Can you trust your fitness tracker?

We tested four top trackers. The results were, shall we say, 'variable'

Fitness trackers remain a popular area of wearable technology, but as we've mentioned before, they aren't going to just magically make you fit by themselves, and they can't always be relied upon for accuracy.

So when we tested four of the biggest-name trackers with heart-rate monitoring built in - Microsoft's Band 2 and Apple Watch at the top end, plus popular lifestyle trackers from Fitbit and Garmin - we weren't neccessarily expecting 100% accuracy… But we were still surprised by the results.

• Our favourite fitness bands are here.

• Our favourite running watches - a different but related category - are here

We took Man V Miles ultra-marathon-running man Kieran Alger along to Guru Performance, a top London sports science clinic, where they have professional equipment for monitoring heart rates and precisely calculating distances run and calories burned. We put the fitness bands (and a slightly 'post-Christmas' Kieran) through their paces, crunched the numbers, and here is what we found…

TLDW? In short, the Microsoft Band 2 performed much as we expected, Apple Watch exceeded expectations and the other two… Not so much.

We won't make any wild claims off the back of this; we've long said that the Fitbit Charge HR, for instance, is still a useful 'lifestyle fitness' device despite its quirks and lack of accuracy… And we still aren't crazy about wearing Microsoft's ugly, overly rigid device (although admittedly, Band 2 is a hell of a lot better than the handcuff-like original Band), in spite of its excellent results and technical innovation.

We also accept that longer, repeated tests would be necessary to draw properly scientific conclusions. However, the results are still, we think you'll agree, pretty eye-opening.

• Wanna get your fitness tested at the Guru Performance Human Performance Lab? Visit the website to learn more, or check out @GuruLDN on Twitter and Instagram…

• Check out Man V Miles here…