What’s Active Range of Motion?

When someone or something indicates that there is full range of motion (ROM) it is important to understand the context in which it is being used for description. Active Range of Motion (AROM) and Passive Range of Motion (PROM) may be very different, and the terms are generally used to describe the movement of various joints of the body. AROM means how far a joint moves without assistance. This motion consists of how far you can move your joint in any given direction. PROM is assessed to determine the amount of movement possible at a joint. PROM occurs when you are relaxed, and an athletic trainer or physical therapist moves your joint to the extreme end ROM to attain the maximum range existing for that joint. It is important to note most joints have more PROM than AROM.

The neck (cervical spine) providing for the motion of the head may have the most difference of AROM to PROM. This is referred to as head and neck motions. As a Certified Athletic Trainer, I noticed this early in my career there was more passive head and neck motion than active, yet to locate the numbers or percentages on the difference when researching was difficult to find. There is not much documentation out there for this specific comparison. Based on my research and experience I conservatively indicate that the head and neck have 15 to 20% more PROM than AROM. This is important to note when you look at how a joint is injured.

Most injuries occur when a joint is forced beyond its extreme, beyond the end of PROM and this is no different for the head and neck. In football (or for that matter, any activity or sport) when the head is hit directly as in helmet to helmet, an indirect hit where the head and neck are whipped into motion, if they go beyond the extreme, past the end PROM that is where the injury occurs. This is where the burner/stinger injury occurs and when the brain is injured after the initial impact of the hit. Brain injury does not just occur from the impact of a collision when the brain comes toward the site of the contact, yet also can occur when the head and neck change directions and move away from the impact with the twisting, turning, and whipping away from the impact.

How do we slow down this twisting, turning movement from going past the end PROM where the injuries happen? One thing we know is the helmet can’t protect this movement as it is attached to the head. Some even claim it adds to the force that is exerted in this motion past the extreme. We believe there is only one way: You must slow the head and neck down, not let it get to the extreme and bring it to a gradual stop. And you must do this with a device that allows for full AROM for the player for performance.

We’ll talk more in the future about ROM in the future when we discuss acceleration and deceleration of the brain from hits. As always, I invite you to connect with me to continue the discussion on this crucial aspect of player safety.