An athlete’s ability to sweat may do more than keep the body cool. It also may prevent the development of exercise-induced asthma (EIA).
New research published in CHEST shows that athletes with EIA produce less sweat, tears, and saliva than those who do not have breathing problems.
Warren Lockette, from the University of Michigan and lead study author, said it is possible that athletes manifest symptoms of exercise-induced asthma simply because their levels of exertion and breathing rate are so high compared with the average, competitive sportsman.
Lockette and colleagues analysed the relationship between fluid secretion rates (sweat, saliva, and tears) in 56 athletic subjects suspected of having EIA. Air movement through the lungs, ie, the FEV1 was measured in otherwise healthy volunteers before and after the administration of methacholine, a drug that can cause airways to constrict in patients with EIA. Researchers then measured responses to the application of pilocarpine, an agent used to induce sweating and saliva production.
Individuals who were most sensitive to methacholine, ie, who had the greatest fall in FEV1, were the least sensitive to pilocarpine-induced sweat secretion – meaning, those subjects who had the most hyperreactive airways tended to sweat the least. Conversely, mean sweating rates were significantly higher among those subjects who were relatively unresponsive to methacholine – the subjects who showed no signs of EIA.
Researchers also found a correlation between the net sweat fluid excretion and net sweat sodium excretion, with sodium excretion rates being higher in subjects who were unresponsive to methacholine compared with those who were responsive.
Additionally, a significant correlation was found between sweat secretion and unstimulated salivary gland flow rates and tear secretion.
“It now appears that how much fluid your airways secrete could be a key determinant in protecting you from exercise-induced sthma,” said Dr Lockette. “So, if athletes sweat, drool, or cry, at least they won’t gasp.”