Effect of Decreasing-rate in Decremental-Load Exercise on Excess Oxygen Uptake

The purpose of this study was to investigate the effect of decreasing rate during decremental-Ioad exercise on excess oxygen uptake (VO2excess). Six healthy male college students participated in this experiment. They carried out an incremental-load exercise and three kinds of decremental-load exercise on a cycle ergometer. Incremental-load exercise was used to determine the maximal work rate and peak oxygen uptake (peak VO2). Then, they carried out three decremental-load exercises starting from a work rate at 90% peak VO2 determined by the incremental-load exercise. The decreasing rates of these exercises were as follows; 30 watts/min (30wEx), 20 watts/min (20wEx) and 10 watts/min (10wEx). In 30wEx, blood lactate accumulation (LA) was abruptly increased immediately after onset of exercise and thereafter showed a constant value throughout the exercise test. On the contrast, in 10wEx, LA gradually decreased after an abrupt increase at the onset of the exercise. VO2 in 10wEx was significantly higher at higher work rates but was lower at lower work rates than in 30wEx. The difference of VO2 between decremental- and incremental-load exercises (VO2excess) was significantly related to ΔLA measured as the difference of LA between rest and exercise in 10wEx (r=0.731, p <0.001) and 20wEx (r=0.492, p