Running is an aerobic form of exercise that can be maintained for a long period of time. It elevates the heart and breathing rate in an effort to bring more oxygen into the system. This oxygen is then used to create more energy to fuel the muscles throughout the duration of the workout. But rather than cool your body down through the release of heat, the body's temperature actually experiences an increase during exercise -- and for several hours afterward.
Starting Exercise
The body's internal temperature increases gradually from a normal state as exercise begins. Heat is produced within the body and is released, and as your internal temperature increases the body's cooling mechanisms start to kick in.
Energy Lost as Heat
As the body tries to cool itself down, it is also tasked with producing energy to fuel exercise. This is more important in aerobic exercise, when energy is produced from oxygen and water and is generated over a longer period of time. According to DrMirkin.com, more than 70 percent of your body's energy used to fuel your exercise is released as heat from the body. Blood fills the capillaries close to the surface of your skin to help this heat escape the body faster during exercise, but your body's temperature still rises and remains elevated for the duration of the workout.
After Exercise
Although the body does cool down after exercise, it does so at a slower rate than it took to get warmed up. Many people experience a slightly heightened body temperature for up to six hours after a workout. During this period, it can be more difficult to fall asleep and you might be more prone to sweating or becoming hot.
Considerations
If you do experience a cooling body temperature during exercise -- or feel like you are cooling down -- it could indicate a serious condition like dehydration or exhaustion. Stop exercising and call your doctor. You may feel cooler after a workout when the sweat is still on the surface of your skin, but this cool sensation is only masking your increased internal temperature.
