscle fiber types. A total of seven fiber types can be identified in human limb and trunk musculature based on the pH stability/ability of myofibrillar adenosine triphosphatase (mATPase). For most human muscles, mATPase-based fiber types correlate with the myosin heavy chain (MHC) content. Thus, each histochemically identified fiber has a specific MHC profile. Although this categorization is useful, it must be realized that muscle fibers are highly adaptable and that innumerable fiber type transients exist. Also, some muscles contain specific MHC isoforms and/or combinations that do not permit routine mATPase-based fiber typing. Although the major populations of fast and slow are, for the most part, established shortly after birth, subtle alterations take place throughout life. These changes appear to relate to alterations in activity and/or hormonal levels, and perhaps later in life, total fiber number. Because large variations in fiber type distribution can be found within a muscle and between individuals, interpretation of data gathered from human muscle is often difficult. Key words: aging, myosin heavy chains, myogenesis, myofibrillar adenosine triphosphate

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Gene Polymorphisms and Fiber-Type Composition of Human Skeletal Muscle

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.22.4.292 ◽

2012 ◽

Vol 22 (4) ◽

pp. 292-303 ◽

Cited By ~ 25

Author(s):

Ildus I. Ahmetov ◽

Olga L. Vinogradova ◽

Alun G. Williams

Keyword(s):

Skeletal Muscle ◽

Muscle Fiber ◽

Human Skeletal Muscle ◽

Fiber Type ◽

Vastus Lateralis Muscle ◽

Type I ◽

Fiber Types ◽

Fiber Type Composition ◽

Type Composition ◽

Type I Fibers

The ability to perform aerobic or anaerobic exercise varies widely among individuals, partially depending on their muscle-fiber composition. Variability in the proportion of skeletal-muscle fiber types may also explain marked differences in aspects of certain chronic disease states including obesity, insulin resistance, and hypertension. In untrained individuals, the proportion of slow-twitch (Type I) fibers in the vastus lateralis muscle is typically around 50% (range 5–90%), and it is unusual for them to undergo conversion to fast-twitch fibers. It has been suggested that the genetic component for the observed variability in the proportion of Type I fibers in human muscles is on the order of 40–50%, indicating that muscle fiber-type composition is determined by both genotype and environment. This article briefly reviews current progress in the understanding of genetic determinism of fiber-type proportion in human skeletal muscle. Several polymorphisms of genes involved in the calcineurin–NFAT pathway, mitochondrial biogenesis, glucose and lipid metabolism, cytoskeletal function, hypoxia and angiogenesis, and circulatory homeostasis have been associated with fiber-type composition. As muscle is a major contributor to metabolism and physical strength and can readily adapt, it is not surprising that many of these gene variants have been associated with physical performance and athlete status, as well as metabolic and cardiovascular diseases. Genetic variants associated with fiber-type proportions have important implications for our understanding of muscle function in both health and disease.

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Human skeletal muscle fiber type percentage and area after reduced muscle use: A systematic review and meta‐analysis

Scandinavian Journal of Medicine and Science in Sports ◽

10.1111/sms.13675 ◽

2020 ◽

Vol 30 (8) ◽

pp. 1298-1317 ◽

Cited By ~ 2

Author(s):

Harald Vikne ◽

Vegard Strøm ◽

Are Hugo Pripp ◽

Terje Gjøvaag

Keyword(s):

Systematic Review ◽

Skeletal Muscle ◽

Muscle Fiber ◽

Human Skeletal Muscle ◽

Fiber Type ◽

Meta Analysis ◽

Skeletal Muscle Fiber ◽

Muscle Fiber Type

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Fiber type transformation in human skeletal muscle.

The Journal of Anthropological Society of Nippon ◽

10.1537/ase1911.94.1 ◽

1986 ◽

Vol 94 (1) ◽

pp. 1-18

Author(s):

Haruhiko SATO

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Fiber Type ◽

Type Transformation

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Abundance of ClC-1 chloride channel in human skeletal muscle: fiber type specific differences and effect of training

Journal of Applied Physiology ◽

10.1152/japplphysiol.01042.2017 ◽

2018 ◽

Vol 125 (2) ◽

pp. 470-478 ◽

Cited By ~ 9

Author(s):

Martin Thomassen ◽

Morten Hostrup ◽

Robyn M. Murphy ◽

Brett A. Cromer ◽

Casper Skovgaard ◽

...

Keyword(s):

Skeletal Muscle ◽

Exercise Performance ◽

Chloride Channel ◽

Human Skeletal Muscle ◽

Fiber Type ◽

Human Muscle ◽

Type I ◽

Maximal Heart Rate ◽

Channel Protein ◽

Slow Twitch

Cl− channel protein 1 (ClC-1) may be important for excitability and contractility in skeletal muscle, but ClC-1 abundance has not been examined in human muscle. The aim of the present study was to examine ClC-1 abundance in human skeletal muscle, including fiber type specific differences and the effect of exercise training. A commercially available antibody was tested with positive and negative control tissue, and it recognized specifically ClC-1 in the range from 100 to 150 kDa. Abundance of ClC-1 was 38% higher ( P < 0.01) in fast twitch Type IIa muscle fibers than in slow twitch Type I. Muscle ClC-1 abundance did not change with 4 wk of training consisting of 30 min cycling at 85% of maximal heart rate (HRmax) and 3 × 30-s all out sprints or during a 7-wk training period with 10–12 × 30 s uphill cycling and 4–5 × ~4 min cycling at 90%–95% of HRmax. ClC-1 abundance correlated negatively ( P < 0.01) with maximal oxygen consumption ( r = –0.552) and incremental exercise performance ( r = –0.546). In addition, trained cyclists had lower ( P < 0.01) ClC-1 abundance than lesser trained individuals. The present observations indicate that a low abundance of muscle ClC-1 may be beneficial for exercise performance, but the role of abundance and regulation of ClC-1 in skeletal muscle of humans with respect to exercise performance and trainability need to be elucidated. NEW & NOTEWORTHY Abundance of the Cl− channel protein 1 (ClC-1) chloride channel may be important for excitability and contractility in human skeletal muscle and may therefore have implications for fatigue development. In this study, we confirmed ClC-1 specificity for a commercially available antibody, and this study is first to our knowledge to determine ClC-1 protein abundance in human muscle by Western blotting. We observed that abundance of ClC-1 was higher in fast compared with slow twitch fibers and lower in trained individuals than in recreationally active.

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