Microsoft Band 2 provides very different heart rate data than the original

As someone with a fairly standard workout routine, I became accustomed to seeing certain data from my Microsoft Band during and after a workout. After using the second-generation Microsoft Band, I"m shocked at how different its heart rate and caloric readings are from its predecessor.

Since my Microsoft Band 2 arrived a week and a half ago, I"ve used it for 14 workouts. When compared to my same workouts with the original Microsoft Band, each workout with the new Band has resulted in an average heart rate at least 10 beats per minute lower, and often up to 25 beats lower. In turn, the average estimate for calories burned between workouts by the two devices can drastically vary.

Microsoft says the Band 2 is more accurate at reading heart rates...

Microsoft has said the Band 2 is about 20 percent more accurate at reading heart rate than the original Band, which would account for the difference in heart rate and caloric results. To help determine where differences originated, I used a Polar H7 chest-worn monitor (which provides far more precise heart rate readings than a wrist-worn fitness tracker) to compare Microsoft"s original and new workout devices. The results showed that there were scenarios when the Band 2 was much more accurate than its predecessor, but also times when it was notably worse.

In the table below, you can see the results of three sets of workouts using the original Band, its successor and the Polar H7 chest strap. For each Microsoft device, I faced the optical heart rate sensor on the inside of my wrist to provide the most comparable results.

Based on the results of each Microsoft device, it seems the original Band does a better job at tracking high-intensity workouts – demanding workouts with little to no rest – while the Band 2 does far better at workouts that don"t quite push the wearer too much from a cardiovascular standpoint.

When it comes to weight lifting, the Polar H7 and manual pulse readings (those taken directly with my hand) indicated the Band 2 was mostly right on the money, whereas the original would occasionally overestimate my heart rate dramatically for an extended period of time. Conversely, the Band 2 had a tough time keeping up with aerobic or anaerobic workouts, consistently underestimating how fast my heart was pumping.

Even common fitness knowledge indicates there are some kinks with the Band 2"s heart rate sensor when it comes to quick, intensive exercises. In an interval workout of six 200-meter sprints each in 26 seconds with 1 minute and 40 seconds of rest, the sensor gave seemingly impossible heart rate readings at times. It"s incredibly unlikely that my heart rate was 115 bpm during my last 200-meter sprint (including similar readings throughout the nearly two minutes before and after it).

Neither Band is a constant heart rate monitor, meaning they won"t measure your heart rate every second, but the Band 2 should have given a much higher reading at some point during that roughly 4-minute timeframe between the second-to-last interval and two minutes after completing the last interval.

...but the accuracy depends on the workout type

People who focus on fast running or high-intensity biking probably won"t get the most accurate results from the Band 2. For those who engage in workouts that aren"t quite as intensive from a cardiovascular perspective (such as weight training or yoga), however, the Band 2 gives much more accurate readings than the first Band. The difference in heart rate between the two devices is roughly in line with Microsoft"s claimed 20 percent difference, though I"m not sure I"d classify it as either an improvement or downgrade.

The good news is that Microsoft can probably calibrate the Band 2"s heart rate sensor to give better readings for aerobic and anaerobic workouts. The accuracy differences between the two generations certainly aren"t a dealbreaker for either device, but it"s something to keep in mind when monitoring your estimated workout results.