Baseline EMG alters muscle synergy activations while preserving spatial structure in healthy and post-stroke subjects.

The study analysed a small public dataset of twelve healthy and ten stroke subjects, and the stroke padding analysis included only nine subjects because some lacked enough baseline time. It tested EMG processing choices, not a therapy, recovery, or patient outcome. Movement onset and offset were defined by an EMG threshold, and kinematic data were unavailable, so the source of baseline activity was uncertain. Only non-negative matrix factorization was used, so other decomposition methods could change the number or structure of synergies. The paper had no ground truth for true CNS synergies, so changes in synergy count or merging cannot be read as direct neural changes. Stroke results were based on upper-limb reaching only and may not apply to walking, hand function, or other tasks.

Funded by the National Natural Science Foundation of China, the Natural Science Foundation of Jiangsu Province, and the Jiangsu Provincial Key Research and Development Program. No other conflict statement is provided in the supplied text.

Do not read a change in synergy count as proof that baseline EMG reveals a new motor module or that stroke recovery can be measured this way. The study tested EMG processing choices, not patient outcomes, and the extra baseline patterns were combinations of existing patterns.