Respiratory muscle fitness and exercise endurance in healthy humans

New evidence exists that the respiratory muscles may limit exercise performance in healthy humans. Four weeks of isolated respiratory training (30 min normocapnic hyperpnea, 5 d.wk-1 significantly increased the endurance time of respiratory muscles and the endurance time of constant-load bicycle tests in sedentary as well as physically active subjects once respiratory muscles had recovered from the training. Minute ventilation and blood lactate concentration were reduced during post-training exercise. Furthermore, respiratory trained subjects had lost the sensation of breathlessness. Maximal oxygen consumption was not affected by respiratory training. The mechanism by which respiratory training improves overall physical performance is as yet unknown.