Heart Rate Zones for Beginners: Is Your Watch Telling You the Truth?

A watch with heart rate is one of the most useful tools for a new runner, especially to keep easy runs truly easy. It's also the easiest way to train badly without realizing it. Here's what to trust and what not to.

Your zones need to be yours

Generic age-based formulas are an estimate designed for lots of people at once, not for you. The most reliable way to set your zones is a lab exercise test. If you don't have one, you can find the top of your easy zone with the talk test:

1. On a flat easy run, after about ten minutes, raise the pace very gradually.
2. Every minute or two, say a sentence of several words out loud.
3. Note your heart rate when you start to wonder whether you can talk comfortably. That's roughly the top of your easy zone.
4. Repeat it another day. If the number is similar, you have your own reference. Since that point of doubt tends to fall slightly above the first threshold, stay a little below it on easy runs.

When the watch and your body disagree, if the watch says "easy" and you can't talk, trust your breathing.

Wrist or chest strap?

In a study comparing a wrist sensor with a chest strap (Sartor and colleagues, 2018), during running the wrist sensor stayed within ten beats of the strap 95% of the time, and across all activities the average error was no more than three beats. It did worse in the gym, with less regular movements. It's one study and one device, so it doesn't apply to every watch. But for easy runs, a good wrist sensor can do the job; for more precision, the chest strap is the reference.

What your watch doesn't tell you

"VO2 max," "training status," "race prediction" and "recovery time" are estimates an algorithm calculates from your data, not measurements. Use them to spot trends, not as the truth. If your watch says you're recovered and your legs say you're not, your legs have more information.

What's really valuable is your history: weekly mileage, your longest run of the last month, and how your pace at the same heart rate changes over time.

The most common watch mistake

Running for the watch instead of for the workout: pushing the last miles so the average pace looks better, or comparing your paces with other people's. Nobody cares about your easy-run pace. What matters is what those runs let you do on hard days.

Zones, the talk test and how to build your week are covered in What the Road Won't Tell You, with every source cited.

Source: Sartor F, et al. Wrist-worn optical and chest strap heart rate comparison in a heterogeneous sample of healthy individuals and in coronary artery disease patients. BMC Sports Science, Medicine and Rehabilitation. 2018;10:10.

This article is for general information and doesn't replace the advice of a health professional.