Does Lifting With a Rounded Back Actually Cause Back Pain?

Keep your back straight when you lift is one of the most repeated safety rules there is, and the evidence behind it is thinner than most people assume. A 2020 systematic review with meta-analysis in the Journal of Orthopaedic and Sports Physical Therapy concluded there was low-quality evidence that greater lumbar flexion during lifting was not a risk factor for low back pain (see [1]). In the seven studies that measured the trunk relative to the pelvis, people with back pain actually lifted with about 6 degrees less lumbar flexion than people without it.

The same research group then took the question into the lab. In a 2021 PLOS ONE study, 21 manual workers with back pain and 20 without each performed 100 lifts while researchers recorded motion and force (see [2]). The workers with pain started out lifting more slowly and more squat-like, with a deeper knee bend and a more upright trunk, and by the end both groups had drifted toward a faster, more stooped style. Of 21 biomechanical variables tested, only one tracked with pain rising during the task, and the authors flagged it as a possible chance finding. The idea that back pain comes from bending the lumbar spine or loading it with more force did not hold up.

Because these studies are cross-sectional, they cannot say which came first. A slow, careful, upright lift may be a response to a sore back rather than protection against one, which is something I see constantly in rehab: people guard what hurts. The older trial data points the same way. A 2008 BMJ systematic review of six randomized trials with 17,720 participants found no evidence that training workers in lifting technique, with or without lifting equipment, prevented back pain or related disability (see [3]).

The honest limit is load. The reviewed studies involved objects ranging from a pen up to 12 kilograms, and the Curtin researchers said studies with heavier weights simply do not exist (see [4]). So none of this says a max-effort deadlift with a rounded spine is fine. What it does say is that posture alone is a weak predictor, and the authors pointed to factors such as repetitive lifting while fatigued, general fitness and gradually built tolerance as more likely to matter. If you want training that adjusts around sore spots instead of policing every rep, our injury-aware workout app comparison lays out the options.

This is general information, not medical advice. Talk to a qualified clinician about your own situation.