Training that improves the cardiorespiratory system and the efficiency of aerobic metabolism. Aerobic training can be divided into three overlapping types: aerobic low intensity training, aerobic high intensity training, and recovery training. The minimum training intensity that will usually result in significant improvements require an oxygen uptake of at least 50–55% maximal oxygen uptake. This corresponds to approximately 70% maximum heart rate. The most effective training intensities are usually between 90 and 100% maximal oxygen uptake, but sessions of long duration and low intensity can be as effective as those of shorter duration and high intensity. See also aerobic training zone, TRIMP.