The plantar aspect change caused by contact with soft surfaces creates and unstable gait and increases the risk of falling, especially in the elderly. This study aimed to analyze gait property by three-dimensional motion analysis on soft and normal surfaces and to clarify the relationship with physical function and fall risk. Twenty-four older people aged 65-88 years old and living independently without any assistive device (7 men, 17 women) performed 5 m of walking with own maximal speed on normal and soft surface walkways. The soft surface walkway used was a low rebound urethane foam mattress. The three-dimensional kinematic gait analysis by sixteen anatomic points was used to evaluate gait property on both walkways. The gait property on soft surfaces tended to be swinging up and down in each joint and to largely lean left and right as compared with the normal surface. Moreover, it tended to decrease in a step length and to increase in a step width. All gait parameters on soft surfaces correlated significantly with functional reach. On the other hand, that on normal surface correlated significantly with leg strength. Gait properties on soft surfaces which changes in plantar aspect during foot contact differs from those on normal surfaces. Walking on soft surfaces may cause an unanticipated inverted pendulum sway supporting a foot contact point because of the disturbance by a sagging walkway; in short, requiring more effort to keep a body balanced. In conclusion, gait on the soft surfaces requires balance ability (functional reach) rather than leg strength.

Demura, S. , Shin, S. , Takahashi, S. and Yamaji, S. (2013) Relationships between gait properties on soft surfaces, physical function, and fall risk for the elderly. Advances in Aging Research, 2, 57-64. doi: 10.4236/aar.2013.22008.