Effects of humid air breathing during arm or treadmill exercise on exercise-induced bronchoconstriction and refractoriness.
Although it has been reported that inhibitory prostaglandins may be a causal factor in exercise refractoriness, it is still unclear whether exercise-induced bronchoconstriction (EIB) and/or other specific "exercise factors" are necessary to trigger their release and render a subject refractory to subsequent exercise. The purpose of this study was to determine whether non-EIB-producing exercise with the legs or arms could produce refractoriness to a standard treadmill challenge. Eight asthmatic subjects with EIB completed three sessions consisting of two exercise challenges separated by a 30-min rest. In all sessions, the second challenge was done on a treadmill while breathing dry air. Conditions for Challenge 1 were the following: Session A = treadmill, dry air; Session B = treadmill, humid air; Session C = arm cranking, humid air. All three conditions produced a significant degree of refractoriness. There was a tendency for the percent protection index to be greater for Session A; however, no significant differences were found among the three sessions. Therefore, it can be concluded that although both exercise and bronchoconstriction may play a role in producing the refractory period, neither severe bronchoconstriction nor intense exercise with the same muscle groups are required to produce refractoriness.
Wilson
B A
BA
School of Human Biology, University of Guelph, Ontario, Canada.
Bar-Or
O
O
Seed
L G
LG
D000328:Adult; D001132:Arm; D001249:Asthma / Q000209:etiology*; D001250:Asthma, Exercise-Induced / Q000209:etiology* / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D006813:Humidity; D008297:Male; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors