LAUSR

BACKGROUND Recent research has indicated that in the upper face a delicate arrangement exists between the muscles of facial expression and the skin. This arrangement allows for immediate transmission of movements following muscle contraction which results in skin movements and skin rhytid formation. OBJECTIVES To investigate age-related changes to the biomechanical unit formed between facial muscles, connective tissue envelope, and skin in the upper face. METHODS A total of n = 76 Caucasian volunteers (30 males, 46 females) with a mean age of 42.2 (18.6) years and a mean body mass index of 24.58 (3.7) kg/m2 were investigated. Three upper facial regions were analyzed for skin firmness and elasticity via cutometry, vertical and horizontal skin vector displacement via 3D-imaging, and muscle activity via surface-derived electromyography. RESULTS Study participants of older age (> 42.2 years) (when compared to younger participants; ≤ 42.2 years) showed increased skin firmness with 0.20 mm vs 0.30 mm with p < 0.001, decreased skin elasticity with 53.2% vs 69.0% (p < 0.001), increased vertical (not horizontal) skin mobility with 3.56 mm vs 1.35 mm (p < 0.001), and decreased muscle sEMG derived signal of the frontalis muscle with 309 µV vs 174 µV (p = 0.039). CONCLUSIONS This study reveals that age-related changes occur in each of the components of the biomechanical unit formed between facial muscles, connective tissue envelope, and skin in the upper face. Knowledge and understanding of such changes can allow for more targeted and individualized surgical and non-surgical aesthetic treatments.