Abstract
The purpose of this study was to determine both the independent and additive effects of prior heavy-intensity exercise and pacing strategies on the VO2 kinetics and performance during high-intensity exercise. Fourteen endurance cyclists (VO2max = 62.8±8.5 mL.kg−1.min−1) volunteered to participate in the present study with the following protocols: 1) incremental test to determine lactate threshold and VO2max; 2) four maximal constant-load tests to estimate critical power; 3) six bouts of exercise, using a fast-start (FS), even-start (ES) or slow-start (SS) pacing strategy, with and without a preceding heavy-intensity exercise session (i.e., 90% critical power). In all conditions, the subjects completed an all-out sprint during the final 60 s of the test as a measure of the performance. For the control condition, the mean response time was significantly shorter (p<0.001) for FS (27±4 s) than for ES (32±5 s) and SS (32±6 s). After the prior exercise, the mean response time was not significantly different among the paced conditions (FS = 24±5 s; ES = 25±5 s; SS = 26±5 s). The end-sprint performance (i.e., mean power output) was only improved (∼3.2%, p<0.01) by prior exercise. Thus, in trained endurance cyclists, an FS pacing strategy does not magnify the positive effects of priming exercise on the overall VO2 kinetics and short-term high-intensity performance.
Highlights
Exercise intensity domains are defined according to the blood lactate and oxygen uptake (VO2) responses obtained during constant-work-rate exercise [1]
The parameters of the VO2 kinetics during the paced exercise trials (FS, ES and SS) with and without prior exercise are presented in table 1
Post hoc analyses revealed a significant reduction in mean response time for the SS (p,0.001) and ES (p,0.001) conditions after prior exercise
Summary
Exercise intensity domains (i.e., moderate, heavy and severe) are defined according to the blood lactate and oxygen uptake (VO2) responses obtained during constant-work-rate exercise [1]. During constant-work-rate exercise performed within the severe domain, the VO2 rises inexorably (as the slow component of the VO2 kinetics increases) to the maximal oxygen uptake (VO2max). Exercise tolerance within the severe domain can be predicted and is defined by the curvature constant of the power– time relationship (W9) [3]. Several lines of evidence indicate that the interaction between VO2 kinetics, W’ and the attainment of VO2max can contribute to exercise intolerance during exercise performed in the severe-intensity domain [4]. Some interventions (e.g., pacing, priming exercise and nitrate supplementation) that are used to improve VO2 kinetics (i.e., t – the time taken to reach 63% of the increase in VO2 above baseline and/or the slow component of VO2 kinetics) can reduce the W’ utilization during the initial phase of exercise, improving performance [5] and exercise tolerance [6] during severe-intensity exercise
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