Heart Rate Zones

Calculating Heart Rate Zones

Heart rate reserve method

Apple Watch can calculate Heart Rate Zones automatically using heart rate reserve method. Apple Watch recalculates your HR zones monthly.

LTHR

Alternatively, you can do a 20 min time trial (i.e. FTPTest) and take the average heart rate from the test. That will be your Lactate Threshold Heart Rate (LTHR). Then use Data Cranker LTHR Calculator to calculate the zones.

Some notes on Apple Watch automatic calculation vs LTHR

I find in recent months that the automatic calculation provided by the Apple Watch is more accurate for me than LTHR based on perceived exertion.

Using Perceived Efforts

Zone 1: Recovery

Walking pace on flat terrain, leisurely bike ride, can maintain a lengthy conversation, make frequenty stops.

Zone 2: Endurance

Also known as fat burn zone. It is very important for long endurance efforts, like long bike rides, long runs, hikes up mountains, etc. This is an effort that can be sustained over several hours. At the bottom of this zone your can breathe through your nose, and can talk in short sentences. At the top of this zone you may need to your mouth open when breathing and can only offer one or two words in response to questions.

Zone 3: Power (aka Tempo)

Mouth open for breathing, not much more strenuous than zone 2, but requires recovery. Short moderate efforts like climbs up small hills, accelerating to catch up with the pack, etc.

Zone 4: Threshold

Can't talk, need mouth for breathing, challenging efforts not longer than 30 mins with recoveries of about a quarter as long as the effort. So, a 6 min effort would require a 90 second recovery. A total of 20 to 60 mins in this zone per workout is adequate to build fitness.

Zone 5: Max Capacity

Very difficult efforts lasting no longer than 10-15 mins. In the literature you'll see this zone broken up into 5a, 5b, and 5c. Acid starts to accumulate in your muscles, which feels like a burning sensation. Efforts in zone 5 require longer recoveries.

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