The objective was to examine the intra-rater (test-retest) reliability of the core stability related tests and to develop a reliable core stability assessment battery. Studies suggest that core stability exercises may improve function and decrease pain in patients with non-specific low back pain (LBP). Reliable clinical tests are required to implement adequate rehabilitation and to evaluate results of these interventions. The study had a test-retest design. Thirty-three different tests that might relate to core stability were identified with their mostly used protocols. Five different components of core stability including endurance, flexibility, strength, functional performance, and motor control were assessed in 38 patients with non-specific LBP. The same testing procedure was performed again after 48-72 hours. Intra-class correlation coefficients (ICCs), standard error of measurement, and minimal detectable change were calculated to assess the intra-rater reliability. The intra-rater reliability of the tests ranged from little to very high (ICC = 0.08-0.98). Partial curl-up (ICC = 0.90), lateral bridge (ICC = 0.95-0.96), trunk flexor endurance (ICC = 0.97), sit-and-reach (ICC = 0.98), single-legged hop (ICC = 0.98-0.97), lateral step-down (ICC = 0.93-0.92), eyes open right and left leg unilateral stance (ICC = 0.97 and 0.91) tests had the highest intra-rater reliability for each core stability component.
The results indicated that the partial curl-up test (strength), side bridge and trunk flexor tests (endurance), sit-and-reach test (flexibility), single-legged hop, and lateral step-down (functional), unilateral stance test with eyes open (motor control) had very high intra-rater reliability. A core stability assessment battery involving these tests can be used in patients with non-specific LBP to assess all components of core stability.