A Comparison of Isolated Lumbar Extension Strength Between Healthy Asymptomatic Participants and Chronic Low Back Pain Subjects Without Previous Lumbar Spine Surgery

STUDY DESIGN: Cross-sectional case-control study. OBJECTIVE: To compare isolated lumbar extension strength between healthy asymptomatic participants and participants with chronic low back pain (CLBP), while controlling for previous lumbar spine surgery. SUMMARY OF BACKGROUND DATA: Deconditioning of the lumbar musculature is common in those with previous lumbar surgery, resulting in decreased strength and endurance. Evidence is required to support whether this is the case for participants with CLBP yet no previous surgery compared with asymptomatic participants. METHODS: Forty-two healthy (25 males and 17 females) asymptomatic participants, and 53 participants with non-specific CLBP (30 males and 23 females) aged between 19 and 76 years were recruited. Maximal isometric isolated lumbar extension (ILEX) strength was examined. RESULTS: A Mann-Whitney U test indicated that ILEX strength was significantly greater in the asymptomatic group compared with the CLBP group (Z = 1441.00, P = 0.014). Post-hoc effect size was calculated to be d = 0.56, showing a moderate effect. CONCLUSION: These results indicate that ILEX weakness and lumbar extensor deconditioning is present independent of surgery and may be a factor involved in CLBP. As such, lumbar extensor deconditioning would appear to be a reasonable target for interventions in CLBP. LEVEL OF EVIDENCE: 3.