The antagonist is the muscle opposite to the agonist or the prime mover in each exercise. This muscle controls the speed of contractions and slows the agonist down at the end of its contraction. It is important that these muscles are not neglected because the efficiency of an agonist’s contraction depends a lot on how these antagonist muscles are capable of performing. For example, if the bicep is contracting the antagonist is the triceps. They stabilize, coordinate and control the bicep contraction. Then they act as a breaking system at the end of the bicep contraction.