Your Max Heart Rate Doesn’t Matter

I don’t care what your max heart rate is. I do want you to work out at a variety of intensities. However, I don’t agree with the common advice to use percentages of estimated max heart rate to set intensity zones. There are better, more intuitive, and more accurate ways to set zones.

Quick disclaimer: If you are currently exercising at a variety of intensities based on an estimated max heart rate value and it is working for you, I will not tell you to stop. The important thing is to work out at a variety of intensities.

Broken Clock

Max heart rate formulas are like a broken clock. They are right twice a day.

Honestly, they may not even be right that often. The point is that when they are right, it has more to do with random chance than reliability.

The formulas I am talking about are the classic “220 − age” and the Tanaka “208 − (0.7 × age),” or any formula that uses your age and some arithmetic. These formulas might tell you the average max heart rate for people of a given age, but they tell you nothing about your max heart rate.

There are people of all ages whose max heart rate is significantly above or below their estimated max heart rate. For example, I am 52 years old and my max heart rate is 195. According to these formulas, it should be about 170.

So, why do these formulas get recommended?

True maximum heart rate is the highest possible heart rate that your body is able to get to. To find it, you would exercise at an absolutely maximum effort and hold it there for long enough for your heart rate to respond.

Most people don’t want to do that. For various health reasons, many people probably shouldn’t even try. Estimated max heart rate formulas are offered as an alternative.

But, what’s wrong with using an estimated max heart rate?

The step after estimating max heart rate is to assign percentages of that number to activity intensity zones. Depending, which model you follow, you might assign 70–80% to a “moderate” zone and 80–90% to a “hard” zone.

If I were to use the formula numbers to calculate my intensity zones, I would actually be working out at a far lower intensity than what I intended to, and I would not get the workout that supports my goals. People whose actual max heart rate is below their estimated max heart rate would have to work too hard to reach their target intensity zones. They may be unable to reach them at all or even hurt themselves trying. This could lead them to give up out of frustration.

Accurate Enough

There are precise methods of taking measurements and setting intensity zones. If you have a world championship race coming up, you can run on a treadmill in lab while hooked up to equipment that monitors your heart rate, the air you breathe out, and the chemicals in your blood. This is not practical for most people. Nor is it necessary.

We only need a method that is accurate enough to meet our goals. Therefore, I recommend you start exercising with the perceived exertion method that I will describe here.

Let’s take the Physical Activity Guidelines for Americans (PAGA) goal of at least 150 minutes a week of moderate aerobic activity or at least 75 minutes of vigorous aerobic activity (or an equivalent combination).

I find that these “moderate” and “vigorous” zones map nicely onto this four zone chart:

(There are other zone systems out there. Some even have different numbers of zones. If someone starts talking to you about a particular zone, just know that their definitions may be different.)

Zone 1 in this system is light aerobic activity. If you find that you are breathing normally and can converse normally as you are moving around, you are in this zone. You may describe this effort as “light” or “easy.” You would rank your perceived exertion as a 3 or 4 on a 1–10 scale.

Zone 2 is moderate aerobic activity. Here you will find yourself taking larger breaths. Your speech needs to be timed around those breaths and no longer flows as smoothly. (If you focus, however, you can time your speech and breaths to appear smooth.) You may describe this effort as “moderate” or “somewhat hard,” and it feels like 5 or 6 on a 1–10 scale.

If you were talking to someone on the phone while exercising in zone 2, they would be able to tell that you were exercising, but you wouldn’t have any trouble holding up your end of the conversation.

Zone 3 is vigorous aerobic activity. Your breathing becomes very deep and you can only speak short phrases between breaths. You may describe this effort as “hard” or “very hard.” Your perceived exertion ranks a 7 or 8.

Zone 4 is above what is discussed in the PAGA. Here you are using oxygen as fast as (or faster) than you can breathe it in. You won’t be able to maintain this effort for long. This is “very, very hard” or your maximum effort. You are breathing as hard as possible and your speech is limited to grunts or single words. Your exertion is a 9 or 10 on a 1–10 scale.

By evaluating how hard you are working, and being honest with yourself, you can tell accurately enough which intensity zone you are in.

Leave the max heart rate formulas in the trash with the broken clocks.

Note: On the chart, VT1 and VT2 refer to ventilatory threshold (which I will cover in a future article). To assign heart rate values to the VT1 point or to both the VT1 and VT2 points, a structured talk test can be performed. Contact me if you would like to know more.

Note: If you would like to learn more about the Physical Activity Guidelines for Americans and/or would like tips on increasing your weekly activity, please read my article “Physical Activity Guidelines for Americans.”