The expert insight:
During workouts, wearables create friction, which can cause irritation, says Joshua Zeichner, MD, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City. Trapped sweat can soften the skin, making it more vulnerable.
You're most likely to experience this if you wear your strap really tight and if it's rubber, which is stiffer than fabric.
To avoid rashes, Zeichner recommends taking off your fitness tracker after every workout, wiping it with a clean towel, and allowing it to dry while you shower. Once a week, rub all of its surfaces with an alcohol wipe, which is safe for electronics.
Before putting your watch back on, apply lotion (he recommends this one) to your wrist. This locks in hydration and forms a protective layer between skin and band.
The bottom line:
If you do all of the above and continue getting rashes, Zeichner suggests switching to a nylon strap. The fabric is very pliable, making it less likely to cause a harsh reaction. If the issue persists, talk to your dermatologist; you may have an underlying issue like an allergy.