Agonist muscles are the primary muscles responsible for producing a specific movement during an exercise or activity. When a muscle contracts to create movement, it is referred to as the agonist. For example, during a bicep curl, the biceps brachii acts as the agonist, allowing the arm to flex at the elbow. In contrast, agonist muscles often work in conjunction with antagonist muscles, which perform the opposite action. This coordinated effort helps maintain balance and control during movement. Understanding the role of agonist muscles is essential for effective training and rehabilitation in fields like physiotherapy and sports science.