A pervading idea in the fitness and therapy industries is that altered or “dysfunctional” movement is simply the product of specific muscle weakness (or imbalance). The solution, of course, is to find the weak muscle and strengthen it. The result: correct movement, and therefore decreased risk of injury and chronic pain.
Is this true? Can strengthening specific muscles improve movement form or technique?
As usual, things are a bit more complicated than that. Let’s gather insight from a few research studies, using one of the most common examples: gluteus medius strengthening for running mechanics.
Why the Gluteus Medius?
For those who are unfamiliar with anatomy: stand up. Rotate your leg so the kneecap points outward (away from the other leg). The motion occurring at your hip joint is called “external rotation”. Now, lift your leg out to the side, as if you are kicking a ball right next to you. That’s called “hip abduction”.
The muscles important for these movements are the glutes, specifically the gluteus medius. Poke your fingers in the back/side of your hip – right below your pelvic bone – and repeat those movements. You should feel the gluteus medius muscle contracting.
The gluteus medius also works to resist the opposite movements – “hip adduction” and “internal rotation”, which looks like your knees knocking together (often referred to as “knee valgus”).
Too much movement and force in that “knee knocking” direction (a.k.a. increased knee valgus stress) is thought to be an important risk factor for serious knee injuries during sports. 1 This type of movement occurs often during running, quick direction changes, and landing jumps.
Therefore, the idea is that strengthening the gluteus medius should help people keep their knees from falling inward and reduce valgus stress.
It’s a nice idea – but does it work?
One study in 2009 trained healthy females with hip rotation exercises, and then observed their running mechanics. 2 After six weeks, the results showed a change in the forces acting on the joints – but no significant change in the actual movement of the legs. Since the study used healthy subjects, improvements might have been hard to find.
Another study from 2011 looked at female subjects who had excessive hip adduction (knees falling together) while running. 3 This time, the training program was quite impressive: training consisted of a hip strengthening and a movement education program, three times a week for six weeks, plus single-leg squat training with neuromuscular re-education with mirrors and verbal feedback on proper form. The results? The hips got stronger, but the movement improved only in the single leg squat (the exercise they practiced) – and not during running!
A similar study from 2012 also trained females with excessive knee valgus using a program that included verbal, visual, and even tactile (hands-on) feedback. 4 The training program involved numerous leg strengthening exercises – especially targeting the glutes. The results again showed stronger hips, and decreased joint loading. Finally, a slight improvement was found in hip and knee movement during running – but only by about 1 to 3 degrees!
Overall, it seems targeted (and even general) muscle strengthening does very little to improve movement patterns during a specific task like running.
Specificity Strikes Again
Why doesn’t movement improve – even when you strengthen the muscles involved in that movement?
One theory is that the body adapts to move in the path of least resistance (not necessarily the best or safest path – just the easiest) and when something might change this preferred movement pattern (like changes in joint forces from stronger muscles) the body simply adapts to maintain it’s old pattern. 5 This is speculative, of course.
More importantly, one must not forget the specificity principle. If the goal is to improve the strength of a specific muscle, then use targeted exercise. However, if one wishes to improve a particular movement or skill, they should practice that movement or skill specifically.
Another study from 2011 trained runners with real-time feedback – information was provided to them about their running mechanics while they actually ran on a treadmill. 6 The runners had eight sessions, and feedback was gradually removed over the last four sessions. At the end of the study, significant improvements in running mechanics were found during running.
Muscle strengthening still has tremendous value. In some cases a person may not be strong enough to move a certain way. This is probably not the case with most activities, although strengthening may make common movements easier. Plus, research does show that hip strengthening leads to improvements in joint loading – which may reduce some cases of acute pain during exercise. 7
However, when it comes to improving movement, nothing is better than actually training movement. Deliberately practice the movement with the goal of making the desired improvements. Don’t just go through the motions.
It’s fine to use different exercises to practice important principles of movement (like avoiding excessive knee valgus) – but then, one must apply those principles to the movement pattern of interest.
Want better running mechanics? Practice better running mechanics.
1. Hewett TE, Di Stasi SL, Myer GD. Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction. Am J Sports Med. 2013 Jan;41(1):216-24. doi: 10.1177/0363546512459638. Epub 2012 Oct 5. Review. PubMed PMID: 23041233; PubMed Central PMCID: PMC3592333.
2. Snyder KR, Earl JE, O’Connor KM, Ebersole KT. Resistance training is accompanied by increases in hip strength and changes in lower extremity biomechanics during running. Clin Biomech (Bristol, Avon). 2009 Jan;24(1):26-34. doi: 10.1016/j.clinbiomech.2008.09.009. Epub 2008 Nov 14. PubMed PMID: 19013697.
3. Willy RW, Davis IS. The effect of a hip-strengthening program on mechanics during running and during a single-leg squat. J Orthop Sports Phys Ther. 2011 Sep;41(9):625-32. doi: 10.2519/jospt.2011.3470. Epub 2011 Jul 12. PubMed PMID: 21765220.
4. Wouters I, Almonroeder T, Dejarlais B, Laack A, Willson JD, Kernozek TW. Effects of a movement training program on hip and knee joint frontal plane running mechanics. Int J Sports Phys Ther. 2012 Dec;7(6):637-46. PubMed PMID: 23316427; PubMed Central PMCID: PMC3537459.
5. Nigg BM. The role of impact forces and foot pronation: a new paradigm. Clin J Sport Med. 2001 Jan;11(1):2-9. Review. PubMed PMID: 11176139.
6. Noehren B, Scholz J, & Davis I (2011). The effect of real-time gait retraining on hip kinematics, pain and function in subjects with patellofemoral pain syndrome. British journal of sports medicine, 45 (9), 691-6 PMID: 20584755
7. Ismail MM, Gamaleldein MH, Hassa KA. Closed Kinetic Chain exercises with or without additional hip strengthening exercises in management of Patellofemoral pain syndrome: a randomized controlled trial. Eur J Phys Rehabil Med. 2013 Jul 2. [Epub ahead of print] PubMed PMID: 23820880.