Supplementary Material for: Influence of Physical Exercise on Epidermal Function: An analysis of Epidermal Biophysical Properties in 327 University Students

Introduction Physical exercise influences the function of multiple organs, including the skin. Previous studies demonstrated an increase in transepidermal water loss rates (TEWL) after exercise. However, TEWL measured shortly after exercise may not truly reflect the epidermal permeability barrier function. And the limited sample size may also affect the generalizability of the findings. Therefore, we assessed the influence of physical exercise on epidermal biophysical properties in a larger cohort prior to exercise. Participants and Methods A total of 327 university students without inflammatory skin disorders or other diseases which may affect epidermal function were enrolled in this study. Epidermal biophysical properties, including TEWL, stratum corneum hydration levels and skin surface pH on the volar site of the forearm and shin were measured with a multifunctional skin physiology monitor. The correlation between epidermal biophysical properties and duration of daily exercise were determined. Results This cohort included 168 females and 159 males with a mean age of 18.91 ± 0.04 years. On the forearm, TEWL were lower in females than in males, while on the shin, both stratum corenum hydration levels and skin surface pH were significantly higher in females than in males. No significant differences in other parameters were boserved between males and females. Overall, there were no significant differences in epidermal biophysical propertied among individuals with various daily exercise duration over the past month although there was a trend of higher stratum corneum hydration levels among individuals with longer duration of exercise. However, TEWL on the shin of females positively correlated with the daily exercise duration. Conclusions. There are slight but significant differences in some epidermal biophysical properties between male and female university students. Overall, exercise does not dramatically affect TEWL, stratum corneum hydration levels and skin surface pH on both the shin and forearm except on the shin of females where shows a positive correlation between the daily exercise duration and TEWL.