Experimental finding show clear differences in skin firmness between age-groups, with skin hydration playing a minor role, according to a recent study. Skin firmness was quantified using handheld devices that measure the force to indent skin 0.3 and 1.3 mm (F0.3 and F1.3). Skin hydration was quantified using handheld devices that measured tissue dielectric constant (TDC) at 300 MHz to skin depths of 0.5 and 2.0-2.5 mm. All parameters were measured bilaterally in the jowl area and volar forearm of 60 women grouped by age <45 years (YOUNG) and ≥45 years old (MATURE). Researchers found:

• All measured parameters were bilaterally symmetrical at jowl and forearm.
• Forearm and jowl indentation forces were greater in YOUNG with statistically significant declines with advancing age with regression relations most evident at shallower indentation depths.
• Quantitative relations for arm and jowl were F_0.3 = 0.256 × AGE + 32.7 mN and F _0.3 = −0.07 × AGE + 17.7 mN.