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"Jim Smith" <[email protected]> wrote in message
news:[email protected]...
> David Wuertele <[email protected]> writes:
<snip>
>>
>> What I don't understand is this: given the test measurement I
>> described above, how can the system determine my fat calories burned?
>>
>> I understand how total calories burned can be computed from power
>> integrated over time. I can also see how total aerobic calories can
>> be computed based on volume of O2 and CO2. But how can the system
>> differentiate calories that were generated by burning fat versus those
>> generated by burning glycogen/glucose?
>
> Carbohydrates are called that because their chemical formula looks
> like (CH2O)n In other words, carbohydrates are composed of "hydrated"
> carbon atoms, every carbon is associated with two hydrogens and an
> oxygen.
>
> Fats, on the other hand, are more complicated, with a typical formula
> being (CH2O)3(CH2)3n(CO2H)3, with n=17 for a typical fat. The key
> point is that there is much less oxygen in fats then in carbohydrates.
>
> When either a fat or a carbohydrate "burns" in the body, it combines
> with oxygen to form carbon dioxide and water. Because carbohydrates
> have more oxygen in them, it takes less oxygen from the atmosphere to
> produce a given quantity of carbon dioxide than when fats are burned.
>
> So, by measuring the quantity of carbon dioxide produced relative to
> the amount of oxygen consumed, it is possible to tell what portion of
> the calories being burned are coming from fat. This quantity,
> VCO2/VO2 is know as the "respiratory quotient." If you body is
> burning purely carbohydrates, the respiratory quotient is 1.0, if you
> are burning purely fat it is about 0.66 A typical value for someone
> just hanging out is about 0.80.
>
> To complicate matters, your body can also burn protein for energy.
What a well thought out, reasoned, response. What I can't figure out is
what it's doing on a rec.bicycles.* newsgroup!
news:[email protected]...
> David Wuertele <[email protected]> writes:
<snip>
>>
>> What I don't understand is this: given the test measurement I
>> described above, how can the system determine my fat calories burned?
>>
>> I understand how total calories burned can be computed from power
>> integrated over time. I can also see how total aerobic calories can
>> be computed based on volume of O2 and CO2. But how can the system
>> differentiate calories that were generated by burning fat versus those
>> generated by burning glycogen/glucose?
>
> Carbohydrates are called that because their chemical formula looks
> like (CH2O)n In other words, carbohydrates are composed of "hydrated"
> carbon atoms, every carbon is associated with two hydrogens and an
> oxygen.
>
> Fats, on the other hand, are more complicated, with a typical formula
> being (CH2O)3(CH2)3n(CO2H)3, with n=17 for a typical fat. The key
> point is that there is much less oxygen in fats then in carbohydrates.
>
> When either a fat or a carbohydrate "burns" in the body, it combines
> with oxygen to form carbon dioxide and water. Because carbohydrates
> have more oxygen in them, it takes less oxygen from the atmosphere to
> produce a given quantity of carbon dioxide than when fats are burned.
>
> So, by measuring the quantity of carbon dioxide produced relative to
> the amount of oxygen consumed, it is possible to tell what portion of
> the calories being burned are coming from fat. This quantity,
> VCO2/VO2 is know as the "respiratory quotient." If you body is
> burning purely carbohydrates, the respiratory quotient is 1.0, if you
> are burning purely fat it is about 0.66 A typical value for someone
> just hanging out is about 0.80.
>
> To complicate matters, your body can also burn protein for energy.
What a well thought out, reasoned, response. What I can't figure out is
what it's doing on a rec.bicycles.* newsgroup!
