Introduction: Low back pain (LBP) is a leading cause of disability and lost work time worldwide. Exercise is recommended by clinical practice guidelines for reducing symptoms of LBP. Resistance training is commonly used due to the hypothesis that it improves function. High Intensity Resistance Training (HIRT) is used in some clinical settings with the aim of increasing strength to build resilience for functional movement, but no previous studies have established the evidence for this approach. We aimed to assess whether HIRT was as, or more, effective than other forms of rehabilitation or no intervention on reducing disability and pain in adult populations with LBP.
Methods: This systematic review and meta-analysis examined randomised controlled trials of adults with non-specific LBP of any duration. Trials were included if the primary intervention was HIRT (any comparator was acceptable) and if they included disability and pain outcome measures. Two team members independently completed all screening and data extraction. Four meta-analyses examined the effect of HIRT on disability, comparing HIRT to other exercise and to physiotherapy at discharge and 6-12 month post-treatment using standardised mean difference. Two meta-analyses investigated with effect of HIRT on pain, comparing HIRT with other exercise at discharge and 6-12 months post-treatment using mean difference. Standardised mean difference [SMD] (or mean difference [MD] when outcomes were consistent) were used for comparisons, and GRADE was used to assess the quality of evidence.
Results: Nine randomised controlled trials met inclusion criteria (n=821 participants). The risk of bias of the studies was low to moderate (PEDro scores 3-7/10, median 6), with weaknesses in the reporting of interventions, comparators and adverse events. HIRT interventions consisted of whole-body exercises, multimodal training or progressive resistance training. Moderate to high quality evidence from four meta-analyses found that high intensity resistance training is as effective as other exercise or other therapy for reducing disability in patients with chronic LBP (SMDs ranged from -0.16 to 0.06). High quality evidence from two meta-analyses found that high intensity resistance training was more effective at reducing pain when compared to other exercise (MDs 0.50 and 0.51) in chronic LBP, however the differences in pain reduction between interventions may not be clinically meaningful (≤1.5/10). No studies investigated acute or sub-acute LBP.
Discussion: This review found that high intensity resistance training is as effective as other treatment or other exercise to improve disability outcomes for people with chronic low back pain, and potentially more effective at reducing pain symptoms than other exercise. Limitations of this review were that there was a small evidence base (9 studies) and only three included studies with interventions that comprised 100% HIRT, as many were multimodal or graded intensity programs.
Impact and application to the field: HIRT should be considered by clinicians in the treatment of LBP. This review highlights a need for further studies to determine optimum HIRT dosage, as well as investigate acute and sub-acute LBP populations.
Conflict of Interest: We acknowledge we have no conflict of interest of relevance to the submission of this abstract
