Flexibility is a topic that is interesting. I think it's important to understand different peoples perception of what they think 'flexibility' means.
There is a saying that goes: "You are as old as your spine is flexible". The human body, it seems, paritially relies on movement to activate, and manually operate certain functions. Circulation in the extremeties (hand and feet which are far from the heart) are an example. A "pooling" effect of the blood occurs if movement doesn't occur, like in bed sores - typical for patients who are treated long term in hospitals. The blood can stagnate causing all kinds of problems. Movement then becomes essential in helping out the cirulatory system and heart by easing their work. Another example is the Lymphatic system. The lymph fluidTemplate:Underconstruction