could be circulatio. Calf pain could be due to circulation problems but can also be do to a tight achilles. Try mild stretching...But if continues please have someone look at it.
Depends on cause. Calf pain can be caused by numerous causes. If your young and otherwise healthy, the pain could be a result of not properly stretching the muscles prior to exercise. In older patients calf pain with exercise can be from inadequate blood flow to the muscles due to blockage in the arteries. A complete history and physical by a physician would likely be able to determine the cause of your symptoms.