In the quest to find an accurate target heart rate range for my client, there are a couple of methods I can use at my disposal. One is simply subtracting a client's age by 220, and taking that number and multiplying by 65 percent, 70 percent or so on. However, when I use the Karvonen method with heart rate reserve, I get an entirely different set of numbers. Also, I have read that 220 is not entirely accurate a number to use in the formula. Can you please tell me what method or formula is the most beneficial for me to find an accurate THR?
A colleague recently addressed this in his newsletter and cited a study that revealed the standard “220 - age” tends to overestimate max heart rate in younger people and underestimate it in older people. The “MHR= 220 - age” obviously implies that max heart rate drops by one beat per year. However, world famous exercise physiologist Per Olof Åstrand has shown that the average drop in max heart rate is 12 beats in 21 years and 19 beats in 33 years for women, yet nine beats in 21 years and 26 beats in 33 years for men.
Meta-analysis performed at the University of Colorado at Boulder covering 351 studies lead to a predicted max heart rate of: MHR = 208 – [.7 x (age)]
An inherent problem in predicting target heart rate is that any formula claiming to predict anything involving human beings is subject to Gaussian distribution (“the bell curve”). Although the statistics are in your favor, you never know exactly where any individual is going to fall within the bell curve.
In “stats talk,” about two-thirds of the subjects will fall within one standard deviation of the mean. The standard deviation for max heart rate is seven to 12 beats per minute depending on the age of the client and the study cited. That means that if the max heart rate is predicted to be, say, 180, then about two thirds of the sample will have actual max heart rates between 192 and 168, that is, 180 ± 12. Conversely, about one third of the sample will have max heart rates outside of that range, and standard formulas would grossly underestimate or overestimate their target heart rates.
Of course, the best target heart rate formula starts with an accurate max heart rate. Anyone who truly needs to do serious heart rate training should have their max heart rate measured, not predicted. For the average client, however, it really doesn't make much of a difference, frankly.
From a business standpoint, you should create a strategic alliance with an exercise physiologist who performs max heart rate testing. A hospital-based program is preferable since taking someone to a max heart rate can have serious consequences. Cardiologists and high-level cyclists, runners and triathletes are your best bets for helping you locate a physiology lab where they do actual max heart rate tests.
Typically, there will be few practitioners in your area who perform these tests, but you can trust that their clients are dedicated enough to invest in a personal trainer who knows how to interpret the data and implement an appropriate training program.
- Tanaka, H., Monahan, K.D., & Seals, D.R. (2001). Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology, 37, 153-156