Stepping Over Obstacles: Gait Patterns of Healthy Young and Old Adults

Abstract

Falls associated with tripping over an obstacle can be devastating to elderly individuals, yet little is known about the strategies used for stepping over obstacles by either old or young adults. The gait of gender-matched groups of 24 young and 24 old healthy adults (mean ages 22 and 71 years) was studied during a 4 m approach to and while stepping over obstacles of 0, 25, 51, or 152 mm height and in level obstacle-free walking. Optoelectronic cameras and recorders were used to record approach and obstacle crossing speeds as well as bilateral lower extremity kinematic parameters that described foot placement and movement trajectories relative to the obstacle. The results showed that age had no effect on minimum swing foot clearance (FC) over an obstacle. For the 25 mm obstacle, mean FC was 64 mm, or approximately three times that used in level gait; FC increased nonlinearly with obstacle height for all subjects. Although no age differences were found in obstacle-free gait, old adults exhibited a significantly more conservative strategy when crossing obstacles, with slower crossing speed, shorter step length, and shorter obstacle-heel strike distance. In addition, the old adults crossed the obstacle so that it was 10% further forward in their obstacle-crossing step. Although all subjects successfully avoided the riskiest form of obstacle contact, tripping, 4/24 healthy old adults stepped on an obstacle, demonstrating an increased risk for obstacle contact with age.

Restricting ankle motion via orthotic bracing reduces toe clearance when walking over obstacles

“…Previous research has demonstrated that older adults attempt to cross over obstacles in the later part of swing because contact with the obstacle later in swing is less likely to cause a trip in comparison to contact early on in swing due to the relatively more posterior position of the body centre of mass in late swing [4]. The authors noted that, although this strategy resulted in higher toe-clearance the trade-off was reduced heel clearance [4].…”

“…The authors noted that, although this strategy resulted in higher toe-clearance the trade-off was reduced heel clearance [4]. Other research has highlighted that, when crossing obstacles leading with their prosthesis, unilateral trans-tibial amputees (with no ability to alter prosthetic 'ankle' angle) attend more to how their heel crosses the obstacle compared to able-bodied controls [19].…”

“…Obstacle clearance has been reported as the distance between the obstacle and the toe or the obstacle and the heel, as these parts of the foot are nearest to the obstacle during crossing [4,13,[19][20][21]. For this reason, the current study takes both clearances into consideration as well as foot placement parameters (i.e.…”

“…Compared to locomotion on flat ground, obstacle crossing requires significant adaptations to gait to ensure that foot clearance over the obstacle occurs with sufficient margins of safety [1][2][3][4]. Tripping on obstacles is a key cause of falls in the elderly [5][6].…”

“…However, the importance of swing phase ankle motion itself in achieving clearance has not been directly researched. Instead it is often simply mentioned that ankle dorsiflexion during swing assists the proximal joints in attaining/increasing clearance [2][3][4]14,17].…”