A hot shower encourages blood flow toward your skin, soothing your muscles. You relax. You feel good. A cold shower does the opposite. In response to the cold temperature, your body will do its best to protect your internal organs, encouraging the blood to flow away from the outer extremities and skin. Why is this good?
When you exercise, your heart rate increases to support your body's needs. Lactic acid builds up in muscles when they're deprived of oxygen, a normal occurrence when your workout is intense and your body dips into its energy reserves (glucose) to meet the intense energy need. When people talk about "feeling the burn," it's the lactic acid that's behind that bite.
Cold temperatures immediately after your cool-down help bring your heart rate down and increase your circulation, which in turn helps reduce your recovery time. The increased level of blood your heart pumped to match your body's needs won't be allowed to pool in your tired muscles, and those muscles will clear the lactic acid more quickly.
Additionally, exercise can cause muscles to become inflamed -- the swelling caused by small tears in the muscle fiber -- and a cold shower may help to minimize soft tissue inflammation and its associated pain.
Overall, if you're healthy, a cold shower after aerobic exercise may help to constrict blood vessels and decrease your metabolic activity, which equals less tissue damage and less swelling. Endurance athletes may want to try something a little more intense as part of their cool down: ice baths. An ice bath involves soaking in cool water for 15 to 20 minutes post-workout, and you can decrease the temperature as you begin to adjust to the cold. Accompany your cold shower with a sports massage, and you'll not only reduce the build-up of lactic acid in your post-workout muscles to reduce soreness and swelling, but you'll also boost your circulation and loosen tight muscles.
Check out the next page to learn more about the benefits of cold showers and ice baths.