Relationship between fear of falling and balancing ability during abrupt deceleration in aged women having similar habitual physical activities.

The purpose of this study was to evaluate the influence of fear of falling on balancing ability during abrupt deceleration in aged women. The subjects were 20 women aged between 67 and 75 years. They were classified into two groups, one having a fear of falling (group FF, n = 10) and another without this fear (group NFF, n = 10). The two groups had similar daily physical activities. Changes in the centre of foot pressure (CFP) were measured during postural sway following horizontal deceleration of the force platform on which they were standing, and the response time and CFP displacement were evaluated. In addition, the electromyogram (EMG) onset in the tibialis anterior muscle and medial gastrocnemius muscle during abrupt deceleration, and its difference between the two muscles were measured. and the relative level of co-contraction of antagonistic muscles (the co-contraction index, CCI) in the lower extremity muscle group was calculated. The response time and CFP displacement immediately after abrupt deceleration were significantly higher in group FF than in NFF (P < 0.05). The EMG onset in the two muscles did not significantly differ between the two groups. The difference in EMG onset between the two muscles was significantly lower in group FF than in NFF (P < 0.05). The CCI was significantly higher in group FF than in NFF (P < 0.05). These results suggest that there were negative effects of a fear of falling on the balancing ability immediately after abrupt deceleration. This may be because a fear of falling increases the co-contraction of antagonist muscles in the lower extremity muscle group.