The wrist based heart rate monitoring of the 735XT looks super cool. As a wow factor it gets 10/10. Just from a tech point of view, those green beams get the heart rate going. But how efficient is it really? How does it cope with activities like running and cycling and does it relate 24/7 activity tracking realistically?
Of course the main plus is discarding the discomfort of a chest heart rate monitor. The wrist based HRM make use of tech called oximetry. This big word means a little beam detects variation in your blood properties as it pulses through your veins: oxygenated blood and less oxygenated blood, dark red and light red blood, happy blood, sad blood, good blood, bad blood, etc. The problem is this little beam gets side-tracked by things like vibration, light that filters in and substances that may obstruct it, like suntan oil.
For 24/7 tracking the 735XT’s wrist HRM performed superbly. My heart rate during sleep, work, play, getting drilled in the dentist’s chair, avoiding bad drivers, all of it, were quite an eye opener as to why life wears me down.
Regarding training, after some solid comparative sessions using the wrist HRM and a chest strap I could draw some conclusions. A time trial bike ride on a very rough road, an extremely technical mountain bike course and a long-ish run were my test sessions. Check the screen shots. The wrist HRM is fine. It has a more spiky profile, but it balances out in the end, and gives acceptable measurements. The run measurement looks the best, since it has the lowest level of vibration. The red profiles represent heart rate.
There are two prerequisites. Firstly, don’t switch the 735XT on and start your activity right away. Initially it spikes high for a few minutes till it locks onto your pulse and then drops to your real heart rate. Allow about 15 minutes before you start your training. If you use it 24/7, it will be fine right away. The second is to make sure it is rather tight during the activity. Luckily the rubber strap was designed with a stretchiness that allows it to be tight without strangling your wrist.
When you use a chest strap, the wrist HRM get disabled automatically and comes back on when you take the strap off. You can also disable the wrist HRM permanently in settings. Also take note that the wrist HRM does not work for swimming. The swim or tri HRM will do that for you.
My final conclusion is that I am very happy with the 735XT wrist based HRM. If you want to split hairs, you might find reasons to question it in some respects. For me it is a big plus and I am still getting used to not having to fumble with my heart rate strap. The wrist HRM is very liberating. Go for it. You won’t be disappointed. The freedom is awesome. Garmin has made life so much life easier.
Till next week, happy training!