Fig. 1

Anatomical bony landmarks and the defined local coordinate system. a To define the thorax coordinate systems, we attached four markers to the spinous process of the seventh cervical vertebra (C7), spinal process of the eighth thoracic vertebra (T8), incisura jugularis (IJ), and processus xiphoideus (PX). b To define the scapula coordinate systems, we attached three markers to the trigonum spinae scapulae (TS), angulus inferior (AI), and angulus acromialis (AA). c To define the humerus coordinate systems, we attached three markers to the most caudal point on the lateral epicondyle (EL), most caudal point on the medial epicondyle (EM), and the acromioclavicular (AC) joint. The glenohumeral joint center was estimated by calculating the marker position of the AC joint (GH)