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Effects of prior very-heavy intensity exercise on indices of aerobic function and high-intensity exercise tolerance

¹Centre for Sport and Exercise Sciences, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds; ²Institute of Biological and Life Sciences, University of Glasgow, Glasgow; and ³Department of Physical Education, Sport and Leisure Studies, Moray House School of Education, University of Edinburgh, Edinburgh, United Kingdom

Submitted 13 December 2006 ; accepted in final form 22 May 2007

A recent bout of high-intensity exercise can alter the balance of aerobic and anaerobic energy provision during subsequent exercise above the lactate threshold (_L). However, it remains uncertain whether such "priming" influences the tolerable duration of subsequent exercise through changes in the parameters of aerobic function [e.g., _L, maximum oxygen uptake (O_2max)] and/or the hyperbolic power-duration (P-t) relationship [critical power (CP) and the curvature constant (W')]. We therefore studied six men performing cycle ergometry to the limit of tolerance; gas exchange was measured breath-by-breath and arterialized capillary blood [lactate] was measured at designated intervals. On different days, each subject completed 1) an incremental test (15 W/min) for estimation of _L and measurement of the functional gain (O₂/WR) and O_2peak and 2) four constant-load tests at different work rates (WR) for estimation of CP, W', and O_2max. All tests were subsequently repeated with a preceding 6-min supra-CP priming bout and an intervening 2-min 20-W recovery. The hyperbolicity of the P-t relationship was retained postpriming, with no significant difference in CP (241 ± 39 vs. 242 ± 36 W, post- vs. prepriming), O_2max (3.97 ± 0.34 vs. 3.93 ± 0.38 l/min), O₂/WR (10.7 ± 0.3 vs. 11.1 ± 0.4 ml·min^–1·W^–1), or the fundamental O₂ time constant (25.6 ± 3.5 vs. 28.3 ± 5.4 s). W' (10.61 ± 2.07 vs. 16.13 ± 2.33 kJ) and the tolerable duration of supra-CP exercise (–33 ± 11%) were each significantly reduced, despite a less-prominent O₂ slow component. These results suggest that, following supra-CP priming, there is either a reduced depletable energy resource or a residual fatigue-metabolite level that leads to the tolerable limit before this resource is fully depleted.

power-duration relationship; W'; oxygen uptake kinetics; slow component; lactate threshold

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