Human Nutrition 3(3+0)

Lesson 9 : BMR-Methods of Measurements and Factors Affecting BMR

Determination of energy metabolism during work

The energy metabolism is profoundly influenced by physical work. The energy metabolism during work can be determined using one of the following equipments: (graph-4 )

1. Douglas bag
2. Max-Planck respirometer
3. Kofranyi-Michaelis respirometer and
4. Integrating motor pneumotachygraph

 

• Douglas bag: The Douglas bag is made of rubber and usually of 100 litres capacity. The subject breathes into the bag for 5 to 6 minutes. The air in the bag is then measured using a gas meter, and a sample taken for the analysis of o2 and co2.

• Max-Planck Respirometer: This instrument is portable and can measure directly the volume of expired air and pass on simultaneously a small quantity into a rubber bladder attached to it. (fig. 111pg). the air is subsequently analysed for CO2 and oxygen. It has been extensively used in the determination of the energy requirements for various types of work.

• Kofranyi-Michaelis respirometer: This is similar in principle to the Max-Planck respirometer and has been commonly used in studies on energy requirements of workers.

• Integrating motor pneumotachygraph: This instrument has been designed by Wolff (1958). It is not used so commonly as other instruments mentioned above.