This study consists of two training experiments using a mechanically braked cycle ergometer. First, the effect of 6 wk of moderate-intensity endurance training (intensity: 70% of maximal oxygen uptake (˙VO2max), 60 min·d-1, 5 d·wk-1) on the anaerobic capacity (the maximal accumulated oxygen deficit) and ˙VO2max was evaluated. After the training, the anaerobic capacity did not increase significantly(P > 0.10), while ˙VO2max increased from 53 ± 5 ml·kg-1·min-1 to 58 ± 3 ml·kg-1·min-1 (P < 0.01) (mean± SD). Second, to quantify the effect of high-intensity intermittent training on energy release, seven subjects performed an intermittent training exercise 5 d·wk-1 for 6 wk. The exhaustive intermittent training consisted of seven to eight sets of 20-s exercise at an intensity of about 170% of ˙VO2max with a 10-s rest between each bout. After the training period, ˙VO2max increased by 7 ml·kg-1·min-1, while the anaerobic capacity increased by 28%. In conclusion, this study showed that moderate-intensity aerobic training that improves the maximal aerobic power does not change anaerobic capacity and that adequate high-intensity intermittent training may improve both anaerobic and aerobic energy supplying systems significantly, probably through imposing intensive stimuli on both systems.