One of the advanced features with the upgraded membership in the Biggest Loser SlimCoach system is viewing heart rate detail for every day you use the device. Just how does this heart rate detail work?

First, it's important to note that you need a heart rate belt - sold separately - to get this detail. The SlimCoach unit itself is just a pedometer and a receiver for the heart rate belt. So make sure you get a heart rate belt to sense this data.

Here is what a typical screen looks like for the results of a single day:



Now, to understand this data, you need to understand a bit about how heart rates work. Your heart rate is how many times your heart beats in a minute. Your top level, using a simple formula, is 226 (for women) or 220 (for men) minus their age. I am 43, so my top level is 226 - 43 = 183. All ranges are a percentage of that value. So my fat burning range is 60-70% of that 183, or 110 to 128. My aerobic range is 70-80%, or 128 to 146. These ranges are fitness industry standards and are used by pretty much everyone. The SlimCoach MyTrak system provides a helpful information button on their page that explains the ranges to you.



But here's the problem. Their chart shows my fat burn range goes from 127 to 140 - which is nowhere near my actual fat burn range. And even if they somehow knew something I didn't, and this was my correct fat burn range, then that means 127 is 60% of my heart rate and 140 is 70%. But the 127 at 60% yields a maximum heart rate of 212. The 140 at 70% yields a maximum heart rate of 200. The displayed VO2Max value starts at 165 - and that's supposed to be 90%. So the top 90% goes from 165 to 212? Or 165 to 200? The math doesn't add up any way I try to examine this chart.

Interestingly, though, that 165 value *is* 90% of 183 - so that one line seems to be in the proper place according to my calculations. The rest aren't, though.

So, if the chart were accurate, this would be a great help with my daily fitness evaluation. The way the chart is laid out now, the displayed areas seem to be quite meaningless, and I'm baffled.

I realize this is a bit confusing, so here's an altered version of the MyTrak graph, with my correct ranges overlaid on it. So the four colored bars on the left - anaerobic, aerobic, fat burn, and recovery, are laid out as they should be at 90%, 80%, 70%, and 60% of my 183 max. Note that the top of the anaerobic section does properly match the top of the MyTrak provided section. However, the other sections are all incorrect.



The below figures are where the lines should be drawn. They are the values at which my lines are drawn on the above chart. The MyTrak version *does* match the 90% value. However, it does not match the lower values. Since it does match at 90% it should by necessity match at the other percentages as well since they are all percentages of the same total.

Max value: 183 (226 - 43)
90% value: 165 (183 * .90)
80% value: 146 (183 * .80)
70% value: 128 (183 * .70)
60% value: 110 (183 * .60)
50% value: 92 (183 * .50)

MyTrak indicated that it incorrectly uses the male value - 220 - for both men and women. So using that logic, the max value would be 220 - 43 = 177.

Then we should have lines drawn at:

90% - 159 (177 * .90)
80% - 142 (177 * .80)
70% - 124 (177 * .70)
60% - 106 (177 * .60)
50% - 89 (177 * .50)

However, the SlimCoach default lines aren't drawn there either. It appears those lines are drawn at:

165 (90% of 183)
152 (80% of 190)
140 (70% of 200)
128 (60% of 213)
114 (50% of 228)

So none of these seem to be percentages of 177.

I'm not sure how their ranges can make sense.

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