Hey James,

Love your site. I have been very interested in functional training since seeing some of your post on Pinkbike. I am a bit confused about the difference between joint flexibility, mobility and how that relates to joint stability… and how that all translates out on the trail. Do you have a past podcast or articles that might help explain these concepts a bit more? Thanks for your time



That’s a good question, here is my quick definition of each:

Flexibility: This usually refers to the length of a muscle and what most people think of when talking about improving a joints range of motion. It is best addressed through stretching, however it is just a part of overall mobility.

Mobility: This refers to how freely a joint can move throughout its full range of motion. Muscle length (flexibility), muscle tension/ tissue quality and how the nervous system controls the joint all come into play. This is why foam rolling/ massage to address muscle tension/ tissue quality, stretching to address muscle length and dynamic mobility/ corrective exercises to address the nervous system are all needed for good joint mobility.

Stability: It is basic engineering – a joint that can get into proper alignment so that the bones are taking most of the stress will be more stable than a joint that can’t and therefore requires the connective tissues to take more stress. If you lack adequate mobility then you will compensate by using muscles, tendons and ligaments to take up the slack. If you can get your joints to line up properly then the bones will take the stress.

A great example of this is people that feel that they have tight hamstrings and try to increase their flexibility by stretching them out. Most of the time the hamstrings aren’t really the problem, it is a lack of overall mobility at the hips that causes the hamstrings to tighten up to make up for the lack of stability that results. If you address the hip mobility issue and allow the hips to get into better alignment then the hamstrings will chill out.

I’ve had people gain 6+ inches range of motion on their toe touch by foam rolling and stretching the quads and hip flexors. The tight quads and hip flexors were pulling the pelvis out of alignment and the hamstrings were tightening up in an attempt to provide stability and to keep the pelvis from getting even more out of alignment. That bad alignment will cause a decrease in authentic stability and since strength and power are built on stability, they will be affected as well.

You need to make sure that you have adequate joint mobility, which leads to better joint stability and then to better overall strength. You are only as strong as your weakest link so for a lot of riders, the key to getting stronger and fitter is actually in improving mobility so that they can move more efficiently and get into better joint alignment. That’s why I’m push the mobility concept so much.

Hope this helps…

-James Wilson-

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