Maximum Heart Rate

Maximum Heart Rate: what is it?

HRmax is almost entirely determined by age and genetics. It is not a fitness marker - a very fit client and a sedentary one of the same age can have the same maximum, and training barely moves it. Its only real job is to be the top of the scale that heart-rate zones are drawn against. That makes accuracy matter: an anchor that is 10 beats out shifts every zone boundary in the plan, and the client trains at the wrong intensity all block without ever knowing.

The estimation formulas and what they are worth

Several published equations estimate HRmax from age. They agree closely in the middle of the age range and diverge at the extremes, where 220 minus age tends to overestimate in young adults and underestimate in older ones. Every one of them describes the average of a population, and individual values scatter widely around that average - by roughly ten beats per minute either side, and considerably more for some people.

How to measure it for real

A field measurement needs a genuinely maximal effort, so it is only appropriate for a screened, healthy, trained client with no cardiovascular risk factors and medical clearance where there is any doubt. A simple protocol: warm up thoroughly for 15 minutes, then run three to four hard hill repeats or 3-minute efforts, each one faster than the last, sprinting the final 30 seconds of the last one. The highest value your monitor records is your working HRmax.

Use a chest strap, not a wrist optical sensor. Optical sensors lose reliability exactly when it matters, at high intensity with high arm movement, and they are prone to reading cadence instead of heart rate. Take the highest value from several hard sessions rather than trusting one number, and discard obvious artefacts - a single beat spike to 220 in an otherwise 175 session is noise.

• Never run a max test on an unscreened, deconditioned or symptomatic client.
• Use a chest strap; wrist sensors drop out at high intensity.
• Test in the mode you program: running HRmax usually reads higher than cycling HRmax.
• Re-check it every couple of years, not every block. It changes slowly with age.

What HRmax does and does not tell you

A high HRmax is not a sign of fitness and a low one is not a problem. What does reflect fitness is the gap between resting and maximum heart rate - the heart rate reserve - and how quickly heart rate falls in the first minute after a hard effort. Both of those improve with training; the maximum itself does not.

Beta blockers and some other medications lower HRmax substantially. For a client on those, heart-rate zones built on any age formula are meaningless, and effort should be prescribed with RPE, pace or power instead.

Using it without over-trusting it

For a general fitness client, an estimated HRmax is fine as a starting point, provided you treat the resulting zones as approximate and cross-check them against how the client actually feels. If a client can hold a conversation at what the chart calls zone 4, the anchor is too low. If they are gasping in what the chart calls zone 2, it is too high.

The pragmatic route for most coaches is to anchor to threshold heart rate instead. A 30-minute all-out time trial gives a threshold heart rate that is individual, repeatable and does not require a maximal test.