Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance

Bailey SJ, Vanhatalo A, Wilkerson DP, DiMenna FJ, Jones AM. Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severeintensity exercise tolerance. J Appl Physiol 107: 1743-1756, 2009. First published October 1, 2009; doi:10.1152/japplphysiol.00810.2009. - 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%triangle) after no prior exercise (control) and after six different combinations of prior exercise intensity and recovery duration: 40%triangle with 3 min (40-3-80), 9 min (40-9-80), and 20 min (40-20-80) of recovery and 70%triangle 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 theV O-2 slow component amplitude; the phase II time constant was not significantly altered with any prior exercise/recovery combination. Exercise tolerance at 80%triangle 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%triangle did not significantly influence exercise tolerance regardless of the recovery duration. These data demonstrate that prior high-intensity exercise (approximate to 70%triangle) 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.