Effects of Two Hours of Heavy-Intensity Exercise on the Power–Duration Relationship

INTRODUCTIONChanges in the parameters of the power-time relationship (critical power (CP) and W′) during endurance exercise would have important implications for performance. We tested the hypotheses that CP and W′, estimated using the end-test power (EP) and the work done above EP (WEP), respectively, during a the 3-min all-out test (3MT), can be reliably determined, and would be lower, after completing 2-h of heavy-intensity exercise. METHODSIn study 1, six cyclists completed a 3MT immediately following 2-h of heavy-intensity exercise on two occasions to establish the reliability of EP and WEP. In study 2, nine cyclists completed a control 3MT, and a fatigued 3MT and constant-power-output tests to 30 min or the limit of tolerance (Tlim) below and above F-EP after 2-h of heavy-intensity exercise. RESULTSIn study 1, EP (273±52 vs. 276±58 W) and WEP (12.4±4.3 vs. 12.8±4.3 kJ) were not different (P>0.05) and were highly correlated (r=0.99; P