The influence of maximal aerobic power on recovery of skeletal muscle following anaerobic exercise

Phosphorus magnetic resonance spectroscopy (P-31-MRS) was used to investigate the influence of maximal aerobic power (VO2max) on the recovery of human calf muscle from high-intensity exercise. The ((V) over dot O-2max) of 21 males was measured during treadmill exercise and subjects were assigned to either a low-aerobic-power (LAP) group (n=10) or a high-aerobic-power (HAP) group (n=11). Mean (SE) (V)over dot O-2max of the groups were 46.6 (1.1) and 64.4 (1.4) ml.kg(-1).min(-1), respectively. A calf ergometry work capacity test was used to assign the same relative exercise intensity to each subject for the MRS protocol. At least 48 h later subjects performed the rest (4 min) exercise (2 min) and recovery (10 min) protocol in a 1.5 T MRS scanner. The relative concentration of phosphocreatine (PCr) was measured throughout the protocol and intracellular pH (pH(i)) was determined from the chemical shift between inorganic phospate (P-i) and PCr. End-exercise PCr levels were 27 (3.4) and 25 (3.5)% of resting levels for LAP and HAP respectively. Mean resting pH(i) was 7.07 for both groups, and following exercise it fell to 6.45 (0.04) for HAP and 6.38 (0.04) for LAP. Analysis of data using non-linear regression models showed no differences in the rate of either PCr or pH(i) recovery. The results suggest that (V)over dot O-2max is a poor predictor of metabolic recovery rate from high-intensity exercise. Differences in recovery rate observed between individuals with similar (V) over dot O-2max imply that other factors influence recovery.