Methodological approaches in electromyography for assessing movement during experimental pain: a scoping review

This scoping review mapped current methodologies used to investigate the impact of experimentally induced pain on voluntary movement in healthy adults through electromyography (EMG). Thirty-eight studies published between 2015 and 2023 were analyzed for pain induction paradigms, EMG acquisition and analysis techniques, and motor tasks. Findings reveal substantial methodological heterogeneity but several converging trends. Most studies employed acute, chemically induced muscle pain models—primarily hypertonic saline—paired with isometric tasks, consistently showing reductions in EMG amplitude and force output at the painful site. In contrast, dynamic and multi-joint tasks (e.g., walking, cycling) typically preserved global performance despite marked reorganization of muscle activity, including increased co-contraction and redistribution to contralateral muscles, reflecting compensatory strategies. EMG analysis was dominated by amplitude and timing metrics, while advanced approaches such as high-density EMG and muscle synergy analysis were rarely used. The few synergy studies indicated that pain does not alter the number of synergies but modifies their structure and timing, suggesting global reorganization rather than loss of degrees of freedom. Methodological gaps include limited bilateral recordings, underrepresentation of tonic pain and joint/tendon models, and lack of pain-intensity standardization. Overall, evidence supports that pain triggers adaptive motor strategies aimed at protecting threatened tissues while maintaining functional performance, underscoring the need for multidimensional EMG analyses and more ecologically valid paradigms.