Max Heart Rate How accurate really is the 220 -minus my age = max heart rate formula? I don't even come close no matter what I do. My max should be 187. Most blogs say I'm just not exercising hard enough. Today I tested this theory: Sprinted for 3 minutes. Then, slowed down to a brisk walk (139). Then did it again (145). Finally, I started at a good clip, nearly a sprint and kept it up for 8 minutes and ended with an all out sprint for about 50 yards (155). Is this cause for concern? Seems oddly low for someone who really isn't in the greatest shape right now.
Currently, there is no definitive way to predict maximum heart rate for a single individual. There are formulae that can give an approximation, but about the only way to get a good estimate on a personal level is to do a maximal treadmill test with monitoring.
As far as the 220-age, that is a bad myth, and wasn't based on a study, but simple observation of 11 different references of both published and unpublished research. This PDF writeup goes through the history of the 220-age origins, and gives some alternate ways to calculate maxHR. However, especially for exercise science, the margin for error is still too large for clinical use, although it may have slightly better use in a non clinical exercise setting.
Many recommend the target to be 70-85% of (220-age) value, rather than value itself. See Mayo Clinic site and American Heart Association page. Moreover, trained athletes often have slower heart rates than those who are sedentary. Hence, slower heart rates are often sign of good exertional ability. Some drugs like beta-blockers slow the heart rate and prevent it from reaching target rate on exercise.
Heart rate checking during exercise is more of a value for persons at extremes of exercise abilities, i.e. those who may be just starting an exercise program and those taking part in competitive athletics. Most other persons can simply exercise to the level that causes some breathlessness and sweating and that is not causing excessive exhaustion, breathlessness or chest pain.