I have a Garmin Fenix 5s to track my heart rate, which typically is pretty accurate. When I go on runs my heart rate is ~170, however when I go on intense hikes i.e. 2000 ft of gain in 1.5 miles, it barely breaks 120. Now, the problem is I definitely feel like I'm working way harder on the hike and feel my heart pounding much more than running.

So, is this likely a technical issue or is there a physiological explanation?

  • 1
    Did you double check your heart rate, e.g. by counting the number of beats for 15sec? I have a Garmin Fenix 5x and I must say, the optical hr sensor is absolutely useless for running, I need to connect a chest belt for sane measurements. May 7, 2020 at 7:37
  • Yeah, I think I'll need to do a manual check to figure out.
    – cloud36
    May 7, 2020 at 18:00

2 Answers 2


Our perception of physical exertion can be very subjective, based heavily upon our proficiency in a given exercise, as well as other factors such as fatigue, mood, and anxiety. If we are regular runners but only occasional hikers, for example, our threshold training runs may feel quite comfortable compared with hikes that, despite not elevating our heart rate so greatly, are in every other way more strenuous and demanding. We can generally push our heart rates to much higher levels in disciplines in which we are highly trained.

That is one possible explanation, but that said, heart-rate monitors certainly can be unreliable at times. Anything that I might say here is going to be conjecture.

I would recommend estimating your heart rate manually for each, then comparing notes. The radial pulse is usually easy to find with experience, but it can be weak in certain individuals, and take some practice to find. (If you are in the latter camp, it is not recommended that you use the carotid pulse, as this can lead to serious complications.)

I hope that is helpful.


Yes, hiking is generally less intensive than running. It doesn't matter how steep you go, it matters how fast you go.

On the other hand, optical sensors are not perfect, and from my experience, they work very bad on low intensity exercises. I don't know if it's an energy conservation mode when you're on low intensity, that is turn off by running, or it's a sweat that block the sensor, but I experience often that my Garmin fails to detect higher heart rate while hiking. Maybe because by running, I try to keep the watch open, so that the sweat doesn't accumulate so heavy, or it's just that higher pace and higher HR keep the energy save mode off...

Don't forget that sport watches are optimized for sports, and other options are added to do extra sales, so it's fully plausible that Garmin engineers have tested and optimized for runs and cycles, but not for walking and hiking.

  • It doesn't matter how steep you go, it matters how fast you go. To be fair, required exertion comes down to many factors, and both steepness and speed can play roles. Sep 20, 2021 at 12:28

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