Apparently, when it comes to your fitness routine, more is not exactly more. In fact, working out too much, too often, with too much intensity and not enough recovery could actually be hazardous to your health. Recent studies have suggested that “chronic training for and competing in extreme events such as marathons, ultramarathons, Ironman distance triathlons and very long distance bicycle races may cause short-term negative cardiovascular effects,” and beyond that, research found a high rate of myocardial fibrosis (the abnormal thickening of the heart valves which could lead to heart failure) in endurance athletes.