Article Title



Stephanie P. Kurti, Sam R Emerson, Joshua R. Smith, Matthew K. Castinado, Craig A.

Harms, FACSM; Department of Kinesiology, Kansas State University, Manhattan, KS

PURPOSE: Previous research demonstrates that respiratory muscle fatigue (RMF) occurs during prolonged aerobic exercise at >85% of an individual’s maximal aerobic capacity (VO2max). High intensity interval training (HIT) is a time efficient strategy to stimulate adaptations that are comparable to traditional endurance training. However, it is not known if RMF occurs during HIT. We hypothesized that RMF would occur during and following a session of HIT. METHODS: Eight healthy men (21.7+1.7 yrs) with normal pulmonary function initially performed a graded exercise test until exhaustion on a cycle ergometer to determine VO2max. Subjects then, in random order, completed two bouts of HIT (7 x 1 min, 2 min recovery between intervals) and three bouts of continuous exercise (CE) tests until exhaustion (~5 min) on a cycle ergometer at the same power output (~90% peak power; determined from the VO2max test). Maximal inspiratory pressure (PIMAX) and expiratory pressure (PEMAX) were measured pre- and post-exercise for both HIT and CE, and following each interval during HIT. Decreases in maximal inspiratory and expiratory pressures compared to baseline were used to determine RMF. RESULTS: There was no differences (p>0.05) in PIMAX or PEMAX pre- or post-exercise for HIT (PIMAX pre: 134 + 51 post: 135 + 50 cmH2O; PEMAX pre: 143 + 41 post: 148 + 46 cmH2O) or CE (PIMAX pre: 135 + 54 post: 133 + 52 cmH2O; PEMAX pre: 146 + 46 post: 148 + 46 cm H2O) indicating no RMF occurred with either type of exercise. Also, there was no difference (p>0.05) in PIMAX or PEMAX following each interval during the bout of HIT compared to baseline values. CONCLUSION: These data suggest that respiratory muscle fatigue does not occur during or following a session of HIT. The lack of RMF under these conditions is likely due to the relatively short intervals of exercise in HIT.

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