Knowing Your Heart Rate on the Trails


Please enjoy the following guest post written by Ambassador @seenonmytrail.

Are you curious about heart rate training and ready to take your trail running to the next level?

I’ve been training by heart rate for a few years and really enjoy the structure it offers, without having to be concerned with a specific pace (which is often irrelevant in a trail situation).

Heart rate training provides feedback to you that is specific to your body on any given day. It also allows for flexibility to adapt your training to suit your terrain, and an opportunity to modify a training plan from the road or track to the trail. It doesn’t take a PhD! All it requires is the desire to monitor your heart rate data and a willingness to run and adapt.

As soon as you start to wear your Garmin 735xt it will begin to gather data. It is important to wear it around the clock if you want accurate resting heart rate data for training.

If you’ve been wearing your Garmin for any length of time, it is possible you’ve already achieved a max heart rate reading; but, most likely, you have not performed at your max heart rate and will need to determine your accurate maximum value. To do this, I recommend Pfitzinger and Douglas’s simple, (but physically taxing), performance test.


  1. Find a hill that is moderately steep and   1/3 to 1/2 mile long. (600m)
  2. Warm up with gentle jogging for 10-15 minutes. Consider stretching for a few minutes, but stay warm.
  3. With your watch on, run uphill as hard as you can for 600 meters. (This should be intense and feel like there’s not another gear left on your body.) Do not stop your watch!
  4. Jog back down and repeat step 3 two more times. (You may not be able to jog back down for a minute or two, but keep the watch running so it can gather data.)
  5. Two minutes after running the last uphill, stop the run and save your run. There should be sufficient data for the watch to adjust your heart rate max, and a new heart rate max should appear on the watch *

TRAINING – (Once your max and resting heart rates have been determined.)

If you performed a heart rate max test, your watch will personalize the training zones to suit your current fitness. This frees you up from being concerned about pace training, because you will be functioning at what is ideal to your body’s specific capabilities.

You will notice that things like sleep and climate will have an effect on your heart rate.

If you have poor sleep, are fighting illness, or are experiencing hot weather, your heart will be working harder, and you will be running slower to reach each training zone. But, be assured that your workout will be what your body can handle and what it needs for the day.

The opposite is also true. If it is a cool day and you are well rested, you may need to run faster to run within your heart rate goal!


To see your heart rate zone, all you need to do is use the bottom left arrow buttons to scroll between screens during your run. Your heart rate zone will be displayed on a separate screen. You can also make your lap heart rate average available in one of the data fields, which provides a better overall measurement for training by each mile or kilometer.


It is a good idea to build a strong base of easy, aerobic running before adding in more intense workouts.

To run easy on trails, you will need to have a lot of self-discipline! When going uphill your heart rate will rise. To keep your run within the easy /aerobic zones, you may need to slow down to a hike. This is perfectly acceptable in trail running. (And, I know of no other way to finish a trail ultra-marathon that has any amount of climbing, than to purposefully hike some sections.)

Starting early with this tactic is good practice, and using your Garmin’s heart rate monitor to tell you when you are extending above the aerobic limit and is helpful in keeping the ultramarathoner from going out too fast.

If you are training for a trail marathon or longer, it’s possible that your goal for every run should be to stay within the training zones of warm-up, easy, and aerobic.

For the rest of us, running shorter distances in trail races, easy and aerobic running should be the foundation composing 75-90% of the plan.



Running up hills is more useful if you are training for shorter races. Still, it is important not to do this too often because of the stress on your body. (In my own running, I have phases of uphill running where I start with one uphill run a week. And, as my body adapts, I may add in one or two more hill workouts a week, until a taper, where I reduce the climbing quite a bit.)

Running uphill will quickly send your body into the tempo / THRESHOLD zone. You can create specific tempo or threshold workouts using hills and your Garmin.

Something I like to do when training for trail races is to substitute a 30-40 minute tempo run (you might do at X:xx pace) with a run that includes a long uphill section on a favorite trail.

After a mile or so of warm-up running in the easy zone, I will run for 30 minutes uphill, keeping an eye occasionally on my watch to see that I am staying within the threshold zone. If it gets above threshold, I need to slow down, or I won’t be able to run for the 30 minute duration. Also, if I run only in the green/ aerobic section, I’m not getting the intensity I need to improve my lactate threshold for races.

Threshold running does not have to be done strictly as one long brick of uphill running. This intensity can be reached on flat trail, road, the track, or can even be done in shorter segments that are repeated. A workout with similar benefit to the one above would be to run for 10 minutes in threshold zone, then jog (green / easy zone) or power hike for two minutes, and then repeat these steps two more times.

The main idea is to spend time at the threshold  zone. (However, if you are training for a race that will be longer than an hour, you may wish to get at least a few runs in with a longer time block of threshold-intensity running.)

INTERVAL / Vo2max running

It is important to note that this zone, zone 5 on your Garmin, is the most intense zone with the most potential for running injury, if done too often or for too long.

Once a week at this Maximum level is plenty for most athletes. Coach Jack Daniels, PhD, suggests these workouts should consist of no more than 10% of your total weekly running volume.

Typically these workouts are done on the track, and look like 6×800 meters at x pace, but for trail running, you will need to think in terms of time spent running.

If your workout is 6×800, and your interval 800 would take 4 minutes on the track, shoot for 4 minutes in the Maximum zone, followed by a recovery jog or hike of 3-4 minutes long, repeated 5 times.

You might opt for a short hill to do this on, jogging down the hill after each bout. Or, you might choose a flat bark path that is smooth and soft. Either way, the goal is to spend as much time in the red/ Maximum zone as possible during each 4 minute rep.

To improve in trail running it’s important to spend as much time as possible on surfaces that mimic your goal race. Doing these workouts on the track are not a bad idea though!


One last workout type is terrifically useful for trail runners.

Once a week it is a good idea to intentionally incorporate some downhill fast running on a short hill, or during a longer run with some short, technical downhill sections. Heart rate zones will not matter for this one, because when running downhill , your heart rate drops significantly.

If your race will contain a good portion of paved surface, it is a good idea to run this as 4-8 30second long bursts of top-end speed, followed by walking or very slow jogging.

If you plan to race on technical trails, doing this on a similar surface will help improve your ability to navigate roots and rocks without tripping.  Just make sure to watch out for other runners!

With all of these tips, training with your Garmin should be fun and produce some fantastic results. Happy trail running!!


Other tips:


If using a 735xt, or other wrist-based Garmin:


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