JONES, A. M., D. P. WILKERSON, M. BURNLEY, and K. KOPPO. Prior Heavy Exercise Enhances Performance during Subsequent Perimaximal Exercise. Med. Sci. Sports Exerc., Vol. 35, No. 12, pp. 2085–2092, 2003.
Purpose: To test the hypothesis that prior heavy exercise increases the time to exhaustion during subsequent perimaximal exercise.
Methods: Seven healthy males (mean ± SD 27 ± 3 yr; 78.4 ± 0.7 kg) completed square-wave transitions from unloaded cycling to work rates equivalent to 100, 110, and 120% of the work rate at V̇O2peak (W-V̇O2peak) after no prior exercise (control, C) and 10 min after a 6-min bout of heavy exercise at 50% Δ (HE; half-way between the gas exchange threshold (GET) and V̇O2peak), in a counterbalanced design.
Results: Blood [lactate] was significantly elevated before the onset of the perimaximal exercise bouts after prior HE (2.5 vs 1.1 mM; P < 0.05). Prior HE increased time to exhaustion at 100% (mean ± SEM. C: 386 ± 92 vs HE: 613 ± 161 s), 110% (C: 218 ± 26 vs HE: 284 ± 47 s), and 120% (C: 139 ± 18 vs HE: 180 ± 29 s) of W-V̇O2peak, (all P < 0.01). V̇O2 was significantly higher at 1 min into exercise after prior HE at 110% W-V̇O2peak (C: 3.11 ± 0.14 vs HE: 3.42 ± 0.16 L·min−1; P < 0.05), and at 1 min into exercise (C: 3.25 ± 0.12 vs HE: 3.67 ± 0.15; P < 0.01) and at exhaustion (C: 3.60 ± 0.08 vs HE: 3.95 ± 0.12 L·min−1; P < 0.01) at 120% of W-V̇O2peak.
Conclusions: This study demonstrate that prior HE, which caused a significant elevation of blood [lactate], resulted in an increased time to exhaustion during subsequent perimaximal exercise presumably by enabling a greater aerobic contribution to the energy requirement of exercise.
Gerbino et al. (14) demonstrated that the performance of heavy intensity exercise (i.e., exercise above the gas exchange threshold; GET), but not moderate-intensity exercise (<GET), speeded the overall pulmonary oxygen uptake (V̇O2) kinetics during subsequent heavy-intensity exercise. This speeding of the overall V̇O2 response was shown subsequently to result from a reduction in the amplitude of the V̇O2 “slow component” with no change in the time constant of the fundamental V̇O2 response in phase II (10,20). In studies in which sufficient time was allowed between exercise bouts to restore baseline V̇O2, prior heavy-intensity exercise resulted in an increased amplitude of the fundamental response and a reduction in the amplitude of the V̇O2 slow component with a similar end-exercise V̇O2 at 6–8 min (3,7,8). This altered V̇O2 response was associated with a reduction in the accumulation of blood [lactate] over the exercise bout, an attenuated V̇CO2 response, and a reduced overall O2 deficit. In keeping with these observations, measurements of muscle blood flow, arterial-femoral venous O2 difference, and the changes in and release of muscle metabolites indicate an increased oxidative contribution to energy metabolism and a reduction in substrate level phosphorylation in the second of two high-intensity exercise bouts with no change in total ATP turnover (1,23). A recent magnetic resonance spectroscopy study has confirmed that prior heavy-intensity exercise results in a significant sparing of intramuscular [PCr] during subsequent heavy intensity exercise (29).
There is consensus, therefore, that prior heavy-intensity exercise reduces the overall O2 deficit, limits the depletion of intramuscular [PCr] and the production of lactic acid, and attenuates the V̇O2 slow component during subsequent heavy exercise. These effects would be expected to increase exercise tolerance (14,17,28) or at least to allow a better tolerance of exercise than might be expected for the prevailing metabolic conditions (14). The purpose of this study was therefore to test the hypothesis that prior heavy-intensity exercise would extend the time to exhaustion during subsequent perimaximal exercise.