As you exercise, your muscles warm up and you feel sweat forming on your brow. Even your breath feels hot. Two ways your body regulates body temperature are perspiration and respiration. Your muscles need a steady flow of energy to keep working.
Heat is created when your muscles make energy. Your body works hard to regulate this temperature change and keep you within a safe range.
Working out makes your body temperature increase.
Effect of Exercise on Body Temperature
Your muscles quickly deplete stored energy when you start exercising. To make more energy, muscles combine oxygen with adenosine triphosphate or ATP. This process creates heat energy as a byproduct.
Muscles generate the most heat because they produce so much energy. In fact, a 2018 study published in the Journal of Thermal Analysis and Calorimetry showed that runners had more heat around their legs than their arms. That's because the legs do most of the work when you're running as opposed to the arms, which hardly contribute.
Extra heat raises your body temperature, so your body needs to eliminate heat as quickly as possible. Temperature sensors tell the hypothalamus in your brain that your body temperature is increasing, and something needs to lower it.
Your hypothalamus is a cone-shaped area in your brain. It secretes hormones that regulate many of your body systems. One of these systems is your body temperature. The hypothalamus works as a thermostat for your body.
Receptors in your body continually send messages to the hypothalamus about your temperature. Adjustments are made to keep your body temperature between 97.5 and 99.5 degrees Fahrenheit. If your body heat rises above that, you can sweat or radiate heat to cool down.
Maintaining Body Temperature
During exercise, extra blood flows to your muscles to bring them nutrients and carry out waste products. The muscles also generate a lot of heat, which warms the blood flowing through them.
During exercise, your body releases heat by pushing warm blood toward your skin. As you get warmer, capillaries near the surface of your skin open up. The main chemical responsible for this is called acetylcholine, according to a 2015 paper published in Advances in Physiology Education.
Warm blood goes to the surface of your skin, which is much cooler than the core of your body. This process is called radiation because heat radiates from your blood out into the environment.
Sweating to Reduce Body Heat
Sweating is another way your body cools off. Sweat glands release fluid onto the surface of your skin. When the moisture evaporates from your skin, it takes heat with it, further cooling off the blood near the surface of the skin.
Sweating doesn't work as well in very humid climates, because the water can't evaporate as quickly. That's when your body has to rely mainly on radiation to disperse heat.
Environment, Exercise and Body Temperature
When you exercise in a climate-controlled environment, like your gym, your hypothalamus keeps your body temperature at a safe level. If you exercise in hot, humid conditions, evaporation is less likely to cool you down effectively. When you work out in water, body heat is transferred to the water, and removed.
If you swim in a hot pool, this is less efficient. Watch for signs of overheating after a workout in hot, humid conditions. Signs include weakness, headache, dizziness, muscle cramps, nausea and vomiting. These are all signals that your body temperature is too high to continue exercising.
- University of New Mexico: Staying Cool When Your Body Is Hot
- Jen Reviews: The Cardiovascular System and Exercise
- Continuing Education in Anaesthesia Critical Care & Pain: Physiological Effects of Exercise
- StatPearls: Physiology, Temperature Regulation
- Advances in Physiology Education: Recent Advances in Thermoregulation
- Encyclopaedia Britannica: Body Heat
- Journal of Thermal Analysis and Calorimetry: Total Body Skin Temperature of Runners During Treadmill Exercise