Better Heart Rate Monitoring with Apple Watch Using Chest Strap Heart Rate Monitor

Last March I decided to purchase a separate chest strap worn heart rate monitor, specifically the Polar H10 Bluetooth Smart HR Sensor, to use with my Apple Watch when tracking my workouts.

You might be thinking, why would you buy a heart rate monitor when the Apple Watch already tracks heart rate?

Heart Rate Zone Training Failure

I wanted to experiment with heart rate zone training (training at a specific heart rate for a period of time) and found that just using the Apple Watch’s heart rate monitor was not ideal. I’d look down at my Watch while running and see the spinning heart icon (meaning it was trying to read the heart rate, but couldn’t find one) and no heart rate would display.

Other times I’d notice my heart pounding and the display would show 45 bpm which I knew was absolutely wrong. You can’t really train at a specific heart rate zone if you can’t rely on faulty data points.

For walking and just daily wear the Watch is great for monitoring heart rate. However, for anything more vigorous there are a few downsides to the built in heart rate monitor.

apple watch heart rate tracking does not collect as many data points as polar h10 chest strap monitor
Apple Watch built-in heart rate sensor logs less data points than Polar H10 chest strap sensor

Downsides to Apple Watch Built in HR Monitor

The Apple Watch uses an optical heart rate sensor which shoots light through your skin to determine your heart rate. There are a few drawbacks to this technology:

  • It’s not very quick to pick up changes in heart rate. Say you start sprinting it won’t detect the uptick in heart rate until a few seconds later
  • You need to have a good contact with your skin. Sudden or quick movements with weights using the arm the Watch is on will sometimes cause missed readings
  • You can’t accurately measure heart rate variability (HRV). While the optical sensor on the Watch can give you an HRV reading (use the Breath app set to one minute and it will calculate your HRV it’s not very accurate.

Advantages to Chest Strap HR Monitor

Instead of an optical sensor (which detects heart rate looking at blood pulsing through your skin) chest strap heart rate monitors have electrodes which detect the electrical signals products by your heart. Using an external heart rate chest strap addresses the drawbacks from using the default heart rate monitor in the Apple Watch.  The main benefits include:

  • More responsive and logs more data points. You can train at a specific heart rate and get almost instant readings. In addition you get more data points so you can see your heart rate changes over the course of a workout
  • Works great for most exercises and activities. I use it in Crossfit WODs and unlike where the Apple Watch would not read heart rate for kettlebell swings or barbell work the chest strap had no issues. Note, burpees while wearing the chest strap can be a little annoying, but you get used to it
  • Syncs with iPhone as well for access to more apps. You can pair the chest strap to your iPhone and uses apps like EliteHRV to measure and track your heart rate variability
  • See your heart rate displayed on cardio machines. Depending on the chest strap monitor model (typically any model that offers ANT+) you can connect with treadmills, rowers, bikes, or anything with a compatible computer display to view your heart rate in real time which makes it easier than having to glance at your watch
polar h10 uses ant+ to broadcast heart rate to exercise equipment
Glance at your watch for heart rate or a compatible machine’s computer to view heart rate in real time using the Polar H10

While a heart rate chest strap monitor is great for monitoring workouts it does suck for other reasons:

  • Sometimes it doesn’t properly connect to your Watch. It’s not fun troubleshooting tech issues right when you are about to start a workout
  • One more gadget to maintain. You have to periodically clean it and change the batteries (I know, 1st world problems)
  • Uncomfortable at first. It felt weird at first, but once you get used to it you kind of forget about it (that is until you do 100 burpees for time)

My Setup and How I Use My Chest Strap

To keep all my workouts centralized I use Apple Watch Workouts to log all of my exercise and activities. For monitoring heart rate it’s great as I can just glance down and Workout app will clearly display my heart rate and other relevant data (like your running pace if doing Outdoor Run workout).

I use bluetooth to pair the Polar H10 chest strap to my Apple Watch. When you pair an external chest strap heart rate monitor with your Watch the Workout app will use the external monitor instead of its built-in optical HR monitor to display and monitor heart rate. If it loses connection or doesn’t pair properly it will default the built-in monitor.

Each time I plug in the monitor to the chest strap, which turns on the monitor, it automatically connects with the Watch. This is how it should be in theory, but I’ve had issues with my Polar H10 not connecting. Normally when this happens I unpair and then re-pair it again. Or in some cases the battery could be dead!

Below are the Apple Workouts I use with my chest strap monitor:

  • Outdoor walking (I walk to my Crossfit gym)
  • Hiking
  • Strength training
  • Rowing
  • Outdoor running
  • HIIT (my go-to for most Crossfit WOD’s)
  • Mixed Cardio (I’ll do 5 minutes of rowing, biking, running and ski erging… so this is my catch all)
apps i use to analyze and track heart rate data

After a Workout I’ll use Cardiogram and Heart Analyzer to review the heart rate activity during the workout. These apps are better than viewing heart rate via the Apple Activity app. Cardiogram and Heart Analyzer are similar and different at the same time. I haven’t decided which I like better, but I’ll write a post about these apps another time.

To monitor and track HRV I use EliteHRV which pairs well with the Polar H10. I’m not an expert in HRV but it is fun to see when you are fully rested a higher HRV and then when you workout intensely and feel worn down that your HRV is lower. Not sure if most people need this data, but if you are nerd it’s kind of fun to track.

Final Thoughts

Get one of these chest strap heart rate monitors if you want to accurately track your heart rate while working out. The uncomfortableness wearing it goes away and for $40-$80 (depending on the model of monitor) you’ll get a lot of good use out of it. The monitors are especially great if you do workouts where your arms are moving all about with or without weight. While I use it for Crossfit it would be equally as good for boot camps, spin classes, etc…

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