Sunscreen formulations do not interfere with sweat cooling during exercise

Abstract

OBJECTIVE: Sweating plays a critical role in maintaining thermal balance and keeping skin cool during exercise. People often wear sunscreens on hot summer days for sun protection. Most recreational sunscreens are designed to be water-and sweat-resistant, so that sweating will not remove or compromise the protection. The objective of this study was to determine whether wearing sweat-resistant sunscreen might impede natural sweating, potentially interfering with thermal regulation and resulting in the elevation of skin temperature. METHODS: We conducted a controlled, randomized, split-face and split-arm clinical study with 24 female subjects wearing an SPF 70 lotion sunscreen on half of the face and an SPF 70 spray sunscreen on one of the forearms at a dosage of 2 mg cm À2. Following sunscreen application, subjects participated in two sessions of indoor exercise to induce clearly visible sweating. RESULTS: We found that both skin temperatures and sweat evaporation rates were significantly elevated after each session, yet there were no significant differences in either skin temperatures or sweat rates between the treated and untreated control sites at any time point for any of the skin sites measured. CONCLUSION: We conclude that the application of tested sweatresistant sunscreen lotions and sprays does not have any measurable effects on skin cooling by natural sweating process. People should continue to use these sunscreens during recreational activities.R esum e OBJECTIF: La transpiration joue un rôle essentiel dans le maintien de l' equilibre thermique et pour garder la peau fraiche pendant l'exercice. Les gens portent souvent des ecrans solaires pendant les chaudes journ ees d' et e pour se prot eger du soleil. La plupart des ecrans solaires r ecr eatifs sont conc ßus pour r esister a l'eau et a la transpiration, de sorte que la transpiration n' elimine ni ne compromet la protection. L'objectif de cette etude etait de d eterminer si le port d'un ecran solaire r esistant a la transpiration pourrait entraver la transpiration naturelle, interf erant potentiellement avec la r egulation thermique et entraînant une el evation de la temp erature cutan ee. M ETHODES:Nous avons men e une etude clinique contrôl ee, randomis ee, h emi-visage et bras droit -bras gauche, avec 24 sujets f eminins portant un lotion solaire SPF 70 sur la moiti e du visage et un ecran solaire SPF 70 sur un des avant-bras a un dosage de 2 mg/cm2. Apr es l'application de la cr eme solaire, les sujets ont particip e a deux s eances d'exercices en salle pour induire une transpiration clairement visible. R ESULTATS: Nous avons constat e que les temp eratures cutan ees et les taux d' evaporation de la sueur etaient significativement elev es apr es chaque s eance, mais qu'il n'y avait pas de diff erences significatives de la temp erature cutan ee ou de la sudation entre les sites trait es et non trait es. CONCLUSION: Nous concluons que l'application de lotions antisolaires r esistants a la transpiration test es et des sprays n'a aucun effet m...

Sunscreen Application, Safety, and Sun Protection: The Evidence

“…An important consideration when applying sunscreen during physical activity is the effect of sweating on sunscreen protection and vice versa. A controlled, randomized, split-face and split-arm clinical study with 24 female participants conducted by Ou-Yang et al 54 found no significant differences in either skin temperatures or sweat rates between the treated (application of sweat-resistant sunscreen) and untreated control skin sites during exercise. As sweating is a crucial process in skin cooling and thermal regulation, this study highlights the safety of using water- or sweat-resistant sunscreen during exercise.…”

Heat-related issues and practical applications for Paralympic athletes at Tokyo 2020

“…Hence, reducing time in the sun and ensuring sun cream is applied frequently is crucial for these athletes. Current research is however inconclusive regarding the effect of sun cream on sweat production and evaporation [57][58][59].…”

Efficacy of ceramide‐containing sunscreen on skin barrier

“…There is a limited amount of research on the impact of sunscreen use on skin homeostasis, and little studies have compared skin homeostasis parameters before and after applying sunscreen. While there have been studies on the effects of sunscreens on TEWL, these have mostly focused on sunscreen use during physical exercise 12 …”

“…While there have been studies on the effects of sunscreens on TEWL, these have mostly focused on sunscreen use during physical exercise. 12 Both a* and erythema exhibit a reduction following sunscreen application. They directly reflects the situation of blood hemoglobin in the dermal papillary layer.…”