Does pain alter the spatial distribution of muscle activity in people experiencing spinal pain? A systematic review and meta-analysis

Numerous studies have investigated the influence of pain on the spatial distribution of muscle activity using high-density surface electromyography (HDsEMG) to understand pain-related motor adaptations in individuals with spinal pain. This systematic review aimed to synthesize the available evidence to determine whether clinical or experimental spinal pain influences the spatial distribution of muscle activity. The review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42024524021, registered April 03, 2024). Electronic databases (MEDLINE, EMBASE, PubMed, CINAHL Plus, and Web of Science), grey literature, and key journals were searched from inception to April 4, 2025. Two independent reviewers screened studies and assessed the quality of studies using the Newcastle-Ottawa Scale and the Consensus for Experimental Design in Electromyography (CEDE) checklist. Data synthesis was conducted by outcome domain, and random-effects meta -analyses were performed when feasible. From 1,099 records, 23 studies (15 clinical pain, 8 experimental pain) met the inclusion criteria. The overall certainty of evidence was rated very low according to GRADE. Meta-analysis showed a cranial shift of erector spinae activity in clinical low back pain (SMD = -0.64 [95%CI: −0.97; −0.32], p = 0.0001, I 2 = 15.4%, τ 2 = 0.085), although this effect was not robust in sensitivity analyses of functional tasks. In experimentally-induced neck pain, a caudal shift of upper trapezius activity was identified (SMD = 1.17 [95%CI: 0.61; 1.73], p < 0.0001, I 2 = 33.4%, τ 2 = 0.31). Further studies using more consistent and comparable methodologies are needed to draw more definitive conclusions.