Objectives: The goals of this study were to verify the reliability and safety of new methods for evaluating trunk muscle endurance, and to compare the differences between healthy subjects and patients with chronic low-back pain.
Design: Randomized and controlled study.
Setting: A referral center and institutional practice, and outpatient care.
Subjects: Ninety healthy subjects (37 men and 53 women average age 46.2 years) and 100 patients with CLBP (40 men and 60 women; average age 45.3 years) participated in this study.
Main outcome measures: During trunk flexor and extensor endurance tests, the subjects were asked to maintain the original positions for as long as possible. The performance time (seconds) for which subject could maintain the position was compared between two groups. Test-retest correlation (r) was also analyzed. The degree of lumbar lordosis was compared in conventional and new methods.
Results: All test-retest correlations were significantly high in both groups (p < .01). The performance time was much longer in the healthy subjects than in the patients with CLBP during any procedures (p < .01). Lumbar lordosis was significantly less in our method than in the Kraus-Weber test (p < .01).
Conclusions: This study demonstrated that our methods for measuring trunk flexor and extensor endurance had high reliability, reproducibility, and safety, and were easy to perform, with no need for special equipment. This study also showed that trunk muscles in patients with CLBP were more easily fatigued, compared with those in healthy subjects.