Ackland et al. (2008) showed that the pectoralis major (clavicular head) displayed a peak moment arm length of 30.2 mm at 120 degrees of shoulder flexion (arms above head) and a minimum moment arm length at 2.5 degrees (length = +3.1 mm) of shoulder scapular plane flexion. (strengthandconditioningresearch.com)
Singers must cultivate exceptional strength and coordination in the rhomboids, middle and lower trapezius, and other muscles involved in scapular retraction, as well as the external intercostals, in order to maintain an elevated sternum and an expanded rib cage while singing / exhaling. (blog.nasm.org)
The Sandbag Pinch Grip Upright Row helps develop grip strength as well as scapular stability. (onnit.com)