Update 5/29/20. One of the “personal training 101” topics that all fitness professionals need to know is how to determine a maximum heart rate. For most people, this means learning the 220 – Age equation. While this equation is used by millions of people for decades, other equations—that are said to be better —also exist. In fact, the 8th edition of the ACSM's guidelines book, for the first time, has covered one such alternative heart rate equation. Endorsement by the ACSM carries a lot of weight which means it may not be long before all other personal trainer books start including it as well. This means trainers need to know it. With that in mind, let's review the traditional heart rate equation and this new equation and see what we can discover.
The Old Heart Rate Equation
This is the equation that is in every exercise science book I own and it's also the equation used by most bikes, elliptical, treadmills etc found in gyms around the world.
Anytime a treadmill asks you your age, this is the equation it's likely using.
Basically, here's how the equation works.
Suppose you are a 40-year-old person (it doesn't matter if you are a man or woman) and you want to exercise on the treadmill at 60-80% of your maximum heart rate ability.
According to this equation, 220 – 40 = 180 heartbeats per minute (bpm).
In theory, this means that a 40 year old heart will beat a maximum of 180 times in a minute, if the person exercises exercise as hard as they can. This is called the maximum heart rate or Heart Rate Max (Max HR).
Since, in this example, you want to exercise at 60% and 80% of the maximum, the target heart rate is calculated this way:
180 X 0.6 = 108 bpm
and
180 X 0.8 = 144 bpm
Tip: to change a percent to a decimal, just move the decimal point two places to the left. Hence, 60.% becomes 0.6 and that’s all you have to do.
Answer: you should maintain a target heart rate of between 108 bpm and 144 bpm
Pretty easy right?
But, the big problem is the answer provided by the 220 – age equation is just an estimation. Your real max heart rate is not exactly 220-your age.
This is why other max heart rate equations exist.
Next, let's look at one of the most popular equations
Trivia. Where did the “220” come from in the equation? Does a baby's heartbeat 220 times a minute. No, it doesn’t. I cover the history of the 220 -age equation in my book, Personal Fitness Training Beyond the Basics.
The New Heart Rate Equation
On page 155 of the ACSM Guidelines For Exercise Prescription (8th edt), another maximum heart rate equation is mentioned. Here is the equation:
206.9 – (0.67 X age)
The ACSM says this equation is “the most accurate” of the various maximum heart rate equations you may have heard of.
This equation looks a bit more complicated than “220 – Age” but it's not too bad. Let's take a look at it by keeping with our 40-year-old person example from above.
Do the work in the parentheses first:
206.9 – (0.67 X 40) = 206.9 – 26.8. This equals 180.1 bpm. Let's round down to 180 bpm.
So the maximum heart rate is 180 bpm.
Notice that this is the same answer we obtained from the 220 – Age equation.
Question: is the answer always the same? Keep reading…
Then, if we wanted to calculate a target heart rate for this person, it's just like we did above. Let's use 60% and 80% again:
180 x 0.6 =108 bpm
180 X 0.8 = 144 bpm
The table below compares the estimated maximum heart rates (in bpm) calculated from both equations.
Age |
220 – Age |
206.9 – (0.67 x Age) |
20 | 200 | 193.5 |
25 | 195 | 190.15 |
30 | 190 | 186.8 |
35 | 185 | 183.45 |
40 | 180 | 180.1 |
45 | 175 | 176.8 |
50 | 170 | 173.4 |
55 | 165 | 170.05 |
60 | 160 | 166.7 |
65 | 155 | 163.35 |
70 | 150 | 160.0 |
75 | 145 | 156.65 |
As you can see, the answers are pretty much the same at age 40 but for other ages, they do not give the same maximum heart rates.
What's The Best Heart Rate Equation?
I'm, not a fan of using target heart rate as a way to calculate how hard you are exercising. Even if the 206.9 – (0.67 X Age) equation yields more accurate results, it sill requires math to do but more importantly it will not work in those taking high blood pressure medications. That's true for all heart rate equations too.
I feel better alternatives to hear rate equations include the Talk Test and RPE scale (Borg Scale). These other methods require no math also work much better with those who are taking medications for high blood pressure/heart disease, many of which are likely to be the clients of personal trainers.
Michael Wood says
Hi Joe – just came across your site – great content – TY
Joe says
Michael, thanks so much. That’s a great website you have too!
Jeff says
I agree, however i’m a bit of a propeller-head and i’m partial to any equation based method. 🙂
Joe says
Jeff, I hear ya. Sometimes, sometimes the math calls to us 🙂
Jeff says
The most accurate, if the client can handle it without undue risk, is performing a max hr test themselves. Using a quality (chest) heart rate monitor and exerting max. effort in the aerobic activity of their choice, a max determination can be obtained. Otherwise, the ACSM formula above along with perceived effort can be used.
Joe says
Jeff, I’d agree that doing max HR test might be most accurate but given the risks in an unhealthy population, I would likely not do it. For what its worth, I still feel heart rate is over used in fitness. I prefer the RPE scale which you mentioned along with the talk test.
Benjamin Bailey says
Surely the use of METS would be more specific and less likely to have external variables which could cause discrepancies in training zones?
For example drug interventions could cause the Hr zones to become irrelevant especially if a client is using a prescription drug such as Tricyclic which can cause noticeable palpitations or tachycardia.
Joe Cannon says
Hi Benjamin, Thanks for sharing. METs are great but most treadmills etc. dont list them. That can make measuring METs challenging. There are tables that list METs for various physical activities, but I’m not convinced that they are very accurate. I personally prefer the RPE scale (Borg scale) above all.