Step length variability at gait initiation in elderly fallers and non-fallers, and young adults

Normal aging is characterized by functional changes in the sensory, neurological and musculoskeletal systems. These changes affect several motor tasks including postural balance and gait. Gait variability has been suggested to be an important predictor of the risk of falling: the age-related increased variability may result of errors in the control of foot placement and/or center of mass displacement. Falls occur most frequently in elderly populations who scored poorly during transfer of quasi-static to dynamic situations, turning and reaching tasks in clinical tests. This suggests that gait initiation, which is a transient phase between standing and walking, could contribute to an increase in variability because, for elderly, muscular synergies associated with gait initiation occur less frequently than for young adults.

To examine if gait initiation and more particularly the variability of the first step length and the duration of the first double support period are more important for elderly fallers than for eldery non-fallers and young adults.

Elderly fallers, elderly non-fallers, and young adults were asked to initiate gait and walk at least 3 strides. Spatio-temporal characteristics of the first step and following strides were collected and across-trials variability analysed.

Elderly fallers showed a much smaller first step length and a longer duration of the double support period. The first step length variability of elderly fallers was more than twice greater than that observed for elderly non-fallers.

Considering the importance of proper initial foot placement for gait initiation and for stepping recovery responses, the first step length variability observed for the elderly fallers may be an important predictor of postural problems.