Exercise, regardless of induced bronchoconstriction or inspired air conditions, does not alter airway reactivity.
The effects of exercise on asthmatic airway caliber are well recognized. Only a few studies, however, evaluated the effects of prior exercise on asthmatic airway reactivity. Eight asthmatic children (ages 10 to 16 years; mean, 12) performed histamine inhalation tests on three occasions assigned in random order: (1) control; (2) 40 to 60 min after exercise (6 min ergometer cycling) done while breathing cold dry (CD) air (temperature = -13 degrees C, relative humidity = 0 percent); and (3) 40 to 60 min after exercise done while breathing warm humid (WH) air (temperature = 33 degrees C, relative humidity = 100 percent). While there was a marked exercise-induced bronchoconstriction (EIB) in the CD test with a postexercise fall in FEV1 of 39.2 +/- 8 percent (mean +/- SEM), there was no EIB in the WH test (4.6 +/- 2 percent). There was no difference, however, in the geometric mean histamine concentration required to produce a 20 percent fall in FEV1 (PC20) among the CD, WH, and control tests (0.52 mg/ml, 0.60 mg/ml, and 0.55 mg/ml, respectively). Airway reactivity in asthmatic children is not influenced by a prior exercise challenge, independent of the conditions of the inspired air during the exercise. Moreover, exercise per se, regardless of development of EIB, does not change the reactivity.
Amirav
I
I
Department of Medicine, J. G. Strijdom Hospital, Johannesburg, South Africa.
Dowdeswell
R
R
Webster
T
T
Plit
M
M
D000293:Adolescent; D000388:Air; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000502:physiology*; D002648:Child; D003080:Cold Temperature; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006632:Histamine; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D001239:Inhalation / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D012119:Respiration / Q000502:physiology
D006632:Histamine