You can use any Bluetooth HR monitor without a watch. The added functionality of a watch is that it’s easier to look at the display without needing to carry something in your hand, which is annoying. But if you’re on a treadmill, a watch truly does not offer anything a phone app doesn’t. Well, maybe cadence but watches aren’t great at that anyway. The Polar Hr monitors and accompanying apps are pretty great.

If the goal is to keep HR within a certain range, seeing your HR on a watch would be much more convenient. I’m not sure you can see HR data in real time on the phone like you can on a watch.

The strap/phone combo worked fine for me until ski season, then I needed a watch. Maybe if you can find an app with heart rate alarms you could put it in your pocket but I had to have mine in my hand so I could see what my HR was.

I’ll just throw in a personal experience with the Wahoo app and chest strap as a caveat (in case that’s the software you’re using). I believe this would only apply to this software, and even then maybe they’ve fixed it by now. My experience was from 2 years ago.

I have the Wahoo TICKR-X heartrate strap, and before I got a watch, I used the Wahoo app to record heartrate data. This combo did NOT work for the Pa:HR feature in Training Peaks if you are trying to do the outdoor test. (I suspect it would have been OK for a treadmill test but I didn’t have access to a treadmill).

For the outdoor test done on a track, I’d get crazy Pa:Hr numbers like -50% or +20%. It took me a while to figure out it was because this hardware and software combo sampled data excessively often, leading to noise in the speed channel. So even if I Was running at a steady slow pace (around 11:30 minute miles if I remember right!) it would sample me at 20 minute mile, then a 5 minute mile, then everything in between, all within a second. It would average out correctly, but for whatever reason the Training Peaks Pa:Hr algorithm would not handle it well. You could even see in the Training Peaks data that the pace and heartrate data was full of major spikes.

Once I got a watch and recorded through that, my data looked way more normal and the Pa:HR numbers made sense. I haven’t used the Wahoo app much since, but perhaps they’ve added features to allow users to smooth out the sampling rate.

Good point. It makes sense that a Garmin device, for example, would have more accurate information and/or calculations than an Apple device. The former is a GPS-focused company.