Heart Rate - Maximum

Maximum

The maximum heart rate (HRmax) is the highest heart rate an individual can achieve without severe problems through exercise stress, and depends on age. The most accurate way of measuring HRmax is via a cardiac stress test. In such a test, the subject exercises while being monitored by an ECG. During the test, the intensity of exercise is periodically increased (if a treadmill is being used, through increase in speed or slope of the treadmill), continuing until certain changes in heart function are detected in the ECG, at which point the subject is directed to stop. Typical durations of such a test range from ten to twenty minutes.

Standard textbooks of physiology and medicine mention that heart rate (HR) is readily calculated from the ECG as follows: HR = 1,500/RR interval in millimeters, HR = 60/RR interval in seconds, or HR = 300/number of large squares between successive R waves. In each case, the authors are actually referring to instantaneous HR, which is the number of times the heart would beat if successive RR intervals were constant.

Conducting a maximal exercise test can require expensive equipment. People just beginning an exercise regimen are normally advised to perform this test only in the presence of medical staff due to risks associated with high heart rates. For general purposes, people instead typically use a formula to estimate their individual maximum heart rate.

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