Keramidas, M. E., Debevec, T., Amon, M., Kounalakis, S. N., & Mekjavic, I. B. (2009). The effect of endurance respiratory muscle training on normoxic and hypoxic performance. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

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"The evidence regarding the effect of endurance respiratory muscle training (RMT) on exercise performance remains equivocal, which may be attributed to the fact that very few studies in the past have used appropriate control or placebo groups. The present study investigated the effect of endurance RMT on normoxic and hypoxic endurance performance."

Healthy males (N = 18) were stratified for age and aerobic capacity; and randomly assigned to either a respiratory muscle training (N = 9) or control training group (N = 9). Both groups trained for one hour on a cycle-ergometer five days per week for four weeks at an intensity corresponding to 50% of normoxic peak power output. Additionally, the respiratory muscle training group performed 30 minutes of specific endurance training of respiratory muscles before cycling. Pre-, mid-, post-, and 10-days after the end of training period, Ss performed blood tests, pulmonary function tests, a VO2max test in normoxia (VO2maxNOR) and in hypoxia (VO2maxHYPO; 12% O2); and a constant power test at 80% of pre-training VO2maxNOR in normoxia and in hypoxia.

Both groups enhanced VO2maxNOR, but only the respiratory muscle training group improved VO2maxHYPO post-training. Only the control group increased peak power output, whereas the respiratory muscle training group had higher values of minute ventilation at the same relative intensity. Both groups increased constant power in normoxia, but only the respiratory muscle training group maintained the adaptation 10 days after training. The constant power test in hypoxia remained unchanged in both groups.

Implication. Endurance respiratory muscle training enhances hypoxic aerobic capacity without an accompanying enhancement in hypoxic exercise endurance performance. Respiratory muscle training does not benefit performance under normoxic conditions.

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