Gluteus Maximus Isometric Strength is Related to Performance-based Function in Chronic Mechanical Low Back Pain: Cross-Sectional Study

Background and purpose Gluteus maximus strength is declined in chronic mechanical low back pain. This decline may be associated with impaired function both self-reported and performance-based ones. More researches are needed to confirm this relation. This study aim is to investigate the association between gluteus maximus muscle isometric strength, and self-reported function and functional performance in patients with chronic mechanical low back pain. Materials and methods This cross-sectional study was conducted at an outpatient clinic. Twenty-four patients with chronic mechanical low back pain with age range between 21 and 45 years were included. All patients were assessed for gluteus maximus isometric strength (bilaterally) and function (self-reported and performance-based) using Hand-held dynamometer, Arabic version of Oswestry Disability Index, and One legged hops test (Single limb triple hop test for distance and Single-Limb crossover hop test for distance, on both sides) respectively. Results There was a significant positive moderate correlation (r=0.44-0.54, P<0.05) between gluteus maximus isometric strength (right and left sides) and one-leg hop tests (Left Single limb triple hop test for distance and right and left Single-Limb crossover hop test for distance). There was no correlation between gluteus maximus strength and Single-Limb crossover hop test for distance on the right side and if gluteus maximus strength and Single-Limb crossover hop test for distance on both sides. In addition, there was no correlation between gluteus maximus strength (both sides) and Oswestry Disability Index. Conclusions Gluteus maximus isometric strength is moderately related to performance-based function. So, It was suggested that implementing high quality randomized controlled trials to confirm the causal relation between gluteus maximus strength and functional performance. It also was recommended that using functional performance tests instead of self-reported ones to assess the efficacy of gluteus maximus strength on disability.