According to the results of our study, we recommend the parameter ratio of elastic recovery to distensibility (U(r)/U(f) ) as well as the gross elasticity (U(a)/U(f)) for evaluation of aging effects on the mechanical properties of skin. Their high correlation with age makes them particularly applicable to represent the influence of aging onto skin mechanical properties. Most suitable localizations to evaluate skin aging are cheek, forearm and neck.

Skin physiological distinctions between the sexes exist and are particularly remarkable with regard to sebum production and pH value.

The protection against water loss and the prevention of substances and bacteria penetrating into the body rank as the most important functions of the skin. This so-called 'skin barrier function' is the natural frontier between the inner organism and the environment, and is primarily formed by the epidermis. An impairment of the skin barrier function is often found in diseased and damaged skin. An influence of ageing on skin barrier function is widely accepted, but has not been conclusively evaluated yet. Therefore, the aim of this clinical study was to assess the potential influence of ageing on skin barrier function, including transepidermal water loss (TEWL), stratum corneum hydration, sebum content and pH value. One hundred and fifty healthy women aged 18-80, divided into five age groups with 30 subjects each, were evaluated in this study. TEWL, hydration level, sebum secretion and pH value of hydro-lipid acid film were measured with worldwide acknowledged biophysical measuring methods at cheek, neck, décolleté, volar forearm and dorsum of hand. Whereas TEWL and stratum corneum hydration showed only very low correlation with subject's age, the sebum production decreased significantly with age, resulting in the lowest skin surface lipids levels measured in subjects older than 70 years. The highest skin surface pH was measured in subjects between 50 and 60 years, whereas the eldest age group had the lowest mean pH. The dorsum of the hand was the location with the highest TEWL and lowest stratum corneum hydration in all age groups. The results show that only some parameters related to skin barrier function are influenced by ageing. Whereas sebum production decreases significantly over lifetime and skin surface pH is significantly increased in menopausal woman, TEWL and stratum corneum hydration show only minor variations with ageing.

The present study verifies the progressive decline of the skin mechanical properties with aging. However, the elastic ability of the skin to recover after stretching is more strongly affected by the aging process than the firmness of the skin. Further, the mechanical properties change differently in men and woman over lifetime.