Skeletal Muscle Fiber Characteristics of World Class Shot-Putters

Abstract

Muscle samples were obtained from the gastrocnemius muscles of eight untrained males and eight world class shot-putters with a mean best performance of 19.77 meters (range 19.14 to 20.33 m). Fiber composition and mean cross-sectional areas were determined from muscle sections incubated for myosin adenosine triphosphatase and alpha-glycerophosphate dehydrogenase activity. Portions of the specimen were analyzed for total phosphorylase, lactate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase activities. The shot-putters displayed a wide range of muscle fiber compositions (13.0 to 67.0% slow twitch-ST) with a mean distribution of 37.8% ST fibers. Although they displayed a greater mean percentage of fast twitch (FT) fibers, their mean distribution was not significantly different (p < .05) from that of the untrained men (46.7% ST). The individual muscle fibers of the shot-putters were 35% larger than those of the untrained, while both groups had ST/FT mean fiber area ratios of 1.0. The measured enzyme activities of the two groups were not found to differ. These data suggest that gastrocnemius muscle composition alone is not a determinant of shot-putting success.