Heel contact changes during walking according to the restricted surface

Maria Joana Duarte Caetano
UNESP ? University of S?o Paulo State/ at Rio Claro ? Biosci

Ana Paula Marques Moreira
UNESP ? University of S?o Paulo State/ at Rio Claro ? Biosciences Institute ? Department of Physical Education

Carolina Rodrigues Alves Silveira
UNESP ? University of S?o Paulo State/ at Rio Claro ? Biosciences Institute ? Department of Physical Education

Lilian Teresa Bucken Gobbi
UNESP ? University of S?o Paulo State/ at Rio Claro ? Biosciences Institute ? Department of Physical Education

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     Last modified: March 1, 2007

Abstract
Most falls among the elderly occur during walking. Changes at heel contact with the ground during walking indicate gait instability and increased risk of falls. Related to gait instability, it is important to study gait changes according to the surface features. In order to contribute to better understanding of balance during walking, especially related to the aging process, the aim of this study was to investigate changes in the horizontal velocity and the ankle dorsiflexion angle at heel contact in elderly and young adults during walking with surface constraints. The gait patterns of 7 elderly (69.4?2.9 years of age) and 7 young adults (23.3?2.3 years of age) were analyzed over an unconstrained surface (UCS) and under two more conditions: over a narrow constrained surface (NCS=19cm width) and a narrow and high surface (NHS=19cm width and 10cm height). A digital camcorder recorded a gait cycle at 60 Hz in the sagittal plan by means of the trajectory of reflexive markers attached on the following right lower limb anatomic points: fifth metatarsal, calcaneus, lateral malleolus and lateral condyle. Dvideow 6.3 software was used for the photogrammetric procedure and Matlab6.5 to calculate the dependent variables. A MANOVA (2 groups X 3 conditions), with repeated measures for condition reveals only condition main effect (Wilks Lambda=0.346; F(9,4)=4.249; p<0.034). Univariate analyses showed differences for horizontal velocity (F(15,1)=6.710; p<0.016) and ankle dorsiflexion angle (F(24,2)=7.051; p<0.005). Post hoc tests revealed decreases in horizontal velocity (p<0.047) at NCS (0.14+0.06 m/s) related to UCS (0.22+0.12m/s), and a trend (p=0.06) at NHS (0.12+0.06m/s) related to UCS. For the ankle dorsiflexion angle, post hoc tests revealed a decrease (p<0.026) at NCS (118.75+4.79?) related to UCS (120.11+4.59?). Since the elderly participants were not considered fragile (no advanced age and no history of falls), we couldn?t show differences between groups. On the other hand, the surface constraints produced changes in the gait pattern indicating caution during walking in order to compensate for the narrow base of support and to increase stability. The ankle dorsiflexion angle is an important variable to measure stumble avoidance, as reducing it can promote better stabilization during NS condition, the most perturbed condition. Thus, such gait deficits are indicative of performance difficulties because they can be predictors of risk of falls.