To build upon my previous post regarding Evidence-based Strength Training of the Gluteus Medius, I wrote the following article for MedBridge Education…
Pain and Gluteal Strength
The gluteal musculature has been implicated in many different pathologies due to its potential impact on lower extremity biomechanics. During weight bearing, the femur moves about a fixed patella and therefore excessive femoral internal rotation and adduction results in increased contact directed primarily at the lateral facet of the patella1. Just 10° of IR can lead to a substantial decrease in PFJ contract area and a 50% increase in joint stress. Coinciding with these findings, Souza et al.2 found that females with patellofemoral pain syndrome (PFPS) demonstrated greater peak hip internal rotation compared to the control group during running, drop jump, and step down. The PFPS group also demonstrated 14% weaker hip abductor strength and 17% weaker hip extensor strength. Wilson et al3, Noehren et al4, and Nakagawa et al5 found that individuals presenting with PFPS demonstrated increased hip adduction during running, jumping, and single-leg squats. This excess femoral adduction creates an increased valgus force about the knee joint, which in turn causes increased loading of the lateral patellofemoral joint. In addition to patellofemoral pain, a hip etiology or influence has also been implicated in iliotibial band syndrome6, anterior cruciate ligament rupture7, and achilles tendinopathy8.
Gluteal strengthening and Rehabilitation
In support of a gluteal etiology, several studies have found the effectiveness of gluteal strengthening in the treatment of lower extremity disorders. A recent systematic review conducted by Santos and colleagues9 found gluteal strengthening decreased the highest intensity of pain experienced during the previous week, pain when ascending and descending stairs, and pain while squatting or sitting for prolonged periods amongst individuals diagnosed with PFPS. Additionally, with regards to rehabilitation following anterior cruciate ligament reconstruction, the inclusion of hip strengthening appears to improve sagittal plane dynamic balance at three months post-ACLR as compared to traditional rehabilitation10.
EMG Activity and Exercise Goals
According to Reiman et al.11 and Escamilla et al.12, moderate electromyographic activity (EMG) activation (21-40% MVIC) is best used to facilitate endurance and neuromuscular re-education; high activation (41-60+% MVIC) in order to promote strength gains.
From Biomechanics to Exercises
Origin: External surface of Ilium between anterior and posterior gluteal lines
Insertion: Lateral surface of the greater trochanter
Primary Function: Abduction of the hip joint; the anterior fibers contribute to hip flexion and hip internal rotation, and the posterior fibers to hip extension and hip external rotation. Additionally, the gluteus medius is responsible for preventing the opposite side of the pelvis from dropping during the stance phase of gait and plays a major role in providing frontal stability for the entire pelvis during walking and other functional activities.
The gluteus medius achieves the highest EMG levels during13,14:
- Side-lying plank with hip abduction
- Reverse clamshell with hip abduction and extension
- Prone plank with hip extension
- Reverse clamshell with hip abduction
- Single-leg Bridge
Additionally, you must consider the interaction of other muscles acting with or against the gluteus medius when determining exercise prescription. It has been proposed that individuals who demonstrate excess femoral internal rotation during functional tasks may be relying too heavily on the tensor fasciae latae to control their pelvis in the presence of weak or inhibited gluteus medius musculature.
Selkowitz and colleagues determined that the following exercises achieved the best Gluteal to Tensor Fasciae Latae Activation Ratio15:
- Side-step with resistance band
- Single-leg bridge
- Quadruped hip extension with knee extended
- Quadruped hip extension with knee flexed
Finally, when progressing your patient towards more functional closed kinetic chain and sport/activity-specific exercises, the following exercises achieve the highest gluteus medius activation13,16,17,18:
- Walking lunge with dumbbell in contralateral hand
- Unilateral mini-squat
- Skater squat
- Unilateral deadlift
- Unilateral wall squat
Exercise prescription is a multi-faceted decision, which is driven by the individual patient’s goals, functional limitations, and the evidence supporting the treatment of these factors. Using EMG studies to drive the selection of exercise is highly valuable, especially during the early stages of rehabilitation or when attempting to isolate individual muscles and/or groups of muscles. However, there are limitations when comparing different studies due to methodological differences (the type of EMG, patient population, data analysis, etc.). Additionally, due to the cost and time to conduct these studies, there are thousands of exercises that have not been evaluated in the literature. In light of this information, these studies should be used to guide your decision making, it should not override your clinical expertise when accompanied by biological plausibility.
Interesting review. My main interrogation remains though. Wich is : are the changes in strength and biomechanics a cause or a consequence of the PFP?
It would makes sense that pain would prompt the individual to change its biomechanics to alleviate the discomfort. And, with time, less utilization of the affected limb might decrease one’s strenght in quad, hamstring and gluts…
Besides, the litterature is equivocal as to the changes in strenght and biomechanics in PFP.
Moreover, the effects of the exercices could be unrelated to changes in strenght or biomechanics (resisted exercices promote the liberation of interlukine-10, an anti-inflammatory cytokine and decrease CNS pain sensitivity) and predictors of a good outcomes (altough of weak quality) could have Fear avoidance behaviors as a champion variable.
It could also be argued that the changes in pain cited in Santos et al could unrelated to a change in glut/hip strength as the change in pain was present before the change in strenght at least in one of the studies(Dolak et al).
I am not saying that hip strenght as no influence on PFP but I am suggesting we be a bit cautious in applying a complex exes regimen with a rational with a strong biomedical logic that might promote greater fear avoidance behaviors.
What’s the Reverse clamshell with hip abduction and extension?
There’s so much out there right now on strength training that’s evidence based and what not. Most of what I’m seeing though are tested on individuals that have been undergoing this form of training for some time. I’d like to see more variations and test subjects – perhaps that’s just me.