Fig. 4. Recovery of PCr following exercise (A) and hypoxia exposure (B) at 15°C (squares) and 25°C (circles). Phosphocreatine levels are normalized to the sum of PCr and P_i and expressed relative to normoxic/resting controls. NMR data were collected at the fishes' acclimation temperature and for each time point an average consisting of 256 spectra gathered over 5 min is shown. Time zero represents the point at which exercise stopped (A) or when fish were returned to normoxic water (B). In A, transfer of the fish from the exercise respirometer to the NMR took 10 min, therefore the recovery trace does not start at zero. Each point represents mean ± s.e.m. N=7–10 for each data point.