The basal or resting heart rate (HRrest) is defined as the heart rate when a person is awake, in a neutrally temperate environment, and has not been subject to any recent exertion or stimulation, such as stress or surprise. The available evidence indicates that the normal range for resting heart rate is 50-90 beats per minute. This resting heart rate is often correlated with mortality. For example, all-cause mortality is increased by 1.22 (hazard ratio) when heart rate exceeds 90 beats per minute. The mortality rate of patients with myocardial infarction increased from 15% to 41% if their admission heart rate was greater than 90 beats per minute. ECG of 46,129 individuals with low risk for cardiovascular disease revealed that 96% had resting heart rates ranging from 48 to 98 beats per minute. Finally, in one study 98% of cardiologists suggested that as a desirable target range, 50 to 90 beats per minute is more appropriate than 60 to 100. The normal resting heart rate is based on the at-rest firing rate of the heart's sinoatrial node, where the faster pacemaker cells driving the self-generated rhythmic firing and responsible for the heart's autorhythmicity are located. For endurance athletes at the elite level, it is not unusual to have a resting heart rate between 33 and 50 bpm.