Sony’s Smart B-Trainer™ is packed with six types of sensors – heart rate, acceleration, GPS, compass, gyroscope and barometer, and records 11 types of running metrics – heart rate, burned calories, distance, time, speed, pace, cadence, steps, stride, running route and elevation. Here, I shall focus on three main features which I feel give it a big edge over the competition: standalone GPS tracking capability; built-in heartrate (HR) monitoring; intelligent music playback and real-time voice coaching.

GPS capability

I’ll start with the GPS tracking capability. As far as I know, it’s the only running headphone on the market which does not require concomitant use of a smartphone to provide GPS tracking capability. I know many runners, myself included, who hate to run with a cumbersome phone. While modern GPS watches have shrunk in size quite a bit in recent years, they still tend to weigh more than the average conventional watch, not to mention the fact that you have to glance at your (swinging) wrist to catch a glimpse of the data. I’ve been pleasantly surprised by the quality of the GPS tracker in Sony’s Smart B-Trainer™. I don’t think I’ve ever had to wait for more than ~30s for it to capture a satellite signal, on par with the best of the GPS watches on the market. In terms of accuracy of data, the distance lap splits generated by Sony’s Smart B-Trainer™ are very close to my Garmin GPs watch (usually less than 5s difference), and the total distance covered is also within the recognized margin of error for GPS watches.  
Above is the data from one of my recent runs where I used Sony’s Smart B-Trainer™ and a Garmin Vivoactive GPS watch concurrently. Data on the left is from the Smart B-Trainer™ and data from the right is from the Garmin. 

Heartrate Monitoring capability

Sony’s Smart B-Trainer™ monitors your HR by means of an infrared sensor pod incorporated into the right ear-piece. A HR sensor of this nature is not unlike a finger pulse oximeter used in a medical setting. It relies on an infrared sensor to detect minute changes in the red spectrum of light radiation from the skin surface to calculate HR. (In theory it might even be capable of calculating your real-time oxygen saturation!) This part gets a bit technical, but basically blood gets pumped around the body in pulses from the heart and so there will be periods of “low-tide” and periods of “high-tide”. “High-tide” corresponds to a darker redness in the skin that corresponds to a specific range of light radiation and vice versa for “low-tide”. The sensor measures the frequency of fluctuations between low and high tide to calculate HR. Sounds easy enough right? Well it actually takes a lot of accuracy to be able to detect fluctuations at up to 200 beats a minute, or over 3 fluctuations per second!

The sensor is protected by a silicone cap. This is the part that perhaps takes a little trial and error to set up correctly. In my experience, two things contribute to erratic or abnormally high HR readings: a) water/sweat getting into the space between the silicone cap and the infrared sensor, and b) loss of contact between the sensor and your ear. It took me a while to figure it out, but the silicone cap serves not only to keep water away from the sensor surface, but also provides some degree of grip to maintain a more stable contact with the ear. I found that loosening the silicone cap to let water evaporate from under the cap between runs helped a lot. In addition, the cap also takes up the potential space between the sensor and the ear so there is no loss of contact, and that appears to be the main reason for providing 3 different sizes of silicone caps. The sizes are demarcated by little dot indentations in the caps; one dot is smallest (or thinnest) and three dots is largest (or thickest). I actually found this method quite ingenious. I’ve tried using the Smart B-Trainer™ using all three size options and the outcome is unequivocal. With the smallest cap, I lost HR sensor contact for almost the whole run; with the medium cap, I got reliable HR for ~50% of the run; and with the large cap, I managed to get accurate and reliable data for essentially the whole run. Unfortunately, the fit recommendations are highly individual, and one runner I spoke to found that the smallest cap works best for him. I recommend trying out the different sizes for short runs to see which gives you the best HR data. 

On the left is a sample run I did recently, and you can see the heartrate was fairly stable in the 160bpm range which is consistent with what I expected for the level of exertion. 


This feature essentially banks on the principle of using the tempo of the music to influence the way you run, e.g. using a faster music beat to increase your pace and/or cadence subconsciously. I have tried out this feature on a few occasions, and I did find that especially for my easy runs where I want to make sure I do not overexert, a slower tempo of music does indeed help to control my HR within a narrower target range. There are more complex variations of these but they are restricted to the premium training plans (still free-of-charge within the “Smart-B Trainer™ for Running” app) developed by ASICS. On a more practical note, I really like that there is voice-over reporting of time, distance, calories, pace and HR at every kilometre split during the run. (You can actually get an impromptu report of the numbers by pressing the power button on the right side ear-piece, but I find that getting data reports every kilometre is sufficient.) This really saves the hassle of looking at your watch whenever it beeps at the kilometre split, and you really don’t notice the convenience it affords until you have tried using the Smart B-Trainer™. As far as music selection goes, you are free to upload your own choice of music to the Smart B-Trainer™ but I have found the stock selection of beats more than sufficient for its purposes.   

Here you can see that for every 10bpm HR range, there is a different selection of tunes to match your pace.

Sony’s Smart B-Trainer™ is currently retailing at S$399, in five colours (yellow, white, blue, pink and black) and is sold at all Sony Store, Sony Centre, specialist dealers or retailers. Head on over to any of these stores to give them a try.


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