Currently, many Garmin devices now come with optical heart rate monitoring, but currently, they DON’T support optical HR whilst swimming. In which case, if you use a Garmin watch for triathlon training or swimming in general, how do you monitor your HR zones? With the Garmin HRM-Swim, that’s how! Plus you might be able to squeeze an extra sport out of it too!
Garmin HRM-Swim Review
Having recently reviewed the Garmin Fenix 3 HR, when you use the swim function, the optical HR sensor switches off, as currently, Garmin are not happy with the accuracy of the sensor when swimming. Seems a very sensible plan.
The issue with swimming is the water simply blocks ANT+ transmission within more than a few centimeters. Thus Garmin has a heart rate strap specifically created for your swimming needs – the Garmin HRM-Swim.
The Garmin HRM-Swim is made of a thick almost webbing material with a sticky back – in order to keep it in place in the water
However because of this, there is very little stretch in the actual blue HR strap, hence why Garmin include three additional strap extenders in the box, and a small elasticated strap so that you can find the right length for your chest.
The additional pieces are swapped in and out, but the hook system we are used to seeing at the end of most HR straps. All the additional strap sections also have a small elastic piece on the end, to make sure you don’t get pulling where the various hooks connect.
The pod on the Garmin HRM-Swim is slightly chunkier than on the standard Garmin Run HRM.
This is because of the added internals to the Garmin HRM-Swim allowing it record and save you swim heart rate data. However one other benefit of the increased height is a narrower device, so during tumble turns etc in the pool, you are less likely to catch yourself than on a normal, wider HRM pod.
The core of the device is actually directly attached to the Garmin HRM-Swim strap and isn’t removable However the blue rubber cap can be pried off the pod in order to change batteries
The CR2032 battery is then exposed by removing the four screws on the face plate. This is the only bit of the device which detaches from the strap.
Some people might be initially concerned that might reduce the life of the strap, given the way normal HRM straps tend to wear over time. However, one facet of that is the expansile nature of the fabric the straps are made of. The Garmin HRM-Swim strap itself is made of a thick weave and feels the most solid of the HRM straps I have seen. I can’t imagine that long-term wear will be an issue with the strap – chlorine within pools notwithstanding.
Using the Device
There is not much really to say, you strap the Garmin HRM-Swim on, and then let it do its thing.
Whilst in the pool the Garmin HRM-Swim RECORDS your swimming data and then syncs it to your device afterwards. But when out of the water can transmit standard ANT+ HRM data.
This all goes back to the fact ANT+ doesn’t go very far in a pool
Here is a simple, if blurring example (I nearly dropped my phone in the pool!)
aaand no HR transmitted
However just slightly out of the water
and we’re back to lovely seeing a lovely ANT+ pulse rate
But what of all the data recorded whilst in the pool? As mentioned before this is stored on the actual Garmin HRM-Swim memory, and when you stop and save your activity, as your Garmin device has already been pair with the Garmin HRM-Swim, it will look for the strap, and instruct it to download that HRM data.
The Garmin HRM-Swim has an internal clock which is synced with your Garmin at the start of a swim, this is how the device is able to accurately pair up your activities to the HRM data.
It is also worthwhile noting that the Suunto chest strap also records underwater, but there you are using a standard strap, which slips much more easily in the pool. Polar using Bluetooth, however, is able to transmit more effectively in water, so doesn’t need memory with their strap.
Conversely with both Polar and Suunto, you also only have one strap f.or all your activities, so carrying less.
Garmin will sell you an all in one strap – the HRM-Tri, to compete directly with Suunto’s offering with an internal memory, but then you also loose the swimming specific strap fabric.
For what it is worth, because of needing to fit so snugly when in the water the Garmin HRM-Swim can be used outside of the pool – just. I decided to test the strap by putting it on to cycle towards the pool
Apart from one brief adjustment made mid-ride actually worked as a perfectly functional HRM strap on the bike ride.
However, I’m not sure I’d advocate actually advocate buying the Garmin HRM-Swim as your sole HRM strap – I did a 60min work out on Zwift with it and did find I had come a little slack by the end of the ride. But that is as much likely to do with the movements and breathing whilst on the bike you are not getting in the pool. To be 100% clear, I have never had an issue with slippage whilst using the Garmin HRM-Swim in the pool.
I’ve also had a crack using the Garmin HRM-Swim whilst running, but again, after about 45mins, I found I had to tighten the strap again. Certainly usable but not perfect when it comes to being used outside the pool.
The Garmin HRM-Swim does exactly what it sets out to do. It’s a very competent swimming HR strap. I don’t think it’s a stretch to say with the material and the sticky backing which it is made of make it probably one of the best SWIM devices on the market. However you might also consider it to have a relatively narrow use case by comparison to the Garmin HRM-Tri, but then you have the increased slippage risk with the TRI strap.
If you are doing a lot of swimming. It’s a great device, with a narrow use case, but the Garmin HRM-Swim fulfills it’s brief excellently – and you might be able to push it to do a little bit more, but don’t blame that strap if it’s not perfect at running too!