Practical question

1. Practical 6.4 [15 marks]
1. [1 mark]
The graph shows a spirometer trace of oxygen consumption when breathing at rest and
during exercise.
[Source: Courtesy of Dr. Dafang Wang for his work at University of Utah.]
What explains the difference between the traces at regions X and Y on the graph?
A. At X, the internal intercostal muscles contract more than the external intercostal
muscles.
B. At Y, the ribcage moves up and out more than at X.
C. At X, the diaphragm flattens more per breath than at Y.
D. At Y, the intercostal muscles contract more slowly than at X.
2a. [1 mark]
A spirometer was used to measure the ventilation rate of a person at rest and pedaling at
22 km per hour on an exercise bike.

2. Calculate the difference in ventilation rate between resting and exercising.
2b. [3 marks]
Explain the change in the tidal volume during exercise.

3. 3a. [1 mark]
The graph shows the ventilation rate and tidal volume of a well-trained runner during
exercise on a treadmill. The tidal volume is the volume of air being moved in and out of the
lungs in each breath.
State the apparatus used to measure the tidal volume.

4. 3b. [2 marks]
Calculate the total volume of air inhaled during one minute during the highest velocity of
the treadmill in this test, giving the units.
3c. [2 marks]
Compare and contrast the effect of increasing treadmill speed on the ventilation rate and
tidal volume in this runner.
4a. [1 mark]
A study was conducted on 25 healthy, non-smoking males to look at the effect of exercise
and altitude on ventilation rate. Subjects were first asked to rest in a sitting position for six
minutes. They then pedalled for three periods of six minutes at increasing exercise
intensity: at 20 %, 30 % and 40 % of their maximal aerobic power. The entire study was
conducted either in normal sea level oxygen conditions or in lower oxygen conditions
simulating an altitude of 4000 m. The results are shown in the bar chart.

5. [Source: E Hermand, et al., (2015), Periodic breathing in healthy humans at exercise in
hypoxia,
Journal of Applied Physiology, 118, pages 115–123.
https://doi.org/10.1152/japplphysiol.00832.2014]
State one other variable that should have been controlled in this study.
4b. [2 marks]
Compare and contrast the effect of increasing exercise intensity at sea level and at an
altitude of 4000 m.

6. 4c. [2 marks]
Outline how ventilation rate could have been monitored in this study.
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