The Effects of High Intensity Interval Training on Pulmonary Function

Abstract

High-intensity interval training (HIT) has been utilized as a time-efficient strategy to induce numerous metabolic adaptations usually associated with traditional endurance training. PURPOSE: To determine if HIT would improve respiratory muscle strength and expiratory flow rates more than continuous moderate intensity exercise training. METHODS: Thirteen healthy untrained subjects were randomly assigned to either a HIT group (n=7) or a continuous training group (CT; n=6). All subjects completed a VO2max test, pulmonary function tests (PFT) including maximal inspiratory (MIP) and expiratory (MEP) pressures, and maximal flow volume loops before and after training. Both groups trained 4 weeks on a cycle ergometer. CT trained 3x/week for 45 minutes at ∼60% VO2max; whereas HIT performed 5-1 minute exercise bouts at 90% VO2max separated by 3 minutes recovery 3x/week. All subjects also completed a 5 mile time trial (TT) before and after training. RESULTS: There was no difference (p>0.05) between groups in height, weight, PFT's, VO2max, or TT prior to training. Following training, both groups significantly increased their VO2max by ∼8%. While both groups increased (p<0.05) MIP and MEP following training, HIT had greater (p<0.05) maximal inspiratory pressure than CT (HIT pre:105.4+6.1, post: 142.3 + 12.7 cmH2O; CT pre:101.7+7.8, post: 123.1+ 11.6 cmH2O). Expiratory flow rates did not change with training. There was a significant improvement in the TT in both CT (5.0+1.5%) and HIT (8.6+2.1%) with no difference (p>0.05) between groups. CONCLUSIONS: Whole body exercise training is effective in increasing inspiratory muscle pressure with HIT eliciting greater effects than continuous moderate intensity exercise. Similar improvements in VO2max and performance were observed with continuous exercise training and high intensity exercise training, suggesting that HIT offers a time-efficient alternative to improving respiratory muscle strength, aerobic capacity and performance.