Whether you're going for a big run on your lunch break or you've decided to sign up for an ultra-marathon, triathlons require lots of intense training that will push your body to the limit. If you thought marathon training was hard, this is a whole new level of putting your body through agony.
Thankfully, you don't have to put in the laps and miles completely alone. There's plenty of wearable tech to give you a helping hand during those early morning or lunchtime sessions.
Fitness tips: How to use heart rate training zones
Below, we've sifted through the best and worst of the GPS watches to help turn you into a speedy swim-bike-runner, so read on for our top triathlon tech picks to help you be, ahem, tri-umphant.
Garmin Forerunner 935
The Garmin Forerunner 935 is a device built for triathletes and serious trainers – a successor to the Forerunner 735XT (discussed below) and a potential upgrade for those with a Forerunner 920XT strapped to their wrist.
Not only do you get a wealth of sports tracking modes, as well as a dedicated triathlon mode for race day, but there's also built-in heart rate monitoring and a plethora of metrics to optimise training and aid recovery. If you're looking for a bit of assistance, you can dive into the training plans offered through Garmin Connect (eight triathlon programmes are currently available, all at varying levels of difficulty), while there's also Connect IQ support, notification support and plenty of battery life to help you go the distance.
Garmin says that you should be able to receive around 24 hours in GPS mode or 60 hours in UltraTrac battery saver mode, and in our testing we've found it manages around 10 days of life even with daily exercise. In short, there should be more than enough here to help track you in training and on race day.
Wareable verdict: Garmin Forerunner 935 review
Suunto Spartan Trainer Wrist HR
Essentially a smaller, slimmer version Suunto Spartan Sport Wrist HR, the Finnish company's latest GPS watch is another which is a reliable option for those training for a triathlon.
This makes tracking multiple sports an even more in-depth experience, with 80 available for you to choose from in total. This list includes the likes of running, trail running, treadmill running, cycling and swimming (open and pool), but there's also a dedicated triathlon option for your perusal. As its name indicates, there's also a optical heart rate monitor on board, and it's one of the most reliable we've tested.
As for battery, the Trainer Wrist HR also excels. Suunto claims you should get up to 10 hours in GPS tracking, as well as up to 30 hours if you lock things into the power saving modes. In our testing, we've found that to be pretty spot on; even with rigorous GPS use, you will comfortably get a week's worth of training out of this device.
Like with Garmin Connect, you can also use Suunto's Movescount platform to help with your training. You can either create your own training programme from the web app or search for other users' plans that fit your level.
Wareable verdict: Suunto Spartan Trainer Wrist HR review
TomTom Spark 3 Cardio + Music
The first thing we should point out here is that TomTom is now officially leaving the wearables game. And while this is obviously a major caveat for those considering whether to plunge themselves into the company's ecosystem, we'd still recommend the Spark 3 purely as a device.
The multi-sport watch retains the built-in music player and still packs QuickGPSFix tech, meaning your location is picked up faster and maintained precisely; a must for keeping a track of your progress.
Real time information, whether you're running, cycling or swimming, is displayed on-screen, while the design also won't weigh your wrist down. It won't supply with you the same detailed metrics as a Garmin, but it's a decent choice for someone who's just venturing into the triathlon training world.
And there's a few options within the Spark 3 range to choose from, with the top of the line giving you access to heart rate monitoring, as well as music storage.
Wareable verdict: TomTom Spark 3 review
Garmin Forerunner 735XT
As you may already know, Garmin's XT range is built for those looking for a serious training companion – these are the multi-sport-specific devices. Since the release of the bulky 920XT way back when, the company has also worked to reduce the size and bring us the successor, the 735XT.
Despite being small enough to wear day-to-day, the watch crams in a powerful battery, optical heart rate monitoring, all-day activity tracking, smartphone notifications and plenty of training metrics.
In terms of battery life, the model tops out at about 24 hours of UltraTrac GPS or 14 hours of pure GPS tracking. And in our experience, we've found that mostly checks out - those who are taking part in a triathlon should have nothing to worry about here.
Like with the Forerunner 935 and other Garmin devices, the same triathlon training plans are also available through Garmin Connect with this watch, so make sure to scour the different options if you need a helping hand in the build-up to race day.
Wareable verdict: Garmin Forerunner 735XT
While the Polar V800 isn't exactly new on the block, it still manages to pack features which make it a worthy option for triathlon trainers.
The headline feature is its fantastic coaching system, which is ideal if you're just starting out with your triathlon prep. With the Polar Flow service also on board, you can create tailored profiles for each sport, zero in on the most minute of details and truly balance your training and recovery. Integrated GPS accurately tracks your runs, while pairing it with a heart rate monitor strap means it works when you hit the pool.
It's housing a 350mAh battery that Polar says will get you 13 hours of training with GPS on and 50 hours in GPS low power mode. We've spent a good few hours running with it four to five times a week with a long two–three hour training session at the end of the week, and the battery life lives up to the claim.
Wareable verdict: Polar V800 review
Garmin Vivoactive 3
Much like the TomTom Spark 3, the Vivoactive 3 could be a a good introduction to someone that's starting to think about venturing into the world of triathlons and wants to track more than one sport.
There's an optical heart rate monitor on board, plus GPS with dedicated apps included for cycling, swimming, running and a whole lot more. It also supports Garmin's Connect IQ apps so you can add additional data fields and features, as well as Garmin Connect for training plans and more.
This is more of a sports watch than smartwatch, still, but features like Garmin Pay and its neat design (something that can't be said for all of Garmin's triathlon-able watches) make this a worthy consideration for those wanting the best of both worlds.
With battery, Garmin quotes up to seven days of battery life on the Vivoactive 3 with normal use, and 13 hours of straight GPS time. Since you're likely to be draining the battery with more than just activity with this device, make sure you're conservative with what's running in the background if you want this to last the distance on race day.
Wareable verdict: Garmin Vivoactive 3 review
Shop for recommended running watches on Amazon
Wareable may get a commission