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This is of course trivially verifiable. To burn 1000 calories in 45 minutes if your body is an average 25% efficient requires around 385W of continous power out

This is of course trivially verifiable. To burn 1000 calories in 45 minutes if your body is an average 25% efficient requires around 385W of continous power output. The majority of women will struggle to output this for a mere minute while most men won't last 5. So no, your 45 minutes of HIIT isn't burning 1000 calories, and if calories are your goal, you would obviously not be doing HIIT in the first place (what's the point in getting nauseous when you can just produce these steady watts). (That said, I still heavily disagree with the grandparent; exercise is as much part of a diet as is calories in / out. If you can do 150W for a grand total of 5 hours every week, that totals 2500kcal or more than an extra days worth. For many people, time spent exercising is also time spent not sitting idly in front of a TV and eating.)

a8da6b0c91d 12y ago
Genuinely curious where you get the 25% efficient number. Is that an established figure for cyclists or something?
- dietrichepp 12y ago
  It would be interesting to know the particulars, but in general you hook up a cyclist up to a dynamometer and a ventilator, and you measure both the amount of work done and the amount of CO2 produced. I say "cyclist" because they're the easiest ones to hook up to a dynamometer.
- revelation 12y ago
  http://www.ncbi.nlm.nih.gov/pubmed/12471319 http://www.ncbi.nlm.nih.gov/pubmed/12471319 quotes gross mechanical efficiency at 24.5 +/- 0.7% for world class cyclists. More importantly, however, http://www.ncbi.nlm.nih.gov/pubmed/15241718 http://www.ncbi.nlm.nih.gov/pubmed/15241718 finds no differences in efficiency between world-class and recreational cyclists. In any case, the "cycling" bit is somewhat of a smoke-screen; it just so happens that it's most easily measured and objective data has long been available through power meters. There is no free-lunch, regardless of the particulars of any sport. (I should however probably clarify that the power numbers quoted above are mechanical power as measured during cycling, which is pretty much the only sport that even has ways of measuring power reliably)
  - deleted 12y ago
    [deleted]

a8da6b0c91d 12y ago

Genuinely curious where you get the 25% efficient number. Is that an established figure for cyclists or something?

dietrichepp 12y ago
It would be interesting to know the particulars, but in general you hook up a cyclist up to a dynamometer and a ventilator, and you measure both the amount of work done and the amount of CO2 produced. I say "cyclist" because they're the easiest ones to hook up to a dynamometer.
revelation 12y ago
http://www.ncbi.nlm.nih.gov/pubmed/12471319 http://www.ncbi.nlm.nih.gov/pubmed/12471319 quotes gross mechanical efficiency at 24.5 +/- 0.7% for world class cyclists. More importantly, however, http://www.ncbi.nlm.nih.gov/pubmed/15241718 http://www.ncbi.nlm.nih.gov/pubmed/15241718 finds no differences in efficiency between world-class and recreational cyclists. In any case, the "cycling" bit is somewhat of a smoke-screen; it just so happens that it's most easily measured and objective data has long been available through power meters. There is no free-lunch, regardless of the particulars of any sport. (I should however probably clarify that the power numbers quoted above are mechanical power as measured during cycling, which is pretty much the only sport that even has ways of measuring power reliably)
- deleted 12y ago
  [deleted]