Fig. 3

Effect of external scapula assistance. a Normalized effect of therapist assistance: Improvement from baseline with therapist assistance, normalized by baseline ability. The assistive forces applied by the therapist in ventral \({{\varvec{F}}}_{ventral}\) and lateral \({{\varvec{F}}}_{lateral}\) direction provided dynamic scapula rotation \(\rho\) while the participant elevated their arm by \({\theta }_{therapist}\). b Relative effect of orthosis assistance: Improvement from baseline with orthosis assistance, normalized by maximal therapist improvement. The assisitve normal force \({\varvec{N}}\) applied on the scapula interface constrained the scapular winging while the participant elevated their arm by \({\theta }_{orthosis}.\) In b, data with negative therapist improvement in a were not considered to prevent discrepancies in data interpretation. a and b Black bar: mean; grey boxes: 95% confidence interval of the mean