The efficacy of strength exercise dosage on pain and disability in people with low back pain: a systematic review of randomized controlled trials

OBJECTIVE: This systematic review aimed to evaluate the effects of strength exercise dosages on pain and disability in individuals with low back pain. DESIGN: Systematic review of randomized controlled trials. DATA SOURCES: MEDLINE, PEDro, EMBASE, Cochrane Library, AMED, and PsycINFO. ELIGIBILITY CRITERIA: Randomized controlled trials comparing strength exercises of any dosage with minimal interventions for pain and disability in individuals with low back pain of any duration. Two reviewers independently screened trials, extracted data, assessed quality, and evaluated evidence using the GRADE framework. Mean differences with 95% CIs were reported. RESULTS: Eight trials were included in the qualitative analysis, five in the quantitative analysis. All studies included in the meta-analysis compared exercise to minimal interventions. No studies regarding specific spine conditions or with pain duration of less than three months were included. Lumbar extension exercises (specific exercises; pain: -19.6 [-25.4 to -13.7]; disability:-12.5 [-14.9 to -10.1]), higher exercise intensities (> 60% 1 RM; pain: -19.3 [-27.0 to -11.6]; disability: -14.2 [-15.7 to -12.8]), lower frequencies (= once per week; pain: -19.3 [-27.0 to -11.6]; disability: -11.8 [-16.2 to -7.5]), and shorter treatment durations (< 3 months; pain: -19.9 [-26.0 to -13.8]; disability: -13.4 [-15.2 to -11.6]) presented statistically significant results in the reduction of both outcomes. Confidence on the evidence was low to very low. CONCLUSION: Our results demonstrated statistically significant results that strength exercises with high intensity, low frequency, and that focus on back extensor muscles have effect on reducing pain and disability in patients with chronic non-specific low back pain. Overall evidence quality was low to very low. Future research should improve reporting of exercise variables in order to refine dosage recommendations. PROSPERO AND OPEN SCIENCE FRAMEWORK REGISTRATION NUMBERS: CRD42024500944. OSF DOI: https://doi.org/10.17605/OSF.IO/D34TJ .