ABSTRACT

　Ground reaction force is often used to predict the risk of injuries but may not coincide with the forces applied to commonly injured regions of the foot. This observational study examined the forces applied to the foot and the associated moment arm made by three foot strike patterns. Ten male runners ran barefoot along a 15m runway at 3.3m/s using forefoot, midfoot, and rearfoot strikes. Three-dimensional coordinates of markers and ground reaction force were recorded. The Achilles tendon and ground reaction force moment arms represented the shortest distance between the ankle joint axis and the line of action of each force. The Achilles tendon and joint reaction forces were calculated by solving motion of the foot equations for each instance during the contact phase of running. The ground reaction force was significantly greater for the forefoot and midfoot strikes than for the rearfoot strikes, whereas there was no difference between the midfoot and rearfoot strikes. The Achilles tendon and joint reaction forces were significantly greater for the forefoot strikes than for the other foot strikes, and these forces were greater for the midfoot strike than for the rearfoot strike. The ground reaction force moment arm was significantly greater for the forefoot strike than for the other foot strikes, and was greater for the midfoot strike than for the rearfoot strike. Meanwhile, there were no significant differences in the Achilles tendon moment arm among all foot strikes. The Achilles tendon and joint reaction forces were greatest for the forefoot strike, followed by the midfoot strike, and rearfoot strike. These differences were attributed mainly to differences in the ground reaction force moment arm among the three foot strike patterns.

DESCENTE SPORTS SCIENCE Vol.38/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE