ABSTRACT

　The purpose of the present study was to clarify the effect of respiratory muscle training in hypoxia on whole-body endurance exercise performance. Eighteen collegiate endurance runners were assigned to control （n=6）， normoxic （n=6）， and hypoxic （n=6） groups. Before and after 6 weeks of respiratory muscle endurance training （RMET）， incremental respiratory endurance test at rest and constant exercise test were performed. The constant exercise test carried out on a treadmill at 95% of the individual's peak oxygen uptake （V・o2peak）．The RMET was voluntary isocapnic hyperpnea under normoxic and hypoxic conditions （30 min/day, 4 or 5 days/week: 28 days total）．During RMET, the initial target of minute ventilation was set to 50% of the individual maximal voluntary ventilation, and the target increased progressively during 6 weeks. Target arterial oxygen saturation （Spo2） in the hypoxic group was set to 90% in the first 2 weeks, and thereafter the target Spo2 was set to 80%. Respiratory muscle endurance was increased following RMET in the normoxic and hypoxic groups, but not in the control group. The time to exhaustion during the constant exercise test also increased after RMET in the normoxic and hypoxic groups, while it was unchanged in the control group. The extent of these increases did not differ between the normoxic and hypoxic groups. These results suggest that the improvement of respiratory muscle endurance after RMET could contribute to improved whole-body endurance exercise performance in endurance-trained runners, and however there are no additional effects when the RMET is performed under hypoxic conditions.

DECENTE SPORTS SCIENCE Vol.41/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE