The effect of experimentally induced acute pain on lumbar movement control: a single blinded three-arm cross-over randomized control trial.

BACKGROUND

Non-specific low back pain exhibits high prevalence and is commonly correlated with deficits in lumbar movement control. Whether pain precipitates these impairments or arises as their sequela remains uncertain. This study investigates how experimentally induced acute pain influences lumbar movement control.

METHOD: Forty-five healthy, pain-free participants underwent three experimental conditions in randomized order: hypertonic saline injection to the lumbar paraspinal muscle (inducing local pain), hypertonic saline injection to the deltoid muscle (inducing remote pain), and isotonic saline injection to the lumbar paraspinal muscle (sham). A standardized, reliable and validated battery of lumbar movement control tests was performed before, during and after each condition and rated by an examiner blinded towards the experimental intervention. Perceived pain intensity was evaluated every 30 s using the numeric rating scale.

RESULTS

While initial analysis revealed a significant overall effect (χ2(8) = 23.45; p = 0.003, W = 0.26), post hoc pairwise comparisons showed no significant differences of movement control test results either within or between experimental conditions. Mean differences following the injections were small (painLB vs sham: MD -0.29, 95% CI -0.70 - 0.12; painARM vs sham: MD -0.16, 95% CI -0.56 - 0.25; painLB vs painARM: MD 0.07, 95% CI -0.41 - 0.55). As expected, pain intensity was significantly lower in the sham condition than in either experimental condition, confirming successful pain induction. Exploratory regression analyses revealed no significant associations between pain intensity on lumbar movement control.

CONCLUSION

Experimentally induced acute pain exerted no detectable effect on lumbar movement control. Across analyses, performance remained stable, indicating short-term robustness to transient nociceptive input.

TRIAL REGISTRATION: DRKS00038877 (retrospectively registered; January 6th, 2026).