Effects of a lower limb functional exercise programme aimed at minimising knee valgus angle on running kinematics in youth athletes

Objectives: To investigate the effectiveness of 8-weeks of lower limb functional exercises on frontal plane hip and knee angles during running in youth athletes. Design: Pre- and post-intervention quantitative experimental. Methods: Nineteen athletes (11 male, 8 female, 11.54 +/- 1.34 years) from a long-term athletic development programme had 3-dimensional running gait measured pre and post an 8-week exercise intervention. Youth athletes randomised to control (upper limb strengthening exercises) or experimental (lower limb functional exercises aimed at minimising knee valgus angle) interventions completed the exercises during the first 10 min of training, three mornings a week. Pre- and post-parallel groups' analysis provided estimates of intervention effects for control and experimental groups. Results: Differences in pre- to post-intervention changes in mean frontal plane angles between control and experimental groups were trivial for the left hip (0.1 degrees) and right knee (-0.3 degrees). There was a small beneficial decrease in right hip joint angle (0.4 degrees) but a very large (ES = 0.77, CI 0.1-3.7) detrimental increase in left knee valgus angle (1.9 degrees) between groups. Conclusion: The 8-week lower limb functional exercises had little beneficial effects on lower limb hip and knee mechanics in youth athletes aged 9-14 years. (C) 2012 Elsevier Ltd. All rights reserved.