Setting heart rate zones on your Garmin watch or device

I see lots of people struggling to set their HR zones on their Garmin watches and this leads to all manner of weird issues. Setting zones should be simple.

First off, what not to do? I would caution against using 220-age to find your max HR. I think that formula may work well for studying large groups of individuals but I suspect doesn’t work well for individuals. Much like BMI.

Max HR or Lactate threshold HR? I think finding max HR is problematic. Max HR will change depending on your training status. If you’re at the end of a heavy block of training, you may not be able to achieve max HR. Finding your max HR isn’t pleasant either. I think it’s better to use LTHR, in my experience, it doesn’t vary much. Most importantly, I think LTHR is more useful, it’s the threshold beyond which your rate of fatigue increases.

Step 1 — determine your LTHR

Joel Friel provides good advice for establishing your LTHR.

To find your LTHR do a 30-minute time trial all by yourself (no training partners and not in a race). Again, it should be done as if it were a race for the entire 30 minutes.

at 10 minutes into the test, click the lap button on your heart rate monitor. When done, look to see what your average heart rate was for the last 20 minutes. That number is an approximation of your LTHR.

This weekend I ran the Leeds Half-Marathon. My average HR for the 85 minutes was 161bpm. I could use that as my LTHR or I could let tell me, which it did. I think either value would work fine.

Screenshot of Weather Up’s widget

Step 2 — personalise your zones

Then I use Garmin Connect to set my zones in my device’s user profile.

My zones happen to be:

  • Z1 -73%
  • Z2 74-86%
  • Z3 87-97%
  • Z4 98-100%
  • Z5 101-

Zone 2 is where I spend most of my training time and is the most important one for me. I did tweak my Z2 range from the defaults. 74-86% of 163 is 120-140bpm and I know I’m still able to breathe easily and have a conversation in this zone.

That’s all there is to it when setting heart rate zones.

Ran a marathon on 9 Oct. And I’ve been struggling to fully recover since. HRV rallied immediately afterwards but cratered 10 days later. Only returning to some form of normality this weekend. Then back to unbalanced after a Saturday workout.

Bucharest Marathon report

Bucharest Marathon race report


I ran the Paris marathon last year and missed a sub 3hr by 9secs. This year’s marathon was a chance to smash my PB. It didn’t work out that way.


Matt Fitzgerald’s training plan was the basis of my training the previous year. For no good reason I chose Pfitzinger’s 18 week 55-70mile plan this time round.

Training was punctured with multiple vacations, poor me. I struggled to find/make the time in my routine to get the med-long runs done. In the end my training consistency wasn’t where it needed to be. That said, I did manage to achieve the necessary running volume during the weeks prior to the race.

I was also nursing a knee injury that impaired my ability to get the volume of running done.


For the taper, I tried to follow what I had done the previous year since that clearly worked. The exception was that I sprinkled in some hard VO2max bike workouts. I’ve been monitoring my HRV throughout the summer and I was puzzled why my watch was telling me that I was strained. Completely the inverse of what I expected and made me worry that my immune system was under some sort of stress that was unknown to me.


Temp at the start was 15° on a clear sunny day. Towards the end it was near 21°.

0-2km Felt good. Ran to RPE. Pace was a comfortable 4m00s.

3-21km Pace dropped to 4m10s. HR was higher than I would have liked to be. Last year it was a few beats above 150, now it was approaching 160. Too close to threshold but I didn’t want to slow down since RPE felt fine.

21-28km The beginning of the end. Maintaining my target pace was becoming more challenging. My hip was starting to hurt. I could feel signs of cramp in my calves. I wasn’t enjoying it anymore.

28-30km Pace dropped to 4m30s. I was fighting my body to keep the target pace. The hip pain was getting worse and I was starting to limp. By 30km the discomfort was too much and I had to walk. It didn’t take me long to come to terms that all the training I’d done wasn’t sufficient. 12k to go, what do I do now? The answer was simple, try to jog to the finish and enjoy the beautiful autumn day in Bucharest.

30-39km No question it was a slog. At 35km I could feel that my cardio had enough.

39-42km Casa Parlamentului was now visible. The end was in sight. I managed to push a little harder and run a couple of final sub-6m/km.

The event

The route was nice. It passed the nicer areas of Bucharest. România in Autumn is beautiful. Temperatures are pleasant. There were a lot fewer runners than at Paris. 600-800 versus the 18000 at Paris. I was frequently running alone. The atmosphere was spartan to say the least. I appreciated the few people who took the time to cheer us on.


Did I go out too hard? It’s possible, but the RPE felt fine. I ran my last marathon to RPE and this one didn’t feel any harder. Did the VO2 bike workouts help or hinder? If anything, it would be the later. They might have allowed me to run faster than my legs could sustain.

I think the main reason why my Paris marathon was successful and this one wasn’t was due to adherence to the plan. Too many vacations. One injury too many. Too few long runs at marathon pace. Getting the volume up to 90km wasn’t itself sufficient.

If I ever attempt another marathon, I will load up Matt Fitzgerald’s plan stick to it religiously.