Which are the three basic muscle contractions?

• A. Concentric, Eccentric, Isometric
• B. Isometric, Isotonic, Isokinetic
• C. Concentric, Isotonic, Isokinetic
• D. Eccentric, Isometric, Isotonic

Answer: (A)

The main idea is how a muscle changes length while it contracts. The three basic contractions are concentric, eccentric, and isometric.

Concentric contractions shorten the muscle as it generates force—like lifting a weight during a curl. Eccentric contractions lengthen the muscle while still producing force, such as lowering the weight slowly. Isometric contractions produce force without changing the muscle’s length, as when you hold a position steady.

The other terms describe how resistance or speed is applied rather than how the muscle length changes. Isotonic and isokinetic refer to movement with varying or constant speed under load, not the actual shortening or lengthening of the muscle.