There are two camps of thought when it comes to training for endurance events that are generally over 10 miles but under 30 miles. One camps says build a base of miles and and do plenty of tempo runs and speed workouts. This sort of hard and fast training works really well with talented athletes because their bodies are able to to absorb the pounding due to their incredible technique. Us amateurs have to take into account the fact that we can not go out and run hard every time because we will just be prone to injury. Amateurs need to train smart. Training at lower heart rates allows your body to get stronger safely not only in your muscles but the support tendons and minor muscles as well. Why does this get the body stronger then the harder fast workouts? I believe its because running at lower heart rates allows an athlete to run within his or her limits from a running gate stand point. This in turn means that the body is running more efficiently mechanically and creating less stress on the joints and tendons. When and athlete runs fast the running gate opens up beyond it’s normal range and pushes into new speed territory which is necessary to actually get faster but doing it all of the time and on your long runs puts your body at a higher risk for injury. Heart monitor training programs will teach you how to build properly and set PR’s safely.