Endurance training isn't for the faint of heart—literally. Although you might often think of endurance activities as marathon training or century cycling, it's actually might less intense. Exercise is considered endurance training when you maintain an elevated heart rate for at least 20 minutes, and it's also commonly referred to as aerobic exercise.
Endurance activity improves the health of your heart, lungs and circulatory system, as well as boosts your overall fitness level. In order to reap these benefits, though, you have to reach a heart rate that falls into the appropriate category.
Endurance Training Heart Rate Zone
To determine if you're in the targeted heart rate zone, first you need to determine your maximum heart rate. Generally speaking, you can determine your maximum heart rate by subtracting your age from 200. For example, if you're 35 years old, subtract 35 from 220 for a maximum heart rate of 185.
The target zone for endurance training is usually between 60 and 85 percent of the maximal heart rate. It is the range in which the exercise activity can be continually performed for the designated time period. In order to train aerobically for endurance, and for the positive physiological adaptations to take place, the exerciser needs to stay within the range. If the intensity is too low, the benefits will be limited, and if it's too high, the workload becomes anaerobic in nature and will lead to faster fatigue.
Resting Heart Rate
Resting heart rate is a benchmark for overall cardiovascular fitness. The resting heart rate — which averages 60 to 80 beats per minute — is the number of heart beats per minute during true rest which is most effectively measured after sleep, while still lying down.
Those that participate in regular endurance training are on the low end of the range, and it is not uncommon to see resting heart rates even lower. In fact, some elite endurance athletes have measured resting rates in the low 30s. Due to other physiological changes in the heart like increased stroke volume and cardiac output, the heart can beat less and still pump an equal volume of blood. Therefore, endurance training progressively decreases resting heart rate.
Heart Rate as a Health Risk Factor
Just as a low resting heart rate can be a fitness benchmark, so can a high resting heart rate. As the resting heart rate increases, it becomes more of a risk factor or warning of potential health conditions. High heart rates are closely associated with other health conditions such as high blood pressure and high cholesterol. If the heart is beating faster to deliver oxygen and nutrients to the body, it simply won't last as long. A study published in Aging Research Reviews outlined a direct correlation with resting heart rates above 70 and a linear relationship with the occurrence of heart attacks.