Working with Vo2 on the Exam
Exam candidates frequently question if they will have to work with Vo2 on their certification exam. Are they going to have to measure Vo2max? How are they expected to do that really big equation? Especially without calculators?
The short answer is that it’s not that scary. Measuring Vo2max, directly, is something that is usually done in a lab. So, no, you won’t be asked to directly measure Vo2max during your exam. But you might be asked to calculate Vo2max or one of it’s components.
Memorizing and understanding the Vo2max equation is the first step. For those with the ACE 3rd edition Personal Trainer manual, check page 9. For those using the ACE Group Fitness Instructor manual, some of the components of Vo2max are discussed on pages 16 and 17. Vo2max is defined as the total capacity to consume oxygen at the cellular level .The Vo2max formula is below:
Vo2max = Cardiac Output x Oxygen Extraction Max
Vo2max = Q x A-Vo2 difference
A great example of working with the Vo2max formula is problem 9, on page 6 of the ACE 3rd edition Personal Trainer Master the Manual workbook. The problem is written below: (hints and guiding information is italicized and underlined)
Calculate oxygen extraction max given the following information:
Max HR: 180 bpm
Max SV: 125mL/beat
Cardiac Output Max: 22,500 mL/min
VO2 Max: 48mLO2/kg/min (The mlO2 is usually written with the Oxygen part (O) missing. Don’t forget it is there.)
The first step is to remember the equation:
VO2Max = Q x AV02 diff or VO2Max = (HRxSV) x (Oxygen Extraction)
And input what we know from the question:
48mLO2/kg/min = 22,500 mL/min x (X)
75 kg x 48mLO2/kg/min = 22,500mL/min x (X) We need to get VO2 in an absolute format, we need to take the weight out of the equation)
VO2Max = Q x AVO2 diff (just a reminder of what the formula is that we are still working with)
3600 mLO2/min = 22,500mL/min x(X) We need to divide both sides by 22,500mL/min to get X alone
.16mLO2/mL blood = X However, we need to see our AVO2/Oxygen Extraction measured in mLO2/100mL of blood.
.16mLO2/mL blood x 100 = 16mL02/100mL blood
16mL02/100mL blood is the correct answer to this problem.
Hopefully this helps explain it for you. I think part of the challenge is that with VO2Max, the equation is written ml/kg/min and we forget that ml is mL of oxygen since the O2 usually isn’t included. This is a reminder to know the specifics of what you are working with, especially labeling and terminology.
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