It is widely accepted that decreased hip strength and stability leads to knee valgus. Excessive frontal plane motion and valgus torque increase the risk for non-contact ACL injuries. While we know that hip abductor weakness is more of an issue in females than males, the question remains to what degree other factors are involved.
Claiborne et al (1) noted that only 22% of knee variability could be linked solely to hip muscles surrounding the hip. In light of this we must look at the whole kinetic chain when assessing movement dysfunction and injury risk. In the most recent issue of the IJSPT, researchers sought to discover how activating the core during a single leg squat would impact the kinematics of 14 female college-age women. They excluded participants with current pain or injury to the lower extremities or torso, or if they had a history of any lower extremity injuries or surgeries in the past 12 months.
The participants were assessed for their capacity to recruit core stabilizer muscles using lower abdominal strength assessment as described by Sahrman (2). This testing model has 5 levels of increasing difficulty used to challenge participants to maintain a neutral spine. The draw back of this method is that it is done in supine versus the standing position of this study, but the author acknowledges this limitation. Out of a possible high score of 5, five of the participants scored a 1 or 2, while the other nine scored a zero.
For the study, a six inch step was used to assess 2 reps of a single leg squat. Each participant was asked to perform the test with the dominant leg to standardize conditions. They performed the reps under two conditions:
1. CORE - engaged abdominal muscles as they had been instructed to do so during the Sahrman test
2. NOCORE - no purposeful engagement of abdominal muscles
How do we use this information to affect our practice? Well, in terms of rehab it seems straightforward and many of us may already encourage patients to activate their core during treatment. However, I think the greater contribution may come in injury prevention programs (particularly ACL programs) where we are looking at all facets of neuromuscular control and appropriate muscle activation patterns.
With any prehab or rehab strategy, we as clinicians, trainers and strength coaches are essentially trying to reprogram the brain to summon and execute a better motor pattern or strategy - feedforward training. We know that healthy individuals tend to have better transverse abdominus and multifidus muscle activation, so it only makes sense to consider activation of local stabilizers as we work on global muscles. Improving core and pelvic stability should only help reduce unwanted frontal plane motion.
With that said, the authors of this study readily acknowledge more work needs to be done with larger clinical populations (including EMG work) to more clearly identify what magnitude the core musculature has on lower extremity motion and displacement.
Keep in mind the proper program will always stem from your ability to assess movement impairment and tissue dysfunction. I suggest beginning with a FMS in the athletic population and incorporating parts of that or the SFMA to compliment your evaluation in the clinic. This will generally reveal the priorities for the corrective exercises. For now, we can use this information in this particular study to be more intentional with our patients and clients suffering knee and hip dysfunction by adding this one simple step to our programming.
1. Claiborne TL, Armstrong CW, Gandhi V, Princivero DM. Relationship between hip and knee strength and knee valgus during a single leg squat. Journal of applied biomechanics. 2006;22(1):41.
2. Faries MD, Greenwood M. Core training: stabilizing the confusion. Strength & Conditioning Journal. 2007 ;29(2):10.
In my last post, I shared some practical plyometric drills with you to help teach proper landing mechanics in an effort to reduce ACL injuries. Yesterday, I presented my comprehensive approach to knee training at our ACL Symposium in Cary, NC.
One of the fundamental errors I see coaches and athletes make is abandoning their pre-season training efforts during the in-season. While athletes need to spend the majority of the in-season focusing on sports skills, they must also maintain the neuromuscular training adaptations acquired in the off-season and pre-season.
In my mind, the phrase “use it or lose it” is applicable for the neuromuscular training effects we see with balance, strength, agility and plyometric training. This is especially true for our high risk female athletes like soccer and basketball players who suffer knee sprains, ACL tears and patellofemoral pain at disproportionate rates.
I often hear coaches say, ” I don’t have time to get workouts done and still accomplish what needs to be done at practice.” While, time management may be difficult, I think coaches could probably squeeze in a single training session lasting 15-20 minutes if they simply knew how important it was to the overall health and performance capacity of their team.
With that said, I like to offer simple, yet effective exercises that can be done on a court or field with the whole team simultaneously without the need for expensive equipment. Exercises should focus on activating the glutes (including the medius and minimus) as well as training the hamstrings more since most female athletes tend to be quad dominant.
These exercises are just as effective for males too. So, in the video below I will reveal some exercises I prefer to do to increase strength and reduce injury risk. Perform 2-3 sets of 8-15 reps focusing on strict form throughout.
As I prepare to present at an ACL Symposium with some of my colleagues this weekend, I thought I would share some of the information I am presenting on injury prevention.
Research consistently shows that neuromuscular training is beneficial in reducing ACL injuries. This type of training hinges on training our athletes to land, plant and cut on a bent knee while shifting the COM (center of mass) forward. Too many times, I see female athletes land with stiff knees in an upright posture relying too heavily on their quads.
Emphasizing hip and knee flexion is vital in order to activate the posterior chain and provided a restraint to anterior tibial translation. When it comes to landing and plyometrics, I feel strongly that we need to focus on repetitive drills that enhance power and teach ideal form.
These exercises should include single and double leg varieties, but more importantly they should challenge the body in the sagittal, coronal and transverse plane. I have included a short video today that illustrates just a few exercises that I incorporate in my training sessions.
Stay tuned as I will share more details about prevention training in future posts.