Under Armour has recently released a new gadget that they say will revolutionise how athletes perform during practice or exercise. They call it Armour39. It measures a few metrics but the one that Under Armour is marketing most is their own version of Nike‘s Fuel. They call it Willpower – it’s how much effort you gave during your exercise.
I do not know the formula or calculation behind them coming up with your Willpower but this gadget makes more sense than Nike Fuelbands which doesn’t really measure things correctly (e.g., the number of calories burned by a bicep curl and lifting a mug of beer are equal).