In our last blog post, we discussed the different ways in which the body is affected by heat. We concluded by warning our readers against the dangers of overheating, noting that a 1993 study advised medical professionals to monitor heatstroke victims for several months after the incident, due to its severity.

You may take pause at the suggested recovery time. Several months? Isn’t this more along the lines of the recovery time needed for a broken bone? It’s a long time, yes, but researchers have examined exertional heat stroke for decades. Many, many studies have found the body experiences severe stress, which can cause issues with the nervous system, cardiovascular system, liver, muscles and even the brain.

Although this blog post provides a somber look at the effects of heat stroke, it’s not meant to “scare” you out of exercising this summer. By all means, go out and enjoy the sunshine! We simply want to warn you against overdoing it and having to take too much off. Use caution, stay hydrated, and you can enjoy being outdoors.

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What is heatstroke:

According to a 2007 study in the Journal of Sport Rehabilitation, exertional heat stroke (EHS) occurs “when a person’s metabolic heat production, coupled with environmental conditions, overpowers the body’s ability to dissipate heat.” That’s science-talk for saying your body can’t cool itself. The body likes to stay at a temperature of 98.6°F (37℃), and it has several mechanisms to ensure it stays there, which include sweating and moving blood to the surface of the skin.

However, when these mechanisms aren’t enough, the body cannot regulate core temperature. This results in stress that can damage internal organs. If this stress is not mitigated, it can eventually be fatal.

Heatstroke is the most extreme version of overheating, and if the victim does not take steps to cool off immediately, it can lead to coma and even death. Common symptoms are dizziness, drowsiness, confusion, staggering, aggressiveness, feeling “cold,” a sudden reduction in sweat-rate, and extreme thirst.

What happens to your body during heatstroke:

When the body overheats, blood is shifted to the surface of the skin. In extreme heat, 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. This, coupled with the rise in core temperature, can cause internal damage.

One of the most common symptoms of overheating is “feeling cold,” despite obvious indications otherwise. As your central nervous system is disrupted from the stress, it goes a little haywire. The cold feeling you get is the result of conflicting signals between your nerves and your brain. This is also the reason you can get confused or aggressive when you overheat.

Other areas of the body are affected as well:

• Liver: Several studies, ranging in time from 1972 to 2006, have found that heatstroke often causes liver damage in runners. A 1980 study by the Canadian Medical Association reported hospitalization due to liver damage in at least one runner who suffered heatstroke during a 10k. It took four months for the runner to recover. In 1972, scientists published a paper in Human Pathology, which found the liver takes between nine days and two months to recover in most heatstroke victims.
• Heart and cardiovascular system: Two studies, in 1999 and 2001, (Intesive Care Medicine and International Journal of Cardiovascular Imaging, respectively) found that heatstroke can cause small tears in the myocardium heart tissue, although these effects are rare. Luckily, the 2001 study also found almost no irreversible long-term damage to the heart.
• Muscular system: Crossfiters may have heard of “rhabdo,” which stands for rhabdomyolysis, or muscle-cell destruction. Sometimes caused by severely overusing the muscles in a workout (like Crossfit, if not done properly), this dangerous condition is also a serious side-effect of heatstroke. The bad news for endurance athletes is that rhabdomyolysis can result in a chronic reduction in lactate-threshold. A 1997 study in the Journal of Neurology found that heatstroke victims reached their lactate threshold in a significantly shorter period of time than a control group. (Lactate threshold is the point at which the body cannot remove lactate build up as fast as it is produced. In general, a higher lactate threshold will allow for greater endurance performance.) Luckily, even if a person experiences rhabdomyolysis, the muscular system can recover relatively quickly in about four weeks.
• Heat tolerance: Heat tolerance, or the body’s ability to dissipate excess heat, can be damaged during heat stroke. In fact, a “heat tolerance test,” (in which a person walks or jogs on a treadmill for 1 – 2 hours in a hot room) is used by many organizations, including the Israeli Defense Forces and the U.S. Army and Air Force, to test whether a recruit is able to return to fighting. Although there is no scientific way of predicting how long an individual’s heat tolerance will be affected, studies have documented heat intolerance lasting everywhere from three weeks to five years. Most sports medical professionals, however, believe one month is enough time for most heat stroke victims to recover.

What to do immediately after overheating:

Knowing the dangers of heatstroke, victims must act fast to repair the damage. In all of the instances listed above, the severity of the injury was highly correlated with the amount of time it took to cool the victim.

We’ll say that again because it’s so important: Every study we’ve listed above concluded that cooling the victim was the most important step to mitigating damage to organs.

If you think you or a training partner are suffering from heatstroke, it’s absolutely imperative to cool off as quickly as possible. If you’re near indoors, go inside immediately. Take a cold shower or ice bath. If you’re outside, get in a shady area and remove excess clothing. Apply cold water or ice packs to areas such as under the arms, on the neck or on the back.

What to do in the days and weeks following heatstroke:

After a person is cooled from heatstroke, it can take anywhere from a week to several months to recover. The length of recovery is usually correlated to how long a person took to cool off. Based on research, recovery is generally a four-step process:

• Step 1: Do not work out for a week, and avoid the heat as much as possible. Your ability to withstand heat is greatly compromised, so it’s imperative to avoid overheating.
• Step 2: Take a self-check to see how you feel. It’s common to feel sluggish and unable to work out, but the symptoms will pass. If, after a week, you still feel like running 30 minutes is a monumental effort, take a few more days off. “The first week after my heatstroke I was lethargic, totally out of it,” Douglas Casa, a heat stroke victim, told The New York Times in 2010. “It took me two or three weeks to get my energy back.”
• Step 3: When you feel up for it, take a “heat test.” Ideally, a test is performed under medical supervision, but you can’t see a physician, try walking on a treadmill for 20 minutes to get your blood moving. If that goes well, keep walking, but don’t go for more than an hour.
• Step 4: Take it easy. It will take at least a month in almost every situation to recovery from heat stroke. During that month, you shouldn’t attempt any hard workouts, and you shouldn’t attempt to workout in the heat. Easy, indoor workouts are the best.

Recover will be unique to your physiology and the extent of the damage.

Conclusion:

Again, this post isn’t meant to scare you off from summer exercise. Instead, it’s an advisory warning. Do not overdo it because the consequences can be very severe. Instead, use caution, and you’ll have a great summer of outdoor activities!

Happy training!

Important Note: The above should not be construed as medical advice. Contact your physician before starting any exercise program or if you are taking any medication. Individuals with high blood pressure should also consult their physician prior to taking an electrolyte supplement. Overdose of electrolytes is possible, with symptoms such as vomiting and feeling ill, and care should be taken not to overdose on any electrolyte supplement.