Lower Extremity Mismatch is an important concept to understand for anyone wanting to improve their fitness programming, whether it is for themselves or for clients / patients.
During the process of bipedal evolution, the structure of the human pelvis changed. The hips positioned themselves more in a frontal plane allowing for more lateral motion (Lovejoy, 2009:326). This allowed for the stabilization needed for the single leg motions that make up the human gait pattern. The problem is that this mechanism was designed during a time when we were much smaller beings. As an aging and overweight population we are stressing this structure which leads to joint disease.
Another lower extremity mismatch occurs from disuse and lack of proper hip and knee motion. As we have become weaker due to mechanization we are less able to appropriately bend our hips and knees. This can cause excessive knee and spinal bending with squatting motions placing a great deal of stress on knee ligaments and the spine leading to joint disease (Marras, 2005:30).
The specificity principle dictates that if we want to improve or strengthen a movement pattern we need to train that specific motion. Single leg strength and balance is critical to human function and performance.
Therefore, the more consistently you train with single leg movements in mind, the more functionally prepared your body will be. Ultimately, training with the lower extremity mismatch in mind will enable you to become functionally stronger, off-setting some of the mismatch that would otherwise deteriorate your optimal health. Functionally speaking, when you take our physiological mismatches into account for the design of your programming you aren't just training arbitrarily, you are training with specificity to your optimal functionality.