Ringworm, despite its name, is not actually caused by a worm, but by an infectious fungus known as tinea. Because tinea is highly contagious and thrives in wet conditions, gyms are a prime breeding ground. Using shared equipment such as cardio machines, yoga mats and exercise balls can expose you to tinea, as can gym pools and showers. Ringworm infection often appears as ring-shaped red spots on your skin and requires treatment with topical antifungal medication.

Wear clean, dry clothes every time you go to the gym. Launder sweaty clothes and swimsuits after every workout, and wash your gym bag regularly as well. Ringworm fungus thrives in damp clothing stored in gym bags and lockers.

Shower after you work out, preferably with an antifungal cleanser. Wear flip-flops to protect your feet and bring your own toiletries rather than sharing. Don't forget to shampoo your hair, especially if you went swimming or your head touched communal equipment.

Bring your own towel and yoga mat. Use towels only once, and clean your mat with sanitizing solution after every class. Look for mat sprays containing the natural antifungal tea tree oil, or make your own by adding two drops of the oil to a spray bottle filled with one-quarter white vinegar and three-quarters water.

Wipe cardio and weight machines with disinfectant wipes before use. If your gym doesn't provide wipes, carry your own in your gym bag.

Avoid skin-to-skin contact with other gym patrons, especially when either of you is sweaty. Save handshakes and hugs for outside the gym.