Fig. 3

Example of an ultrasound of the pectoralis major (PMa) muscle (pars clavicularis) at a long (top) and short muscle length (bottom), in a relaxed state. The lighter blue in the ROI in the lower picture signalizes a higher muscle stiffness, as it occurs in the longer muscle length. SWE, shear wave elastography; PMa, pectoralis major; ROI, region of interest