Lab 1: Submaximal physiological assessment

What is the method of collecting an air sample and analysing it using a Douglass bag?

1. Evacuate all of the Douglass bags using a pump

2. Connect a Falconia tube/mouthpiece to the first empty bag

3. Ask the participant to wear a noseclip and place the mouthpiece in their mouth

4. Allow time for habituation and to remove ambient air from the tubing

5. Once habituated, open the Douglass bag to begin air collection and start a timer

6. When the air collection process ends, close the Douglass bag and the participant can remove the mouthpiece and noseclip

7. Connect the Servomex gas analyser tube to the Douglass bag

8. All at the same time, start a timer, turn on the Servomex gas analyser and open the sample valve for the Douglass bag used

9. Analyse the sample for one minute, recording the F_EO₂, F_ECO₂ and sample volume during gas analysis after 45 seconds

10. When the analysis period ends, turn off the Servomex gas analyser and close the sample value simultaneously

11. Attach the tube for the pump to the Douglass bag and open the Douglass bag with the expired air sample

12. Ensure the dry gas meter is at zero, then turn on the pump to evacuate the bag

13. Record the remaining volume of air in the Douglass bag and the expired gas temperature

How is power output calculated for a cycle ergometer?

Power output = ([total cradle mass x 9.81] x [1.622 x flywheel revolutions])/time

What are the assumptions of the simplified power output equation for a cycle ergometer?

Friction is assumed to be a constant value

Why must gas volumes be standardised?

• To allow for comparison of different sets of data collected in different ambient conditions

• Gas volumes change with varying temperature, humidity and pressure

• At higher temperatures or lower pressures, molecules are further away from each other

• Water vapour takes away space from any gas, so the more water vapour, the less space available for oxygen and carbon dioxide

What are gas values standardised to?

Conditions at 0°C, 760 mmHg and dry conditions

What is the equation for converting ambient gas volume to standardised gas volume?

V_{E STPD} = V_{E ATPS} x ([BP - SWVP]/760) x (273/[273 + T])

where BP is barometric pressure in mmHg, SWVP is saturated water vapour pressure in mmHg

What is saturated water vapour pressure dependent on? (1)

Temperature

What is the equation to calculate saturated water vapour pressure?

SWVP = 1.1001 x T - 4.19

What is the underlying principle of the Haldane transformation?

The proportion of nitrogen in any inhaled air sample is 79.04%, so if more than 79.04% nitrogen is expired, the only explanation is that the percentage of the other exhaled gases has decreased, which can only be explained by the inhaled percentage of these gases being greater than the exhaled percentages

How is exhaled nitrogen volume calculated?

F_EN₂ = 100 - (F_EO₂ + F_ECO₂)

How is the inspired air volume calculated using the Haldane transformation?

V_I = (F_EN₂/F_IN₂) x V_{E STPD}

How is VO₂ calculated?

VO₂ = VO_{2 inspired} - VO_{2 expired}

How is VCO₂ calculated?

VCO₂ = VCO_{2 inspired} - VCO_{2 expired}

How is RER calculated?

RER = VCO₂/VO₂

When is indirect calorimetry valid?

When a physiological steady state can be attained