Nature vs. nurture: can exercise really alter fiber type composition in human skeletal muscle?

This essay looks at the historical significance of two APS classic papers that are freely available online: Gollnick PD, Armstrong RB, Saubert CW IV, Piehl K, and Saltin B. Enzyme activity and fiber composition in skeletal muscle of untrained and trained men. J Appl Physiol 33: 312—319, 1972 ( http://jap.physiology.org/cgi/reprint/33/3/312 ). Gollnick PD, Armstrong RB, Saltin B, Saubert CW IV, Sembrowich WL, and Shepherd RE. Effect of training on enzyme activity and fiber composition of human skeletal muscle. J Appl Physiol 34: 107—111, 1973 ( http://jap.physiology.org/cgi/reprint/34/1/107 ).

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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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540 MORE IMMEDIATE RELATIONSHIP BETWEEN HIGH-ENERGY PHOSPHATE COMPOUNDS AND FIBER TYPE COMPOSITION IN HUMAN SKELETAL MUSCLE

Medicine & Science in Sports & Exercise ◽

10.1249/00005768-199405001-00542 ◽

1994 ◽

Vol 26 (Supplement) ◽

pp. S96

Author(s):

H. Takahashi ◽

S. Kuno ◽

H. Shimojo ◽

S. Katsuta ◽

Y. Itai

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Fiber Type ◽

High Energy ◽

High Energy Phosphate ◽

Fiber Type Composition ◽

Type Composition ◽

Phosphate Compounds

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Energy-rich phosphates in slow and fast human skeletal muscle

AJP Cell Physiology ◽

10.1152/ajpcell.1995.268.4.c869 ◽

1995 ◽

Vol 268 (4) ◽

pp. C869-C876 ◽

Cited By ~ 53

Author(s):

K. Vandenborne ◽

G. Walter ◽

L. Ploutz-Snyder ◽

R. Staron ◽

A. Fry ◽

...

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Fiber Type ◽

Phosphate Content ◽

Lateral Gastrocnemius ◽

Fiber Type Composition ◽

Type Composition ◽

Slow Twitch ◽

Gastrocnemius Muscles ◽

Muscle Biopsies

We investigated the relationship between energy-rich phosphate content and muscle fiber-type composition in human skeletal muscle using a combination of 31P-nuclear magnetic resonance spectroscopy (NMR), histochemical, and biochemical analyses of muscle biopsies. Localized 31P spectra were collected simultaneously from the predominantly slow-twitch soleus muscle and the mixed (fast-twitch and slow-twitch) medial and lateral gastrocnemius muscles, using B1-insensitive Hadamard Spectroscopic Imaging. Biopsy samples were taken from the soleus and lateral gastrocnemius muscles before NMR investigation and analyzed for fiber type composition and succinic dehydrogenase (SDH) activity. Fiber-type composition was determined based both on myofibrillar actomyosin ATPase activity combined with cross-sectional area and on myosin heavy-chain composition. Localized spectroscopy demonstrated a significantly (P < 0.001) higher P(i)/phosphocreatine ratio in the soleus muscle (0.15 +/- 0.01) compared with the medial (0.12 +/- 0.01) and lateral (0.10 +/- 0.0) gastrocnemius. However, in vitro analysis of muscle biopsies showed only a moderate relationship between the basal phosphate content and myofibrillar actomyosin ATPase-based fiber-type composition and SDH activity, respectively.

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