M.J. Leonetti, C.M. Bishop, K.M. Edinger, D.A. Oldham, S.R. Moore, P.A. Wamboldt, J.L. Wheeler, AND R.S. McCulloch.

Gonzaga University, Spokane, WA

Previous studies have evaluated differences in lower limb biomechanics between shod and unshod running conditions, yet limited research has been done to assess whether differences in jump landings are adopted under such conditions. Moreover, further research of lower limb biomechanics, especially knee valgus, could aid clinical assessment of risk for lower limb injury such as ACL tears. PURPOSE: The purpose of this study was to compare muscle activation and knee valgus observed during drop vertical jump (DVJ) landings under shod and unshod conditions. A secondary purpose was to evaluate the clinical applicability of using 2D motion capture data to evaluate knee valgus by comparing the estimated angles to those measured using 3D goniometers. METHODS: Eleven recreationally active females (19.9±1.2 yr., 58.4±6.5 kg, 166.0±4.5 cm) were recruited from Gonzaga University to participate in this study. Subjects performed three shod and unshod DVJs relative to their individual jumping abilities. Knee valgus was measured via electro goniometers and by 2D motion capture. 2D ratios were calculated using 6 equations attempting to predict a relationship with the 3D system. EMG recordings of biceps and rectus femoris activation were also obtained for the two conditions. RESULTS: No significant differences were found between shod and unshod conditions for muscle activation or goniometer measures. The 2D valgus ratios calculated were not significantly correlated to 3D goniometer values (r values ranged from -.146 to .054). CONCLUSION: Jump landings performed barefoot did not influence subjects to adopt a more ideal landing strategy. The present study suggests that there is no change to barefoot landing mechanisms between shod and unshod conditions, and the potential for decreased shock absorption from unshod landings could increase the likelihood of lower limb injury. This study also did not find a clinical application of using 2D motion capture techniques to infer 3D knee movements.

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