I wrote a review of my Basis monitor after having used it for 6 weeks. After having used it for more than three months, I still like it but now I’ve discovered a huge glitch in it: the heart rate monitoring. In short: Basis heart rate monitoring is very inaccurate, essentially showing and recording wrong data or no data at all as soon as you move around.
I discovered it quite early on when looking at the “data details” view. Here’s a screenshot:
Each dot means that Basis has a data sample. As you can see, the data samples are fewer – in some cases non-existant – at certain points. These points have one thing in common: I’m not sitting still or lying down. In the morning I take a 40 minute walk to work. The middle of the day was lunch. I left work at 6 to take a Bodycombat class, then I walked home. This means that Basis only has fairly accurate data for when my pulse is low and I’m being still.
I decided to put the Basis to the test. I have a Polar FT80, which uses a chest strap to monitor your heart rate (Basis actually monitors your pulse, which is a result of your heart rate, while Polar monitors the electric impulses created by the heart). I used it to see how the Basis monitor compared in three scenarios:
1) Aerobic exercise (in my case, a Bodycombat class)
2) Weight lifting (in my case, a Bodypump class)
3) Moving around (in my case walking to the gym)
Here’s a breakdown of the data:
According to my Polar monitor, my heart rate averaged 157 and maxed out at 179 during that hour. The Basis monitor failed to log enough data to create a graph, and it recorded a high of 148 (lower than my average heart rate for that hour) and an average of 116. At least it got the calories somewhat right: 802 to my FT80′s 1058.
Again, the pictures look different. I do get a pretty high heart rate during a Bodypump class, due to loading up the bar; the Polar monitor shows an average heart rate of 137 and a high of 169. The Basis: high of 138 and average of 107. If we look at the calories, my Polar FT80 reports 706 calories, the Basis monitor 251 (and since the Basis cannot zoom in on 60 minutes it’s actually showing the count for 75, 15 minutes longer than the Polar)
This walk was 3,2 kilometers (2 miles) and took 45 minutes – a pace of 4 miles per hour. It’s a brisk walk, but nothing extraordinary. And yet the Basis fails: it shows a high of 141 (the Polar gives 122) and an average of 85 (the Polar says 100). The calorie count for the Basis was about 200, while the Polar said 299.
Once I realized how bad the Basis was at recording heart rate whenever I’m not sitting or lying down, I decided to do another test: check how accurately it displays the current heart rate. I wore my Polar FT80 for a whole day, and checked my heart rate on both monitors at random times, and I wrote down what I was doing at that time. Here’s the graph:
(Note: when standing and walking, I waited a couple minutes before checking the monitors, as to give the Basis monitor a chance to catch up and eliminate any lag.)
It turns out that the Basis displays an inaccurate heart rate whenever I’m doing anything else than sitting down.
Basis did address the heart rate monitoring in a blog post in November 2012 (before the first units had shipped). However, I don’t think that that blog post is honest about how bad the Basis is at recording your heart rate. It basically displays one thing right: your heart rate when you sleep, and sit.
The bigger problem is that Basis’ poor heart rate monitoring also affects the calorie count. If you look at the calories burned during my walk, Basis says 200 calories when the actual number was 50% higher (the Polar FT80 is accurate, because it uses VO2max in addition to sex, age, weight and height). During the aerobic exercise the Basis monitor showed 800 calories, when the actual number was more than 30% higher. The weight lifting was the most incorrect calorie measure; Basis says 251 when the actual result was 180% higher. The reason the Basis did better for aerobic exercise is that you move your arms a lot in Bodycombat, while you move them less in Bodypump – so the higher calorie consumption comes from the accelerometers, not from the heart rate monitor.
Even once Basis opens their API, you can’t do much with the heart rate data except for the resting heart rate. Considering that they still cannot take any new orders, and devices like Amiigo soon coming out I’m changing my recommendation: don’t wait for the Basis. A second generation has potential, but the first is not worth the money.
I’ve been comparing the Fitbit One, Nike Fuelband, Jawbone Up, Basis and Bodymedia when it comes to calorie consumption and sleep, and will return with a summary of which of these devices are accurate and which are not.