VO2max Measurement and Analysis - University of …rrobergs/426L17VO2max.pdfDr. Robert Robergs Fall, 2010 VO2max Issues 1 VO 2max Measurement and Analysis Dr. Robert A. Robergs, Ph.D.,

Dr. Robert Robergs Fall, 2010

VO2max Issues 1

VOVO22max Measurement and Analysismax Measurement and AnalysisDr. Robert A. Robergs, Ph.D., EPC, FASEP

Director:Exercise Physiology Laboratories

Exercise Science ProgramThe University of New MexicoAlbuquerque, NM 87131-1258

www.unm.edu/~rrobergs

Early History

Archibald Vivian Hill

“In running the oxygen requirement increases continuously as the speed increases, ….; the actual oxygen intake, however, reaches a maximum beyond which no effort can drive it. The oxygen intake may attain its maximum and remain constant merely because it cannot go any higher owing to the limitations of the circulatory and respiratory system.”

(Hill A.V. and H. Lupton. QQ J Med 1923; 16:135-171.)

In performing his research, Hill used,• discontinuous running protocols• limited running speeds

• 6-7 subjects

• combined data from multiple subjects


VO2max Issues 2

Time or Intensity

VO2

VO2max

Cardiorespiratory limitations

What is VO2max

Duration should be ~8-10 min

• The maximum rate oxygen can be taken in (pulmonary), transported (circulatory), and utilized (peripheral) for energy production.

• The maximal rate at which the body can consume oxygen during exercise.

Definitions:

Other “less correct” terms!“aerobic power” “aerobic capacity”

“maximal cardiorespiratory capacity”


VO2max Issues 3

Powers and Howley, 1997, p: 50

“VO2max represents the physiological ceiling for the ability of the oxygen transport system to deliver O2 to contracting muscles.”

Wilmore and Costill, 1994, p: 11

“…. Oxygen consumption peaks and remains constant or drops slightly, even though work intensity continues to increase…. The best single measurement of cardiorespiratory endurance and aerobic fitness.”


VO2max Issues 4

Robergs and Roberts, 1998, p: 227

“… the maximal rate that the body can consume oxygen during exercise… detected as a plateau despite further increases in exercise intensity...”


VO2max Issues 5

Determinants of VO2max

Cardiac Output

CENTRAL PERIPHERAL

oxygen delivery capillary density

fiber dimensions

Peripheral Oxygen Diffusion

muscle massPO2 gradients

O2 supply demand relationships

A-aPO2

SaO2

VO2max = Qmax x a-vO2max

[Hb]

HR x SV


VO2max Issues 6

0 2 4 6 8 10 12 14 160

400

800

1200

1600

2000

2400

2800Subject #2Subject #3

Time (min)

VO2

(mL/

min

)

Plateau???

Clear plateau

For 34 subjects, breath-by-breath data with an 11 breath average, and based on VO2 50 mL/min for VO2max and closest neighboring data point. VO2 plateau incidence = 86%

• No universally recommended procedures for processing VO2 data from breath-by-breath indirect calorimetry, or from time averaged systems.

• No standardized criteria or recommended methods for detecting either of a VO2 plateau, the maximal rate of oxygen consumption (VO2max), or a peak VO2 in the absence of a VO2 plateau (VO2peak).

• Increasing use of breath-by-breath indirect calorimetry in education, research and professional practice

• The lack of any objective criteria to follow when processing decreases the validity of measurement.

Background


VO2max Issues 7

Challenges• How do researchers in exercise physiology currently collect and process data?• How long should the protocol be?• What type of protocol should be used?• What causes the “noise” in breath-by-breath VO2data?• Should this “noise” be reduced? If so, how?• What is a VO2 plateau?• How can a VO2 plateau be objectively determined?• What is VO2max vs. VO2peak?• How can VO2max and VO2peak be objectively determined?

1.01.52.02.53.03.5

VO2

(L/m

in)

What causes the “noise” in breath-by-breath VO2 data?

2.17 0.3 L/min, with a range of 1.4 – 3.3 L/min

1025

40

5570

VE S

TPD

(L/m

in)


VO2max Issues 8

0 2 4 6 8 10 12 14

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

MeasuredPredicted

Time (min)

VO2

(L/m

in)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0 Pred VO2 = 0.9572(Meas VO2) + 0.0898R2 = 0.9572SEE = 0.059 L/min)

Measured VO2 (L/min)

Pred

icte

d VO

2 (L

/min

)

Variability 96 % explained by a two-factor model of VE and FEO2

0 2 4 6 8 10 12 140.0

0.5

1.0

1.5

2.0

2.5

5%error

Time (min)

VO2

(L/m

in)

Variability Remaining


VO2max Issues 9

Should this “noise” be reduced?

YES

How should this “noise” be reduced?

0 5 10 15 200.00.51.01.52.02.53.03.54.04.5

a=bb

Time (min)

VO2

(L/m

in)

0 5 10 15 200

1

2

3

4b=15 s

Time (min)

VO2

(L/m

in)

0 5 10 15 200

1

2

3

4c=30 s

Time (min)

VO2

(L/m

in)

0 5 10 15 200

1

2

3

4d=60 s

Time (min)

VO2

(L/m

in)

0 5 10 15 200

10

20

30

40

15 s

30 s

60 s

e

Time (min)

Bre

aths

Time Averaging


VO2max Issues 10

0 5 10 15 200.00.51.01.52.02.53.03.54.04.5

a=bb

Time (min)

VO2

(L/m

in)

0 5 10 15 200

1

2

3

4

5b=5 breaths

Time (min)VO

2 (L

/min

)

0 5 10 15 200

1

2

3

4c=11 breaths

Time (min)

VO2

(L/m

in)

0 5 10 15 200

1

2

3

4d=21 breaths

Time (min)

VO2

(L/m

in)

0 5 10 15 200.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

21 breaths

11 breaths

5 breaths

bb

Time (min)

Tim

e In

terv

al (m

in)

Breath Averaging

0

1

2

3

4a

VO2

(L/m

in)

0

1

2

3

4d

VO2

(L/m

in)

0

1

2

3

4b

VO2

(L/m

in)

0 50 100 150 200 2500

1

2

3

4e

Data Points

VO2

(L/m

in)

0 50 100 150 200 2500

1

2

3

4c

Data Points

VO2

(L/m

in)

muscle

cardiovascular

ventilation

Digital Filtering


VO2max Issues 11

Digital Filter Example

0 2 4 6 8 10 12 14 16 180

500

1000

1500

2000

2500

3000

3500

4000

rest exercise

Time (min)

VO2

(mL/

min

)

linear regress ion

initial deviation from linearity

VO2 plateau at VO2max

12 13 14 15 16 17 182750

3000

3250

3500

3750

Time (min)

VO2

(mL/

min

)

What is a VO2 plateau?


VO2max Issues 12

What is VO2max or VO2peak?

0 2 4 6 8 10 12 14 16 180

1

2

3

4

5

Time (min)

VO2

(L/m

in)

Data Example

10 11 12 13 14 152000

2400

2800

3200

3600

4000treadmill running

Time (min)

VO2

(mL/

min

)


VO2max Issues 13

Conclusions

• Clear rationale for processing breath-by-breath VO2 data to decrease “noise”.

• Processing best done by digital filtering

• Still formulating and debating criteria and methods to quantify VO2 plateau, VO2max, VO2peak

• In the absence of a VO2 plateau, what are valid criteria to use to verify a “true” VO2max?

Documents

VO2max Measurement and Analysis - University of …rrobergs/426L17VO2max.pdfDr. Robert Robergs Fall, 2010 VO2max Issues 1 VO 2max Measurement and Analysis Dr. Robert A. Robergs, Ph.D.,