
The Body's Response to Sports Injury. A bruise or 'contusion' is damage to small blood vessels which causes bleeding within the tissues. A muscle strain is a small tear of muscle fibres and a ligament sprain is a small tear of ligament tissue.The Body's Response to Sports Injury. A bruise or 'contusion' is damage to small blood vessels which causes bleeding within the tissues. A muscle strain is a small tear of muscle fibres and a ligament sprain is a small tear of ligament tissue.