Assessment of Arm Motions with Fall Direction in Human Subjects

Abstract

Abstract Falls are a common and serious problem among older adults. This study examined the role of the direction of fall on the movement of arms. The specific aims of the study were to characterize the arm motion in response to a fall perturbation and to determine if there was any correlation between the side of fall and the motion of either arm. Electromagnetic motion sensors were placed on left/right upper arm, left/right forearm, thorax (T1) and sacrum (between S1 & S2) on 12 subjects. Controlled falls occurred in four directions: anterior, posterior, and medial-lateral directions. The assessment of average arm motion patterns displayed different characteristics in different directions. Analysis of variance showed that peak shoulder rotation had a significant interaction between the left/right lateral fall directions and arm side measured (side*direction p< 0.05). In case of shoulder abduction, left and right lateral fall directions' interactions were significant for the interaction of side*direction (p<0.05). For elbow flexion, the interaction of side*direction (p=0.096) did follow a trend though not significant in the medial lateral directions. It was hypothesized that left/right arm response in lateral falls would correspond to the fall direction and the pattern would reverse for falls in the opposite direction. It was further hypothesized that in anterior/posterior falls; differences in arm motions would exist and be symmetric across both arms.