The disproportionate increase in V·O2 ("extra V·O2") reported at elevated intensity during incremental exercise (IE) might result from the same physiological mechanisms as the V·O2 slow component observed during heavy constant work rate exercise (CWRE). Moreover, it has been demonstrated that prior heavy exercise can diminish the V·O2 slow component. The aim of this study was to evaluate whether prior heavy exercise also alters the "extra V·O2" during IE. Ten trained sprinters performed three tests on a cycle ergometer: Test 1 was an IE; Test 2 consisted of six minutes of a CWRE (90 % of V·O2max) followed by six minutes at 35 W and by an IE and Test 3 was composed of two CWRE of six minutes separated by six minutes of exercise at 35 W. For each IE, the slope and the intercept of the V·O2/work rate relationship were calculated by linear regression using data before the first Ventilatory Threshold (pre-VT1 slope). The difference between V·O2max measured and V·O2max expected using the pre-LT slope was calculated (?V·O2). We also calculated the difference between V·O2 at min five and V·O2 at min three during CWRE of Test 3 (?V·O2(5' - 3')). V·O2max was significantly higher than V·O2exp during IE of Test 1 and Test 2. ? V·O2 during IE did not differ between Test 1 and Test 2 (+ 259 ± 229 ml · min-1 vs. + 222 ± 221 ml · min-1). During Test 3, six subjects achieved five minutes of exercise during the second CWRE and ? V·O2(5' - 3') was significantly decreased during the second CWRE (338 ± 65 ml · min-1 vs. 68 ± 98 ml · min-1, n = 6). These results demonstrate that the amplitude of the "extra V·O2" during IE was not affected by prior exercise, whereas the slow component of V·O2 evaluated by ? V·O2(5' - 3') during CWRE was lowered. This implies that prior exercise does not have the same effect on the slow component of V·O2 and on the "extra V·O2". Therefore we were unable to demonstrate a relationship between the V·O2 slow component and the "extra-V·O2" phenomenon during IE.
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