National Academy of Sports Medicine (NASM) Certified Personal Trainer (CPT) Practice Exam

The correct characterization of muscle activation involves concentric, eccentric, and isometric contractions.

Concentric muscle activation occurs when a muscle shortens while generating force, which is commonly seen during the lifting phase of an exercise, such as during a bicep curl when the elbow flexes. Eccentric activation happens when a muscle lengthens while under tension, which can be observed during the lowering phase of an exercise, such as when the bicep slowly lowers the weight back down to the starting position. Isometric activation occurs when a muscle generates force without changing its length, such as holding a static position like a plank or wall sit.

Recognizing these different types of muscle contractions is essential for understanding how muscles perform during various activities, which is vital for designing effective training programs. This three-part classification allows trainers to target specific strength and endurance goals by manipulating how muscles are activated during different exercises.