This study aimed to continue our characterization of
finger strength and multi-finger interactions across the lifespan to include those in their 60s and older. Building on our previous study of children, we examined young and
elderly adults during isometric
finger flexion and extension tasks. Sixteen young and 16
elderly, gender-matched participants produced maximum force using either a single
finger or all four
fingers in
flexion and extension. The maximum voluntary
finger force (MVF), the percentage contributions of individual
finger forces to the sum of individual
finger forces during four-finger MVF task (force sharing), and the non-task
finger forces during a task
finger MVF task (force enslaving), were computed as
dependent variables. Force enslaving during
finger extension was greater than during
flexion in both young and
elderly groups. The flexion-extension difference was greater in the
elderly than the young adult group. The greater independency in
flexion may result from more frequent use of
finger flexion in everyday manipulation tasks. The non-task
fingers closer to a task
finger produced greater enslaving force than non-task
fingers farther from the task
finger. The force sharing pattern was not different between age groups. Our findings suggest that
finger strength decreases over the
aging process,
finger independency for
flexion increases throughout development, and force sharing pattern remains constant across the lifespan.
