Effects of short-time hydration on skin extensibility.

Vertical cutaneous extensibility was studied before and after 1, 2, 5 and 10 min hydration by application of tap water. After hydration, we noted an increase in all rheological parameters linked to elasticity whereas viscosity and hysteresis parameters were unmodified. These modifications took place from the first minute and increased thereafter. Men and women showed identical values prior to hydration. After hydration, an extensibility gain was noted only in the women, men's extensibility being unmodified. Studying rheological behaviour as a function of age, we showed similar modifications in younger and older groups, the extensibility gain being greater in the older group. Prior to hydration, the stratum corneum was extremely rigid and extensibility was comparable between men and women. Hydration, softening the horny layer, allows a rapid extensibility gain proportional to the reduced thickness of the dermis, especially in women and older subjects.