Q I started training for marathons four years ago and I’m running my fourth this year. My question is – how high is too high for a heart rate? I’m almost 52 years old, 178cm and 84kg. I run relatively slow (5:44 marathon last year) and never ran distance before I started four years ago.
Most of the time my Garmin shows me at about 160 beats per minute during a work out – a few times it’s climbed over 170. I use the Galloway walk-run method and during the walk breaks my heart rate drops to 140 or below.
My wife (not a runner) is convinced I’m going to blow up my heart and die. Can you set her straight? – PAT
[hr]
A Maximum heart rate for age is an elusive number. The usual equation is 220 – age = maximum heart rate (MHR), but that does not play out well when you look at individuals as many can tolerate higher heart rates and others cannot attain the formula driven number. This formula was empirically derived from young athletes. A study by Tanaka in 2001 looking at a broader age distribution showed that this formula often underestimated the MHR in older subjects and a revised formula fitted to the data resulted in this formula: MHR = 208 – 0.7(age). Another look at this by Gellish in 2007 showed good correlation to stress testing results using MHR = 207 – 0.7(age) with a p value of <0.001.
So calculating your MHR using the 3 formulas we get 168, 172, and 171 respectively. These numbers probably do not seem very different to you and they seem the same to me too.
In reality, the heart rate tolerance is specific to each individual and is best determined by experience. The role of MHR for runners is to provide a guide for training. The role in medicine is often to provide an end point for exercise stress testing; some stress tests are terminated at calculated MHR or a predetermined percentage of MHR. In clinical testing of athletes, the standard is to push the exercise load to a symptom limited test to exhaustion which may drive the maximum heart rate well above the calculated number.
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. If you can maintain a rate of 160 during your workouts and races, your MHR is well above that.
The Garmin is pretty good at detecting heart rates and your numbers are probably accurate. You can hand count your pulse to cross check the Garmin’s accuracy during your workouts.
To summarise, you are unlikely to “blow up your heart” as you have a proven load tolerance. If your heart rate increases at the same work load 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.
