Book Description

Backward movement is an aspect of daily life for most individuals and it is a crucial element in most sporting activities. Backward walking is a basic component of backward movement. In direct contrast to forward walking, backward walking has received only minimal attention in the published literature. The present investigation was undertaken to provide basic information describing the backward walking cycle in man. Two 16 mm film records were synchronized by means of an impulse generator which simultaneously activated internal timing lights within each camera. Camera One photographed the subject's lateral aspect, while Camera Two, equipped with a split lens, photographed the subject's anterior aspect and the four simultaneous oscilloscope electromyograms. The subject alternated backward and forward walking trials until a total of nine walking trials had been completed in each direction. The position of the four pairs of surface electrodes was changed after three walking trials in each direction, such that a total of twelve left lower extremity muscles were examined during each gait. The backward walking cycle was first divided into specific events, phases and sub-phases which corresponded to the divisions of the forward walking cycle. The principle of moments was utilized to calculate the position of the body center of mass and the cosine law was utilized to calculate joint angles of the left hip, knee and ankle in selected frames of Film One. The position of the lateralmost point on the left hip was determined from corresponding frames of Film Two. The following are the major results of the study: (1) the backward and the forward walking cycles were each divided into three stance phase sub--phases and two swing phase sub--phases on the basis of five specific events, (2) normal backward walking was slower than normal forward walking in terms of cadence and horizontal velocity, (3) backward stride and step lengths were shorter than forward stride and step lengths, (4) within each gait the vertical displacements of the top of the head and the calculated body center of mass were similar, (5) peak- to-peak vertical displacements of the body center of mass were significantly greater during backward walking than during forward walking, (6) the vertical high points of the body center of mass during both gaits occurred shortly after malleoli--even of mid--stance of alternate legs, (7) the vertical low points during backward walking occurred near the end of the double limb support periods, while during forward walking the vertical low points occurred at the start of double limb support periods, (8) lateral and peak-to-peak lateral-medial displacements of the lateralmost point on the left hip during backward walking were similar to the corre sponding forward walking displacements. However, medial displacements during backward walking were significantly greater than medial displace ments during forward walking, (9) changes in the horizontal velocity of the body center of mass, calculated over 5% divisions of the walking cycles, were small and inconsistent during both gaits. Overall, there was a tendency for horizontal velocity to decrease slightly as the body ascended to its vertical high points and then to increase slightly as the body descended toward its vertical low points. However, within each gait the mean ascending horizontal velocity did not differ significantly from the mean descending horizontal velocity, (10) the joint excursions of the left lower extremity during backward stance and swing phases were approximate reversals of the joint excursions observed during the corresponding forward walking phase, (11) the total joint range of motion observed at the hip and the knee was slightly greater during forward walking, (13) ankle joint excursion was similar during both gaits. However, during backward walking this range was achieved through increased dorsiflexion and decreased plantarflexion as compared to forward walking, (14) the muscles of the left lower extremity were electrically active for longer periods of time during backward walking and also demonstrated a greater degree of inconsistent electrical activity during backward walking.