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UBC Theses and Dissertations

The asthmatic athlete: metabolic and ventilatory responses during exercise with and without pre-exercise medication Ienna, Tiziana Mona


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) (age = 26.1 ± 5.7 yrs; ht = 173.6 ± 10.5 cm; wt = 66.4 ± 10.8 kg; VO₂max = 57.0 ± 4.9 ml.kg-¹.min-¹), and 8 moderately trained (MT) (age = 24.1 ± 3.1 yrs; ht 183.1 ± 11.8 cm; wt = 78.6 ± 15.3 kg; VO₂max = 51.3 ± 4.8 ml•kg⁻¹1min⁻¹ ) with exercise-induced asthma (ETA) under 2 randomly assigned experimental conditions: salbutamol ( S )( 2 puffs = 200ɥg) or placebo (PL) was administered via metered-dose inhaler 15 minutes prior to exercise. The exercise task was 4 continuous 5 minute increments on an electronically braked cycle ergometer representing 25, 50, 75, and 90% of the subject’s VO₂max. VO₂, minute ventilation (VE), respiratory exchange ratio (RER), % saturation (SaO₂), and HR were continuously measured during exercise. A venous catheter was inserted in the subject’s antecubital vein to allow measurement of blood lactate (La) 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. The data failed to show significance (p > 0.05) between treatment conditions at any stage of exercise with respect to VO₂, VE, RER, HR, and SaO₂. However, among the HT group the mean HR for the 4 exercise conditions was significantly higher under placebo (151.7 (PL) vs. 147.2 (S): p = 0.01). No difference was found in La during exercise or in recovery. Pre-exercise PEFR was significantly higher (582(S) vs. 545 L.sec-’(PL): p =0.003 ) when pretreatment was salbutamol, but prior to treatment there was no difference between the two pre-exercise PEER’s. Mean PEER measures for the exercise and recovery conditions were significantly higher ( 600.1(S) vs. 569.6 (PL): p = 0.002) with the salbutamol treatment. Scheffe’s post-hoc comparisons indicated a significant difference in mean PEER measures with respect to the two treatments between low intensities (25 % and 50 %) and high intensities (75 % and 90 %) of exercise. There was no difference in the physiological response to exercise between groups based on training status. It was concluded that although salbutamol affects the PEER, these asthmatic athletes do not have altered metabolic or ventilatory responses during exercise.

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