Which type of muscle action tends to produce the greatest post-exercise discomfort (DOMS)?

• A. Concentric contractions only
• B. Eccentric and isometric actions
• C. Concentric and eccentric together
• D. Isometric contractions only

Answer: (B)

Delays onset muscle soreness (DOMS) mainly comes from microtrauma to muscle fibers and surrounding connective tissue after exercising, especially when the muscle is lengthening under load. Eccentric contractions—where the muscle is actively lengthening while producing force—cause greater disruption to sarcomeres and the structural elements of the muscle than concentric work. This greater damage triggers a stronger inflammatory response and more soreness in the following days.

Isometric contractions, where the muscle holds a constant length under tension, can also produce soreness if the work is intense or held for a long time. When a workout includes both eccentric work and substantial isometric loading, the muscle experiences multiple forms of stress—lengthening under load plus sustained tension—leading to more damage and, therefore, greater post-exercise discomfort than either action alone.

Concentric contractions (muscle shortening) typically produce less microtrauma, so they tend to lead to less DOMS in comparison. DOMS commonly peaks 24 to 72 hours after exercise as repair processes occur.