On Court Sun Protection Gets Technological.
Sweating and toweling remove much of the sunscreen you initially put on. I've heard recommendations for reapplication every changeover for big drippers.
If you are one who needs to be reminded here are a couple of new options:
Coppertone's MyUV Alert for iPhone (image above) can look up an area's UV index and provide customizable sunscreen application reminders based on what you are doing under the sun. You can't use this during a USTA match where phones are banned on court but this is great for practice days. You can also email Coppertone coupons from the app. Good savings on a summer necessity. Free from the App store.
Another option is the UVSunSense bracelet. The bracelet acts as a sun-sensitive gauge. Apply sunscreen to your body and to the wristband before playing outside. Watch as the band changes colors so you know exactly when you need to reapply and when you need to get out of the sun.
The wristband’s four color stages let you know when your sunscreen is wearing off. It starts off as orange when removed from the packaging and turns purple when exposed to the sun, indicating it has been activated. When it becomes dark brown it is time to immediately reapply sunscreen. If the band turns a salmon color, the user should get out of the sun completely (or cover up), having approached the recommended daily limit of UV radiation.