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Mio Fuse Heart Rate Based Activity Tracker Review

Mio Fuse Activity Tracker Review Sundried

Who Are Mio?

Mio Global is a company that specialises in heart rate based activity trackers. Founded in 1999 by Liz Dickinson, Mio Global led the market in wrist-based heart rate monitoring technology before it became a widespread trend in the fitness industry. Mio now boast 5 different products in their range: the Fuse, the Alpha 2, the Slice, the Link, and the Velo. Their latest product, the Mio Slice, introduces Personal Activity Intelligence which you can read more about here

The Fuse is Mio’s answer to an all-day activity tracker. It records steps, calories, distance, pace, heart rate, and now it also tracks sleep.


The Fuse watch comes in 3 colours: cobalt, crimson, and aqua. This watch doesn’t blend in as a regular watch like the Garmin watches, instead, it sits proudly on your wrist and is quite clearly a fitness band. The flat band design is easy to wear under long sleeves and hugs even a small wrist comfortably. It features small circular holes to allow the skin to breathe which is really important in an activity tracker as it can be the case that after a sweaty workout, you are left with sweat rash under your activity band or watch. 

Set Up

When you purchase the Mio Fuse, inside the box is your watch and its charger, which attaches easily with a little magnetic USB clip. Once charged, you are ready to start tracking with your phone. The battery charge lasts about 7 days including an hour's daily workout tracking. The Fuse connects your data using the Mio GO app. Once downloaded, you set up a profile, entering basic details such as age, gender, weight etc. to ensure the monitor is producing accurate feedback. After completing this easy setup, you need to connect your strap as a known device via Bluetooth. I found that if your phone's Bluetooth is already connected to a lot of other devices, it will struggle to connect, so make sure you switch off any unnecessary Bluetooth connections to enable the band to be easily recognised.

Testing the Heart Rate

When you start training, the Mio Fuse asks you to enter its separate workout mode to enhance the heart rate accuracy. While this may seem a simple request, this has taken me a bit of getting used to. Pressing and holding the Fuse’s centre button will cause the watch to flash ‘FIND’ while it searches for your heart rate. Once it's found your reading, another touch of the centre button will set ‘GO’ and you’re on your way. The difficulty I had was that the buttons are very sensitive and so I had to be careful not to start workouts by mistake. That being said, the buttons are designed so that they only activate when the watch is in a horizontal position to avoid accidental tracking, it just so happens when you're sat at a computer your wrist is also in a horizontal position; but my random one-minute workouts are getting less and less frequent, so I think that comes with practice.

Mio Fuse Back Workout

Above is the first workout I completed wearing the Mio Fuse, which was a weights session at the gym. My rep ranges are reasonably high - between 8-12 repetitions - meaning my heart rate should be reasonably steady and within Zone 3 for moderate activity. As you can see, my average heart rate was 123 bpm and I’d usually get a reading of about 130bmp for the same routine from my heart rate chest strap so it is pretty accurate.

I decided to try partnering my Fuse with a HIIT (High Intensity Interval Training) session to see how it coped with the heart rate tracking of a more demanding workout.

Metafit Workout Data

Above is a Metafit workout. This class is designed to push your body to the max, using lots of plyometrics and compound bodyweight exercises with swift changes and very little rest between intervals, lasting just 25 minutes. Usually, my chest strap reads my heart rate at about 175 bpm. As you can see above, my average heart rate is 143 bpm with a maximum of 179 bpm. The average heart-rate seems a little low, but when you look in detail at the time frame, it appears to be my warm-up which is dragging the average down.

Metafit Mio Fuse Workout Data

As you can see, my heart rate sits firmly in Zone 4. Exactly where it should be in the ‘Hard Activity’ category. The Mio Fuse has done well here and met my expectations for performance feedback on this workout. As you can also see from these snapshots, the app allows you to name your exercise. Mio GO suggests a list of activities you can scroll down and if your exercise isn’t listed, you can enter your own name under ‘other’. This is particularly useful for those who do a lot of training to quickly find workouts.

Overall, I have found with most wrist-based heart rate readings that the readings drop slightly when compared to a chest strap, simply due to the nature of the monitor standing more of a chance at being effective when it's strapped right on top of the heart rather than down on a wrist. However with the Mio Fuse, all my heart rate zones are very accurate, the watch monitors the highs and lows of my training effectively and it is the most accurate heart rate readings I have seen from a wrist-based monitor thus far.

Mio Fuse Fitness Activity Tracker

Good Vibrations

The Fuse also has another secret weapon to keep you pushing through your workout: it vibrates. The Fuse keeps you constantly aware of how hard you're working by vibrating as you travel through different training zones, which is a unique feature that no other activity trackers offer. These vibrations are accompanied by a colour-coded flashing light and the colours of the lights match the colours of each of your training zones on the app, so you are constantly being reminded of how you’re doing. The fact that Mio specialises in the heart rate monitoring aspect of activity tracking shines through with this feature. 

Is It Waterproof?

The Mio Fuse is water resistant to 30m. Whilst I am yet to take the watch for a swim, it was unphased by my shower and sweaty workouts. 

New Feature: Sleep Monitoring

Most activity trackers on the market now track your sleep, so Mio has stayed up-to-date with the rest of the market. The app lets you see the amount of time you spent in bed, the efficiency of your sleep, the percentage of which was light or deep sleep, and your resting heart rate. The watch doesn’t automatically track your sleep, so you do have to put it into sleep mode, but this isn't too much hassle.

Mio Fuse Sleep Monitoring

Mio Fuse Sleep Monitoring

As you can see, I had an almost perfect night’s rest. The feedback on your resting heart rate can then be used to monitor your level of fitness; there are plenty of online charts to calculate how you're doing for your age and gender. Typically, the lower the resting heart rate, the better, as it suggests the heart is getting bigger and stronger due to exercise and, therefore, it takes fewer beats to pump your blood around the body.

Mio Fuse Sleep Monitoring

Mio Fuse Sleep Monitoring

It is recommended that adults achieve 7-9 hours sleep for optimal recovery and brain functioning. Although we can survive on less, we give our muscles time to recover, repair and grow during our sleep, so being able to monitor how efficiently you’ve slept is a great training tool for any athlete.

The App

The Mio GO app itself is simple and easy to navigate around. The main page greets you with a dashboard highlighting all your daily activities from steps to workouts and sleep. With a simple touch of any of these activities, you can unlock the full details of your performance. To sync new activities simply drag the screen down and the feed will update. The app was straightforward, uncomplicated and precise, with detailed and poignant feedback for both training and recovery.


As an activity tracker, the Mio Fuse has all the basics we’d expect and would be a good watch with these alone, but the addition of accurate heart rate tracking is a game changer. In addition, Mio is constantly updating the app and the watch's features, so it’s sure to continue improving just as your training does.

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