ACSM Personal Trainer Certification Practice Exam

What is the outcome of concentric contraction in a muscle?

1. Lengthening of the muscle

2. Shortening of the muscle

3. No change in muscle length

4. Variable contraction strength

The correct answer is: Shortening of the muscle

Concentric contraction refers to the type of muscle contraction in which a muscle generates force while shortening. During this process, the muscle fibers shorten in length as they pull on the bones they are attached to, causing movement at the joint. This type of contraction is typically observed when lifting a weight or performing an activity where the muscle has to overcome resistance. For instance, during a bicep curl, as you lift the weight towards your shoulder, the bicep muscle contracts concentrically, resulting in the muscle shortening. This is in contrast to eccentric contractions, where the muscle lengthens as it controls the lowering of a weight. In concentric contractions, the primary focus is on the production of force while effectively reducing the muscle's length to execute movement. Understanding this concept is fundamental for trainers and clients alike, as it impacts effective program design and the mechanics of strength training exercises.