As impressed as we were with the TomTom Runner and Multi-Sport, it was obvious at the time that there was plenty of room for improvement.

A year later and TomTom is refreshing its watches with the new "Cardio" versions, which bring all the familiar features of the first two but with one big added extra - a built-in heart rate monitor.

Not just that, but (so far) a highly accurate one. The original Runner and Multi-Sport could be paired with a separate heart rate monitor but wrapping that strap around yourself and pairing it with the watch was a lot of extra hassle.

Having an optical monitor on the watch not only saves time, it's also a lot more comfortable. No more awkward pad licking (you know exactly what I'm talking about).

Cardio

Like the original sports watches, the TomTom Runner Cardio is focused on, well, running, while the Multi-Sport throws in added features for tracking cycling and swimming. As a cycling device it works well, and can even be synced with TomTom's wheel-mounted cadence tracker.

It's okay for swimming, but the HR monitor can't work underwater and nor can the GPS. It tracks you with an accelerometer, tracking lengths of the pool.

As you've probably guessed from the photos, TomTom hasn't gone for anything radically new in design. The new watches do come in a nice new red outfit though, and you can opt for either a red and black or a red and white version.

The main watch unit is now held in a lot more securely (a gripe I had with the first watches) so it'll no longer slip out unless you apply a fair bit of pressure.

Cardio

Witness the fitness

But enough on the cosmetics - how good is that heart rate monitor? First thing, in order to get the monitor working you need to make sure the watch is strapped snugly above the wrist bone.

This ensures it will get a clear reading of your pulse, which it does through two green LEDs on the back that calculate your heart rate by detecting changes in blood flow. It's pretty cool stuff.

You'll want to make sure the watch is tight enough to prevent it moving about on your workout. Luckily the watch fits comfortably around the arm so that shouldn't be much of an issue, but letting it slip down will mean a loss of accuracy.

Cardio

I found that it didn't take long for the watch to find and display my heart rate, and it was easy to monitor the all-important "zone" I was in when running or pumpin' iron - a "treadmill" setting lets you use the watch without GPS, in the gym or home.

On my test run I strapped last year's TomTom Runner onto my other wrist and strapped a heart rate monitor to my chest so I could compare the results. As it turned out, the readings were consistently close and often identical (the Cardio watch tended to be a couple of seconds behind in bpm adjustments, which I would have expected anyway).

Cardio

But that wasn't enough assurance for me, so I also tested the Multi-Sport Cardio's heart rate monitor against a hospital ECG machine. Once again, the results were impressively in sync.

The new monitor also means you can train in your optimal heart rate zone - easy, fat burn, endure, speed and sprint - and the watch will alert you if you need to speed up or slow down. Zones are calculated based on your age and are not user definable but if you're not an elite athlete, that's probably not an issue.

GPS

The other reason for the relatively high price of the Multi-Sport Cardio is the GPS tracking. You'd expect TomTom to know what it's doing here, but there are a few issues.

The main one is the time it takes for the GPS to lock. Anyone with a vague notion of what GPS is (needs to see the sky to get a look at the satellite signal, compared to phones which can use Wi-Fi and cell towers to help out) should accept they can't get a lock inside a house so it means a bit of loitering on the outside pavement while it makes the connection.

However, at times the Multi-Sport Cardio can take several minutes to get going. It's frustrating, because on other occasions, in the same place, it takes just seconds. You can turn on assisted GPS via TomTom's mobile app (it syncs with the wearable via Bluetooth) but I didn't find this alleviated the issues.

The other issue, which is not unique to this by any means, is that it struggles to track your elevation. So if you're taking on mighty hills, it thinks you've climbed a molehill, and conversely, it'll sometimes think a perfectly flat road is Mount Etna. There is a version of this with an altimeter but that pushes the price to £329.

Juice up

Battery life is okay. I got something like six to seven hours of use per charge. However, while that might not sound like a lot, this isn't a smartwatch that you'd wear outside of training - it's far too chunky for one thing. This is an exercise companion that you'll strap on when you stick your running shoes on and slip off at the end. Most users will sync this every time they train, and plugging in via USB also charges it up, of course.

Cardio

That's if you use USB - Bluetooth syncing between the watch and its mobile app is also possible and this means your heart rate data will also now be transferred over quickly with the rest of your workout stats.

Cardio

Perhaps the biggest sticking point I have with the Cardio right now is the price: £249 ($390, AU$469).

I'm not saying it's over-priced but realistically, if you're a casual fitness enthusiast, this probably isn't for you. If you just want something for swimming or the gym it's of limited appeal too.

However, more committed (or wealthy) runners, cyclists and triathletes will love the range of features here, from zone training to being able to "race" yourself onscreen to beat your personal best.

Verdict

The heart rate monitor is impressively accurate, the watch is comfortable enough and the GPS, despite some niggles, generally works well. This is pitched at serious (but not elite) runners and cyclists, and it hits the mark in many ways. Is it worth the relatively high price when your smartphone, a range of apps and strap-on HR monitors can replicate practically all of the functionality? That's up to you, sir/madam…