THE CARDIORESPIRATORY RESPONSE TO SUBMAXIMAL EXERCISE IN SUBJECTS WITH ASTHMA FOLLOWING PRETREATMENT WITH CONTROLLED-RELEASE ORAL SALBUTAMOL AND HIGH-DOSE INHALED SALMETEROL

Treatment for exercise induced asthma (EIA) in sporting competition is controlled to prevent the use of agents which might enhance physical performance. There is little information concerning the effects of the long-acting inhaled, and oral, sustained release type bronchodilators on the cardiorespiratory effects of submaximal exercise. The aim of t his study was to compare the cardiorespiratory effects of submaximal e xercise in patients with EIA before and after pretreatment with high-d ose inhaled salmeterol xinafoate (SX) and controlled release oral salb utamol (CR). Patients were treated with SX (100 mu g b.d.) and CR (8 m g b.d.) for greater than or equal to 3 days in a double-blind randomiz ed cross-over design, with a 5-14 day washout period between treatment s. A submaximal exercise test (total exercise time 6 min, final 3 min at 60% of (V) over dot (speak)) was performed prior to each treatment period, and repeated at 1, 6, and 12 h postdose at the end of the trea tment period. Two subjects were withdrawn from the study. Three subjec ts required relief medication after 1 h (CR) and one subject after 6 h (SX) and they did not perform further exercise tests. Both treatments increased baseline FEV1, with SX producing significantly greater pre- exercise bronchodilation than CR (P=0.04). Following CR, there were no significant differences from the pretreatment values for (V) over dot O-2, (V) over dot (E), respiratory exchange ratio, heart rate, ventil atory equivalents for (V) over dot O-2, and oxygen pulse during the su bmaximal exercise challenge. Following SX, there were no significant d ifferences for any of the exercise variables except for (V) over dot ( E) at 6 and 12 h (mean increase 4.27 1 min(-1) at 6 h, P<0.01 and 4.69 1 min(-1) at 12 h, P=0.05). The changes in ventilation following SX di d not have an effect on oxygen consumption, and the ventilatory effici ency ((V) over dot (E)/(V) over dot O-2) remained unchanged. The findi ngs from this study demonstrate that, despite exercising from a higher baseline FEV1, short pretreatment periods with controlled release ora l salbutamol and with inhaled salmeterol do not confer any cardiorespi ratory advantage during submaximal exercise in subjects with EIA.