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Source publication
Background/Purpose: In the frame of a development of a formulation to be used in perineal massage in pregnant women, a screening program was built up among compositions with elasticising properties. Methods: This was an open-label, controlled study in 21 volunteers. The participants applied once, on the volar surface of both forearms, five formulat...
Context in source publication
Context 1
... healthy female volunteers, aged 24 to 55 years (mean ± SD, 45.10 ± 9.82), were enrolled in the study, after providing written informed consent. The percentage change in torsiometric parameters relative to baseline at 30 min after application of the test products on the volar surface of the forearm is summarised in Figure 3. Skin elasticity was not affected by test product 1, slightly but not significantly reduced by test product 3, and was slightly but not significantly increased by test products 4 and 5. ...
Citations
... Immediate extensibility (Ue) is a measure of how many degrees the skin rotates 0.02 seconds after torque is first applied. Immediate elastic recovery (Ur) is a measure of how many degrees the skin rotates 0.2 seconds after torque is turned off [17]. ...
Objective:
To decode the feeling of skin tightness after application of a cosmetic product and how to soothe this discomfort. To pursue this aim, we considered the ingredient's effect on stratum corneum (SC) biomechanics to differentiate between consumers prone to tightness from those that are not and correlate these effects with mechanoreceptor activation.
Methods:
In vivo clinical trials were used to assess the tightness perception dichotomy between groups of Caucasian women; in vitro experiments were used to measure the mechanical stresses induced in the SC after cleanser and moisturizer application; and in silico simulations were used to illustrate how the measured mechanical stresses in the SC result in the development of strains at the depth of cutaneous mechanoreceptors, triggering tightness perceptual responses.
Results:
Before any cream application, women prone to tightness tend to have a more rigid SC than their less sensitive counterparts, however cleanser application increases SC stiffness in all women. Surprisingly, no correlation was found between tightness perception and hydration measurements by the Corneometer or barrier function, as evaluated by transepidermal water loss (TEWL). Self-declared tightness and dryness scores were strongly associated with a self-described sensitive skin. After application of the optimized moisturizing formula, Osmoskin® containing natural waxes with good filming properties, consumers report a strong decrease in tightness and dryness perception. These results match with laboratory experiments where the cleanser was shown to increase SC drying stresses by 34%, while subsequent application of Osmoskin® decreased stresses by 48%. Finite element modeling (FEM), using experimental results as input, elucidates the differences in perception between the two groups of women. It makes clear that Osmoskin® changes the mechanical status of the stratum corneum, producing strains in underlying epidermis that activates multiple cutaneous mechano-receptors at a level correlated with the self-perceived comfort.
Conclusion:
Integration of the in vivo, in vitro, and in silico approaches provides a novel framework for fully understanding how skin tightness sensations form and propagate, and how these sensations can be alleviated through the design of an optimized moisturizer.
The mechanical and structural properties of human skin are extensively documented. In addition, it is well-established that aging affects the structure, function, and appearance of skin. However, there are few reviews that have focussed exclusively on the biomechanics of skin aging as is the focus of this chapter. A number of techniques are used to characterize the biomechanical properties of skin in vivo. The techniques that are largely used in vivo are based on suction, torsion, or indentation. In vivo, a number of studies have examined age-related changes in the elastic and viscoelastic properties of skin. The varying results and interpretations of the findings are summarized in this chapter. The techniques that have been used to characterize skin biomechanics in vitro are also covered. In vitro, tensile and indentation techniques are widely used. However, there are few studies that have conducted research on human skin in vitro to determine the effects of aging. The overall mechanical behavior of skin with aging is discussed in the context of its structure. The chapter also discusses the need to better characterize age-related skin biomechanics for successful application of microneedle devices in the elderly.
