Are static and dynamic balance abilities correlated with handgrip strength in healthy elderly?

Several studies report that basic motor abilities, including muscular strength and static and dynamic balance influence the risk of falls in elderly people. However, the relationship between these features is not fully clear. In this study, we measured static posturography and TUG (performed using force platform and wearable inertial sensors) with handgrip strength (HSG) and determined the correlation between balance and HSG performances. Twenty-two healthy individuals (10M, 12F, age 68.0 SD 8.3) underwent a 30 s static posturography and instrumented TUG using an inertial sensor attached at the lower lumbar level. The center-of-pressure (COP) time series acquired with the force platform were processed to calculate: sway area, COP path length, maximum COP displacements and velocities in AP and ML directions. For the TUG, acceleration data allows calculating: duration of the trial, duration of sit-to-stand, intermediate turning, final turning and stand-to-sit phases. HSG was measured using a validated dynamometer. Pearson’s product-moment correlations was calculated by setting the significance level at p=0.05. We found significant positive correlations of HSG with sway area (r=0.462), path length (r=0.510) COP displacements and velocities in AP and ML direction (r=0.576 and 0.422 for displacements, r=0.563 and 0.414 for velocities). Moreover HSG is negatively correlated with TUG duration (r=-0.604) and final rotation phase (r= -0.509). Such results suggest that HSG is a good predictor of static balance, while muscular strength seems to be less of an influence in dynamic balance tasks like TUG.