Flexibility vs. Mobility

Mobile or Flexible?

 

Do we need mobility or flexibility? The answer is an emphatic yes, however, it's not “mobility or flexibility”, it should be "mobility and flexibility". For all of those that just don’t have time to stretch or work on mobility, you’re setting yourself up for bad things. I know this is by far the least exciting and “non-sexy” part of exercise, but possessing adequate range of motion and the ability to move properly is important.

First let’s differentiate something; mobility and flexibility are not the same thing. Flexibility refers to movement that happens in the muscle. If a muscle can stretch to an optimal distance that’s good flexibility. However, flexibility is just part of our overall mobility.

Mobility requires good flexibility, but also unrestricted joint movement. In a larger context, when focusing on functional movement, proper neuromuscular control and adequate stability are also necessary. In other words we must be able to control our bodies in space.

First lets look at someone lying on his or her back and pulling their knee to their chest. This requires good hip mobility to do, but it’s not totally functional until the kinetic chain is closed and the feet are on the ground. This is a passive movement and has little to do with joints outside of the hip and knee. It also doesn’t require the muscles of the hip and thigh to fire because it’s passive and lastly, stability isn’t required due to the supported, lying position. So while this is an example of good mobility, it’s not totally functional because the person is lying down. Due to the nature of this blog, we should be more concerned with functional movement so think of mobility as the capacity to actively move a joint through a full range of motion.

In comparison to the above example, think of performing a bodyweight squat. This is an active movement that requires much more than just muscle flexibility and joint mobility; one must also possess a good amount of stability and muscular control. Some may be able to squat to a point similar to the position were the knee was pulled to the chest and others may be nowhere close. Why?

Poor squat - limited range of motion, bi-lateral pronation of the feet and a general lack of stability

Despite the theatrics this is a good, deep squat - feet flat with weight on the heels, knees tracking over the feet, shoulders upright and general stability under load.

While flexibility can restrict mobility, we need nice pliable and balanced muscles to allow a healthy joint to move through its full range unimpeded, the joints themselves can also cause limited range of motion. Joints can and do become dysfunctional due to imbalances and injury. So while you may possess flexible muscles, you may not achieve optimum range of motion because the joint itself is limited. This is why we want to work on mobility and flexibility, dynamic type movements and stretching.

Lets look at the squat example one more time; if one cannot perform a good squat, but also shows limitations in pulling their knee to their chest we may find that the person’s posterior chain (glutes, hamstrings, gastrocs, soleus, etc.) is overactive (tight) and limiting range of motion. This would be corrected by working on the flexibility of the aforementioned muscles through myofascial release and stretching. This could also be indicative of some sort of hip joint limitation requiring joint mobilization type exercises. However, if a person cannot perform a good squat, but can lie on their back and pull their knee to their chest we have a different issue, usually lack of stability.

Because the joints can move unimpeded we’re not having flexibility or joint issues, but the squat is still unattainable. Usually this is an issue of stability because the body will limit range of motion if it’s notably unstable. This is generally due to weak core and hip muscles and I think the fix here is self explanatory, we always want to strengthen weak areas. So while stability is a subject for another time, all of this plays into mobility, at least when concerning functional actions.

The take home message here is that stretching, myofascial release and mobility work should not be after thoughts to ones training program. These are key training elements that can eventually limit progress or worse, lead to injury when not in working order.