2. Use the Right Sunscreen and Body Lotions for Effective Thermoregulation
Maintaining core temperature whilst running is fundamental to superior performance and the prevention of exertional heat stroke. Runners require protection from UV radiation and other elements such as the wind without compromising sweat production and evaporation. Whilst clothing certainly can provide protection from the elements, two studies (Zhang et al, 2012; David & Bishop, 2013) have shown that clothing does limit convection and evaporation.
Many runners use sunscreen and other body lotions/creams to protect their skin in lieu of clothing, or use lotions, oils or creams to enhance their performance such as heat rubs, magnesium oil, or sodium bicarbonate creams. However, some skincare products also negatively impact sweating and thermoregulation, and in turn performance.
A study published in the Journal of Athletic Training (Aburto-Corona & Aragon-Vargas, 2016) investigated the effect of 2 different water-resistant sunscreens on sweat production in athletes exercising in the heat. The authors also compared the sunscreens against a control (no lotions) and an antiperspirant.
Sweat patches were applied to the scapular region of 20 healthy men and women whilst they undertook 2 exercise sessions over 2 consecutive days. The researchers assigned skin treatments (antiperspirant, Sunscreen A, Sunscreen B, or no lotion) whilst athletes pedalled an exercise bike at 80%HRmax for 20 minutes in a controlled room of 30°C and a relative humidity of 60%.
Both sunscreens were water based, and SPF50. Sunscreen A was a chemical sun filter, Sunscreen B was physical sun block (titanium dioxide), and the active ingredient in the antiperspirant was aluminium chloride.
The main result from the study was that Sunscreen B hindered sweat production to the same extent as the antiperspirant.
Treatment with Sunscreen A was not different to the Control Group for sweat production.