Effects of different loads and carrying systems on selected biomechanical parameters describing walking gait

Abstract

The effects of two different systems on selected biomechanical parameters of walking gait, while carrying loads of varying magnitude, were investigated. Ten healthy males who were not regularly engaged in carrying tasks walked a distance of 20 m for ten trials for each of the following five conditions: (i) normal walking without any external load; (ii) 20% and (iii) 40% body weight carried using a backpack system; and (iv) 20% and (v) 40% body weight carried using a doublepack system which distributed the load equally between the front and back of the subjects. The experimental set-up consisted of a Kistler force platform interfaced to a Tektronix 4051 Graphic Calculator, two super 8 mm movie cameras and a photoelectric timing system. Force data (417 Hz) were obtained for ten trials along with side- and rear-view film data (100 fps) for three of the trials for each of the subject conditions. In addition, selected aspects of foot-position data were acquired from a minimum of six footprints from one trial for each subject condition. Walking speed was controlled at 4·5 ± 0·3km/h. Parameters describing the temporal relationship of the gait pattern and values describing the spatial relationship of foot position were evaluated. Selected variables describing the components of the ground-reaction-force-time curves were also examined. Finally, selected kinematic and kinetic parameters were evaluated for four functional subphases of the support period. Comparisons using a one-way ANOVA with repeated measures were conducted to examine differences between parameters describing the load-carrying conditions and normal gait. Results from the analysis revealed that both the light and heavy loads substantially modified the normal walking gait pattern. Interactions between the load conditions and carrying systems were tested using separate two-way ANOVA with repeated measures. Significant ordinal interactions as well as significant main effects were found between the two carrying systems for some parameters, suggesting that the doublepack system was more effective than the conventional backpack system, especially for carrying the heavy load.