answer:It does sound like there’s something funky going on, Poser. 220 is higher than most people’s absolute maximum. I don’t know how old you are, or whether your heart is super-strength, but most basic heart rate calculators will tell you if you’re 20, your max hr is like 200, and gets lower as you get older. Mine definitely goes up and down but not usually by more the 10 bpm unless I’ve changed my pace. Does it slip around while you run? sometimes if mine starts to slip down, it’ll go down by 20 or so bpm, but then it usually goes down to zero pretty quickly. sorry i dont know anything about reebok hr monitors. i use polar’s entry model, and would recommend it. all i can tell you is that it’s not heart rate monitors in general. beyond that, i dont know if it’s that model or your particular device.