HOW WE PUT THEM THROUGH THEIR PACES

I TESTED eight trackers by wearing them all on the same arm for a moderately active day, from 7am to 11pm. The strangest thing was that they collected such conflicting data, they could have been recording different days and a different person! All companies were approached for comment.

Fitbit Charge 2 (£139.99, fitbit.com)

STEPS: 10,661 CALORIES BURNT: 1,906 Average resting heart rate: 61 beats per minute. The average for a 30-year-old woman is 60-80bpm. The lower the number, the fitter you are.

VERDICT: comfortable to wear. The results fell squarely in the middle of all eight trackers — so it may be the most accurate, though the calorie count seemed a little high. Samsung Gear Sport (£199, samsung. com/uk) STEPS: 11,508 CALORIES BURNT: 489 Average resting heart rate: 73bpm VERDICT: Too chunky for my liking and the most expensive of the lot, this tracker gave a high step count, but a low calorie reading. This may be because, unlike the others, it doesn’t record calories burnt while resting; that is, through the biological reactions occurring inside my body. Nokia Steel HR (£169.95, johnlewis.com) STEPS: 6,337 CALORIES BURNT: 2,145 Average resting heart rate: 77bpm VERDICT: This one looks like an ordinary watch — the digital screen is just a small circle on the face. It didn’t beep once and was so silent I thought it had broken. This may explain the low step count, which simply can’t be right. Nor can the high calorie count; I think there must have been a glitch. Garmin Vivosport (£169.99, buy.garmin.com)

STEPS: 11,775 CALORIES BURNT: 1,965 Average resting heart rate: 66bpm

VERDICT: Slim, sleek and unobtrusive. Its results seemed fairly accurate, though it vibrated a lot (to congratulate me on my vigorous activity) while I was whisking eggs, which may explain the elevated step count. A brand spokesperson says: ‘There are inherent limitations with the technology that may cause some of the heart rate readings to be inaccurate under certain circumstances.’ TomTom Touch (£79.99, tomtom.com) STEPS: 13,924 CALORIES BURNT: 892 Average resting heart rate: Not tracked VERDICT: As it’s made by the people who design satnavs, I would have expected the step count to be more accurate — I definitely didn’t walk this far. The touch screen is hard to use and I was disappointed that for some reason it didn’t pick up my heart rate. Polar A370 (£159.50, polar.com)

STEPS: 9,848 CALORIES BURNT: 1,963 Average resting heart rate: 63bpm

VERDICT: halfway between a digital watch and a fitness band, this one looks sporty and is easy to use. The calories and heart-rate seem accurate, but I’m sure I reached the 10,000-step mark. A spokesperson says: ‘When using a Polar device, we will ask you for information on age, height, weight and sex, so we can produce the information most relevant to you.’ iFit Vue (£71.99, argos.co.uk)

STEPS: 10,507 CALORIES BURNT: 1,721 Average resting heart rate: (not tracked)

VERDICT: With its small screen and tiny text, this is best avoided if, like me, you don’t have great eyesight. Yet for the price, it’s surprisingly accurate. Stuart Palmer of IcoN health & Fitness (which makes the band) says: ‘It’s not uncommon that different brands will show different data readings.’ Amazfit Bip (£69.62, amazon.co.uk)

STEPS: 5,926 CALORIES BURNT: 82 Average resting heart rate: 101bpm

VERDICT: Everything about these readings seems wrong, from the low step count and minimal calories burnt to my extremely high resting heart rate. It buzzed annoyingly throughout the day. A spokesman says my data ‘seems normal’, adding: ‘The sensor measurements of any activity tracker can be affected by many different factors.’