W ' Reconstitution Accelerates More With Decreasing Intensity In The Heavy- Versus The Moderate-Intensity Domain

IntroductionThe purpose of this study was to investigate the effect of the recovery intensity domain on W ' reconstitution. We used the W '(BAL) model as a framework and tested its predictive capabilities (W '(PRED)) across the different intensity domains. MethodsTwelve young men (51.7 +/- 5.9 mL center dot kg(-1)center dot min(-1)) completed a ramp incremental test, three to five constant power output (PO) tests to determine critical power (CP) and W ', and minimally two trials to verify the maximal lactate (La-) steady state. During four experimental trials, subjects performed two work bouts (WB1 and WB2) at P6 (i.e., PO that predicts exhaustion within 6 min) separated by a recovery interval at CP-10 W, Delta gas exchange threshold (GET)-CP, GET, and 50% GET, respectively. WB1 was designed to deplete 75% W ', and the recovery time varied to replenish 50% W '. WB2 was performed to exhaustion (W '(ACT)). W '(PRED) was compared with W '(ACT) to evaluate the accuracy of the W '(BAL) model. Excess postexercise oxygen consumption was calculated as the difference between the measured and the predicted oxygen uptake during recovery. ResultsW '(ACT) averaged 49% +/- 24%, 69% +/- 24%, 81% +/- 28%, and 93% +/- 21% for CP-10 W, Delta GET-CP, GET, and 50% GET, respectively (P = 0.002). W '(PRED) overestimated W '(ACT) in CP-10 W (34% +/- 32%, P = 0.004) and underestimated W '(ACT) in 50% GET (24% +/- 28%, P = 0.013). Excess postexercise oxygen consumption was lowest in CP-10 W (P < 0.01) and higher in GET compared with Delta GET-CP (P = 0.01). ConclusionWe demonstrated that W '(PRED) overestimated and underestimated W '(ACT) in the heavy- and moderate-intensity domain, respectively. Therefore, the practical applicability of a single recovery time constant, which only relies on the difference between the recovery PO and the CP, is questionable.