Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists

Skeletal muscle buffering capacity (βm), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, sub maximal?interval training (HIT) undertaken by six well-trained competitive cyclists [mean maximal oxygen consumption ( O_2max)?=?66.2 ml?·?kg^?1?·?min^?1]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. βm increased from 206.6 (17.9) to 240.4 (34.1) μmol H⁺?·?g muscle dw^?1?·?pH^?1 after HIT (P?=?0.05). PPO, time to fatigue at 150% PPO (TF₁₅₀) and 40-km cycle time trial performance (TT₄₀) all significantly improved after HIT (P?40 performance before HIT (r?=??0.82, P?40 was close to significance (r?=??0.74). βm did not correlate with TF₁₅₀. These results indicate that βm may be an important determinant of relatively short-duration (