Identification of elderly fallers by muscle strength measures

Abstract

For efficient prevention of falls among older adults, individuals at a high risk of falling need to be identified. In this study, we searched for muscle strength measures that best identified those individuals who would fall after a gait perturbation and those who recovered their balance. Seventeen healthy older adults performed a range of muscle strength tests. We measured maximum and rate of development of ankle plantar flexion moment, knee extension moment and whole leg push-off force, as well as maximum jump height and hand grip strength. Subsequently, their capacity to regain balance after tripping over an obstacle was determined experimentally. Seven of the participants were classified as fallers based on the tripping outcome. Maximum isometric push-off force in a leg press apparatus was the best measure to identify the fallers, as cross-validation of a discriminant model with this variable resulted in the best classification (86% sensitivity and 90% specificity). Jump height and hand grip strength were strongly correlated to leg press force (r = 0.82 and 0.59, respectively) and can also be used to identify fallers, although with slightly lower specificity. These results indicate that whole leg extension strength is associated with the ability to prevent a fall after a gait perturbation and might be used to identify the elderly at risk of falling.

Fig. 1

Pictures of the experimental settings for a right plantar flexion moment measurements, b left knee extension moment measurements, c leg press push-off force measurements, d jumping measurements, and e tripping experiments

Fig. 2

Averaged group differences in capacity measures between fallers and non-fallers. Maximum (max) and rate of moment development (RTD) of plantar flexion moment (ankle_max and ankle_rtd) and knee extension moment (knee_max and knee_rtd), maximum and rate of force development (RFD) of leg press push-off force (legpress_max and legpress_rfd), jump height (jump_h), and hand grip strength (hand_f). Significant differences between groups are indicated with p-values

Fig. 3

Distribution of the individual values of maximum leg press push-off force (legpress_max) with jump height (jump_h) and hand grip strength (hand_f) for fallers and non-fallers. Crosses indicate the incorrect classified cases (x for legpress_max, + for jump_h and hand_f)