Neural Noise- Muscle synergy analysis is used for clinical characterization of upper limb motor recovery after stroke.1
- EMG-based synergy extraction provides methods for physiological time series and motor control.1 1
Weekly enrichment (2026-07-20)
- The study (Archives of Physical Medicine and Rehabilitation, doi 10.1016/j.apmr.2025.05.019) compared muscle synergies before and after 20 sessions (1 hour/day, 5 days/week, 4 weeks) of conventional, robotic-assisted, or virtual-reality upper-limb treatment in 62 people with stroke.2
- Participants improved overall on the Fugl-Meyer Assessment Upper Extremity (FMA-UE change Δ=7.14±7.46 points, p<0.001), but the number of muscle synergies on the affected side did not change (8.8 before vs 8.7 after, p=0.374).3
- Patients were stratified into 34 Responders and 28 Non-Responders using the FMA-UE minimal clinically important difference (Δ>5 points).3
- Only Responders significantly reduced the percentage of merged muscle synergies (a “de-merging”; p=0.004 in the preprint analysis, p=0.016 post-treatment), while Non-Responders did not.2 3
- Non-Responders instead showed a significant increase in synergy similarity to the unaffected limb (p=0.006), and between-group merging changes differed significantly (p=0.025).2
- No significant changes appeared in the fractionation index for either subgroup (between-groups p=0.952); a muscle was counted toward merging or fractionation only if its synergy weight exceeded 0.20.2
- At baseline, the most severely impaired Responders (FMA-UE<20 points; n=8) exhibited greater synergy merging.2
- The affected limb’s synergy vocabulary grew from 13 components before treatment to 14 after, versus 16 in the unaffected limb, and post-therapy both groups’ motor-function profiles resembled the unaffected limb.2 3
- The authors conclude EMG-based muscle synergy analysis carries prognostic value that could help personalize post-stroke upper-limb rehabilitation, with methods relevant to myoelectric and BCI decoding.2