The protective effects of continuous and interval exercise in athletes with exercise-induced asthma

Abstract

MCKENZIE, D. C., S. L. MCLUCKIE, and D. R. STIRLING. The protective effects of continuous and interval exercise in athletes with exercise-induced asthma. Med. Sci. Sports Exerc., Vol. 26, No. 8, pp. 951–956, 1994. To determine the effect of two forms of warm-up on postexcrcise bronchoconstriction in athletes with exercise-induced asthma, 12 moderately trained persons with asthma (age = 26.5 ± 2.2 yr; height = 169.2 ± 2.6 cm; weight = 64.3 ± 2.6kg; VO_2max = 52.7 ± 1.3 ml · kg^-1. min^-1) were tested under three experimental conditions: continuous warm-up (CW), interval warm-up (IW), and control (C). CW consisted of 15 min of treadmill running at a velocity corresponding to 60% VO_2max followed by an exercise challenge test (ET = 6 min at 90% VO_2max). IW involved 8 X 30-s runs (1.5 min rest between bouts of exercise), at an intensity equivalent to 100% VO_2max followed by an ET. C consisted of only the ET. FEV_1‘ FVC, and MMEFR were measured prior to the experimental conditions, repeated before the ET, and every 2 min during a 25-min passive recovery period, using a Breon spirometer. Postexercise changes in pulmonary function were recorded as the largest decrease in FEV_1’ FVC, and MMEFR during the recovery period, and expressed as a percentage of baseline values. Significant differences were detected in %FEV₁ (34. 6, 16.7, 29.7: P = 0.009), %FVC (30.0, 10.7, 21.0: P = 0.03), and %MMEFR (50.0, 30.2, 43.4: P = 0.05), in comparing C, CW, and IW, respectively. Scheffe's test detected significance (P < 0.05) between C and CW for all three dependent variables; no statistical significance between C and IW or IW and CW occurred. These data indicate that a continuous warm-up of 15 min at 60% VO_2max can significantly decrease postexercise bronchoconstriction in moderately trained athletes.