Fig. 7.

Poststroke alterations in muscle synergies are related to abnormal task performance. For each target force direction, the black triangle represents the number of stroke subjects who initially failed the corresponding target match with constraints on arm posture. In subsequent ad hoc trials, stroke participants repeated these force directions without constraints on arm rotation. Each red triangle represents the number of stroke survivors who achieved a match during the ad hoc trials. The targets additionally matched were mostly localized in the lateral (+Fx) and upward (+Fz) directions.