Validity and reliability of clinical tests for trunk muscle function


Physical Therapy


PURPOSE/HYPOTHESIS: Low back pain (LBP) is one of the most common reasons to visit a health care provider. Limited performance of the trunk musculature has been implicated in individuals with LBP. Several endurance tests for the trunk musculature recently have been described in the literature, and are finding increasingly common use in the clinic. An emerging literature has begun to address measurement properties for these tests; however, a systematic literature review has yet to be completed. The purpose of this project was to assess the current literature that documents the validity and reliability of clinical measurements for trunk muscle performance in individuals with and without LBP.

NUMBER OF SUBJECTS: Twenty articles were screened, and 10 primary research studies were analyzed that documented the reliability or validity of clinical tests for trunk muscle function.

MATERIALS/METHODS: A systematic literature search was conducted to identify primary research articles related to intratester reliability, intertester reliability, and normative values for objective clinical tests of trunk muscle function. CINAHL, the Cochrane Library, and PubMed were searched for articles with the following key words: abdominal endurance test, abdominal manual muscle testing, abdominal plank exercise, and trunk isometric exercises. Screened articles also were hand searched for additional references. Articles were graded according to their strength of evidence using Centre for Evidence-Based Medicine criteria. Outcomes measures in observed studies were too heterogeneous for a planned meta-analysis, so a narrative literature synthesis was completed.

RESULTS: Twenty articles were screened, and 10 primary research studies were analyzed. The side-bridge test (intraclass correlation coefficient [ICC]2,1 = 0.81-0.97), Sorensen test (ICC2,1 = 0.78), and trunk flexor endurance test (ICC2,1 = 0.89-0.98) each had at least moderate-level evidence of interrater reliability. Diagnostic accuracy to predict the presence of LBP was established for the Sorensen test, supine double straight leg raise, and trunk flexor endurance testing in 1 study. Normative values for individuals with LBP and for nondisabled individuals were identified for the modified Sorensen test and the trunk flexor endurance test.

CONCLUSION: Current approaches to trunk stability testing generally demonstrate adequate intrarater and interrater reliability. Emerging areas of study include establishment of normative values, although this information is not yet ready for widespread clinical application.

CLINICAL RELEVANCE: Clinical tests of trunk muscles that measure isometric endurance are increasingly common in the clinic. Information from this systematic literature review and critical synthesis suggests clinicians can use these approaches with confidence regarding test reliability; however, application of normative data and information about the diagnostic accuracy of these tests with respect to the presence of LBP require additional research.

Document Type


Publication Date


Publication Title

Journal of Orthopaedic and Sports Physical Therapy


American Physical Therapy Association

Conference Dates

February 3-6, 2014

Conference Location

Las Vegas, NV









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Abstract from poster presentation at the APTA Combined Sections Meeting 2014 Orthopaedic Section Poster Presentations