Abstract

Plasma ammonia (NH3) accumulation was determined during an incremental maximal exercise test on a bicycle ergometer and during recovery in six endurance trained (VO2max=63.2 +/- 1.77 ml/kg/min) and seven untrained (VO2max=53.5 +/- 2.45 ml/kg/min, p<0.05) male subjects. Venous plasma NH3 levels were determined at every work stage and at min 2, 5, 10 and 20 of recovery. Because blood NH3 accumulation is related to muscle fibre composition, muscle biopsies were obtained from 11 subjects to determine fast-twitch (FT) fibres. Data were analysed using ANOVA (n=13) and ANCOVA (n=11) where FT fibres was used as the covariate. Trained subjects exhibited a significantly smaller increase in plasma NH3 accumulation at 300 watts and at min 5 of recovery when compared with the untrained group (p<0.05). When muscle fibre type was used as a covariate, smaller increases in NH3 were found for the trained group at both 250 and 300 watts (p<0.05) and at min 5 of recoveery, (p=0.07). These data suggest that training reduces plasma NH3 accumulation during intense exercise and during the initial stages of recovery. Verf.-Referat