Anaerobic performance in middle and long distance runners

The purpose of this study was to investigate the relationships between blood lactic acid (LA) accumulation, maximum anaerobic power, glycolytic enzyme activity, and skeletal muscle fibre composition in endurance trained runners. Venous LA was measured in 15 male middle distance (MD) and long distance (LD) runners before and after a 30 second all out ergometer ride. Muscle biopsies of the lateral gastrocnemius muscle were obtained prior to exercise for determination of lactate dehydrogenase (LDH), and phosphofructokinase (PFK) enzyme activities and histochemical classification of fast twitch (FT) and slow twitch (ST) muscle fibres. Significant differences were observed in %FT fibre composition (47.8(MD) and 34.6 (LD), and mean VO2 max values were significantly higher in the LD runners (62.8 (MD) and 68.7 (LD) ml.kg.-1 min.-1). Blood lactate values following maximal treadmill running were significantly higher in the MD group (15.0 mM) when compared with LD runners (11.9 mM). Total anaerobic power output was calculated according to the "Wingate Anaerobic Test" at 51 (MD) and 49 (LD) kpm. kg.-1 min.-1 and mean post-exercise LA values were 8.6 mM (MD) and 8.0 mM (LD). Similar non-significant differences were observed when muscular power was determined via the "Margaria Test" (109.6 (LD) kgm.sec-1). Correlations were determined and the best relationship was between PFK and %FT (R = 0.84). The data suggest that the ergometer test was of insufficient duration, and thus did not result in maximal accumulation of LA and/or metabolically produced LA is removed rapidly in endurance trained muscle. Endurance training in middle and long distance runners fails to produce high value for anaerobic power tests.