Abstract
We investigated the hypothesis that a session of maximal concentric contraction exercise (CE) might impair muscle oxygenation and muscle blood flow. Ten healthy males performed a single bout of 70 maximal elbow flexion CE. Before and after CE on day 1 and over the next two days, maximum voluntary isometric torque (MVT), plasma creatine kinase activity (CK), serum myoglobin, elbow joint range of motion (ROM), subjects' perception of muscle soreness(SOR), and muscle oxygenation kinetics (using near infrared spectroscopy; NIRS) within biceps brachii were assessed. MVT and ROM decreased while SOR increased significantly after CE (p<0.05), but recovered within the next day. There were not any significant changes in CK or myoglobin. Resting muscle oxygen saturation, oxyhaemoglobin and muscle oxygen uptake increased, and deoxyhaemoglobin decreased significantly after acute CE, and recovered by day 2. Although the changes in NIRS-derived variables were not significant in most conditions during isometric contractions of different intensities(i.e. 30%, 50% and 80% of MVT), there was a consistent pattern of change for those variables (i.e. decreasing immediately after CE, recovering on day 2 and increasing on day 3). Interestingly, the pattern of change in NIRS parameters mirrored CE-induced changes of MVT. In conclusion, concentric exercise did not produce prolonged changes in muscle oxygenation. The changes observed in NIRS-derived variables under resting condition may reflect an excess post exercise oxygen consumption.