Question:
The question I have is whether to add both the calories
used by the muscles during rowing AND the calories used
to maintain the sweat mechanism in determing how many
total calories I have burned while rowing. Adding the
'sweat calories' more than doubles the calorie figure
and as such has a big impact on the dieting aspects of
the workout.
Answer:
1. The website you are looking at is a website selling Infra-red sauna's as a
method of weight-loss. Not exactly a trust worthy site.
2. Consider the mechanism of sweating and how it cools you. The body only puts
water on the surface of the skin, it does not vaporize it. Putting water on
the surface of the skin does not actually consume much energy. It is only when
that water is evaporated by the air that heat is transferred from the body to
the air and thus the body is cooled.
Now in a Sauna, that heat is coming from the Sauna rather than from exercise so
the body does not actually have to provide any energy in order to vaporize that
water, it is simply getting to hot because the Sauna is adding calories in the
form of radiant heat to the body.
So while evaporating sweat does require calories, those calories do not
necessarily need to be food calories and in the case of the sauna, they would
seem to come from the sauna rather than the persons metabolic processes.
If you want to do this exactly, you need to measure these things exactly and
that includes measuring your actual energy expendature rather than just
estimating it.
Your question is sort of like asking if one needs to include the heat lost
through the radiator when computing the fuel mileage of the car. The answer is
that the heat lost through the radiator is accounted for via the efficiency of
the engine.
So when they suggest that you burn 350 x 45min/30 min = 525 calories rowing,
this is just a guess. If you do the energy balance and assume a 25%
efficiency, this corresponds to a value of 200 watts mechanical energy output
and about 400 calories would be heat which then be transferred to the air via
the evaporation of water on the skins surface.
