18 Lab 3: Calorie Burn of Exercise
liyuchon
Acknowledgment
This project is made possible with funding by the Government of Ontario and through eCampusOntario’s support of the Virtual Learning Strategy. To learn more about the Virtual Learning Strategy visit: https://vls.ecampusontario.ca.
PHY255 Stay-At-home Experiment 3
Measuring the Calorie Burn of Aerobic Exercise
What you will do
Use the built-in accelerometer of the phone to monitor the breath rate and heart rate before and after vigorous exercise. Then estimate the calories burn during the exercise.
What you will need
- A smart phone installed with the Phyphox app
Theoretical Background
Most of the energy consumed by a person comes from the oxidation of carbohydrates during aerobic respiration. When oxidized, 1 mole of glucose molecule will react with 6 moles of oxygen, yielding [latex]670kcal[/latex] of energy. This also means that aerobic respiration can produce [latex]4.83kcal[/latex] of energy per liter of pure oxygen (assuming that carbohydrates are the sole source of energy).
When breathing at the resting rate, the lung of a human inhales/exhales about [latex]0.3~0.5L[/latex] of air (depending on the body height and the fitness level). When breathing at the maximal effort, the lung of a human inhales/exhales about [latex]3~5L[/latex] of air (also known as the “lung capacity”). Since the oxygen content in the inhaled air is about 20%, and the oxygen content in the exhaled air is about 15%, we can estimate the volume of oxygen consumed per breath.
In the experiment, the respiratory rate (i.e., the rate of breathing) will be measured using the Phyphox app. The volume of air exchange of the lung per breath will be estimated using subjective judgment. The total volume of oxygen consumed will then be calculated. Combining with the estimations of energy per liter of oxygen and volume of oxygen per breath, we will reach an estimation of the calorie burn during the exercise.
Procedures
- (Preparation 1/2) In the Phyphox app, choose the “acceleration with g” sensor. Lie down on a flat surface. Place the phone vertically below the sternum bone, on the thoracic diaphragm (as shown in the left panel of the figure below at the location of the star).
- (Preparation 2/2) Start a measurement. Normally breath for a while, then stop the measurement. (When you start/stop measurements, try to keep your motion as gentle as possible, so as not to create spikes of acceleration.) If there are no strong spikes at the beginning or the end, at least one of the panels should show a prominent feature corresponding to the movement of the diaphragm during breathing. (In the right panel of the figure below, five breaths were captured. Both x and y accelerometers showed the movement). The total time it takes for the breaths can be more accurately read after saving the data as a csv file. This will be the way we measure our respiratory rate.
- Use the method above, lie down and record about 10 breaths when you are rest