The heart controls its own contractions through electric impulse. Muscle fibers might get longer, shorter or stay the same during muscle contraction. An eccentric muscle contraction occurs when the muscle increases in length, such as when doing a push-up. concentric contraction occurs when the muscle decreases in length, such as when performing a bicep curl. An eccentric contraction occurs when the muscle increases in length, such as when doing a push-up. Ad. Muscle contractions can result in either movement or no movement.