Effect of exercise intensity on the slow component of oxygen uptake in decremental work load exercise

The paper sought to determine the exercise intensity where the slow component of oxygen uptake (Vo(2)) first appears in decremental work load exercise (DLE). Incremental work load exercise (ILE) was performed with an increment rate of 15 watts (W) per minute. In DLE, power outputs were decreased by 15 W per minute, from 120 (DLE(120)), 160 (DLE(160)), 200 (DLE(200)) and 240 (DLE(240)) W, respectively. The slopes of Vo(2) against the power output were obtained in the lower section from 0 to 50 W in all DLEs, and in the upper section from 80 to 120 W in DLE(160) and from 100 to 150 W in DLE(200) and DLE(240). The power output at exhaustion in ILE was 274 +/- 20 W. The power output at the ventilatory threshold (VT) obtained in ILE was 167 +/- 22 W. The initial power output in DLE(160) was near the power output at VT. The slopes obtained in the upper sections were 11.4 +/- 0.9 ml x min(-1) x W(-1)1 in DLE(160), 12.8 +/- 0.8 ml x min(-1) x W(-1) in DLE(200), and 14.8 +/- 1.1 ml x min(-1) x W(-1) in DLE(240). The slope obtained in DLE(120) was 10.9 +/- 0.6 ml x min(-1). There were no differences in slope between the upper and lower sections in DLE(160) but there were significant differences in slopes between the upper and lower sections in DLE(200) and DLE(240). Thus, the slow component, which could be observed as a steeper slope in DLE, began to increase when the initial power output in DLE was near to VT.