ABSTRACT

　Managing the load on the Achilles tendon（AT） during jump landing is important in preventing AT injuries. Although foot kinematics may be associated with AT loading, these relationships are unclear during landing. The purpose of the present study was to determine the forefoot, midfoot, and rearfoot kinematics associated with AT force during a drop vertical jump（DVJ）．Thirty-five participants（25 males, age: 21.8±1.9 years old）performed the DVJ from a 30-cm high box. The landing phase was assessed using a three-dimensional motion analysis system. Dorsiflexion, eversion, and abduction of the forefoot, midfoot, and rearfoot were calculated using a multi-segment foot model. The AT force was estimated from the ankle flexion angle and plantarflexion moment. The relationship between the peak AT force and each foot angle was evaluated using correlation analysis and multivariate regression analysis. In correlation analysis, the AT force and rearfoot abduction were negatively correlated （ρ=-0.355, P=0.036）．No other significant correlations were found. In multivariate regression analysis, the variance inflation factors for forefoot dorsiflexion and abduction angles were large, so these variables were excluded due to multicollinearity. The rearfoot abduction （β=-0.523, P=0.004） and forefoot eversion （β=-0.445, P=0.012） were factors significantly associated with the AT force（R2=0.273, P=0.006）．The present study found that the increase in AT force during the landing task was associated with a decrease in rearfoot abduction and forefoot eversion. Foot orthoses that modify these kinematic characteristics may be useful in managing the AT loading during jump landings.

DECENTE SPORTS SCIENCE Vol.46/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE