Age- and sex-related differences in upper-body joint and endpoint kinematics during a drinking task in healthy adults

The objective kinematic assessments of activities of daily living are desired. However, the limited knowledge regarding age- and sex-related differences prevents the adaptation of these measurements to clinical settings and in-home exercises. Therefore, this study aimed to determine the effects of age and sex on joint and endpoint kinematics during a common activity of daily living, specifically, drinking from a glass.

In total, 32 healthy adults (18 males and 14 females) aged 22-77 years performed a drinking task comprising reaching for a glass, bringing it forward and sipping, returning it, and placing the hand back to the starting position, which was recorded using a three-dimensional motion-capturing system. A two-way analysis of variance was used to statistically compare joint angles at five different time points and endpoint kinematic variables in the four drinking phases between older and younger age groups and sexes.

Wrist radial deviation was greater in older adults than in younger participants at all five different time points (F = 5.16-7.34, p ≤ 0.03, η² = 0.14-0.21). Moreover, lesser shoulder abduction and greater shoulder internal rotation and forearm pronation when moving and returning the hand to the starting position were observed in the female group than in the male group (F = 4.21-20.03, p ≤ 0.0497, η² = 0.13-0.41). Trunk flexion was lower in the female group than in the male group at all time points (F = 4.25-7.13, p ≤ 0.0485, η² = 0.12-0.19). Regarding endpoint kinematics, the performance time in the reaching phase was longer in older adults than in younger individuals (F = 4.96, p = 0.03, η² = 0.14). Furthermore, a shorter time while returning the hand to the starting position was observed in the female group than in the male group (F = 9.55, p < 0.01, η² = 0.22).

The joint kinematics of drinking were partially characterized by an age effect, whereas endpoint kinematics were scattered in all drinking phases. Sex-related effects in most upper-body motions and postures may cause rapid motions in females. Therefore, clinicians could use this knowledge for precise assessments and to suggest feasible in-home exercises.