Optimizing the 'priming' effect: influence of prior exercise intensity and recovery duration on O_2 uptake kinetics and severe-intensity exercise tolerance

摘要

It has been suggested that a prior bout of high-intensity exercise has the potential to enhance performance during subsequent high-intensity exercise by accelerating the O_2 uptake (V_(O_2)) on-response. However, the optimal combination of prior exercise intensity and subsequent recovery duration required to elicit this effect is presently unclear. Eight male participants, aged 18-24 yr, completed step cycle ergometer exercise tests to 80% of the difference between the preestablished gas exchange threshold and maximal V_(O_2) (i.e., 80%DELTA) after no prior exercise (control) and after six different combinations of prior exercise intensity and recovery duration: 40%A with 3 min (40-3-80), 9 min (40-9-80), and 20 min (40-20-80) of recovery and 70%DELTA with 3 min (70-3-80), 9 min (70-9-80), and 20 min (70-20-80) of recovery. Overall V_(O_2) kinetics were accelerated relative to control in all conditions except for 40-9-80 and 40-20-80 conditions as a consequence of a reduction in the V_(O_2) slow component amplitude; the phase II time constant was not significantly altered with any prior exercise/recovery combination. Exercise tolerance at 80%DELTA was improved by 15% and 30% above control in the 70-9-80 and 70-20-80 conditions, respectively, but was impaired by 16% in the 70-3-80 condition. Prior exercise at 40%DELTA did not significantly influence exercise tolerance regardless of the recovery duration. These data demonstrate that prior high-intensity exercise (approx70%DELTA) can enhance the tolerance to subsequent high-intensity exercise provided that it is coupled with adequate recovery duration (>=9 min). This combination presumably optimizes the balance between preserving the effects of prior exercise on V_(O_2) kinetics and providing sufficient time for muscle homeostasis (e.g., muscle phosphocreatine and H~+ concentrations) to be restored.