Abstract
Muscle fiber distribution and muscle enzyme activity (m. vastus lat.) were investigated
in 10 elite sprint cyclists and 12 nonathletes. The ratio of fast to slow muscle fibers
was 2:3 in cyclists and 3:2 in nonathletes. The mean diameter of each muscle fiber
type was significantly higher in the athletes. The mean enzyme activity values in
µkat · g-1w.w. for cyclists and nonathletes, respectively, were as follows: triosephosphate
dehydrogenase (TPDH), 6.2 and 3.78; lactate dehydrogenase (LDH), 4.4 and 4.59; citrate
synthase (CS), 0.154 and 0.13; hydroxyacyl-CoA dehydrogenase (HAD), 0.041 and 0.07.
The mean difference between groups in TPDH and in (TPDH+LDH)/(CS+HAD) ratio were statistically
significant. Maximum voluntary isometric strength (knee extension) was about 17% greater
in cyclists than the mean value for Czechoslovakian men of the same age. A strong
positive correlation (r = 0.72) between the percent of fast glycolytic fibers (type II B) and isometric strength
was observed in the cyclists. Further more, mean weight-compensated maximal oxygen
consumption (V̇O2max, ml · kg-1 · min-1) for all subjects (n = 22) was significantly related to percent of slow oxiḋative fibers (type I) (r = 0.75) and to the mean diameter of type II B (r = 0.58), fast oxidative-glycolytic fibers (type II A) (r = 0.68) and type I fibers (r = 0.59).
Key words
sprint cycling - muscle fiber distribution - muscle enzyme activity - maximum isometric
strength
