Impact of age on muscle and kinematic responses to an obstacle trip while walking

Introduction

This study examined the impact of age on muscle and kinematic responses to an obstacle trip while walking.

Materials and Methods

102 older (65–90 years) and 26 young (21–35 years) people were unexpectedly tripped using a pop-up obstacle that contacted their left foot while walking on an 8-m walkway. Kinematics and lower limb muscle responses during the first and second recovery steps were measured.

Results

Following a trip, older people more often lowered their tripped foot before the obstacle and fell into the harness, compared to young (P < 0.05). When the tripped foot was immediately lifted over the obstacle, older people showed greater co-contraction of ankle muscles and faster peak activation of plantar-flexors but slower, shorter and lower recovery steps than young (P < 0.01). When the tripped foot was immediately lowered, despite similar muscle responses, older people took shorter and lower steps to clear the obstacle and were less stable than young (P < 0.01).

Conclusions

Lower-limb muscle responses to an obstacle trip in older people may be quick but inefficient (co-contraction), resulting in poorer recovery steps and more falls compared to young people. Exercise interventions should aim to improve muscle capacity and motor skills required to prevent falls following unexpected trips.