Muscle force and activation on each head of the tricep brachii is different at shoulder flexion angles, keeping the elbows tight to the sides in full extension of the lower arm the long head of the tricep plays a major role. Allowing an elevation of the shoulder not to exceed 10 degrees assures maximum activity of the long head of the tricep. As the shoulder elevation angle increases the medial head of the tricep becomes the dominant extensor of the three headed muscle. Regardless of shoulder elevation when the arm is flexed between 85 and 110 degrees the medial head generates its most force.
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