Based on Power
The amount of calories you burn closely parallels the amount of
work you perform.
One can accurately estimate caloric use with power meters. Many power meter bicycle computers give a caloric figure.
These figures are more accurate than those estimated with heart rate monitors that do not measure power.
A joule is one watt of power for one second. There are 3,600
seconds in an hour. One kilojoule equals 1,000 joules. Therefore, averaging 100 watts of power for one hour yields 360 kilojoules of work.
Since a kilojoule equals 0.24 calories,
5 and since the body is
about 24% efficient in converting energy to muscular work, kilojoules of work provide a good estimate of calories burned.
That is to say if your total ride work is 1,200 kilojoules, you
have also burned about 1,200 calories in producing that work.
In calories, you burn roughly 3.6 times the average watts you
maintain over an hour.
Summary
As an aerobic endurance athlete, you may need many more
calories than a sedentary person.
You can estimate exercise energy
requirements. Without a power mete
r, many estimates may be very
rough.
5 Technically one kilojoule equals 0.24
kilo
calories. A scientific kilocalori
e is popularly referred to as a
calorie.
Nutrition for Sports, Essentials of 37
