When a fighter receives a groin shot, it is usually not the pain inflicted on the penis, rather the testicles which brings the fighter to his knees. The testicles are heavily innervated and when they receive blunt force trauma, a parasympathetic response is triggered which causes a visceral pain and sometimes the feeling of nausea. A severe blow to the groin or likewise to the kidneys or liver can cause blood vessels to dilate and a drop in heart rate. This decreased blood flow can cause one to pass out. Inevitably, even if one does not lose consciousness, people lose their ability to stay upright. Other common symptoms from groin shots are dizziness and higher body temperature. If there is enough damage, the testicle can rupture or swell so great that it impedes blood flow which leads to a surgical emergency.