Experimental Analyses of Load Carrying Effects on the Peak Traction Coefficient between Shoe Sole and Floor during Walking

This paper presents the effect of load carrying (position and weight of load) on the maximum peak values of traction coefficient between shoe sole and floor during walking on level walkway. Gait experiments were conducted by five healthy male adult participants walking on the force plates with carrying the loads. Each subject was tested at step length of 0.75 m and at walking speed of 1.4 m/s. They were instructed to carry the loads by three different ways; a 2-handed load carrying, a back-pack load carrying, and a waist level front load carrying. Weight of load was 49, 98, 147 or 196 N for each way of load carrying. For a waist level front load carrying, the maximum peak traction coefficient at heel strike period |Fh/Fn|h statistically significantly (p < 0.01) decreased with increasing of weight of load. On the other hand for other ways of load carrying, |Fh/Fn|h was not affected significantly (p > 0.05) by weight of load. For each way of load carrying, the maximum peak value of traction coefficient at toe-off period |Fh/Fn|t had tendency to increase with increase of weight of load. The relationship between the slip potential and the COM position change by load carrying were also discussed.