The mechanics of moving along a curved path suggest that runners must change their body positions and thus adjust their lower extremity function as they accomplish a track turn. The purpose of the present study was to investigate the changes in the kinetics and kinematics of the lower extremity as runners proceed around the turn of a 400-m track (radius 31.5 m). Five skilled runners served as subjects in the study and were required to perform 10 trials in three conditions, running at 6.31 m/s plus or minus 5% (4:15 min/mile pace). The right and left limbs on a track turn and the right limb on the straightaway were evaluated using ground reaction force data and kinematic data from high-speed film. Statistical analysis of the 18 ground reaction force variables and 4 kinematic variables suggested that the right and left limbs at the midpoint of the track turn were asymmetrical and that most of the differences occurred in the first portion of the footfall Significant differences were found in the touchdown angle, maximum pronation angle, all mediolateral variables, and in the vertical variables describing the collision phase of the footfall (p < .05). The data suggest that the etiologies of injuries to the right and left lower extremity differ, with right foot injuries being of the impact type and left leg injuries being of the overpronation type.
Joseph Hamill, formerly with, the Biomechanics Laboratory at Southern Illinois University is Carbondale, is presently with the Department of Exercise Scieace, Boyden Gym, University of Massachusetts, Amherst, MA 01003. Michael Murphy and Donald Sussman were with the Biomechanics Laboratory at Southern Illinois University at the time of this writing.