NETA Personal Trainer Practice Exam 2025 - Free Personal Trainer Practice Questions and Study Guide

During the lowering phase of a squat, the muscle action that takes place is eccentric action. Eccentric muscle actions occur when a muscle lengthens while under tension, which is crucial for controlling movements and absorbing forces. In the context of a squat, as the individual lowers their body toward the ground, the quadriceps, hamstrings, and gluteal muscles are all lengthening while still contracting to control the descent. This is essentially the opposite of concentric action, where muscles shorten to produce movement, such as when standing back up from the squat position.

Isometric action refers to a muscle maintaining tension without changing length, which does not occur during the lowering phase as the muscles are actively lengthening. Isokinetic action involves a constant velocity of movement against varying resistance, typically requiring specialized equipment, and is not applicable in this instance either. Thus, it is clear that the lowering phase of a squat prominently features eccentric muscle action.