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Exercise is essential for our health. And when you’re exercising—or doing anything—outdoors, using sunscreen is important to protect your body from skin-damaging ultraviolet (UV) rays. Overexposure to UV rays can cause skin cancer.
However, many people who are active outdoors think that sunscreen reduces exercise performance by making us overheat. But, rest assured: New research published in the Journal of Applied Physiology found that sunscreen does not cause overheating during exercise.
In the study, volunteers in their 20s exercised in a hot room on six different days. There were three tests in a hot and dry environment (up to 111°F in low humidity) and three in a warm and humid environment (93°F with up to 63% humidity). The participants wore mineral-based sunscreen, chemical-based sunscreen or no sunscreen for each environment.
In all six trials, the volunteers walked on a treadmill at a moderate intensity (3.5 miles per hour at a 4% grade). Either the temperature (in the hot and dry environment) or the humidity (in the warm and humid environment) was increased every five minutes until the participants’ body temperature began to rise.
The air or room temperature and the humidity that causes our body temperature to increase represent our “critical environmental limit.” This limit is important because we want to know whether sunscreen causes an unsustainable rise in body temperature at a lower ambient temperature or humidity than without sunscreen.
However, in this study, sunscreen did not affect the environmental limits in the hot-dry or warm-humid environment. Sunscreen also did not affect how hot or uncomfortable people felt while they exercised. Finally, wearing sunscreen did not affect how much the volunteers sweated or how wet their skin got during testing. These results show that sunscreen probably does not impair how the body deals with exercise in the heat.
This research on body heat regulation is important because of the increasing frequency, duration and intensity of heat waves worldwide. Future studies can determine whether sunscreen affects body temperature regulation in middle-aged and older adults because we know already that aging increases susceptibility to heat stress.
So, don’t worry about sunscreen reducing your heat tolerance when you’re outside. It’s time to lather it on. And it won’t mess up your drip.
Thanks for reading!
Joseph C. Watso, PhD, is the Cardiovascular & Applied Physiology Laboratory director and an assistant professor in the Department of Health, Nutrition and Food Sciences at Florida State University. He studies strategies to improve cardiovascular health across the lifespan.
Special thanks to the APS Communications and Editorial Staff.