It is in the release process rather than the contraction process that motion problems will develop. Every move produces its greatest stress upon a specific point. It can be so small that you do not realise its presence. With continued use, the spasm becomes aggravated and begins to add more fibres to itself. As it enlarges, it causes pressure.
Pressure causes discomfort and pain.
A muscle that cannot accommodate the movement placed upon it will pull or even tear. Thus, a movement normally within the safe context becomes unsafe when shortening and spasm are present. Because of the interrelationship between muscles, so you have the development of trigger points manifesting themselves on other muscle areas rather than the original source of pain. These are referred by the term 'satellite trigger points'. They are likeliest to occur at the edges of large muscles.