How many times have you stopped during a workout to wipe a bead of sweat off your forehead? Exercise raises your core body temperature, especially if you work out hard in a warm environment at a vigorous intensity. During a HIIT workout, you might find your whole body drenched in sweat! Sweating is the body’s cooling mechanism, and you can really work one up when you’re pushing your body hard. If you didn’t have the ability to sweat, your body temperature could climb to dangerously high levels during a workout.
Your body likes to maintain body temperature within a narrow range. If sweating didn’t occur, your internal temperature would climb to the point that it would endanger normal bodily functions. In fact, some people suffer from a condition called anhidrosis and lack the ability to sweat normally. When they exercise, they experience lightheadedness, dizziness, and muscle cramps. As you might expect, they’re also at higher risk of heat stroke and heat exhaustion, and it’s important to do everything you can to keep from overheating. One way to do that is to drink plenty of fluids before, during, and after a workout.
You might wonder how being physically fit impacts how much you sweat and whether how much you sweat is a marker of fitness or lack of. What does research say about sweating and physical fitness? Do fit people sweat more or differently than less physically fit individuals?
Why Fit People Sweat More
Research shows people who are physically fit sweat more during a workout and sweat earlier when they do the same workout as someone less physically fit. Your body adapts to physical activity in a number of ways. One way is by making adjustments and adaptations that allow better control of core body temperature.
When your core body temperature rises, as your muscles contract rapidly and produce heat, your circulatory system responds by dilating superficial blood vessels that release heat to the outside of the body. Once the vessels open up near the surface of the skin, heat leaves the body through conduction, convection, radiation, and evaporation. Interestingly, wiping the sweat off of your skin with a towel can interfere with heat loss as it reduces the release of heat through evaporation.
How does your circulatory system know when to dilate blood vessels to release heat? A portion of your brain called the hypothalamus acts as a thermostat and monitors for changes in body temperature and responds accordingly. It plays the biggest role in maintaining healthy body temperature. Once the hypothalamus sends the signal, your heart and blood vessels get in on the action. Superficial blood vessels dilate and the heart pumps faster to send more blood to the surface of the skin to release more of that heat! It’s a carefully orchestrated system that helps you avoid a dangerous rise in body temperature. Research clearly shows that fit people make the necessary adjustments faster than sedentary folks, and as people get fitter, they release heat faster. In fact, sweating starts within a few seconds of vigorous exercise in fit people, and this response is faster and more efficient than in sedentary folks. It’s one of the ways your body adapts to exercise. It kicks into gear the necessary mechanisms you need to weather a hard workout. So, you sweat more and sweat sooner and faster.
Another difference between fit and sedentary people in terms of sweating is that fit people lose fewer electrolytes per volume of sweat they release. This is another protective mechanism your body uses to keep you safe during a tough workout. You become a more economical sweater. You lose fluid and heat but fewer electrolytes. Interestingly, women usually produce less sweat than men, as each sweat gland releases less fluid in females.
Hydration is what helps you stay safe and perform your best when you exercise. Even mild dehydration can negatively impact exercise performance. Once you’ve lost 2% of your body weight in water, exercise performance steadily drops off. When you’re dehydrated, exercise feels harder and becomes harder to sustain. In general, you should drink 7-12 ounces of fluid 30 minutes before a workout. Every 20 minutes, drink 4 to 8 ounces of cold fluid.
However, there isn’t a one-size-fits-all approach to hydration. Some people naturally sweat more profusely and lose more electrolytes in their sweat. One way to determine if you’re adequately hydrating is to weigh yourself before and after a workout. Urine color is also a good indicator. If you’re well hydrated, your urine should be the color of pale lemonade or lighter. Darker than this is a sign that you’re not hydrating well enough.
What should you hydrate with? If you’re exercising for an hour or less, hydrating with water is sufficient. If your workouts are longer, you can benefit from an electrolyte-rich beverage to replenish electrolytes you lose through sweating. Rather than buy a sports drink, coconut water with a pinch of sodium is sufficient. There are advantages to commercial sports drinks that contain carbohydrates if you’re doing a long, grueling workout. During a challenging workout, you use up glycogen stores and this can reduce your performance. But you don’t need them for daily workouts that are less than an hour or so.
The Bottom Line
If you’re physically fit, you probably sweat more and earlier than your friend or neighbor who doesn’t work out. Just as your body adapts to exercise in other ways, it becomes more efficient at regulating your core body temperature. That comes in handy when you’re working out in a hot environment. Regardless, make hydration a priority! It’s not only important for your performance and comfort but for your health.
· The Naked Scientists. “Is someone who starts sweating sooner fitter?”
· Med Sci Sports Exerc. 2007 Feb;39(2):377-90.
· USADA. “Fluids and Hydration”