Sports and exercise puts the body and its structures under great mechanical stress. This stress can lead to injuries, which generally fall into three categories: overload, overuse, and direct trauma.
Overload injuries are caused when excessive load and/or stretch is put through a structure. This will cause the structure to fail and tear, ranging from a partial to a complete tear. This sort of injury is usually seen in muscles, tendons and ligaments and have various different names – sprains, strains, pulled muscles, etc. In more extreme cases overload can cause bone fractures. These injuries are commonly caused by jumping & landing, stop/start sprinting, and quick change of direction.
Overuse injuries are caused by the repetitive loading or irritation of a structure. Over time this causes the structure to tear, become inflamed, or degenerate. Overuse injuries can affect almost any structure within the body depending on the action that is repetitive.
Biomechanics may also play a part in such sporting injuries, as incorrect biomechanics can predispose an athlete to certain injuries or even cause the injury itself.
The last category of sporting injuries involves direct trauma or collision. This includes an athlete falling onto the ground, running into an object, colliding with another athlete, or even being punched. Obviously this causes damage to the tissues involved, usually in the form of bruising.