Platelets, or thrombocytes, are the colorless blood cells important for plugging holes in blood vessel walls. Thrombocytopenia, a low blood platelet count generally is associated with an immune system disorder, a blood disorder or as the side effect of certain medicines. Low platelet count is rarely serious, as the symptoms are generally mild. There is a correlation between platelet count and distance runners, particularly marathoners.
Low platelet count is associated with excessive bruising, the appearance of rashes of pinpoint-sized dark red spots on the lower legs, spontaneous bleeding from your nose or gums, prolonged bleeding when cut or after dental work, blood in the stools or urine and unusually heavy menstrual flow.
Effects of Exercise
According to a study on the "Effects of Marathon Running on Platelet Activation Markers" in the "American Journal of Clinical Pathology", several studies showed increased platelet levels associated with strenuous activity. The majority of the studies found elevated platelet counts and evidence of platelet activation following extended periods of exertion. As most heart attacks are the result of a platelet rich group of blood clots, these studies show that strenuous exercise can prove both beneficial to preventing heart attacks and a trigger to cause them.
A follow-up study of 32 participants in the 2005 Boston Marathon revealed that there was a marked decrease in platelet concentration, shape and mass indicating an increase in platelet activation during the race. This was attributed to a race induced "anemia" thought to be the result of the mechanical trauma to red blood cells as the feet impact with the ground.
Distance runners benefit from a balanced diet to avoid deficiencies in folic acid, iron or vitamin B12. Exercise exercising immediately after injury or treatment that has caused a loss of blood is contraindicated. Cut down on foot trauma by using properly padded shoes designed for running. Ask your physician about the risks of training if you have suffered in blood or immune disorders. These precautions may help reduce the increased platelet activity associated with prolonged exertion.