Three terms you may hear in fitness are range of motion, flexibility, and mobility. The first is definitely the most common, especially in the yoga space. The latter is a buzzword that may not always be used properly. It is beneficial to know the difference between all three terms.

Range of Motion

To begin, range of motion (ROM) is really the most important term of the three, as it is the granddaddy. Range of motion is the measurement of a movement of a joint. A physical therapist might actually note the specific degrees of your joint using a goniometer, which is similar to a 360˚ protractor with two arms to follow the limbs. (If you remember using a protractor in geometry.)

As we measure, ROM, the focus is more on the end range more than anything else. For hip flexion, when you bring your knee up to your chest, the number of degrees you can move from the start position to the end point is measured

ROM is measured passively and actively. 

Passive range of motion is the full spectrum of movement with some light assistance and without using muscles to move the joint. When you are on your back and pull your knee into your chest with both arms, that is passive ROM of hip flexion. 

Active range of motion is how much you can move a joint with no assistance and by using just the strength of the muscles. Using the same analogy as above, when you are laying on your back the amount of movement you create by bringing your knee into your chest without using your arms is the active ROM of hip flexion.

If you lay down and do both tests on your own, you may notice that your passive ROM is greater than active ROM. You may even observe one leg has a different ROM than the other. It is common for us to have imbalances between sides. 

Most joints have hard limits for ROM. When bones are hitting bones, there is nowhere else to go. When you fold a piece of paper in half, the other side ends its ability to move further. Each of us has slightly different structures that can limit the complete ROM. This is why some people (like me) can never be contortionists. 


Flexibility is the passive range of motion of muscles and connective tissues at a joint and range of joints freely. (Sometimes to include without pain). While this may seem to be the same, here we are talking about the soft tissue that can affect the ROM. 

If we go back to the hip flexion test, start by bringing your knee into the chest as far as you can actively. Now straighten your leg. To have your leg straight, chances are high that your hip flexion ROM decreased. This is because the hamstring muscles on the back of the leg do not have the flexibility to maintain your hip flexion. The soft tissue is impeding your full ROM. We can stretch your hamstrings and that will improve your flexibility to match closer to the joint’s true ROM.


Mobility is the ability to actively move through your full range of motion. When you are on your back and lift your leg straight up into the air several times is mobility. 

The direction of gravity can also challenge mobility. Try to do the same move while standing by kicking your leg straight up in the air. Gravity will make the muscles need to work more and potentially decrease your active range of motion. 

How does flexibility, range of motion, and mobility fit into a fitness program?

Now that you understand the terms, let’s talk about why and how to bring flexibility, range of motion, and mobility into your fitness program. For this we will mostly discuss ROM with the focus on flexibility and mobility.

Flexibility has long been included with fitness programs, especially after a workout. For some modalities, like yoga, it has been the main focus. However, this has its downfalls with some yogis developing yoga butt due to overstretched hamstrings.

As mobility is more active and focuses on the strength of muscles around a joint, it can help improve ROM and flexibility while increasing the stability of a joint.

If we go back to our test of hip flexion test using passive and active flexibility, the difference of ROM between the two is a gap that needs to be addressed. Ideally, the gap should be relatively small with about 10-25% difference. If there is a big difference between the two in terms of measurable ROM, a few things can be happening. 

  1. Muscle strength is low and it requires more strength training.
  2. A muscle is being inhibited due to an imbalance, injury, and/or neurological issue.

By focusing on mobility and active range of motion, we can begin to develop strength in the muscles that need it. Especially if we move the joint in ways that will better challenge the muscles in relation to gravity or with tension. For example, focusing on lifting the knee for hip flexion while standing would be better than doing it on our back. Unless we add a resistance band to the thigh/foot that requires more muscle recruitment to bring the knee in.

Earlier in my fitness career I stayed away from strengthening muscles that were deemed “tight” due to poor posture in my clients. Now I know that a muscle might be tight because it is weak and strengthening it could actually have done more for my clients.

In fact, more studies have come out that found that strengthening a muscle improved it’s flexibility. Especially if you worked in its full range of motion.

For hypermobile people, this fact of full range of motion is crucial. Many trainers may still have their clients move away from strengthening toward end ranges if they go beyond normal, such as a hyperextended knee. Allowing clients to work through their ROM, they will develop better stability with their strength would be far more beneficial for their body.

Trying to activate a muscle that is being inhibited can be trickier. Working with a physical therapist or someone trained in techniques (Muscle Activation Technique or Neurokinetic Therapy) to uncover these spots would be ideal.

When we add mobility training into our fitness routines, we can improve strength, stability, and flexibility. Together these can help reduce chronic aches and pains, improve posture, and allow you to be more active to live your life.

In my Not Your Normal Yoga classes, I use therapy balls to help improve proprioception to an area while affecting the fascial layers that can be stuck. We also use controlled movements and different techniques to help strengthen muscles. Together these can help to improve the recruitment pathways to a muscle.

Kate Hamm combines her 15+ years of experience in the fitness industry and high-end resort program development into sought after wellness coaching and adventures at AnamBliss. Visit for more information on coaching services and future retreat dates and locations.

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