The recently developed clipless pedals with medio-lateral rotational capabilities have been associated with claims of enhanced cycling biomechanics. The purose of this study was to determine the effects of freedom of movement of the foot on lower extremity frontal plane movement as measured by tibial tuberosity patterns and to relate these to sagittal plane leg motion. Four recreational and four competitive cyclists rode a stationary bicycle at 90 rpm under a constant workload using adjustable pedals. Five pedal conditions were tested (A: no motion, B: ± 3°, C: ± 5°, D: -1° to +5° and E: _5° to +1° of motion). Subjects were videotaped in the frontal and sagittal planes simultaneously. The video records were analyzed using a Peak Performance video analysis system. Ten continuous crank revolutions were sampled for each condition; averages of maximum medial positions, lateral positions, medial/lateral range, and standard deviation of range were calculated. A two-way ANOVA (pedal condition and experience) was used to compare mean values of each variable. No significant differences in average maximum positions, ranges, or variability were found for the five pedal conditions (p>.10). Recreational cyclists were found to display significantly larger average maximum medial/lateral ranges when compared to competitive cyclists (p=.06). Mean maximum medial/lateral range was 2.2 cm for all data and 1.9 and 2.6 cm for competitive and recreational groups, respectively. Subjects ranged from 1.3 to 4.0 cm of medial/lateral movement. Maximum medial/lateral x-coordinate positions occurred at similar degrees of crank and knee angle across conditions for a given subject but were different between subjects. Clipless pedal systems did not significantly change frontal plane leg kinematics during stationary cycling in the population studied. The observed motions were individually characteristic and were dependent on cycling experience.
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