Does strengthening the abdominal muscles prevent low back pain--a randomized controlled trial.

Objective: To investigate the effects of abdominal muscle strengthening exercise on low back pain (LBP) risk reduction.

Methods: We compared the effects of abdominal muscle strength (AMS) exercise and back education with back education only on 402 asymptomatic subjects with weak AMS. The primary outcome was the percentage of subjects with at least one episode of LBP at 24 months. A diary was used to monitor compliance.

Results: There were no statistically significant differences between experimental (E) and control (C) subjects at 24 months for LBP episodes (E: 34.7%, C: 30.4%; C-E = 4.2%, P2 = 0.481; 95% CI -16.1%, 7.6%). The LBP episodes were also not statistically significantly different at 6 months (E: 13.2%, C: 16.1%; C-E: 2.9%, P2 = 0.493; 95% CI -5.3%, 11.0%) or at 12 months (E: 24.8%, C: 23.6%; C-E = -1.2%, P2 = 0.818; 95% CI -11.6%, 9.2%). Adjusting the data for strata and baseline AMS did not alter the findings. Imputed results for LBP episodes at 6 months (C-E: 4.8%, P2 = 0.191; 95% CI -2.4%, 12.0%), 12 months (C-E: -1.0%, P2 = 0.821; 95% CI -9.5%, 7.6%), and 24 months (C-E: -3.3%, P2 = 0.483; 95% CI -12.6%, 5.9%) were also not statistically significantly different.

Conclusion: Back education and abdominal exercise instructions are similar to back education alone. There were no group differences in LBP episodes, possibly due to noncompliance with the exercise program. While the estimated benefit of 2.9% at 6 months from the complete data and 4.8% from the imputed data were not statistically significant, a larger study or future metaanalyses may be needed to confirm whether there is a clinical benefit or whether these results should be considered a chance finding.