When you do a cardio workout, do you have to constantly reach for a towel to wipe the sweat off of your face? Is there a small puddle of water underneath you after a high-intensity workout? Sweating is a mechanism your body uses to eliminate heat and bring down your core body temperature when you work out – and there’s lots of variation in how much each person sweats. On the other hand, some people believe profuse sweating is a sign they’re out of shape. Is there any truth to this idea?
What Sweating Says about Your Fitness Level
Sweating heavily during a workout doesn’t mean you’re not fit. Sweat rates are highly variable. Losing between a liter and a liter and a half of sweat per hour during vigorous exercise is about average, and people with larger body masses will typically sweat more than their smaller counterparts.
Temperature and humidity of the environment are two other factors that impact sweat rates. When the relative humidity of the environment you’re exercising in is high, sweat evaporates more slowly and you have to towel off more during a workout. That’s why the heat index is a better indicator than the temperature of how comfortable and uncomfortable exercise feels and how much you’ll sweat. The heat index takes into account both temperature and humidity. Any time it’s harder to lose heat (in a humid environment) your core body temperature climbs more and you feel more sweaty and uncomfortable.
Fit Individuals Tend to Sweat Sooner
Sweating earlier and more profusely may be a sign of a HIGHER fitness level. Athletes and individuals who are aerobically fit are more efficient at releasing heat and tend to sweat earlier in a workout than less fit individuals. If you regularly spend time exercising in the heat, you’ll sweat sooner and more profusely because your body is heat-acclimated and better able to deal with heat. It usually takes about two weeks of exercising in a hot environment to become heat acclimatized.
During heat acclimatization, your body makes a number of adaptations that makes it more efficient at releasing heat – plasma volume increases, heart rate decreases, fewer electrolytes are released through sweat, blood pressure response to exercise improves and there’s redirection of greater amounts blood flow to the surface of the skin so that sweating can occur. As a result, your body becomes more adept at eliminating heat and working out in a hot environment. To become heat-acclimated, you have to EXERCISE in a hot environment. You won’t get the same benefits by sitting or doing light work in a hot environment and you won’t maintain these benefits unless you contain to work out in the heat.
Other Causes of Excessive Sweating During Exercise
As you can see, sweating early and sweating a lot can be a sign of fitness but there are other causes of excessive sweating. Profuse sweating can be due to hormonal fluctuations, stress, and anxiety, a sign of low blood sugar or low-grade fever or a symptom of an overactive thyroid gland. In these cases, you’re likely to experience excessive sweating when you’re resting too. Some medications also increase the sweat rate. In addition, there’s variation in how many sweat glands a person has. Some people naturally sweat more than others.
There is a condition called hyperhidrosis where the main symptom is excessive sweating, usually in specific areas like under the arms or the palms of the hands. This condition tends to run in families and the sweating doesn’t occur just with exercise. It occurs at rest too. Anxiety, spicy foods, caffeine, and stress can aggravate this condition. Almost 3% of the population has hyperhidrosis.
What Sweating Means
Sweating a lot during exercise is no indication that you’re in bad shape. Fit people and those who are heat acclimated sweat sooner and sweat more. There’s also lots of individual variation in sweat rates based on body size, genetics and number of sweat glands so the amount you sweat during exercise doesn’t necessarily mean a whole lot. Excessive sweating is more concerning if you sweat a lot at rest. This can be a sign of medical problems like an overactive thyroid or a manifestation of anxiety.
Sweating during exercise may be a good sign. It means you’re exercising vigorously enough to get your core body temperature up. Want to know what your sweat rate during exercise is? Weigh yourself without clothes before and after working out for an hour. For each kilogram your weight dropped between the two weigh-ins, you lost about a liter of fluid. Of course, you’ll have to take into account any water you drank during exercise. Your sweat rate will vary with the temperature and humidity of the environment you’re exercising in as well as the intensity of your workout. This gives you a better idea of how much fluid you need to replace after a workout.
The Bottom Line?
Sweating is a normal response to exercise and there’s a lot of variation in sweat rates. The most important thing is to make sure you’re rehydrating and are aware of the signs of heat exhaustion and heat stroke and take steps to protect yourself from dehydration.
Armstrong, L. E. (Ed.) (1998) Encyclopedia of Sports Medicine and Science.
Canadian Medical Association Journal 172 (1): 69–75.
Exercise Physiology: Theory and Application to Fitness and Performance. Powers and Howley. (2009)