Skin biomechanical properties: in vivo evaluation of influence of age and body site by a non-invasive method.
OBJECTIVE
Biomechanical properties of the skin are evaluated in vivo by torsion or extension methods. We assessed their modifications as function of age, probe diameter and regional body site.


METHODS
For measuring skin extensibility (or traction), we used a non-invasive suction device on a total of 37 volunteers, consisting of (A) 14 younger women (30.1±7.6 years) and (B) 23 older women (60.2±6.5 years). Measurements were performed on three different areas with 4 different probe diameters. The parameters used were (UE ) extensibility; (UV ) plasticity; (UR ) tonicity; (UR UE ) elasticity; the difference between the lowest point of the last curve (5th) and that of the 1st is the fatiguability. Concurrently, we measured on each volunteer the microdepressionary network (mDN) length.


RESULTS
Generally, tonicity, extensibility and elasticity decreased; fatiguability increased and plasticity stayed the same; all of these factors apply regardless of age. Results are more homogenous on the volar face of the forearm and with 2, 4 and 6 mm probe diameters. As a general trend, mDN length decreases with age.


CONCLUSIONS
The knowledge of this variation is important in interpreting the results obtained after product application. Standardisation of measures with the 2-mm probe will allow product efficacy determination and the comparison of different products.
Centre ?Étude et de Recherche en Cosmétologie, 4, Square Villaret de Joyeuse, F-75017 Paris, FranceCentre de Recherche Yves Rocher, 7-9, avenue François-Vincent Raspail, F-94117 Arcueil Cedex, France.
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Couturaud
Centre ?Étude et de Recherche en Cosmétologie, 4, Square Villaret de Joyeuse, F-75017 Paris, FranceCentre de Recherche Yves Rocher, 7-9, avenue François-Vincent Raspail, F-94117 Arcueil Cedex, France.
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Coutable
Centre ?Étude et de Recherche en Cosmétologie, 4, Square Villaret de Joyeuse, F-75017 Paris, FranceCentre de Recherche Yves Rocher, 7-9, avenue François-Vincent Raspail, F-94117 Arcueil Cedex, France.
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Khaiat
aging; elasticity; extensibility; mDN (microdepressionary network); suction