MariposasRange of Motion (ROM)
Range of motion, usually shortened to ROM, refers to the full arc of movement available at a joint or across a series of joints during an exercise. A squat taken to full depth uses a greater ROM than one stopped at parallel, and that difference changes which muscles get loaded and how hard they work. The common misconception is that more ROM always equals a better workout. In reality, the useful range is the one your joints can move through with control and without compensation elsewhere in the body. Mobility limitations, injury history, and exercise goals all shape what an appropriate ROM looks like for any given lift or movement. Partial ROM work does have legitimate uses, particularly for overloading a specific portion of a lift or working around an injury, so the goal is usually to understand your available range and train to expand it over time rather than forcing depth you haven't earned yet.
Example
A lifter doing Romanian deadlifts might find their hamstrings pull them into lumbar flexion before the barbell reaches their mid-shin. Their functional ROM stops at the point just before the lower back rounds, and that is where they should hinge for now. Over several weeks of consistent work, as hamstring flexibility improves, that stopping point gradually moves lower toward the floor.