IN-SHOE PLANTAR PRESSURE CHANGES DURING NEGATIVE GRADIENT GAIT AT VARIOUS VELOCITIES

Abstract

For most participants, fitness walking involves a range of conditions, such as walking on different surfaces, over uneven terrain, and up and down hills. Although the mechanics of gait have been investigated thoroughly, the plantar pressure patterns during negative gradient (NG) gait are not well understood. Also, the preferred walking speed during actual NG walking conditions could differ from the usual fitness walking pace (Wall & Charteris. 1986). Therefore, the purpose of the study was to investigate the effects of NG and walking velocity on the plantar pressures of the foot during fitness walking. Eight female fitness walkers who M a natural overground pace of 4.1 + .2 d s were selected. Each subject performed five trials for each of 5 grades (0, -4, -8, - 12 and -16%) and three velocities (3.8.4.1 and 4.4 m/s) while walking on a treadmill. Pressures from six sensors attached to the plantar surface of the right foot were collected (200Hz) using a Langer Electrodynography in-shoe pressure system. After normalizing to body mass, a two-way repeated measures ANOVA (p c -05) was used to assess the effect of velocity and gradient for the peak pressure (PP) values of each sensor. The heel sensor values were variable. Therefore, only a trend of increased PPs during increased NG was evident. The 5th metatarsal PPs displayed significantly greater values as the gradient increased. The relationship is reversed for the remaining forefoot sensors (1st. 2nd. and 3rd metatarsals). Increasing the velocity significantly increased the heel region PP values, but decreased all forefoot region PP values. These results suggest that as the NG increases, a trend of increased PPs are demonstrated for sensors most active during the impact phase. PP values that occur during the propulsive phase are inversely related to gradient and velocity. The gradient effect on the forefoot region could be due to a decrease in the normal component of force during the double support phase. Also, velocity and NG results are influenced by the unique biomechanical constraints of treadmill gait.