Ready to take your swimming to the next level? Looking for an accurate way to measure heart rate while in the water? Here is a breakdown of the best waterproof heart rate monitors to take with you to the pool.
Pushing yourself in the pool is hard. Particularly for those who train on our own. By ourselves with the black line and the pace clock we circle round and round, crushing lap after lap.
The volume and monotony can lull us into complacency, however. Luckily, there are countless ways to progress in the water: intervals, stroke rates, splits, goal times, volume, and of course, heart rate.
By measuring and tracking our heart rate we have a fool-proof way of making sure that we are doing the right kind of training while in the water.
The benefits of training with a waterproof heart rate monitor are legit:
- It keeps you honest about how hard we are actually working. Sure, the workout might “feel” hard, and it’s easy to say that we are “working hard” in the water—but without an objective measure of our effort it’s pretty easy to sandbag our reps. Heart rate tells us with cold precision how much exertion we are truly throwing down.
- Helps you stay in your prescribed training zones. This is particularly useful on recovery days, where the goal is to keep your heart rate low. We’ve all had situations where the momentum of the workout led us into pushing ourselves when we were supposed to be taking it easy. Conversely, a heart rate monitor is there to let us know that we are also not pushing ourselves enough on days when high intensity is called for.
- It’s another way to measure progress in the pool. One of the cool things about tracking your training, whether it is with a waterproof fitness tracker or an old fashioned log book, is seeing improvement first-hand. Those moments when you are able to swim at a faster speed while maintaining a lower heart rate than the last time around provides you a critical jolt of confidence and motivation that keeps you coming back for more.
The Problems with Trying to Measure Your Heart Rate While Swimming
It’s likely that you learned the old-school method of checking your heart rate at some point during your swim career: Stick to fingers against the side of your neck, and count the pulses of blood for six seconds, and then multiplying that number by 10 (for example, if you counted 13 “beats” over a six-second period, your BPM is 130).
While this method can give us a fairly decent approximation, it’s not entirely accurate.
Along came the wearable companies, from the waterproof Fitbits to the Garmin Swim watch, with wrist-strapped devices that purported to be able to tell you your heart rate at any given time while wearing it. While all of them will measure heart rate on land, not all of them will be able to measure heart rate in the water.
And the reason for this is because wrist-based fitness trackers use that flashing green light (called optical heart rate sensors) to measure blood volume against your skin to generate a heart rate reading.
But doing this in water is almost impossible. Water literally gets in the way, the wearable slides up and down, or otherwise gets jostled, and ends up producing unreliable data (when it manages to produce data at all).
Although wearable companies will happily tell you how accurate their optical sensors are, this is only in a best case scenario (i.e. when you are dry and barely moving your arms).
And even then, the results aren’t that great.
The Journal of the American Medical Association, in their own research, found that the wrist-strapped wearables they tested weren’t able to produce a reliable heart reading during moderate exercise.
In fact, none of the four devices that they tested, which included popular wearables such as the Apple Watch, Fitbit Charge and Mio Fuse, were able to come close in terms of heart rate accuracy compared to a chest-strap.
This is why—if you are serious about measuring your heart rate while you are swimming—you should be using a chest-strap to record your BPM.
Instead of a flashing light that requires constant contact against the skin and almost perfect laboratory-like conditions to work even moderately well, with chest straps, your heart rate is measured via the small electrical bursts that are given off by your heart as it contracts and sends blood hurtling to your muscles.
Moral of the story?
If measuring and targeted heart rates is a key part of your training program, a chest-strapped heart rate monitor is easily your best bet for getting the best and most accurate results.
The Best Heart Rate Monitors for Swimmers
Okay, so we’ve beaten the drum on how much better chest-strapped heart rate monitors are for swimming.
Now for a breakdown of the three best ones, ranked in terms of awesomeness.
1. Garmin HRM-Swim (Best Pick)
The Garmin Swim topped our list of best swim watches, so it is no surprise that the Garmin HRM-Swim slides into the top spot of our best waterproof heart rate monitors.
There are two versions of this particular heart rate monitor, the Garmin HRM-swim, which is designed for pool use, and the Garmin HRM-tri, which, as you can probably guess, is designed for the full spectrum of triathlon disciplines. The HRM-swim is thicker to reduce the likelihood of sliding off while you are swimming.
Anyhoo. Back to the HRM-swim.
As mentioned, it’s thicker than most chest straps so that it lessens the odds it will slide down your abdomen when you push off. To further insure that the strap doesn’t slide around, the inside of the heart rate monitor is made of a sticky, silicone-ish material that sucks up on onto your skin.
Additionally, Garmin designed this bad boy to withstand the corrosive chemicals that our neighborhood pools are frequently treated with.
It transmits data wirelessly to your Garmin watch—note that you can’t just download heart rate results to your computer, it has to be synced up to a compatible device (Garmin Swim, Fenix 5, etc.), and has a battery life of 235 hours according to manufacturer’s specs (so really, probably closer to 200).
The Garmin HR-swim retails for around $100.
2. Polar H10 Waterproof Heart Rate Sensor (Runner Up)
Polar is one of the longtime heavyweights in the wearable category, and their heart rate monitors have been best-in-class for years.
The Polar H10 is their most recent waterproof heart rate monitor. The strap is made of a soft textile, with silicone-framed electrodes dotted along it to get the most accurate measurement possible. (The silicone helps keep the electrodes from sliding while you are stroking along.)
Some of the best triathletes in the world swear by the Polar H10, including Ironman champion Sebastian Kienle. The Polar H10 is accurate, comfortable, and can be synced up against one of the Polar smartwatches or via the Polar app that is free to download and use. (This is a big plus compared to the Garmin strap, which is only usable with Garmin watches.)
The biggest improvement that the H10 features compared to its predecessor, the Polar H7, is battery life, with the H10 coming in at a hefty 400 hours compared to 150 hours for the H7.
3. Suunto Smart Sense Heart Rate Monitor
Lastly, we have the Suunto heart monitor, one of the lesser known wearable brands.
Unlike the Garmin heart rate monitor, with the Suunto you can transfer data to a Suunto smartwatch or to the Suunto Movescount app. This chest strap is small, and it s versatile, as it can be used on dryland as well with comfort (the sticky insides of the other two chest straps make running and biking a tad uncomfortable).
You can play around with different colors as well, and the strap is good to use up to 30m in depth.
More Stuff Like This:
The Best Waterproof Fitness Trackers for Swimming. Our comprehensive breakdown of the top wearables and fitness trackers for swimmers.
Waterproof Fitbits for Swimmers. Fitbit—one of the most popular wearables on the planet—have two waterproof fitness trackers for swimmers. Here are reviews of both of Fitbits waterproof trackers for swimming.
The Top Underwater and Waterproof MP3 Players for Swimming. Ready to level up your swim workouts with music? Here’s a breakdown of the most popular underwater and waterproof iPod/mp3 players on the market today.
