The specificity of endurance training on muscular power and muscle fibre size

Abstract

In an effort to further examine the specificity of training concept, six female student volunteers (mean age=25.3 years) were endurance trained three times a week for a period of twelve weeks. The training consisted of thirty minutes of continuous running per workout. Identical test batteries were administered prior to (pre) and immediately following (post) the treatment period. Each battery of tests consisted of three measures of muscular leg power (vertical jump test, 18-29 m sprint, and the Margaria Step Test), and two measures of cardiovascular endurance (Cooper's 12 minute run, and V˚O₂ max during treadmill running). A muscle biopsy from the lateral aspect of the gastrocnemius muscle was also included. The biopsy specimens were stained for myosin ATPase. Percentages of fast twitch (FT) and slow twitch (ST) muscle fibres as well as mean individual FT and ST fibre areas were determined. The training produced significant changes in the exercising subjects for thel2-minute run (p=0.006)and VO₂max(p=0.003). No changes were found in the tests of muscular power or individual fibre areas. These data indicate that the endurance training program was of sufficient intensity to effect an increase in cardiovascular fitness. However, these improvements in endurance were not accompanied by any significant changes in muscular leg power or individual muscle fibre size.