Running, Triathlon
June 19, 2018

Heart Rate Monitors: Wrist-Based vs. Chest Straps

So, you’re in the market for a new heart rate monitor and are being torn between a wrist-based monitor and a traditional chest strap.

It’s a common point of friction that I see many athletes rubbing up against, as they try to determine which will be the best option for them.

Both forms of monitoring have their pros and cons and this can make it a little confusing when trying to decide which is the better way to go.

While it is never ideal to spend too much time obsessing over gear, it’s useful to carefully consider what is going to be the best option for you. Your experience and the quality of your training will be affected by the device you choose to monitor your training and progress so it’s an important decision.

In today’s post, I thought I would share my some things to consider when deciding on which monitor to use. My thoughts come from my experience as an athlete, but also through observations in our lab and from feedback from hundreds of athletes we work with.

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Considerations When Buying A New Monitor

Price. You obviously have unique financial circumstances that affect your choice in monitor. While you may want the monitor that looks cool and has all the bells and whistle, this may not always be possible.

When limited in budget, it’s important that you decide on what is a need vs a want. From my perspective, here is what you need: Duration, heart rate, avg heart rate. That’s it. If you can afford a monitor that has those features and has pace, that’s ideal as you’ll be able to use heart rate over pace to track your progress.

Use. The type of training you do and where you plan to use the monitor are important. Certain types of exercises seem better suited to one type of monitor over another so knowing your primary focus and how you plan to use the monitor is a good way to steer your decision making.

Ability Level. The objectives of a beginner athlete often differs dramatically from that of someone who has been training at a high level for years. Where you fall on this spectrum should affect your thought process in making a decision on which monitor to use.

Running Watch Or Fitness Tracker. You need to determine between a dedicated running watch and a fitness tracker. Just because a fitness tracker has a heart rate monitor built in, doesn’t mean that it is going to be a good fit for you. Your use of the monitor and ability level should be considered when deciding between these two.

The Pros And Cons Of Wrist Based Heart Rate Monitors

Pros

Convenient. An obvious pro for wrist-based monitors is their convenience. There are no straps you need to wear, wash and maintain. This simplicity makes using them easy and improves consistency in their use.

Comfort. Because wrist-based monitors are baked right into your watch, they’re usually more comfortable to use than a strap.

Accurate At Low Intensity. One of the big cons I hear of wrist-based monitoring is their accuracy. From my experience, this is not the case, although that comes with a caveat.

At low-intensity, wrist-based monitors seem to be fairly accurate. We do a lot of testing in our lab using a chest strap. Often, athletes use their wrist-based monitors at the same time. In my experience of witnessing hundreds of tests like this, wrist-based monitors prove to be accurate.

Running watches with wrist-based monitors are usually within 1 to 2 beats of the strap. Well-known fitness trackers like Fitbit and Apple Watch are usually within 2 to 3 beats of the strap.

Cons

Inaccurate. As I mentioned in the pros list, wrist-based monitors are fairly accurate at low intensity. Unfortunately, this does not seem to be the case when you increase the intensity.

In the later stages of our testing when the athletes are working hard, the numbers begin to show a different picture. Instead of being out by between 1 to 3 beats, they’re often out by upwards of 5bpm. I have seen many off by as much as 20bpm.

This has also been my experience in my own training where my heart rate numbers are skewed as I up the pace.

Placement And Tightness. The placement and tightness of the strap on a wrist-based monitor are very important for its ability to measure your heart rate accurately. I suspect this is part of the reason for their lack of accuracy at higher intensity.

If you place them correctly and do them up as tight as they need to be for accuracy, they become uncomfortable. As such, most athletes are wearing them too loosely and as the intensity goes up and the arms begin to move more aggressively, the monitor begins to move about and lose its accuracy.

Forearm Tension. If you use a wrist-based monitor and do an exercise where the tension in your forearm changes (think strength exercises), you’ll often see very different readings to what you will see from a chest strap.

Unreliable. Because of all of the above, wrist-based monitors don’t typically lend themselves to reliable and consistent heart rate monitoring.

The Pros And Cons Of Heart Rate Chest Straps

Pros

Accurate. When compared with wrist-based monitors, chest straps are more accurate at low intensity and at high intensity. This is a very important consideration if you’re serious about achieving the best results possible from your training.

I would suggest you place a higher importance on this than on some of the other pros and cons on the list.

Reliable & Consistent. A chest strap is more accurate and therefore it is more reliable and consistent too. Heart rate always has a lag but with a strap, it limits the lag you see on your monitor and it makes interpreting the numbers while running easier than a wrist-based monitor.

Cons

Comfort. While I have comfort down as a con, this is not always the case. Comfort – or discomfort rather – is the main pain point I hear from athletes when talking about chest straps. This has not really been a con in my own experience. So long as you have a good quality strap and you wear if often, you tend to forget you’re even wearing it.

Maintenance. The downside to a strap is that you have to clean it after each run to keep it in good working order. This can be a bit of hassle but could be worth it for the extra accuracy it offers.

You May Forget It. Because a strap is an additional piece of equipment, there’s a chance you leave it behind when you pack your gear.

Pairing Issues. While uncommon, sometimes you can experience pairing issues when trying to connect your strap to your monitor. This is not something I have personally had much of an issue with but it does happen.

In Closing

While there is no right or wrong choice per se, it is worth considering the above points when making a decision regarding whether to use a chest strap or a wrist-based monitor.

If you’re doing a lot of high-intensity training or are looking for accuracy, a chest strap is definitely the way to go.

If most of your training is at a low intensity or convenience outweighs accuracy, a wrist-based monitor may be a good option.

I personally mix it up. I’ll often use a wrist-based monitor for my easy or less important runs. For more important runs and for hard sessions and races, I will always connect and use a chest strap.

AuthorBen PulhamBen Pulham is a former professional triathlete and the founder of Coached, a heart rate training programme that helps you optimise, track and enjoy your training.