The Asthmatic Athlete: Metabolic and Ventilatory Responses to Exercise With and Without Pre-Exercise Medication

To determine whether asthmatic athletes have normal physiological responses to exercise without pre-exercise medication, we studied 17 female and male asthmatic subjects, 9 highly trained (HT) and 8 moderately trained (MT) under 2 conditions: salbutamol (S) 200 mg taken via inhaler 15 minutes prior to exercise or placebo (PL). The exercise task was 4 continuous 5 minute increments representing 25, 50, 75 and 90 % of the subject's VO₂max. VO₂, minute ventilation (V,), respiratory exchange ratio (RER), % saturation (SaO₂), and HR were continuously measured during exercise. Blood lactate (LA) was measured each minute throughout exercise and recovery. Post-medication, exercise, and recovery measurements of peak expiratory flow rates (PEFR) were made using a Mini-Wright flow meter. No differences (p > 0.05) between treatment conditions were found at any stage of exercise with respect to VO₂, V_E, RER, HR and SaO₂ However, among the HT group the mean HR for the 4 exercise conditions was significantly higher under PL (PL = 151.7; S = 147.2; p = 0.01). No difference was found in LA during exercise or in recovery. Pre-exercise PEFR was significantly higher when pretreatment was S (S = 582; PL = 545 I · sec^-1; p = 0.003). During the exercise and recovery conditions mean PEFR measures were significantly higher (S = 600.1; PL = 569.6; p = 0.002) with the S treatment. Bonferroni's test detected a difference in PEFR measures between S and PL at 25 % and 50 % VO₂max and 3 and 15 minutes into recovery. There was no difference in the physiological response to exercise between groups based on training status. It was concluded that although S affects the PEFR, these asthmatic athletes do not have altered metabolic or ventilatory responses during this incremental exercise protocol.

Key words

Exercise-induced asthma - highly trained athletes - metabolic responses - ventilatory responses