Hello! Just a simple question. Yesterday, I put on my heart rate monitor. I did an oldie, but goodie, powermax....at full blast with 8 inch step....then I did imax 2. My goal is to burn 700 calories per day. After this....that thing said I burned like 623.....for TWO WORKOUTS! WHAT! Then this morning.....I did first section of Body max 2....then Circuit Max.....and half way through Circuit Max it said I burned about 340....I was so frustrated that I took it off and threw it across the room! How can I work out so hard and not burn more calories than a simple walk!!!! Do you think it needs batteries or something....or do I!!!! Thanks a bunch for your help!