Learn how to race faster by training slower. Aerobic fitness is the most important aspect of endurance racing and training too hard can harm this. The 180-Formula and Heart-Rate Monitoring The easy way to ensure you're training at the right intensity every session. An important training companion to assist you in developing optimal endurance and better fat-burning is a heart-rate monitor. This simple device is a valuable tool that not only guides your training but is part of an important assessment process, and can even be used in some competitive situations. A heart monitor is really a simple biofeedback device. Unfortunately, most people use their heart-rate monitors only to see how high their heart rate gets during a workout, or evaluate the morning, resting heart rate. Heart rate is directly related to, and a reflection of, the body’s oxygen need. The heartbeat, the outcome of the heart’s muscular contraction to help pump oxygen-rich blood through the body, is also associated with systolic blood pressure, while diastolic blood pressure reflects relaxation of the heart as measured between beats. The relationship between two heartbeats is associated with heart rate variability, reflecting our parasympathetic aspect of brain and nervous system function—this being an important factor for professionals to assess heart health and for athletes to evaluate recovery from training and racing.