In physical therapy and rehabilitation settings, the terms “passive range of motion” and “active range of motion” are recently used in conjunction with your treatment.
Although most people have a big understanding of range of motion in general, the differences between passive and active range of motion can be confusing.
But what is range of motion? What is passive range of motion and active range of motion? How can you increase your range of motion?
Keep reading to find out!
We will cover:
- What Is Passive Range of Motion?
- What Is Active Range of Motion?
- What Is Active-Assisted Range of Motion?
- How to Improve Range of Motion
Let’s get started!
What Is Passive Range of Motion?
Range of motion, in general, describes the movement that you have in any joint, typically measured at an angle in degrees using a tool called a goniometer.
Passive range of motion, also called PROM for short, refers to the amount of permissible movement you have around a joint when assisted or moved by another person, such as a physical therapist, or when you use a stretching rope or another assistive device to deepen the stretch and move your limb through a wider range of motion.
Passive range of motion can also potentially be provided by a mechanical device or machine. For example, after ACL reconstruction surgery, your doctor or physical therapist might give you a device called a continuous passive motion machine, or CPM machine for short.
This device goes around your leg at the knee and moves your knee through a designated range of motion for flexion and extension automatically.
You do not have to use your muscles, but the CPM machine helps ensure that the tissues of your knee are moving and stretching as much as they need to properly heal without creating any type of adhesions or excessive scarring while you cannot be weight-bearing on your leg.
Ultimately, passive range of motion is an indication of how much flexibility you have in the tissues around a joint.
What Is Active Range of Motion?
Active range of motion, often referred to as AROM, is the amount of movement that you have around a joint when controlled by your own muscles.
While passive range of motion is an indication of your flexibility, active range of motion is an indication of your mobility or the amount of functional movement you are able to attain at a joint.
Active range of motion is particularly important because it affects how your body moves and performs both during exercise and daily activities such as walking, getting into or out of bed or a chair, climbing stairs, putting away groceries on a high shelf, and getting up and down from the floor.
What Is Active-Assisted Range of Motion?
It’s important to note that there is actually a third type of range of motion that may be measured or referred to in physical therapy settings, particularly after surgeries.
This is termed active-assistive range of motion, or AAROM for short.
Active-assistive ROM refers to the range of motion in a joint that you can attain with some amount of your own muscular involvement and some amount of assistance.
It is typically used in reference to postoperative rehabilitation, where the patient might be able to move their injured body part to some degree but requires assistance to attain the desired range of motion for rehabilitation.
The assistance might come from a physical therapist or some sort of device or machine. For example, after an ACL reconstruction, you will go to physical therapy to regain strength and mobility in your knee.
In order to protect the tissues while they are healing, you might be permitted to extend your knee using your quads within a limited active range of motion (Active ROM).
Then, under the experienced supervision of your physical therapist, you might be able to attain some additional range of motion with the therapist manually guiding your knee into more of an extended position while you simultaneously are contracting your quads.
The end range of extension that these combined efforts would yield is considered active-assisted range of motion (AAROM).
What Affects PROM and AROM?
Studies suggest that passive range of motion may decrease with age. These findings are likely extended to active range motion as well, particularly because evidence suggests that muscle strength declines with age, and muscle strength is one of the primary determinants of mobility and active range of motion.
Therefore, some amount of reduced range of motion may be in response to aging. With that said, staying active and deliberately working on your flexibility and mobility can potentially increase your passive and active range of motion.
Passive range of motion is usually limited by tightness in the antagonist muscles that oppose the movement, which may be due to inactivity, overuse, spasm, genetics, and other factors.
There are typically four possible reasons why you might have pain or limitations with active range of motion, which might occur in isolation or in combination with one another.
The four primary factors that might limit a ROM include the following:
- Weakness or injury in the muscles that must contract to move the joint, which will either limit permissible movement or elicit pain.
- Tightness, spasm, or injury in the antagonistic (opposing muscles), which will either limit permissible movement or elicit pain.
- Sprain or injury to the ligaments and joint capsule, which will elicit pain during movement.
- Degenerative joint disease or osteoarthritis in the joint, which can cause pain and crepitus with movement.
How to Improve Range of Motion
Increasing your range of motion is potentially possible, depending on the reasons for the limitation.
With passive range of motion, if you have tightness in the muscles that oppose the movement, you will have increased passive ROM.
For example, with hip flexion, tight hamstrings will limit the amount of permissible forward movement of the hip.
Stretches that target tight muscles and mobility exercises that loosen tight connective tissues can be helpful for increasing flexibility and improving passive range of motion.
To maximize the effectiveness of these stretches and mobility exercises, it is usually useful to use assistance, such as gravity, a stretching rope, your own hands pulling on the limb, or the help of another person, to provide additional force during the stretch to help you attain the end ranges of motion that you cannot access under your own volition (active ROM).
In our example of tight hamstrings, this might include lying on your back and using a stretching rope or a belt around the heel of your foot and then pulling on both ends to bring your leg as high up and forward as possible.
You could also stand up and place your leg up on an elevated surface and lean your trunk towards the leg to provide force from your weight to increase the stretch.
Tools such as foam rollers and massage guns can also potentially increase muscle stiffness and improve passive range of motion and flexibility.
Consistently performing self-myofascial release with these types of tools, particularly after your workouts, may help you see improvement in passive ROM over time.
If you are looking for suggested products, consider the Roll Recovery R4 Foam Roller and the Theragun Pro for top mobility tools that every athlete should have in their tool kit.
Increasing your active range of motion is a little more complicated.
In cases where muscle weakness, rather than antagonistic muscle tightness, spasms, or injuries in any of the tissues are the limiting factors for AROM, the best way to improve it is to strengthen the muscles controlling the movement in combination with a flexibility program that also retrains the neuromuscular system to access the newly acquired ROM.
Working with a physical therapist, particularly one adept with programs designed to improve mobility, such as FRC, is highly recommended.
FRC, which is short for Functional Range Conditioning, refers to a specific scientifically-based trademarked system that is aimed at improving mobility and joint control through various targeted exercises.
Dynamic warm-up exercises such as walking lunges, hip swings, fire hydrants, high knees, butt kicks, a skips, carioca drills, and arm windmills can also be helpful for strengthening and mobilizing the tissues, ultimately increasing active range of motion.
Much like other aspects of health-related fitness, such as muscular strength and cardiovascular endurance, flexibility and optimal range of motion is prone to the “use it or lose it” principle.
Being consistent with your flexibility and mobility routines is the best way to make progressive improvements in your PROM and AROM.
For a whole list of mobility exercises to help with your ROM, check out our mobility for runners guide, complete with step-by-step instructions and videos.