The number of repetitions of the McGill tests to reliably determine core muscle endurance in subjects with and without chronic nonspecific low back pain: A cross sectional study

Abstract

McGill tests are popular and practical clinical tests for evaluating the isometric endurance of core muscles. Previous studies have reported the mean or maximum rate of the McGill tests from one to three times of Mc Gill tests. Objective: To assess the number of repetitions of the McGill tests to reliably determine core muscle endurance in subjects with and without nonspecific low back pain. Methods: The participants were 50 (24 males and 26 females) sedentary subjects with and without chronic nonspecific low back pain. Isometric core muscle endurance of the trunk flexion, extension and lateral flexion (right and left) was measured using the McGill tests. The order of the test was set randomly and each test was repeated three times with 5-minute rest intervals. The subjects were recruited from state and private companies and organizations and were purposefully assigned into low back pain and without low back Pain group. In each test, three trial scores, maximal score and mean score were reported. The frequency of reporting maximal score in first, second and third trial was determined and compared within groups using McNemar test and between groups using Mann-Whitney U test. Results: For all Mc Gill test, the maximum score trials was significantly greater than the mean score in both groups (P <= 0.001). For trunk flexion endurance, the probability of obtaining the maximal score in the first couple of trials was up to 80 and 92, 76 and 84 for the trunk extension endurance, 72 and 76 for right lateral flexion endurance and 92 and 76 for left lateral flexion endurance in LBP and WLBP subjects respectively. Conclusion: Two repetitions of McGill tests seem to be sufficient to detect core muscle endurance in subjects with and without chronic nonspecific low back pain.