Review: Mio Alpha Strapless HR Watch and ANT+ MioLink

Most of us that have a Garmin or similar, will likely link it to a heart rate strap. These straps are a simple fabric band that you wear around your chest, which transmits your heart rate to your device (normally via ANT+ or Bluetooth).

Heart rate straps have a number of disadvantages though: they can feel restrictive, they can slip down, they need washing and they don't last forever - there was a demand for an alternative, and it's arrived in the form of optical heart rate monitoring found in the Mio range.

The Mio Alpha and the MioLink measure your heart rate at the wrist, using an optical sensor to monitor your pulse. The sensor is a tiny square on the back of the watch, and either side of it is a small green light that is shone onto your wrist to help the sensor's recording capabilities. The technology does away with the need for a chest strap completely, and provides a neat solution for those that want to monitor their heart rate with ease, and for prolonged periods of time.

Mio produce two products that I've been trialling: the Mio Alpha watch and the MioLink band.

The Alpha looks and feels like a normal sports watch; it's a size that you could wear it as an everyday time piece (yep, it does tell the time too) and it is robust and waterproof enough for even UK winter conditions.

The Alpha monitors your heart rate with its optical sensor, and then transmits it onto the digital screen on the device. It also has the capability to wirelessly transmit the readings to a Bluetooth Smart device such as an iPhone or Android unit, and therefore give a heart rate reading on apps such as Strava, Wahoo Fitness and other open-source options.

The Alpha features an "activity mode" which engages the sensor (you don't have to have it on all the time) and also provides a timer on the clock interface. At the end of each activity, you can halt the timer and then recall data from the last workout such as average heart rate and workout duration. It's a useful means to see how hard you've worked.

Another neat feature on the Mio Alpha is the customisable heart rate zone. Once you're in "activity mode" you can set a target activity zone and set a warning (in the form of a beep and a flashing LED) for when your heart rate varies above or below this bracket. When you recall the data at the end of a workout, you can also find out how long you have been 'in the zone' for during your activity.

This is a smart looking and well made watch, that works very well as a timer and heart rate monitor as well.

The Mio Alpha watch is available at Wiggle (Link)

The MioLink is a stripped back version of the Alpha. It's a smaller unit (with a lower price tag) that uses the same optical reading technology, but rather than displaying it on the unit, it transmits it to any ANT+ or Bluetooth device.

Like the Mio Alpha, the MioLink also has a heart rate zone function. Rather than just one bracket though, the Link can have up to five zones that you can customise on the Bluetooth linked app. You're alerted to the zone you are in through a discrete but surprisingly visible LED on the Link, which flashes different colours dependent on the zone.

Both the Alpha and the Link are comfortable watches/bands to wear, and the soft silicone strap feels sturdy and durable. Battery life is good, at around 20 hours for the Alpha when HR monitoring is in use, and about 8 hours for the Link. The units are recharged through a magnetic USB clip that fixes magnetically to the back of the unit.

The biggest question of all though, is how accurate are they?

The answer, is pretty damn accurate. Tests have been done on both of the units by independent labs, and they've found that this technology may actually be more accurate than chest straps; reading within +/- 0.3BPM of true heart rate.

I found that when seated or running the units were highly responsive, and very accurate: giving similar readings to a chest strap working independently in parallel. There does seem to be a bit of a lag in pick-up on the Mio units when using them in dark conditions, or if you cover the unit under a long sleeve top, but this is only minor. The units also seemed to struggle a bit in particularly wet conditions (although I expect this might be because I have quite hairy arms!). Overall though, both units proved to be a very accurate way of monitoring your heart rate, and for their primary intended use - running - they work faultlessly.

If you're a runner or do it as cross training, these are a very neat and convenient HR monitoring option.

Another benefit of the Mio technology over traditional HR straps, is that it also allows continuous heart rate monitoring: I'll write more on this in a separate blog, as there's too much to explain here. But essentially, by monitoring your heart rate over the course of a day, you can gauge how well rested your body is, and how productive or potentially damaging it could be to train - interesting stuff.

Both the Alpha and the MioLink are very interesting devices then, and they both work very well at their primary function, as well as having neat additions like the heart rate zone feature. If you're fed up with putting on a slightly damp chest strap or looking a bit odd if you wear it under a lightly coloured t-shirt (they tend to look a bit like a bra strap), then the Mio Alpha and MioLink are well worth looking into.

The Mio Link is available from Wiggle (Link)


  1. Good review, thanks. Did you test accuracy with the watch worn inboard of the wrist? That is, with the sensors contacting with the inside of the wrist?

  2. Hi Richard, yes - when cycling I wore the watch inboard on the wrist. It seemed to be accurate the majority of the time, accuracy only slips slightly when it was worn under a close fitting long sleeve jersey, or in very damp conditions.


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