| Summary: | 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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