Comparison Of Unanticipated Backpedal And Cutting Tasks: Implications For Rehabilitation Progressions

PURPOSE: There has been a considerable number of previous investigations on the biomechanics associated with cutting change of direction tasks; however, there has been significantly less work related to changing direction from a forward run to backpedal. The purpose of this study was to compare the biomechanics of unanticipated cutting and unanticipated backpedaling. It was hypothesized that the backpedal task would elicit higher sagittal plane and lower frontal and transverse plane demands than cutting. METHODS: The subjects in this trial were 134 adolescent female soccer players (age: 13.5 ± 2.1 years, height: 157.3 ± 10.1 cm, mass: 50.8 ± 11.2 kg) who completed biomechanical testing as part of a larger randomized controlled trial. All participants completed six trials of an unanticipated agility task while instrumented for standard 3D motion analysis. Participants ran towards a set of inground force plates and were given a visual cue to perform either a 1) 90-degree cut or 2) transition from forward running to backpedaling. Kinematics at the time of initial ground contact (vertical ground reaction force >10 N) were collected for the left limb using standard three-dimensional analysis and separately averaged across 3 successful trials for each task. Repeated measures ANOVAs identified differences in hip, knee, ankle biomechanics between the tasks (α < 0.05). Cohen’s d effect sizes were calculated for all identified significant differences. RESULTS: There was a statistically significant difference between the tasks at initial contact, such that the cut elicited greater hip abduction (p < 0.001, d = 0.70), hip internal rotation (p < 0.001, d = 1.40), knee flexion (p < 0.001, d = 1.07), knee abduction (p < 0.001, d = 0.24), and ankle inversion (p < 0.001, d = 0.29) than the backpedal task. CONCLUSIONS: The backpedal task elicited lower levels of hip (frontal and transverse plane), knee (sagittal and frontal plane), and ankle (frontal plane) motion at initial contact than the cutting task. The results indicate that the frontal and transverse plane dominant cutting tasks may be a good therapeutic progression following backpedal tasks. The findings also suggest that clinicians need to educate patients on performing the transition from forward running to backpedaling with greater knee flexion to promote safer movement patterns.