Labeled Water Technique for Determining Energy Expenditure

The rate of energy consumption of an aerobic tissue is roughly proportional to its rate of oxygen consumption. What is the rate of energy consumption of resting muscle compared with exercising muscle  

Skeletal muscle represoits about 40% of the mass of an adult 70-kg man. Imagine that the man spent 1 to 2 hours per day in strenuous exercise and engaged in sedentary activities for the remainder of the day. Conunent on the difference in the expected energy requirements of a sedentary person and a person who exercises 1 to 2 hours per day. 

DOUBLY LABELED WATER TECHNIQUE FOR DETERMINING ENERGY EXPENDITURE 

A knowledge of O2 consumption and RQ can be used to calculate the total amount of megajoules expended per day, as outlined earlier in ihis chapter. 

The RQ can be determined directly, by taking breath samples during the course of the day. However, this method of determining the RQ is confining, and defeats 

The use of direct calorimetry is not a convenient technique, since it requires a specially constructed room and the confinement of human subjects for a day or longer in the room. The doubly labeled water technique offers a convenient alternative, providing that one has a machine to perform isotope ratio mass spectrometry. The doubly labeled water technique is used to measure the rate of total CO2 production in the body. This number alone is not sufficient to allow one to calculate the total energy expenditure. But the value for COj production (moles COi/day), along with the RQ, allows one to calculate the oxygen consumption using the following formula  

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Doubly Labeled Water Technique for Determining Energy Expenditure Issues in Energy Nutiiticn Refetences Bibliography... 

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