There's a reason you don't see big, fat athletes contesting the 100m Olympic sprint and it's nothing to do with fitness. How is any moderately obese runner supposed to train properly when rivers of sweat keep short-circuiting their GPS sports tracker?

Now the floodgates of perspiration can burst asunder, thanks to the fully waterproof 310XT GPS watch from Garmin.

If it can cope with being immersed to a depth of 50 metres, it can certainly cope with a 'glowing' sprinter or 'rosy' cyclist.

Heavy going

The 310XT itself is on the heavy side, weighing in at....