title: Exercise-induced asthma - a comparison between two modes of exercise stress.
abstract: Two types of treadmill exercise were performed by 10 asthmatics (mean age 32.4 +/- 8.9 years). One type of exercise was a steady state, submaximal effort lasting approximately 7 min. The other was a short, supramaximal effort designed to exhaust the subjects within 50 s. Ventilatory studies as well as gas exchange, arterial blood lactate (LA) and pH were measured pre- and post-exercise. The submaximal exercise caused the expected increase in Raw (19%) and a decrease in FEV1 (21%) and MMEF (20%) measured 10 min following exercise. In contrast, only the MMEF was reduced (26%) at 10 min after the short-exhaustive exercise. It was concluded that short (less than 1 min) and highly intense exercise challenge may cause a drastic fall in MMEF with no changes in FEV1.0 or Raw. It is postulated that the unequal ventilatory response to the two exercise modes is responsible for a greater respiratory heat loss during the long-submaximal exercise and consequently for the greater obstruction of the large airways. In addition the short-exhaustive exercise performed in this study may serve as a simple and accurate tool for detecting small airway obstruction as measured by the MMEF.
mesh_terms: D000328:Adult; D001249:Asthma / Q000209:etiology* / Q000503:physiopathology; D001250:Asthma, Exercise-Induced / Q000209:etiology*; D001784:Blood Gas Analysis; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008297:Male; D010993:Plethysmography, Whole Body; D012119:Respiration; D013312:Stress, Physiological / Q000150:complications
chemical_list: D007773:Lactates; D019344:Lactic Acid