The rapid stops and starts involved in soccer place a high demand on our soft tissues and many players experience tight and stiff muscles (recall that the sensation of stiffness beyond what it should be could also be related to nutrition). This tightening of the fascial system due to trauma is a protective mechanism that can arise from either micro-trauma over time or acute injuries such as a contusion or strain. Remember, if the fascial components lose their pliability they become restricted and are a source of tension for the rest of the body. This becomes evident at the cellular level as well as mechanically within the collagen in which the ground substance solidifies. When the collagen develops cross-links that are fibrous and dense, the elastin loses its resiliency which causes disruption in the extracellular matrix leading to inflammation and pain. The tight areas of fascia are often referred to as trigger points, knots, adhesions, and scar tissue. There aren't actually knots in the muscle, but mal-alignment of tissue due to trauma and injury, poor motor patterns, and psychological stress. These restrictions in tissue cause inefficient movement patterns, screw with joint function, and contractile tissues to work much harder to attain the ranges of motion needed in soccer.