NETA Personal Trainer Practice Exam

An antagonist muscle plays a crucial role in movement by counteracting the action of the agonist muscle. When the agonist contracts to produce a movement, the antagonist relaxes to allow this action to occur smoothly. This relationship is fundamental for control and stability during various movements. For instance, during the act of flexing the elbow, the biceps brachii acts as the agonist, while the triceps brachii is the antagonist, which relaxes to allow the flexion to happen.

Understanding this dynamic is essential for trainers when designing workout programs, as balancing the strength and flexibility of both agonist and antagonist muscles helps prevent injuries and improve overall performance. The other options do not accurately describe the function of antagonist muscles; they either suggest unnecessary assistance, a concurrent action, or a lack of impact, all of which misrepresent the essential opposing relationship that defines how antagonists operate in relation to agonists.