Are you maxed out?


While running with an older running friend the other day, he looked at his heart rate monitor, then asked me if I knew how high is too high for a heart rate, because his wife had told him she was convinced he is going to blow his heart up! Damned good question, I said, so I decided to look into it, and found that maximum heart rate is an elusive number, especially for runners. 

When calculating your maximum heart rate (MHR) for your age, the usual equation used is 220 minus your age, but that does not apply to everybody – many people can tolerate higher heart rates, while others cannot get to the formula-driven max, no matter how hard they push themselves. Also, this formula was developed many years ago from studies of young athletes, but more recent studies looking at a broader age distribution have shown that this formula often underestimates the MHR in older subjects, and thus Tanaka and co. came up with a revised formula in 2001 of MHR = 208 – (0.7 x age). A further study in 2007, by Gellish and co., revised that still further to MHR = 207 – (0.7 x age).

Now my friend is 52, so using the three different formulas, we get an MHR of 168, 172, and 171 respectively, so the difference is minor. The good news, for his wife, however, is that he said his heart rate monitor usually hovers around 160 during his workouts, only occasionally going over the 170 mark, and his heart rate drops to 140 or below during the regular walk breaks he includes in all workouts, so he appears to be safe from an imminent heart meltdown, according to basic MHR calculations.


According to Dr William Roberts, a medical doctor who specialises in sports medicine, heart rate tolerance is specific to each individual and is best determined by experience. “The closer you are to your MHR during your workouts and races, the shorter the duration of exercise that you will be able to maintain at that pace, but if you can maintain a rate of 160 comfortably during your workouts and races, as in this case, then your MHR is well above that.”

“This subject is unlikely to ‘blow up his heart,’ as he has a proven load tolerance, but if your heart rate increases at the same workload or your exercise tolerance drops off unexpectedly, you should consult with your physician. If you develop chest pain, pounding heart beats, increased heart rate, or dizziness during your workouts, you should stop and seek medical advice, because something has changed. It is never a bad idea to discuss your exercise, health and risk factors with your physician, and at age 52, you should be meeting with your physician every year or two to look at health and prevention issues.”


To effectively use a heart rate monitor in your exercise life, you should aim to work out within specific heart rate zones that fall within a particular percentage of your heart rate. Here is a general guideline used by exercise physiologists, who say that most of your workout should be done in zones 1 or 2.

Zone 1: 60 to 70% – very comfortable effort, use this for warm-up and cool-down.
Zone 2: 71 to 80% – comfortable enough to hold a conversation, most training is done here.
Zone 3: 81 to 93% – comfortably hard effort, you may be able to say short, broken sentences.
Zone 4: 94 to 100% – hard effort, the pace is sustainable, but conversation is a few words at a time.