Using Your Watch to Train with Heart Rate

Heart Rate Month was three posts, but why stop there. I was thinking that something explaining how to make the most of using your watch with heart rate was worth writing about. So here we are.

One thing to hold onto throughout, because it's the key to everything below: the watch's job is to confirm what you already suspected, not to tell you what to do. Set it up so it can do that quietly, and it's brilliant. Set it up badly and it'll spend an hour nagging you.

Put Your Own Numbers In. Once.

Almost every watch ships with heart rate zones built from your age. You know what I think of that by now — we covered it properly in the last set of posts — so go into the settings and put your real numbers in. Your max heart rate, your resting heart rate, and let it rebuild the zones from those.

Our five zones deliberately line up with the structure your watch is already using:

• Zone 1 — Warm-up

• Zone 2 — Easy

• Zone 3 — Steady

• Zone 4 — Threshold

• Zone 5 — Maximum

  
  

That's not a coincidence. It's one less thing to translate at the side of a track. What's in the training manual, what's in the Full Potential app, and what's on your wrist should all say the same thing.

While you're in there, one more check. Most watches let you choose whether zones are calculated from a percentage of max heart rate or from heart rate reserve. If yours offers it, choose heart rate reserve. I showed you the numbers last time — the two methods can put your threshold floor above where the other method puts your threshold ceiling. Same runner, same day. It matters.

Do this once, properly, and then leave it alone for a few months.

Wrist or Chest Strap?

I started using wrist-based heart rate in 2012, and they were, to put it kindly, appalling. For years I wouldn't go near one. If the number mattered, it was a chest strap or nothing.

That's simply not true any more. In 2026 I'm very confident in the heart rate coming off my Apple Watch. Is it as sensitive as a proper strap from Garmin, Polar or Wahoo? No, I don't think it is. But it does a really, really good job, and for the vast majority of running it's more than good enough.

So my honest position: wear the strap when the number is the point — threshold sessions, a max test, anything you're going to make decisions from — and don't worry about the wrist for everything else. If you are going wrist-only, wear it snug and sit it a bit further up your arm than feels natural. A loose watch will happily lock onto your cadence and report that back to you as a heart rate, which is a fun way to ruin a session.

The Screen I'd Set Up for Interval Sessions

Here's the practical bit. For interval work, I want three fields on the screen, in this order:

Lap time. Heart rate. Lap pace.

Lap time goes first because it's the only number on there that's definitely true. Your watch's distance is an estimate; the clock isn't. Run your intervals to time rather than distance and the whole session gets more honest.

Heart rate sits in the middle because that's the read on how hard you're actually working, once the weather and the hills and last night's sleep have all had their say.

Lap pace goes last as a sanity check — and note lap pace, not instantaneous pace, which jumps around far too much to be useful. Lap pace also gives you something clean to review afterwards.

Then use the workout feature on the watch so it counts you in and out of each rep, and your session arrives already chopped into neat laps for you to look over with a coffee.

The Beeping. Let's Talk About the Beeping.

If you've trained to zones for more than about a week, you've met this. You set a zone alert, and the watch spends the session beeping at you every time you drop under the bottom of it.

And here's the thing — it's usually beeping at you for something you can't do anything about. You're thirty seconds into a rep and your heart rate is still climbing. You've crested a hill and it's dipped. You've stopped at a junction. None of that is a mistake, but the watch doesn't know that, so it nags.

I'll be straight with you: this is largely something you live with. Some watches will let you set only an upper alert; plenty are all-or-nothing. There's no clever setting that fixes it.

So my recommendation is simply to turn the alerts off and glance instead. A look at your wrist every couple of minutes tells you everything the beep was going to tell you, without the running commentary. You stay in charge of when you check, which is the entire point.

Your Heart Rate Is Always Catching Up

This is the thing I most wish people understood before they start, because it explains about half the frustration.

Heart rate lags. You start a rep, you're working hard immediately, and the number on your wrist is still reporting what you were doing a minute ago. It takes somewhere in the region of a minute to a minute and a half to catch up with you. Which means for anything shorter than a couple of minutes, heart rate is a review tool, not a live one. Run those reps to effort and to pace, and look at the heart rate afterwards.

It drifts, too. On a long run, or on a warm day, you can hold exactly the same effort and watch the number creep upwards. That's cardiac drift, it's completely normal, and it does not mean you're suddenly working harder. It's one of the reasons running in the heat needs a different set of expectations.

And it moves for all sorts of reasons that have nothing to do with the session: how you slept, what your week's been like, caffeine, a cold you haven't noticed yet, a heavy block of training. If the number looks strange today — oddly high, or oddly reluctant to shift — that's usually information about you rather than about the run.

Guess First, Then Look

This is my favourite drill, and it's free.

Before you look at your watch, guess. Say a number in your head — "I reckon that's 152" — and then glance down and see how close you were.

Start with it as a light thing you do once or twice on an easy run. Then, when you fancy making it formal, do it properly: at the end of every rep, guess before you hit or hear the lap button beep.

How long does it take to get good at? As long as it takes. Some people are far more in tune with their body than others, and I don't say that as a criticism — it's just how it is. But everyone who does this regularly gets better at it, and that's the whole prize. You're building the judgement yourself rather than outsourcing it to a strap. Do it long enough and the watch stops being an instruction and becomes a second opinion.

Co-pilot, not pilot. You're still flying the plane. The Talk Test is doing the same job from the other direction — if the zone says you're bang on but you can't get four words out, believe your lungs.

On Race Day, I Turned Mine Off

I have never raced to heart rate. Not once. I refused to let a number push me off what I'd come to do.

I remember standing at the start of a race, looking down in the first mile, and seeing a figure a good deal higher than I wanted to see. And in that moment I thought: I need to turn this off. Because on race day you push yourself harder than you ever do in training — harder than you think you're capable of — and a number that looks alarming at mile one will do precisely nothing except plant a doubt in your head that you'll carry for the next two hours.

I know some runners use heart rate to hold themselves back in the early miles, and if that genuinely works for you then crack on. It never worked for me. And I wouldn't ask anyone to hold a specific heart rate zone for an entire race — it's too aggressive and too difficult a thing to do.

But afterwards? Afterwards is where it earns its keep. Looking back at the data from a race and seeing how much harder I'd pushed than I thought I could is one of the more useful things I've done. It genuinely reframed what I asked of myself in training. Harder isn't better — but knowing what your actual ceiling looks like tells you a lot about where the rest of it should sit.

A Quick Word for the Triathletes

If you're riding as well as running, don't port your running zones straight onto the bike. Heart rate at the same perceived effort typically sits somewhere around 5 to 15 beats lower on a bike than it does running — you're seated, your upper body is largely along for the ride, and there's no impact to absorb.

How big the gap is depends on you and on how well trained you are in each sport, so there's no universal number to subtract. Build a separate set of zones for the bike. Two sports, two sets of numbers.

To Summarise

• Put your own numbers into the watch, not the age-based defaults — and use heart rate reserve if you're offered the choice

• Strap when the number matters, wrist is fine for the rest

• Interval screen: lap time, heart rate, lap pace

• Turn the zone alerts off and glance instead

• Give heart rate time — it lags at the start and drifts late on

• Guess before you look

• If in doubt, run to effort, not pace

  
  

Get the watch set up properly and it fades into the background, which is exactly where you want it. It should be making your training easier, not giving you something else to be annoyed about.

Thinking about an autumn race? If you want heart rate training built properly into your plan from day one — zones set correctly, sessions that actually fit together — drop me a line. We'll build a block that gets you to the start line fit, fresh and ready to run your best. [Book a coaching package →]