Kurti, S. P., Emerson, S. R., Smith, J. R., Castinado, M. K., & Harms, C. C. (2014). The effect of a high-intensity interval-training session on respiratory muscle fatigue. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 104.

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"Previous research demonstrates that respiratory muscle fatigue occurs during prolonged exercise at >85% of an individualís maximal aerobic capacity (VO2max). High-intensity interval-training is a time efficient strategy to stimulate adaptations that are comparable to traditional-endurance training. However, it is not known if respiratory muscle fatigue occurs during high-intensity interval-training."

This study tested the hypothesis that respiratory muscle fatigue would occur during and following a session of high-intensity interval-training. Healthy men (N = 8) with normal pulmonary function initially performed a graded exercise test until exhaustion on a cycle ergometer to determine VO2max. Ss then completed two randomized bouts of i) high-intensity interval-training (7 x 1 minute, 2 minutes of recovery between intervals) or ii) three bouts of continuous exercise tests until exhaustion (~5 minutes) on a cycle ergometer at the same power output (~90% peak power; determined from the VO2max test). Maximal inspiratory mouth pressure and expiratory mouth pressure were measured pre- and post-exercise for both high-intensity interval-training and continuous exercise, and following each interval during high-intensity interval-training. Decreases in maximal inspiratory and expiratory pressures compared to baseline values were used to determine respiratory muscle fatigue.

There were no differences in inspiratory mouth pressure or expiratory mouth pressure pre- or post-exercise for high-intensity interval-training or continuous exercise indicating no respiratory muscle fatigue occurred with either type of exercise. Also, there was no difference in inspiratory mouth pressure or expiratory mouth pressure following each interval during the bout of high-intensity interval-training compared to baseline values.

Implication. Respiratory muscle fatigue does not occur during or following a session of high-intensity interval-training. The lack of respiratory muscle fatigue under these conditions is likely due to the relatively short intervals of exercise in high-intensity interval-training.

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