HRM

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Okay, I just (tried) to set up my information on my new HRM and think I have it correct. I hope. My question is this, I have searched through previous topics about this and am still confused as to what I should be putting into this thing.

Basically, it's a cheap Walmart Brand for $50.00 but it allows you to put your age, height, weight your low and your hi heart rate. So, with this, I put in my hi heart rate as my 65% of max which is (according to most sites is 220 minus your age=185) and then mulitply by 65% which equals 120 as my target heart rate. Is this supposed to be my hi heart rate, though? Some sites say it should be higher and I know the percentage for weight loss (which is what I am trying to accomplish) says 65%. Some sites say 226 for females - I am really confused by this...

Also, what would my low be? Does that matter? The range that is in one of my books says 55% (which would be low rate) is supposed to be 102 and high is 120 (65%).

Does this sound right. Some sites say my high at 65% is 143 target? I am wondering too if this thing just figures it out on it's own because I already put in my age/height/etc. ?