Performance on the single-leg squat task indicates hip abductor muscle function

Crossley, Kay M., Zhang, Wan-Jing, Schache, Anthony G., Bryant, Adam and Cowan, Sallie M. (2011) Performance on the single-leg squat task indicates hip abductor muscle function. American Journal of Sports Medicine, 39 4: 866-873. doi:10.1177/0363546510395456

Author Crossley, Kay M.
Zhang, Wan-Jing
Schache, Anthony G.
Bryant, Adam
Cowan, Sallie M.
Title Performance on the single-leg squat task indicates hip abductor muscle function
Journal name American Journal of Sports Medicine   Check publisher's open access policy
ISSN 0363-5465
Publication date 2011-04-01
Year available 2011
Sub-type Article (original research)
DOI 10.1177/0363546510395456
Open Access Status DOI
Volume 39
Issue 4
Start page 866
End page 873
Total pages 8
Place of publication Thousand Oaks, CA, United States
Publisher Sage Publications
Language eng
Formatted abstract
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 6 SD: age, 24 6 5 y; height,
1.69 6 0.10 m; weight, 65.0 6 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%; k = 0.800-0.600). Similarly, intrarater agreement was excellent to substantial (agreement 87%-73%; k = 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.mBw¯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.
Keyword Patellofemoral joint
Core stability
Clinical assessment
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ
Additional Notes originally published online February 18, 2011

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
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Citation counts: TR Web of Science Citation Count  Cited 108 times in Thomson Reuters Web of Science Article | Citations
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