Breathing bag (long plastic bag with markings to show litres)
Two way mouthpiece
Place nose clip on the subject and get them to make 5 normal breaths through the mouthpiece and into the bag. The mouthpiece should be of a design with a valve which allows air to enter the mouth on inhalation, with exhaled air being passed into the bag.
Roll the bag down from the mouthpiece end and read off the volume of gas contained within.
Get your subject to perform a light exercise, such as jogging on a treadmill or performing star jumps, for two minutes, with the noseclip removed so that they can breath normally.
Repeat the measurement of air volume produced from 5 breaths.
Another set of exercise should be performed for for minutes and measurements made. This should be repeated with exercise intervals increasing by two minutes each time up to a maximum of ten minutes.
The subject should be encouraged to breath as normally as possible in all cases.
Should your subject become light headed stop the experiment, remove the mouthpiece and nose clip and allow them to breath deeply for a few minutes. Ensure that the area where the exercise is taking place is free from obstruction. Ensure that your subject is in general good health before taking part. Ensure that the mouthpiece is sterilised prior to use, or has a disposable extension which is used.