Muscles that work in pairs are known as what?

• A. Isokinetic and Kinetic
• B. Isometric and Isotonic
• C. Antagonistic and Agonistic
• D. Kinetic and Static

Answer: (C)

Muscles that work in pairs across a joint form an antagonistic and agonistic relationship: one muscle (the agonist) contracts to produce a movement, while its partner (the antagonist) stretches or relaxes to allow that movement and then can contract to reverse it. This pairing enables smooth, controlled motion, such as bending and straightening the elbow. For example, when you bend the elbow, the biceps acts as the agonist, driving flexion, and the triceps serves as the antagonist, relaxing to let that bend occur (and vice versa when extending the elbow). The other terms describe types of contractions or general movement ideas rather than the paired mechanism of muscles across a joint, so they don’t capture the idea of working in opposing pairs as clearly.