H.Hand, K.Garbuz, M. Etten, T.McGrew, J.H. Zhang-Lea

Affiliation: Department of Human Physiology, School of Health Sciences, Gonzaga University, Spokane, WA.

Knee valgus, also known as “knock knees” is an inward pronation of the knee joint and is commonly seen in running during loading and stance phases. Although there are previous studies on gait retraining programs and running form, there is no research on knee valgus after a one-time training session. PURPOSE: To determine if a 12-minute training program using visual and verbal cues will immediately reduce knee valgus in runners when running on a flat and downhill slope. METHODS: We invited runners with a tibiofemoral angle (TFA) over 6° to participate in this study. The side of leg with greater TFA was selected as the training leg. Eight runners ran at their self-selected speeds on a flat and 3% downhill surface for 3 minutes each. Then, participants were randomly assigned into either a flat or downhill training session for 12 minutes. During training, we provided them with visual feedback of their running gait via a live-stream camera, and verbal cues with instructions on how to reduce knee valgus. Immediately after training, all participants repeated two running trials on a flat and 3% downhill surface. We collected lower limb joint kinematics at 60 Hz for 10 seconds during running using a marker-less motion capture system, and measured their maximal TFA during stance phase for 5 consecutive strides from the training leg. RESULTS: Prior to training, we found no difference in TFA between running on a flat (7.95±2.53°) and a downhill surface (8.07±2.95°, p=0.645). Runners trained on a downhill surface increased TFA from 6.88±2.22° pre-training, to 7.16±2.55° post-training (p=0.045) on a flat surface-demonstrating a medium effect size (Cohen’s D=0.734). However, there was no difference when running downhill (p=0.082). Runners trained on a flat surface did not show difference between pre- and post-training regardless of running on a flat (p=0.074) or downhill surface (p=0.109). CONCLUSION: Our findings demonstrate that a 12-minute training program could potentially increase knee valgus in our participants immediately. Post-hoc power analysis showed that 22 participants will be enough to reach statistical power equal to 0.80.

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