Modeling the depletion and reconstitution of W′: Effects of prior exercise on cycling tolerance

Thirteen healthy male subjects (age 28 ± 7 years) performed tests for critical power and W′ determination and two square-wave high-intensity exercises until exhaustion either with prior very-heavy intensity cycling (EXP) or without (CON). Prior exercise bout induced a depletion of 60 % of W′. After 10 min of recovery, W′ reconstitution was not fully achieved (∼ 92 %). Time to exhaustion and Δ blood lactate concentration were significantly lower in EXP compared to CON (595 ± 118 s vs. 683 ± 148 s; 3.5 ± 1.2 mmol.L−1 vs. 8.8 ± 2.3 mmol.L−1; p < 0.05, respectively). Oxygen uptake (VO2) and heart rate were significantly higher in EXP, during the first 150 s of exercise (p < 0.05). The carbon dioxide production kinetics was significantly slower in EXP (mean response time = 87.8 ± 17.8 s vs. 73.7 ± 16.6 s in CON; p < 0.05). Thus, prior exercise impairs high-intensity cycling performance which can partly be explained by physiological disturbances linked to W′ depletion.