Mobility vs Stability
July 1st, 2015| Dr. Matthew DiLallo DC, MA, CSCS
Every joint in the body has a specific function and is prone to certain levels of predictable dysfunction. As a result each joint has specific training needs. Injuries closely follow joint dysfunction and problems at one joint usually present themselves either upstream of downstream from the issue. Mobility is defined as the ability to produce a desired movement and stability is defined as the ability to resist and undesired movement.
Mobility vs. Stability
Every joint in the body has a specific function and is prone to certain levels of predictable dysfunction. As a result each joint has specific training needs. Injuries closely follow joint dysfunction and problems at one joint usually present themselves either upstream of downstream from the issue. Mobility is defined as the ability to produce a desired movement and stability is defined as the ability to resist and undesired movement. The determining factors for mobility are the architecture of the joint, the integrity of the surrounding soft tissue, and the neural control of the musculature surrounding the joint. Stability is created by both passive and active influences. The joint capsule, ligaments, and the structure of the joint generate passive stability while active stability is governed more by the motor control of the musculature surrounding the joint. When a joint that is designed for mobility becomes immobile, the joints designed for stability are forced to move due to compensation, thus making them less stable and often causing pain. For example, an immobile ankle can cause the stress of force production during squatting or running to be transferred to the knee. In general, the ankle, hip, shoulder and thoracic spine are meant for mobility while the knee, lumbar spine, and scapula and cervical spine are designed for stability. A lack of ankle mobility can cause knee pain, lack of hip mobility can result in low back pain, and a loss of thoracic mobility can result in neck, shoulder, or low back pain (remember both upstream and downstream effects). As with everything there is always an exception to the rule. In this case the hip can be both immobile and unstable. Instability of the hip can cause knee pain (due to internal rotation and adduction of the femur) and immobility can cause low back pain (compensatory excessive lumbar range of motion due to lack of hip flexion/extension).
How do we determine if we have a dysfunction going on? Well there are many different ways to assess this, but by far the easiest is the presence of pain. Painful tissues are dysfunctional tissues. Pain at rest, moving, or even when compressing a tissue is an indication for dysfunction in the tissue system. Direct pressure or compression to tissues should not cause pain. Living in pain is not normal. People react to pain almost in the same way they react to hearing a smoke detector go off, they just simply pull the battery out. The sound, like pain, is a warning of some other problem that is going on. Icing a sore knee without examining the ankle or the hip is similar to pulling the battery out of the smoke detector. The relief is short lived and does not solve the underlying issue.
Your body is governed by the SAID principle (specific adaptations to imposed demands), which means that your body reacts to the stressors that are put on it. If you sit for the majority of the day, your body will adapt to be able to sit all day. The myofascial tissue around the hip flexor muscles tighten and go into chronic contraction to better handle the chronic hip flexion, this in turn tilts the pelvis anteriorly which causes the hamstrings to become elongated (anyone have tight hamstrings?) and the gluteal muscles become neurologically inhibited due to the chronic activation of the hip flexor muscles (via reciprocal inhibition). This causes the pelvis and hips to become immobile and unstable which causes compensatory motion at both the lumbar spine and the knee (upstream and downstream).
A good place to start on your mobility/stability journey is to simply start moving around. One way to do that is to start rolling around on a foam roller or lacrosse ball. Find the painful, dysfunctional tissue and get it moving. Spend about 2 minutes mobilizing a painful area and move on to the next one. This simple yet effective tool will help you with your training and in your daily life.