Before heart rate monitors became standard, keeping track of your steps was the reason you’d wear a device all day, rather than just strapping one on for a workout. An accelerometer in the device senses movement and software translates certain movements into steps. It’s an imperfect method to say the least, as anyone whose fitness tracker has buzzed to celebrate a step goal while you’re sitting on the bus will know. That’s not to say counting steps is pointless. Movement – steps or otherwise – is good and more movement is better, and it’s the little encouragements and challenges to induce you to move more and move regularly that can be beneficial to your health.
Heart rate monitoring
It was once a feature restricted to high-end trackers, but most wearables now offer optical heart rate tracking. Some will only record your heart rate constantly during activities and take periodic measurements throughout the day to preserve battery life, but we think you should expect 24/7 monitoring on anything that costs over £100.
With heart rate tracking comes a wealth of other information, including an estimate of your VO2 max and resting heart rate, both of which are good measures of your overall cardiovascular fitness. High-end sports trackers also use heart rate tracking to provide info on the effect of your training session and how long you should spend recovering afterwards.
Optical tracking is usually pretty accurate during day-to-day life, but is more hit and miss during exercise, especially intense workouts. That can be especially problematic when certain tracker brands offer training sessions to follow that rely on you working on certain heart rate zones. Getting a tight fit with your tracker can help, but don’t expect miracles – if you want more accurate heart rate tracking it’s wise to link your device to a chest strap via Bluetooth or ANT+ if possible.
Sleep is just as important as exercise and diet when it comes to your overall health. Many trackers now record how long you spend asleep and break that down into periods of deep, light and REM sleep, allowing you to gauge your sleep quality.
This information can be useful if you pay attention to what might be responsible for a bad night’s sleep (eg booze) or a good one (eg no booze), but there is a limit to how useful this information can be. It’s not like steps where you can actively try harder to get more. However, the better devices can help nudge you towards better habits, allowing you to set reminders for a consistent sleep schedule.
The addition of a GPS chip in the device means your tracker will accurately record speed, distance and elevation during outdoor activities like running and cycling. Cheaper trackers will use an accelerometer to estimate distance covered, with mixed results – see the perennial “fitness tracker doesn’t accurately track a marathon” story that comes out before the London Marathon every year. That exposé uses an accelerometer, while virtually every runner in the London Marathon will be using a GPS tracker. Some trackers offer an in-between option that connects to your smartphone and uses its GPS signal to offer more accurate tracking, which obviously means you need to have your phone on your person throughout your session.
A device with built-in GPS capability will be far more accurate in measuring distance than an accelerometer’s estimate, but it’s still not perfect. A manufacturer may decide to take readings less frequently to save the battery, which is why when you zoom into a map of your tracked route it can look as if you’ve passed through a building. Since a GPS signal is reliant on line of sight between your device and a satellite, it also means clouds and running in built-up urban areas can skew readings. If you’re committed to exceptionally accurate tracking, look out for trackers that offer compatibility with other satellite tracking systems – that’s GLONASS, the Russian equivalent of GPS, or Galileo, the EU’s satellite system.
Having an intervals mode on your fitness tracker is useful for guiding you through all types of workouts, if only because it will stop you extending your rest sections way beyond what they should be. On running and triathlon watches you’ll also often have the ability to set up more complex workouts, with work periods based on targets like distance, heart rate or pace, rather than just time. You’ll find a simple intervals mode on most mid-range fitness trackers, but for more complex customisable workouts you’re generally looking at spending over £250 on a sports watch.
If you’re keen on exercising outdoors then navigation is a great feature to look out for. It will not only stop you getting lost mid-run, hike or ride, but it’ll also help you to explore new places and avoid repeating the same routes near your house until you’re thoroughly bored with them. You can find basic breadcrumb navigation – where you get a line showing a preloaded course and pointer to show your position – on watches that cost from £200, while watches with full maps and on-the-go route mapping cost over £500.
Almost all trackers offer some degree of water resistance, which means you can run in the rain or take a shower with them, but if you’re a keen swimmer you need not only a fully waterproof design, but also a dedicated swim tracking mode – some of the cheaper swimproof Fitbits merely offer automatic recording of time in the water.
We recommend settling for nothing less than the ability to track your laps in the pool automatically. More advanced watches will also offer stroke recognition and record stats like stroke rate and SWOLF, the latter a measure of your efficiency in the water.
Triathletes will also want an open-water swimming mode that uses a device’s GPS. This is something you’ll rarely find outside dedicated multisport watches that cost at least £250.
Having space for music on your tracker provides one more reason to leave your phone behind when exercising. Most smartwatches offer this feature now, and while all can stream stored tracks, some – like the Apple Watch – can handle their own data connection through either WiFi or, if you’re happy to pay a monthly data fee to a mobile network, a 4G sim.
We think the ability to sync with streaming services wirelessly is a key feature to look out for here. Being able to transfer over your favourite exercise playlist via wires is useful, but you can end up listening to the same music over and over again because let’s face it, plugging things in is a pain. If you can link to Spotify (which Garmin, Samsung and Android watches do), Apple Music (Apple Watch) or Deezer (Fitbit) and update that playlist wirelessly it’s much easier to put new tracks on your watch. However, you’ll need a premium account for those streaming services to use this feature, no matter which watch you use.
NFC payments (contactless)
With the ability to make payments from your watch, you can also leave your wallet behind when exercising outdoors. Smartwatches from tech companies like Apple and Samsung have got this down, having partnered with all the big banks when bringing payments to smartphones, but Santander is the only high street bank working with Garmin and Fitbit. More challenger banks are signed up, though, and there are third-party services available that are the digital equivalent of pre-paid debit cards.