RECOVERY OF POWER OUTPUT AND MUSCLE METABOLITES FOLLOWING 30-S OF MAXIMAL SPRINT CYCLING IN MAN

1. The recovery of power output and muscle metabolites was examined fo llowing maximal sprint cycling exercise. Fourteen male subjects perfor med two 30 s cycle ergometer sprints separated by 1.5, 3 and 6 min of recovery, on three separate occasions. On a fourth occasion eight of t he subjects performed only one 30 s sprint and muscle biopsies were ob tained during recovery. 2. At the end of the 30 s sprint phosphocreati ne (PCr) and ATP contents were 19.7 +/- 1.2 and 70.5 +/- 6.5% of the r esting values (rest), respectively, while muscle lactate was 119.0 +/- 4.6 mmol (kg dry wt)(-1) and muscle pH was 6.72 +/- 0.06. During reco very, PCr increased rapidly to 65.0 +/- 2.8% of rest after 1.5 min, bu t reached only 85.5 +/- 3.5% of rest after 6 min of recovery. At the s ame time ATP and muscle pH remained low (19.5 +/- 0.9 mmol (kg dry wt) (-1) and 6.79 +/- 0.02, respectively). Modelling of the individual PCr resynthesis using a power function curve gave an average half-time fo r PCr resynthesis of 56.6 +/- 7.3 s. 3. Recovery of peak power output (PPO), peak pedal speed (maxSp and mean power during the initial 6 s ( MPO(6)) of sprint 2 did not reach the control values after 6 min of re st, and occurred in parallel with the resynthesis of PCr, despite the low muscle pH. High correlations (r = 0.71-0.86; P < 0.05) were found between the percentage resynthesis of PCr and the percentage restorati on of PPO, maxSp and MPO(6) after 1.5 and 3 min of recovery. No relati onship was observed between muscle pH recovery and power output restor ation during sprint 2 (P > 0.05). 4. These data suggest that PCr resyn thesis after 30 s of maximal sprint exercise is slower than previously observed after dynamic exercise of longer duration, and PCr resynthes is is important for the recovery of power during repeated bouts of spr int exercise.