Interval training as an alternative modality to continuous exercise in patients with COPD.

Understanding of what constitutes a training load adequate to induce training effects in patients with chronic obstructive pulmonary disease (COPD) is still evolving. The present study investigated whether interval training (IT) is effective in terms of inducing measurable improvements in physiological response and compared its effects on exercise tolerance (ET) and quality of life to those of continuous training (CT). Thirty-six COPD patients, with a forced expiratory volume in one second of 45+/-4% of the predicted value (mean+/-SEM), were randomly assigned to CT (exercise at 50% of baseline peak work-rate) or IT (work for 30 s at 100% of peak work-rate alternating with 30-s rest intervals) groups that cycled 40 min x day(-1) and 2 days x week(-1) for 12 weeks. After training, both groups showed significantly improved ET (IT, 57+/-6 to 71+/-8 W; CT, 57+/-5 to 70+/-6 W) and total quality-of-life score of the Chronic Respiratory Disease Questionnaire (IT, 77+/-3 to 88+/-2; CT, 78+/-3 to 93+/-2). At identical levels of exercise, minute ventilation was significantly reduced (IT, 35.8+/-2.5 to 31.7+/-2.5 L x min(-1); CT, 36.4+/-2.7 to 32.5+/-2.7 L x min(-1)). The magnitude of improvement in these variables was not significantly different among groups. The present data expand on the principles of exercise prescription for chronic obstructive pulmonary disease patients by demonstrating that interval training elicits substantial training effects, which are similar in magnitude to those produced by continuous training at half the exercise intensity but double the exercise time.