Antagonistic muscles are pairs of muscles that work against each other to create movement. When one muscle contracts, the other relaxes, allowing for smooth and controlled motion. For example, when you bend your arm, the biceps contracts while the triceps relaxes. This coordinated action helps maintain balance and stability in the body. These muscle pairs are essential for various movements, including walking, running, and lifting. The agonist is the muscle that contracts to produce movement, while the antagonist opposes that movement. This relationship is crucial for activities that require precision and strength, ensuring efficient body mechanics.