Why Does Body Temperature Increase During Exercise?

When you exercise, your body needs to produce energy to feed your muscles and kick off metabolic processes that keep you going. The harder you work, the more energy you produce, which increases your body temperature. Your body has natural processes that work to manage core temperature, but it's impossible to avoid some increase during strenuous physical exercise.

How warm your body becomes during exercise largely depends on how hard it's working. If you're sprinting, you'll produce more energy and heat than if you're out for a light jog. When you're not exercising, your average temperature will hover between 97.7 and 99.5 degrees. During intense exercise, your temperature can easily spike to 104 degrees or higher, according to the University of New Mexico.

Because your muscles fire more during intense exercise than during leisurely pursuits, core temperature spikes when your muscles contract quickly. Since the human body is only 25 percent efficient, most of the heat produced as a result of your increased metabolism will be lost to the surrounding environment, but what stays behind can make a hotter, more stressful core environment for your nervous system.

The hypothalamus is the part of the brain charged with monitoring and managing core body temperature. If your body temperature increases, the hypothalamus responds by attempting to cool you down. One of the most efficient ways to disperse heat is through evaporation. To do this, your body kicks off a sweat response by dilating blood vessels and warming the surface of your skin. This is why remaining hydrated is so important during intense exercise, especially if you're working out in hot weather.

If your nervous system is unable to regulate your body temperature at a safe level, you could be hit with some heat-related illnesses. These illnesses range from minor heat cramps and rashes to severe cases of dehydration, heat exhaustion and heatstroke. Understanding the warning signs of these dangerous conditions is your first line of defense. If you experience headache, weakness, nausea, dizziness or confusion during exercises, especially in the heat, stop, rest and rehydrate.