NEW YORK (Reuters) - Whether you're interested in running a marathon or staving off the chronic diseases of ageing, to reap the rewards of your efforts getting into the zone is essential. Experts say knowing and staying within your heart rate training zone is an easy way to pace the intensity of your workout. "Exercisers need to get to at least a moderate level of physical activity in order to reap the benefits," said Dr. Adrian Hutber of the American College of Sports Medicine. "Your goal is to get to a stage where you're fit enough to exercise within your heart rate training zone. ... read more..