Why You Should Soak in a Hot Bath After Exercising in the Heat

When the temps start soaring, there are ways to help your body adapt. Maridav/Shutterstock

If you run, walk or are active in any way on a sweltering day, you know how hard it can be to cope with the heat. No matter how much water you drink or how many breaks you take, it feels impossible to cool off. And after your workout, the shower just can't get cold enough.

But it turns out we may be looking at the problem all wrong; we should be soaking in a hot bath instead. That's part of a heat acclimation strategy suggested by researchers and exercise pros to help outdoor enthusiasts safely handle summer temperatures.

But first, a little biology.

What hot weather does to your body

Exercising in hot weather puts extra stress and strain on your body. The combination of the exercise plus the air temperature and humidity can raise your body's core temperature, according to the Mayo Clinic.

To cool things down, your heart works harder to send more blood circulating through your skin. In turn, that leaves less blood for your muscles, which raises your heart rate.

If it's not just hot, but also humid, that creates extra stress because sweat doesn't easily evaporate from your skin. That makes your body temperature go even higher.

If your body does its job right, then everything works together to adjust to the heat. But your natural A/C can misfire — especially if you're exposed to heat and humidity for an extended period while sweating heavily and not drinking enough fluids.

That's when you can end up with a heat-related illness ranging from heat cramps to heat exhaustion and heatstroke.

Getting used to the heat

bucket of ice
Athletes will often plunge an arm into ice to cool down quickly. omyim1637/Shutterstock

Coaches and researchers have developed the concept of heat acclimation to help athletes get accustomed to warm weather gradually over the course of days or weeks. Slowly getting used to the heat helps the body adapt in several ways, such as sweating more and sweating earlier.

With young athletes, for example, there are typically very specific guidelines about summer athletic practices. They'll start with limited hours of practice, gradually increasing the time and intensity of exercise. They also make sure to stay hydrated and make sure they have access to plenty of methods to immediately cool off like ice towels or tubs of ice.

You may not want to stick your hand into a bucket of ice, but you can do the same heat acclimation thing by slowly increasing your time and intensity when exercising outdoors. It may help if you can start in the months leading up to the really hot temperatures by working out while wearing several layers of clothing so you can get your body used to warmth and sweating.

Researchers test cold and warmth

Some athletes battle soaring summer digits by precooling — they plunge an extremity into ice or drink freezing beverages in hopes that lowering their body temperature will help them withstand the heat more effectively. A team of scientists from the University of Brighton and other academic institutions decided to test precooling versus heat acclimation to see which might be the better bet.

For the small study, published in the Journal of Strength and Conditioning Research, nine recreational runners ran a 5K race on a treadmill in a lab where the room temperature was cranked up to 90 degrees. On another visit, the runners did the same thing, but this time, they thrust their arms into tubs of ice before they ran and wore cooling underwear and vests.

Then the scientists started acclimating the runners to the heat by gradually raising the temperature in the room to nearly 99 degrees. They slowly pedaled an exercise bike for 90 minutes, while closely supervised for any problems. Then they ran the 5K again.

For their final visit, the runners (who were now heat acclimated) ran the 5K after precooling with the icy plunge and while wearing the chilly undergarments.

The subject group was small, obviously, but the results found that the non-acclimated, non-precooled race was the slowest. The runners were faster after precooling and even faster after acclimating themselves to the heat. They didn't gain much by precooling once they had already adjusted to the heat.

What this means for you

woman soaking in bathtub
Regular baths may have a preventive effect against cardiovascular disease. (Photo: Alliance/Shutterstock)

What you can take from this experiment is that "you will receive a bigger bang for your buck from acclimating to the heat rather than by temporarily cooling yourself down" with chilled clothing and icy army plunges, Carl James, who led the study while at the University of Brighton, tells the New York Times.

Acclimation, of course, requires patience and planning as you slowly increase your workouts as your tolerance level increase. The process can require anywhere from four or five days to two weeks, says James.

Or, he suggests, "lie in a hot bath, heated to at least 40 degrees Celsius" (about 104 degrees Fahrenheit) "for 30 minutes after a 30-minute run," he says, which can magnify the way your body adapts to the heat more quickly.

Just remember that acclimating to the heat doesn't mean you're invincible outdoors. Symptoms like nausea, headache, dizziness, muscle cramping and cold, clammy skin are all signs of heat-related illness and a good reason to find shade, water and some A/C.