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Dr. Mirkin Answers a Question
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Maximum Heart Rate Formula
By Gabe Mirkin, M.D.Many of the standard tests used to measure heart function are based on a nonsensical MAXIMUM HEART RATE formula, that predicts the fastest your heart can beat and still pump blood through your body. Although this formula is the golden standard used today, it is not based on science.
In 1970, a good friend, Sam Fox, was the director of the United States Public Health Service Program to Prevent heart disease. He is one of the most respected heart specialists in the world. He and a young researcher named William Haskell were flying to a meeting. They put together several studies comparing maximum heart rate and age. Sam Fox took out a pencil and plotted a graph of age verses maximum heart rate and said it looks like maximum heart rate is equal to 220 minus a person's age. For the last 30 years, this formula has been taught in physical education and heart function course and has been used to test heart function and athletic fitness. In the 1960s, Sam Fox was very helpful to me when I was competing, planning and setting up running programs, but the whole concept of maximum heart rate and the formula that it is equal to 220 minus your age is ridiculous.
The formula is wrong because your legs drive your heart. Your heart does not drive your legs. Maximum heart rate depends on the strength of your legs, not the strength of your heart. When you contract your leg muscles, they squeeze against the blood vessels near them to pump blood from your leg veins toward your heart. When your leg muscle relax, your leg veins fill with blood. So your leg muscles pump increased amounts of blood toward your heart. This increased blood fills the heart and causes your heart to be faster and with more force. This is called the Bainbridge reflex that doctors are taught in their first year of medical school. The stronger your legs are, the more blood they can pump, which causes your heart to beat faster.
A pencil mark plotted on a graph during an airplane flight more than 30 years ago has been the accepted formula for maximum heart rate for more than 30 years and the medical community has accepted this dogma for more than 30 years.
Dr Mirkin's reports and opinions are for information only, and are not intended to diagnose or prescribe. For your specific diagnosis and treatment, consult your doctor or health care provider.
Dr Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is one of a very few doctors board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. For more information visit URL: Dr Mirkin.
Support for Dr. Mirkin's Position
"[I]nquiry into the history of this formula reveals that it was not developed from original research, but resulted from observation based on data from approximately 11 references consisting of published research or unpublished scientific compilations. Consequently, the formula HRmax=220-age has no scientific merit for use in exercise physiology and related fields. A brief review of alternate HRmax prediction formula reveals that the majority of age-based univariate prediction equations also have large prediction errors (>10 b/min).
Article about maximum heart rate. Robert A. Robergs and Roberto Landwehr, The Surprising History of the "HRmax220-age" Equation, Journal of Exercise Physiology online, Volume 5 Number 2 May 2002.
Comment #1
Some studies indicate that exercise raises the maximum heart rate. That may not apply for people who have irregularities in the pattern of their heart beats as shown in a stress electro-cardiogram.Using the most accurate formula available, I estimate my own heart rate maximum at 155 bpm, 9 bpm higher than the formula "220-age". However, a stress test showed an irregularity that shows up around 130 bpm, a level that is 85% of the higher estimated maximum heart rate and 90% of the lower estimate. For me, the difference in formulas does not matter, since I have to stick to 130 bpm as the practical maximum for working out.
If you are over 40, you should have a stress electro-cardiogram before engaging in vigorous exercise, anything that makes you puff when you breathe or makes your heart rate go above 70% of 220-age.
(The formula may not be based on science, but it might keep you from having a heart attack!)
Comment #2
How many other rules do we follow that have no scientific basis?For example, you will find that most dietary experts recommend that you consume a maximum of one gram of protein for every kilogram (0.45 gram/pound) of body weight, sometimes expressed as grams per unit of lean body mass.
However, evidence from experiments suggest that dieters and older adults may need about 60% more protein to conserve muscle mass. This is equivalent to 1.6 g of protein per kg of body weight (0.75 g/pound).
Reference: When you lose fat, will you lose muscle and bone too?
Whey protein, in particular, has been shown to reduce hunger in dieters and to promote muscle gain during weight training.
Whey protein has the additional advantage of being free from saturated fats that may pose a risk to arteries.