For the longest time, I always associated excessive valgus or frontal plane motion of the knee during single leg activities to be the thing that put people at greatest risk for non-contact knee injury. I never really even considered speed at which that motion occurs as a factor. So, play along with me for a moment. Standing on one leg, you can slowly move your knee into 10, 15 and 20 degrees of valgus without it hurting or injuring anything. Now imagine (and I don't encourage you to try) if you moved your knee into 20 degrees of valgus at 220 degrees/sec. That might not only hurt but may cause some damage. We know that ground reaction forces range anywhere from 4-8 times body weight in jumping and bounding activities (Nordan and Frankel Basic Biomechanics of the Musculoskeletal System - 4th Edition). Considering this, can you imagine your knee falling into 20 degrees of valgus at those high rates of speed under those kinds of loads?
What we know now, is that we can impact those speeds with the proper training. We know that when speeds are high, that including some strength and endurance training for the core (planks and side planks specifically) as well as gluteus medius and maximus training that we see an associated decrease in speeds of valgus. In addition, simple training in single leg activities where the athlete is controlling not only the frontal plane motion of the knee but also the pelvic motion, that these athletes have better control of their speeds of valgus in single limb performance and perform better on our 3D assessment.
Obviously, exercises that can address this are limited only by our imagination. There are 100s of different ways to approach. A couple of my favorites include:
Lumbar Hip Disassociation with Spiral Technique
Side Stepping with Resistance
Side Planks with CLX
Plank Clock Walks
These are most effective if done in a fatigued state. Typically, we will do these at the end of practice or at the end of performance training. This way, you don't have to do as many sets and reps and there is much better carry over from performance on the exercises to how the athlete moves when they are tired.
Stay tuned next week as we continue our discussion looking at how direction of movement impacts speed. If you enjoy this blog, please share with your colleagues, athletes and training partners and please be sure to follow us on instagrm @ bjjpt_acl_guy and twitter @acl_prevention. Train hard and stay well. #ViPerformAMI #ACLPlayItSafe