What to do if i lose circulation in my arm when i throw a ball. how can i help this?

Thoracic Outlet: Sometimes the artery as it travels from it's origin to your arm can be compressed between the first rib and muscle. This is known as thoracic outlet. This would be the most common cause, and the symptoms can be improved through various excercises once it has been established that the artery is not damaged, which can be another cause. A visit to your physican should be a priority for diagnosis.