How maximum heart rate shapes your training zones

You and the person next to you can both be at 140 beats per minute and see different colours on the screen. A heart-rate zone expresses your pulse relative to a reference value. In a percentage-of-max system, that reference is your maximum heart rate.

Maximum heart rate is the highest rate your heart can reach during maximal effort. It's usually estimated from age to begin with. Understanding that estimate helps you make sense of the colours and decide when your settings need a closer look.

Start with the calculation

In the five-zone system used here, Zone 2 runs from 60% to just below 70% of maximum heart rate. If your maximum is 180 beats per minute, those boundaries are 108 and 126. At 126, you enter Zone 3.

Multiply your maximum by the percentage you want. The calculation is straightforward. The uncertainty is in the maximum you start with.

What the age formulas tell you

The familiar formula is 220 minus your age. At 40, that gives an estimated maximum of 180 beats per minute. It's a convenient starting point when you don't have a measured value. The American Heart Association describes age-based targets as averages, to use as a general guide.

Another estimate is 208 − 0.7 × age. Tanaka and colleagues proposed it in 2001 after analysing 351 studies involving 18,712 people and checking the result in a separate laboratory study.

Here's what the two formulas predict, in beats per minute:

Age	220 − age	208 − 0.7 × age
25	195	190.5
40	180	180
60	160	166

Both describe a relationship between age and maximum heart rate across a group. Neither measures your own maximum. Switching formulas changes the estimate, but it doesn't tell you which one is closer for you.

How an estimate changes the colour

Suppose your profile has a maximum of 190, but your actual maximum is 180. At 130 beats per minute:

• The screen calculates 130 ÷ 190, or about 68%, and shows Zone 2.
• Using 180, the same pulse is about 72%, which falls in Zone 3.

Your effort hasn't changed. The reference number has. An overestimated maximum can make a session look easier on screen, while an underestimated one can make it look harder.

These bands help organise training, but crossing a colour boundary doesn't identify an exact physiological threshold. Read the number alongside your breathing and how hard the effort feels.

A higher maximum doesn't mean you're fitter

It's tempting to compare your highest reading with someone else's. That comparison tells you little about fitness. In the Tanaka study, the relationship between age and maximum heart rate was similar across different levels of habitual physical activity.

Medication also matters. Beta-blockers slow heart rate and affect its response to exercise. If you take them, ask your clinician how to judge exercise intensity rather than relying on an age formula.

What you can learn from your own readings

Start with recordings from sessions you've already done. If a reliable trace shows 185 beats per minute during a hard effort, a maximum of 175 is too low. That reading tells you your maximum is at least 185. It doesn't prove you reached your limit.

Check the trace before changing your profile. An isolated jump that immediately disappears deserves a sensor check. Look at the surrounding readings and whether the change fits what you were doing.

If you need a measured maximum for training, discuss a supervised test with a qualified professional. A graded exercise test increases the workload progressively while your response is monitored. The test and supervision should suit your health, training history and activity. You don't need to add an all-out test to your next class just to replace an estimate.

Heart-rate reserve uses a different calculation

Some training plans use heart-rate reserve, also called the Karvonen method. This includes your resting heart rate:

Target heart rate = resting heart rate + intensity × heart-rate reserve

Your reserve is your maximum minus your resting heart rate. With a maximum of 180 and a resting rate of 60, the reserve is 120. A target at 60% of reserve is then 60 + 0.60 × 120 = 132 beats per minute.

Compare that with 60% of maximum alone, which is 108. The same percentage gives different targets because the methods use different starting points. Check which method a training plan uses before copying its percentages. Heart-rate reserve still needs a maximum, so it doesn't remove uncertainty in that value.

Using the board during a class

The Pulz8 board gives you and your coach a reason to check in. If the colour repeatedly seems out of step with your effort, describe what you're feeling. Can you speak comfortably? Has the effort been steady, or did you just start an interval?

Check the sensor and the profile settings before adjusting the maximum. A colour alone can't tell you which setting is wrong. A credible reading above your stored maximum is more useful evidence than trying to reach a particular colour.

Keep track of where your maximum came from: an age formula, a recorded effort or a supervised test. That helps you and your coach judge how much confidence to put in the zone boundaries.

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This article is for training education. If you have a heart condition, take medication that affects heart rate, or are new to exercise or returning after illness, seek medical advice before attempting a maximal test.