What best defines an agonist muscle?

An agonist muscle is one that is primarily responsible for producing a specific movement during an exercise or activity. When a muscle contracts and shortens, it is actively engaged in creating movement, making it the prime mover in that action. For example, during a bicep curl, the biceps brachii acts as the agonist as it contracts to lift the forearm towards the shoulder.

In terms of muscle function, the agonist works in coordination with other types of muscles. Antagonist muscles, which perform the opposite action, will relax during the movement, allowing the agonist to perform its function effectively. Additionally, stabilizer muscles stabilize the body, while synergist muscles assist the agonist by preventing unwanted movement. Understanding the role of agonist muscles is crucial for designing effective workout programs and ensuring safe and efficient movement patterns.