Earlier, we mentioned in-ear optical HRMs. They're neat because they're built into sports headphones, so you essentially get two devices for the price of one. While these devices cost a lot more than other HRMs, they're a good value if you're also in the market for a new pair of wireless sports headphones.

The accuracy of the devices listed below is good for steady runs, cycles, and workouts - but accuracy can dip during HIIT and workouts that flex the wrist. Most Garmin devices now come with optical heart rate monitoring. The challenge with such devices is they don’t support optical heart rate while underwater. So, in this case, how would you rate your HR zones? It connects to devices using ANT+ - and has a 5ATM waterproof rating that makes it safe for pool and open water swimming. Figure out how important battery life is to you and how often you want to charge or replace it. Some chest strap heart-rate monitor batteries can last over a year, while others can last around 500 hours. This will vary per device and how often you use it.Additionally, the most common worry of any swimmer for their swimming heart rate monitor is the corrosive materials most pools have for treatment. While the Apple Series 8 Watch is not cheap—especially if you get the cellular version—they are incredibly durable. To get the best from them, rinse your Apple watch after swimming to protect them from chlorine and salt. ✅ PROS To manually monitor a swimmer’s heart rate while training, they should place their fingers on their preferred pulse and count every time they feel their pulse beat for 10 seconds and multiply by six to get their heart rate. Depending on your fitness and skill level in the water, your zones should be set 10 to 15 beats-per-minute lower than they are on land. For well-trained swimmers under the age of 19, maximal heart rate will only be 5 to 7 BPM lower. It should be noted that the colder the temperature of the water, the lower your swimming heart-rate zones will be. This is due to a physiological response called The Diving Reflex. Thankfully, most indoor lap pools maintain a consistent temperature all year long, so this may not be a factor you need to consider. Data is viewable inside Apple's Workout app, but the benefit of having a strong collection of third-party apps means you can also view that data in places like Strava and Runkeeper.

HRM-Swim by Garmin topped our list of the best swimming heart rate monitors; chest straps that are snug-fit lessen the odds of falling or sliding off your abdomen as you push your way through the waters.

Fitbit Ace 2

Resting heart rate is easy to measure. You can read it by feeling your pulse with two fingers and counting it. You can also read it using a free app (such as this one from Azumio) and a smartphone camera. It's simple to calculate resting heart rate with or without a device, as well as compare data across methods. With a battery life of 235 hours, it won’t let you down in terms of recording all the data you need while swimming. Final Thoughts

Using a waterproof heart rate monitor during your swimming workouts will help you measure your heart rate accurately, which will, in turn, help you to manage your workouts correctly and gain better results. This device will also give you a factual measurement to understand your workouts better and determine whether you are working at your full capacity. The Fitbit Charge 4 is a slim, stylish-looking watch that has a great range of features including GPS for open water swimming, heart rate monitoring, and calorie expenditure. It is waterproof for up to 165 feet/50 meters and is compatible with Android/iOS/Windows.To effectively use a heart rate monitor during your swim, it’s essential to understand the different heart rate zones and what they mean for your training. Heart rate zones are a way of categorizing different levels of effort based on your maximum heart rate. Each zone corresponds to a specific percentage range of your maximum heart rate, and training within these zones can help you achieve different training goals. Resting heart rate – or pulse rate – is number of times your heart beats per minute (bpm) when you aren't active. This can vary widely from person to person and anything between 60-100 bpm can be considered 'normal' levels of resting heart rate, according to the British Heart Foundation. Pulse rate varies throughout the day and tend to be the lowest at certain stages of sleep. Pair it with your Garmin Smartwatch, and you can use it for up to 10 months for a daily hour of physical activity.