Heart rate tracking on headphones was probably a mistake

Athletes usually choose a chest strap, armband or fitness watch to assess their health and efforts. However, a relatively niche (and strange) option is to wear wireless headphones with heart rate monitoring. I only recently heard about this technology and immediately decided to test whether the headphones’ heart rate accuracy was good enough for serious athletes.

When I heard about the Sennheiser Momentum Sport, which sends HR data to the Polar Flow app, I wondered if Polar H10 users would want or trust an earphone solution or if this targets more fans. occasional.

Some athletes like standalone LTE smartwatches for training without a phone, but I don’t know of any. any of them athlete who would like to train without a watch, especially since you would lose things like GPS, running fitness data and a quick overview screen. So rather than replace a fitness watch, maybe these fitness headphones could provide more accurate data.

I decided to test several wireless heart rate headphones, but the more I looked, the more I found unique and discontinued products like Bose SoundSport Pulse and Jabra Elite Sport. I wondered why these brands hadn’t incorporated HR technology into other workout headphones: consumer apathy or unreliable results?

I tested the Sennheiser Momentum Sport and Anker Soundcore Liberty 4 headphones with my favorite Garmin fitness watch and a COROS heart rate monitor on several runs and walks, to judge whether or not I can rely on the headphones for heart rate data. precise training.

Headphone heart rate accuracy test

The Anker Soundcore Liberty 4 makes its workouts available only through the “Wellness” page of the companion app. You cannot export your workouts to other fitness apps like Strava or even see your workouts unless the headphones are connected. The barebones workout results page shows an average HR, a graph, and defined HR zones which I was unable to change.

In other words, Anker’s decision to force you to use its app makes the data virtually useless to athletes. Still, I had previously run three miles with the Liberty 4, Garmin Forerunner 965, and COROS HRM synced to another COROS watch, so I did my best to interpret the data.

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The COROS HRM determined an average of 147 bpm on my three-mile run. My Garmin Forerunner 965 measured 148 bpm; The chart above shows times when it comes down slower than the cuff when my pace slows or misses small changes in heart rate. This generally equates to few errors, which is what you would expect from a reliable optical HR monitor.

As for the headphones, Anker calculated an average of 149 bpm, which doesn’t seem too inaccurate at first glance. But looking closely at the heart rate graph, I reach 167 or 168 bpm for sustained stretching during my run; neither Garmin nor COROS measured me at a frequency higher than 159 bpm.

There’s also the simple fact that when I ran with the Soundcore app open, my heart rate seemed to fluctuate much more erratically than my watch or HR band. This may give an average close to the right result, but it didn’t leave me feeling confident. And in the end, the right earbud – which tracks heart rate – drained its battery much faster than the left.

I switched to the Sennheiser Momentum Sport because it exports to the Polar Flow app; This meant I could directly compare heart rate graphs and better test the earbuds’ heart rate accuracy. To start, I took an impromptu four-mile walk with my headphones and Garmin watch, followed by a five-mile run.

For walking, Sennheiser fell short of Garmin by 1 bpm; Given that Garmin often averages around 1 bpm above my arm and chest straps, that’s not a bad result. I noticed a few anomalies in the graph where Sennheiser was bumping my heart rate well above my actual effort level, but generally speaking it was tracking my Forerunner data pretty closely.

For comparison, my run results were disappointing:

Things started off wonderfully. Sennheiser once again had some high issues during the first few miles, but calmed down and followed Garmin closely throughout the first 3.5 miles. Then I decided to pick up my pace, so much so that the Momentum Sport couldn’t keep up: they averaged about 10 bpm less, sometimes only 5 bpm less, but frequently up to 15 bpm less.

Sennheiser finished with an average of 153 bpm, just two shy of Garmin’s estimate. That’s perfectly sufficient for an everyday athlete looking for calorie burn data, but it’s not accurate enough to make a serious athlete happy.

I decided to do another proper test. I used Sennheiser’s fit test to confirm I had the right size earbuds, put on my COROS band and Garmin watch, and did another run split into two activities: one at a slow pace, the other an intense track workout.

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Imagine my intense frustration to discover that Sennheiser and Polar failed to sync properly. For my short run workout and track workout, the Polar Flow app stopped receiving new information and locked my heart rate at a set point. I didn’t notice it because I kept my phone in my pocket during shopping.

You might assume that you need to keep the Polar Flow app open, but that wasn’t the case in my previous tests. Additionally, you can see the track workout above showing that it suddenly started receiving heart rate data near the end, with my phone still in my pocket. For this brief overview, it was about the same: the Sennheiser Momentum Sport was about 10-20 bpm below my actual heart rate.

A niche for a reason

I started this earphone heart rate accuracy test with complete optimism that the results would turn out. I had a vague feeling that my ears would provide a reliable window into my heart, the same way you can check someone’s pulse with their wrist or neck. Instead, I came away disappointed.

I’ve never gotten results that suggest I should trust workout headphones as much as a fitness watch; the wobbly data reminded me more of smart rings, which are accurate under ideal conditions but can struggle with precise training data and higher heart rates. Additionally, I wasn’t able to wear open-back headphones, which are much safer and more comfortable while running.

The Sennheiser Momentum Sport also tracks body temperature during workouts, but that too was a disappointment.

I used a professional-level temperature sensor during a track workout in March and found that my body reached a mild fever (101ºF / 38.3ºC) at maximum effort. Sennheiser said my body heat never exceeded 97.8°F. I suspect the outside airflow kept my ear canals cooler than the rest of my body and these headphones would work better for a gym workout.

A weightlifter who hates wearing watches at the gym could get away with wearing heart rate headphones instead and get decent results for an overall number of calories burned. Otherwise, I just don’t see the need for this technology, at least until a company can get more consistent data.