Why does an eccentric contraction generate more force than a concentric contraction (at the same velocity)?

Answer 1

During an eccentric contraction, the force opposing the contraction of the muscle is greater than the force produced by the muscle. Rather than working to pull a joint in the direction of the muscle contraction, the muscle acts 'brakes' or slows the movement of a joint, and lengthens while generating force. Though the force generated by the muscle is less than the force opposing contraction, it may still be below the maximal force the muscle could potentially produce.

Answer 2

Concentric Contraction

Answer 3

Concentric contraction uniformly reduces the radius of lumen. Eccentric contraction causes localised reduction of radius. Uniform motion needs less force.