A comparison of the free moment pattern between normal and hyper-pronated aligned feet in female subjects during the stance phase of gait

F Yazdani, M Razeghi, S Ebrahimi


Background: Excessive range of adductory free moment of the ground reaction force may potentially increase the risk of lower extremity injuries by applying a higher torsional load transmitted to the proximal parts.

Objective: It was hypothesized that the free moment pattern might be different between hyper-pronated and normal feet subjects. Moreover, a correlation would exist between peak adduction free moment and peak ankle-foot complex abduction at the stance phase of walking.

Methods: Thirty female participants were divided into two groups of asymptomatic hyper-pronated and normal feet. Kinetic and kinematic data were collected using a single force plate and a six-camera motion analysis system during three successful free speed walking trials. Ensemble average curves were extracted from the time normalized individual trials of the stance phase for both free moment and peak ankle-foot complex abduction parameters.

Results: Significant differences in peak adductory free moment, peak ankle-foot complex eversion and peak ankle-foot complex abduction were found between normal and hyper-pronated groups (4.90±0.97Vs. 5.94±0.88, P < 0.01), (3.30±0.95Vs. 6.28±1.47, P < 0.01) and (4.52±1.16Vs. 8.23±2.52, P < 0.01, respectively).

A significant positive correlation was found between the peak adduction free moment and peak ankle-foot complex abduction in both groups, which was more strongly positive in hyper-pronated group (r = 0.745, p < 0.01, normal group, r = 0.900, p < 0.01, hyper-pronated group).

Conclusion: As a good measure of torque which is transmitted to the lower extremity, may free moment be a useful biomechanical indicator for both clinical and research purposes.


Ankle-foot complex; Flat foot; Free moment; Kinetic; Ground reaction force

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DOI: https://doi.org/10.22086/jbpe.v0i0.639

eISSN: 2251-7200        JBPE NLM ID: 101589641

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                                                                        Chairman and Editor in Chief

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