The watch that knows more about you that you do

Watches are getting SMART. Very smart. And Garmin has plenty of data to benchmark your fitness and data to work out things about you that you may not even know yourself. For example, do you know your VO2 max? And your race times? Maybe you do, but Garmin also knows. And after just one run it will get pretty close to sharing this data with you. 

Garmin Forerunner 235

Sleep Tracking with the Garmin Forerunner 235

Telling your sleep tracking device when you are actually asleep is not really great. There is a window between arming your watch and actually falling asleep. Also, you have to remember to actually click the sleep button. And on most watches and trackers it is not just a single button press. You will need to turn on the lights to follow the process to put the device to sleep, probably delaying the time it takes you to get to sleep by several minutes... Anyway, the Garmin Forerunner 235 you do not tell it when you go to sleep. It just knows! In the software when syncing the app with your watch, you will let it know your standard sleep and wake times. For most of us we have some sort of routine. But that is it. From here, we let the device take control. And as of today, it seems the latest software update on the Garmin Fenix 3 also has removed the functionality to tell the watch you are off to sleep (although this version of the Fenix 3 does not have the built in heart rate monitor). 

Heart Rate Monitor Without Chest Strap

The nice thing about wrist based heart rate tracking is not having to 1. Wear a chest strap, 2. remember your chest strap, 3. Remember to put it on once you have got dressed and not having to strip down once you are ready to leave, 4. Wash your chest strap, 5. worry about pairing your chest strap, 6. Have an uncomfortable chest strap on sliding around your body giving missing and blank data.... etc. 

Saying that, it is very hard for wrist based devices to compete with the accuracy of chest based tracking when they are fitted correctly. 

Heart rate tracking throughout the day

So the Garmin Forerunner 235 tracks your heart rate throughout the day. And yes, this does have an impact on battery life. But if you are sitting and there is less change in your heart rate data, it will start to take a reading less frequently. You can look at your screen and get a snapshot of the last 4 hours of data. See what your heart rate has been up to. Did that last phone call really take you over the edge?

Why do we want heart rate monitoring?

Training with heart rate data has so many benefits. If you are new to heart rate tracking and training I suggest you read our post about training with heart rate data. There are many benefits ranging from how hard you are training through to your rest and recovery. Many purists do not want or see a need to know this info. But for many tech heads the data is one extra toy that helps you get up to train. 

Other reports you can pick up in Garmin Connect include a pie chart of activity categorised into Highly Active, Active, Sedentary and Sleeping. Giving that being sedentary is twice as likely to kill you then being overweight (source NHS), this is useful info. It may even save your life!

Heart rate monitor gps watch

If you are looking for an activity tracker watch, with GPS and heart rate this probably is the watch for you. For a watch with heart rate monitor built-in it is a new benchmark. 

Heart Rate Data Accuracy

My first run for comparing the heart rate accuracy data was 6.5k run. With some on road, on beach running. Garmin Fenix reports an average heart rate of 170 bpm (using a trusted arm band heart rate monitor from Scosche tested and collaborated against chest heart rate trackers).  The Forerunner 235 reports 169 bpm.

Fenix data below in green and the Forerunner 235 in red. Overlaid for comparison. 

Heart Rate Data compared with Garmin Fenix 3 and Forerunner 235

As you can see the charts do not completely align. For comparison when I tested a Mio Fuse wrist based heart rate tracker the data matched almost exactly:

Mio Fuse Heart Rate Data Overlaid with Garmin Fenix 3

After a two hour bike ride the average heart rate from the two devices was only 1 bpm different. 

Fenix 3 and Garmin Forerunner 235 Heart Rate Data Compared

Overall the data matches pretty closely apart from a few places where something obviously goes wrong. 

VO2 Max

After a few runs it has adjusted my VO2 max to 49. My Garmin Fenix 3 is 54 for running and 50 for cycling. VO2 testing will be comping soon to see how accurate the data is, but after 4 runs the watches were almost in sync with each other. 

Garmin Connect Via the App 

With Garmin products you can only have one device set-up as an activity tracker, so I created a new account on an old phone. No problems with this process but when I wanted to login to Garmin's website online to view the data you can only login with email. No idea what I used here. I only have my connect name. Quick(ish) call to Garmin and they could help me out here. I thought I would share this in case someone else is stupid enough to do the same!


As a watch that does everything this really is an excellent device. Activity tracking, heart rate and running all to the highest of quality. If you are after a fitness tracker read up on the other wearables we have reviewed. Or you may already be sold on the Garmin Forerunner 235.