Original article written by Dr. Merkel
Don’t Depend on Maximum Heart Rate Formulae
The standard maximum heart rate formula (MHR=220-age) is supposed to predict the fastest your heart can beat and still pump blood through your body. It is not accurate. This month, researchers at Northwestern Medicine announced that the formula for women should be 206 minus 88 percent of a woman’s age (Circulation, July 2010).
However, this formula is also inaccurate.
In 1970, Dr. Sam Fox, one of the most respected heart specialists in the world, was on a plane with a young researcher named William Haskell. They put together several studies comparing maximum heart rate and age.
Dr. Fox plotted a graph of age verses maximum heart rate and noticed that maximum heart rate appeared to equal to 220 minus a person’s age. Since they reported this formula, it has been taught in physical education courses and used to test heart function and athletic fitness.
The formula is wrong because your legs drive your heart rate; 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 muscles 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. The stronger your legs are, the more blood they can pump, which causes your heart to beat faster.
In 2002, a study of 43 different formulae for MHR concluded that no acceptable formula currently exists.
The formula that fits better than others is:
HRmax = 205.8 – (0.685 – age)
It has a standard deviation of 6.4 beats per minute, which is very large (Journal of Exercise Physiology, May 2002). A study from Liverpool, England showed that the maximum heart rate for athletes is lower than for aged-matched sedentary people.
The maximum heart rate of male athletes was calculated to be 202 – 0.55 – age, and for female athletes, 216 – 1.09 – age. Weight lifters and runners had similar maximum heart rates, which were significantly lower than the age-matched sedentary people. The athletes have hearts that can pump more blood with each beat than the hearts of sedentary people, so they do not beat as often (International Journal of Sports Medicine, January 2008).
All MHR formulae are based on averages. They can be used to help you plan and monitor your exercise program, but should not be interpreted as absolute limits or goals.
If you want to train to become fast, use the following: Three times a week, never on consecutive days, either race or push the pace so that you are at your anaerobic threshold and then use bursts to exceed it to become short of breath. On the other four days, take it easy and do not put pressure on your muscles.
The standard Maximum Heart Rate formula (MHR = 220 – age) does not apply to highly fit athletes.
Dr. Pinna says:
This article on Maximum Heart Rate ties in splendidly with Peak Exercise. As we saw in Dr Mercola and Peak Exercise, stressing the body beyond its normal limits, changes the total reaction of the body to its environment. After a bout of Peak Exercise, the body responds by losing fat and producing Growth Hormone which facilitates the growth of new muscle.
With a knowledge of Maximum Heart Rate, we know how far we must go to reach Peak Exercise. This allows us to arrive at the best fitness state possible for our body and our age.
Don’t forget to subscribe to our newsletter in order to receive timely messages!