Monday, April 18, 2011

Performance on the Single-Leg Squat Task Indicates Hip Abductor Muscle Function

Background: Contemporary clinical expertise and emerging research in anterior knee pain indicate that treatment of hip muscle function will result in greater effects, if such treatments can be provided to those with hip muscle dysfunction. Thus, it is imperative to develop and evaluate a clinical assessment tool that is capable of identifying people with poor hip muscle function.

Hypothesis: The clinical assessment of single-leg squat performance will have acceptable inter- and intrarater reliability. Furthermore, people with good performance on the single-leg squat will have better hip muscle function (earlier onset of gluteus medius activity and greater lateral trunk, hip abduction, and external rotation strength) than people with poor performance.

Study Design: Cohort study (diagnosis); Level of evidence, 2.

Methods: A consensus panel of 5 experienced clinicians developed criteria to rate the performance of a single-leg squat task as "good," "fair," or "poor." The panel rated the performance of 34 asymptomatic participants (mean ± SD: age, 24 ± 5 y; height, 1.69 ± 0.10 m; weight, 65.0 ± 10.7 kg), and these ratings served as the standard. The ratings of 3 different clinicians were compared with those of the consensus panel ratings (interrater reliability) and to their own rating on 2 occasions (intrarater reliability). For the participants rated as good performers (n = 9) and poor performers (n = 12), hip muscle strength (hip abduction, external rotation, and trunk side bridge) and onset timing of anterior (AGM) and posterior gluteus medius (PGM) electromyographic activity were compared.

Results: Concurrency with the consensus panel was excellent to substantial for the 3 raters (agreement 87%-73%; = 0.800-0.600). Similarly, intrarater agreement was excellent to substantial (agreement 87%-73%; = 0.800-0.613). Participants rated as good performers had significantly earlier onset timing of AGM (mean difference, –152; 95% confidence interval [CI], –258 to –48 ms) and PGM (mean difference, –115; 95% CI, –227 to –3 ms) electromyographic activity than those who were rated as poor performers. The good performers also exhibited greater hip abduction torque (mean difference, 0.47; 95% CI, 0.10-0.83 N·m·Bw–1) and trunk side flexion force (mean difference, 1.08; 95% CI, 0.25-1.91 N·Bw–1). There was no difference in hip external rotation torque (P > .05) between the 2 groups.

Conclusion: Targeted treatments, although considered ideal, rely on the capacity to identify subgroups of people with chronic anterior knee pain who might respond optimally to a given treatment component. Clinical assessment of performance on the single-leg squat task is a reliable tool that may be used to identify people with hip muscle dysfunction.


We use movement like this in my offices every day and find this test to be very reliable indicator of hip patho-mechanics

1 comment:

Injury prevention Toronto said...

First just a note on why I continue to read your sigh. I have done various exercises with different teachers /coaches weights / martial arts over the years (now 53) and think that most / all do exercises based on what’s works for them or what they were taught to teach but none that could program what worked well for me. With the advent of the internet I have been able to work out a program that is working really well but extracting the gems from the garbage is a tedious task. Your articles have seeded many researches because so many including this due to the balance you strive for between extremes (with appropriate pros and cons). In regard to hips and probation some 18 months ago I developed sciatic pain and associated muscle spasms. Before the episode I both strongly probated and externally rotated when standing. What is interesting is that during the treatment by a physic for a period of 2/3 days my degree of probation and rotation became totally plastic. Once it settled I no longer probated (after 50 years). Rotation was markedly different in each leg though I have since pushed them to be symmetrical. So hips also affect probation! Hope this is relevant enough.
Mr. Computer Guy
Injury prevention Toronto