Germs love a warm, moist environment. That means they love locker rooms. Many people come and go there, and some may be carriers of illness even if they show no symptoms. Skin infections are the most common danger. These range from boils and impetigo to herpes simplex and ringworm. An alarming one in three Americans suffers from a skin disease [source: Brody]. Ordinary colds and flu can spread easily in the gym as well.
Precautions are even more important if you play a sport like basketball, squash or wrestling where you might have contact with another person. The combination of someone else's sweat and minor abrasions on your own skin can spread disease. Even if you're just using workout equipment, it's probably been touched by others. So, a thorough shower is your first defense against infection.
To minimize the chances of catching something, always use your own soap (preferably an anti-bacterial soap), shampoo and razor. Be sure to lather your entire body, not just your armpits and groin. Afterward, dry yourself carefully; apply fresh dressings to any cuts or scrapes and put on clean clothes.