During the Olympics one could see how different athletes trained by looking at the shapes of their bodies. In fitness they say “you get what you train for”. In track, the Richards Ross and Felix had balanced, elongated muscles and flat abdominal muscles. They looked like they trained biomechanically efficiently in a balanced, elongated, Pilates way. Jeter on the other hand looked imbalanced, had overdeveloped muscles and had a very round torso. You could see the two distinct shapes on the field. 1) The athlete with open shoulders and a flat stomach. and 2) the overdeveloped, bulky body, round torso that reflects the athlete training in a shortened manner. The round torso indicates the athlete performs roll up type exercises by shortening the body and pooching the rectus abdominis, rather than lengthening the body back. The large upper trapezius indicates overuse of that area, and a lack of efficient scapular recruitment and Serape muscular wrap that connects the centers. While waiting for the take off, the athlete will use the deltoids. At the take off of the race, the athlete will definitely use the latissimus dorsi to pull the ground back. When the arms swing during the running phase, they should be under-swinging and coming from the armpit, so I wonder why certain athletes want to have bulky upper trapezius muscles. You will see them swinging their arms with their shoulders up (which does not look comfortable). You could also see the gymnasts with different bodies. Some had rounded shoulders, some had nice open shoulders.