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

To determine the effect of two forms of warm-up on postexercise 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; VO2max = 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% VO2max followed by an exercise challenge test (ET = 6 min at 90% VO2max). IW involved 8 x 30-s runs (1.5 min rest between bouts of exercise), at an intensity equivalent to 100% VO2max, followed by an ET. C consisted of only the ET. FEV1, 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 decrese in FEV1, 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% VO2max can significantly decrease postexercise bronchoconstriction in moderately trained athletes.