Thanks Miranda! OK the dog story just made me LOL! About a year or so ago I did manually set my HR Max and VO2 on my F6 and had good reading after that. I think since the strap battery has been dying the readings were progressively getting crazier until it was showing me at over 200 BPM. I recently bought a new Polar F7 and oddly it doesn't seem to have the ability to manually set those things BUT it's also giving me very realistic calorie burns so go figure, maybe they improved something? All I want to know is my calories is that too much to ask :-O No seriously, I feel at least so far the new F7 is giving pretty good readings, they aren't way off from treadmills or even MyFitnessPal's website which before they were way off. The new F7 also has the ability to change the friggin' battery yourself thank goodness.