ACSM Personal Trainer Certification Practice Exam

In which contraction type does the muscle lengthen while producing force?

1. Concentric Contraction

2. Eccentric Contraction

3. Isometric Contraction

4. Isokinetic Contraction

The correct answer is: Eccentric Contraction

The type of muscle contraction where the muscle lengthens while producing force is known as an eccentric contraction. During this type of contraction, the muscle fibers are activated and generate force while the muscle is extending. This often occurs when a muscle is working against an external load that is greater than the force the muscle is producing. As a result, the muscle elongates as it resists the bending or stretching caused by the load, which is essential in activities such as lowering weights or controlling the descent during exercises like squats or lunges. Eccentric contractions play a critical role in enhancing muscle control, stability, and injury prevention, as they help manage the deceleration of movement and eccentric loading of the muscles. This is why eccentric contractions are fundamental in various rehabilitation and strength-training programs.