Many daily activities and sporting events require an individual to perform brief periods of maximal exercise (i.e. < 10s) interrupted by limited periods of recovery. In the first study an intermittent maximal exercise test was used to examine the decline in power output with successive exercise periods and identify the changes in the metabolic environment associated with such exercise. The exercise protocol consisted of ten 6s maximal sprints with 30s recovery between each sprint on a cycle ergometer. The results suggest that phosphocreatine (PCr) and anaerobic glycolysis provided the majority of the energy to sustain an average power output (MPO) of 870.1 ±159.2W in the first sprint. In the final sprint, however, no change in lactate concentration was apparent, yet the average power output was still 73% of that in the initial sprint. It was suggested that the energy was derived from PCr degradation and oxidative metabolism.