Fitness & Health, Sport & Exercise Science

Exercising after heatstroke

Britain’s Jim Peters was the greatest marathon-runner of his day and set repeated world records but never won gold at a major Games.

The nearest he came was in the 1954 Commonwealth Games in Vancouver, when he entered the stadium with a massive 17-minute lead, only to slow, stagger and collapse with heatstroke yards from the finish.

Peters, his skin a deathly mottled grey and a collar of foam streaming from his mouth, was carried away on a stretcher never to run competitively again.

Over 50 years on and heatstroke still remains poorly understood, or even misunderstood, by the medical community. Although experts know how it is caused and that it damages tissues and organs, they are at odds as to the recovery time and process.

As a person exercises in the heat, blood gets diverted to the surface of the skin for cooling. The hotter the person gets, the more blood is diverted — as much as 25 percent of the body’s blood can end up going to the skin instead of to exercising muscles and to organs like the intestines, kidneys and liver.

One result can be heat exhaustion where the person may collapse, unable to continue exercising. Another result however is heatstroke, a much more serious condition characterized by delirium or coma.

In treating cases of heatstroke, the first thing that should be done is to immediately cool the person, with an ice bath, cold water, or cold towels.

But the real damage can be insidious, researchers say. Most people know that with heatstroke you are exposed to heat, you exercise and you collapse. What they they don’t know is what happens in the days, weeks and months that follow.

An old, and incorrect, idea is that heatstroke involves damage to the hypothalamus, a brain region that regulates body temperature.

However autopsy studies and some MRI scans of people who had heatstroke, indicate the hypothalamus is not damaged. Injured brain regions include the cerebellum and the cerebral cortex, which is why people pass out,

Much more worrying though is lasting damage to the liver and kidneys. One study of distance runners who had had heatstroke and underwent repeated liver biopsies, indicated that their livers were still recovering four months later.

A study by the US Army’s Research Institute for Environmental Medicine found that 30 years after soldiers had heatstroke they were still at increased risk of death from liver failure and other organ damage.

But just when is it safe to return to exercise? Most doctors follow guidelines from professional organizations that say it is necessary to wait at least a week after you have left the hospital. Then, if a medical assessment indicates that you seem to have recovered, you can gradually return to exercise.

Source: New York Times

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