Skin mechanical properties present adaptation to man's upright position. In vivo studies of young and aged individuals.

In tall animals dependent tissues are stiffer to prevent oedema formation in the upright posture, but whether the same adaptation is operating in man is not known. Skin elasticity and distensibility were measured in vivo in 18 young and 15 aged individuals in the morning before getting up (baseline) and 12 h later. In young individuals skin was stiffer (less distensible) and less elastic in the acral parts of the extremities (ankle, forearm). In the evening distensibility and elasticity of the skin increased. In aged individuals skin was less elastic and no diurnal variability in elasticity and distensibility was detected. We propose that these unique mechanical properties of the acral skin reflect a major role of the integument in the protection against the gravitational stress and the development of the postural oedema. Altered skin mechanical properties may contribute to the poor compensation for gravitational stress in elderly.