International Sports Sciences Association (ISSA) Trainer Practice Exam

Which of the following statements about muscle contractions is true?

1. Concentric contractions lengthen the muscle.

2. Isometric contractions change the muscle length.

3. Eccentric contractions lengthen the muscle against resistance.

4. Muscle contractions are only voluntary actions.

The correct answer is: Eccentric contractions lengthen the muscle against resistance.

Eccentric contractions are characterized by the muscle lengthening while it is under tension, which occurs when a muscle is actively engaged against a load, like lowering a weight or resisting gravity. This type of contraction is crucial for various movements and play an important role in muscle control and stability. During eccentric contractions, the muscle fibers are contracting while also elongating, which allows the muscle to manage and control the force exerted upon it effectively. Concentric contractions, on the other hand, involve the muscle shortening as it generates force, while isometric contractions occur without a change in muscle length, maintaining tension without movement. Additionally, muscles can also contract involuntarily, as in reflex actions or during functions like the heartbeat, demonstrating that muscle contractions are not solely voluntary movements. Understanding these distinctions helps clarify the role and mechanics of different types of muscle contractions in physical activities.