Exercise in the heat: could the poison also be the cure?

Posted on Tuesday, October 8, 2019

Thermometer showing intense heat.

In ancient times, there were tales of paranoiac rulers and megalomaniac kings who, fearing that their enemies would try to have them poisoned, would start drinking a small dose of poison every day to develop a resistance to the toxins.

This might seem like a foolish thing to do, but it looks like there might be some truth behind these archaic methods after all.

When Professor Glen P. Kenny and his team at the HEPRU Lab at the University of Ottawa set out to discover how older individuals living with type 2 diabetes would react to exercise in hotter temperatures, they unexpectedly discovered that the poison could also be the cure.

Their study, published in the Journal of the American Medical Association, demonstrates that exercise-heat stress can be both “friend and foe” to those living with type 2 diabetes.

“Our work shows that older men with type 2 diabetes show less ability to dissipate heat during exercise in a hot environment relative to their healthy counterparts, which can cause increases in body temperature and heart rate that may elevate the risk of health complications,” explained Professor Kenny, University of Ottawa Research Chair in Environmental Physiology. “However, the data also shows that those impairments may be offset by brief, supervised exercise training in a hot environment. That is a very important piece of information, since exercise is a cornerstone in the management of type 2 diabetes.”

Indeed, after 7-days of brief and supervised exercise training in a hot environment, it seemed that subjects with type 2 diabetes appeared to adapt and minimize future health risks. Results also suggest that thermoregulatory function in individuals with type 2 diabetes appears to adapt to exercise training in the heat better than in healthy subjects.

These conclusions are intriguing. However, this study is certainly not an excuse for individuals living with type 2 diabetes to throw caution out the window.

“Everyone, especially those who live with type 2 diabetes, should still be very cautious when performing strenuous exercise, particularly in the heat,” added Kenny. “We would recommend that they exercise indoors, in a cool and/or dry and well-ventilated environment. When performing activities outdoors in the heat, they should try to limit the activities to the early or later hours of the day, when temperatures are at their lowest. Exercising in the direct sun should also be avoided and, when possible, intersperse rest or breaks periodically in a cool ventilated location.”


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