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Data Processing From Indirect Calorimetry: Recommendations and Guidelines

Data Processing From Indirect Calorimetry: Recommendations and Guidelines. Robert A. Robergs, Ph.D., FASEP, EPC. Exercise Physiology Laboratories, Exercise Science Program, University of New Mexico. A.V. Hill. Maximal Oxygen Consumption (VO 2 max). VO 2 max. V E F E O 2 F E CO 2. VO 2.

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Data Processing From Indirect Calorimetry: Recommendations and Guidelines

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  1. Data Processing From Indirect Calorimetry: Recommendations and Guidelines Robert A. Robergs, Ph.D., FASEP, EPC Exercise Physiology Laboratories, Exercise Science Program, University of New Mexico

  2. A.V. Hill Maximal Oxygen Consumption (VO2max) VO2max VE FEO2 FECO2 VO2 Cardiorespiratory limitations Time or Intensity

  3. Background • 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.

  4. Challenges • How do researchers in exercise physiology currently collect and process data? • What causes the “noise” in breath-by-breath VO2 data? • Should this “noise” be reduced? • How should this “noise” be reduced? • What is a VO2 plateau? • How can a VO2 plateau be objectively determined? • What is VO2max? • What is VO2peak? • How can VO2max and VO2peak be objectively determined?

  5. How do researchers in exercise physiology currently collect and process data? • Survey conducted over internet • International sport science email discussion list (www.sportsci.org) • n = 75 • Breath-by-breath = 48% • Time averaged mixing chamber = 25% • Either depending on purpose = 27% • Data processing = 30 s (38%), 60 s (18%), 20 s (11%), a moving average of 5-11 breaths (10%), 15 s (8%) and the middle 5 of 7 breaths (7%), other (8%) • Check for VO2 plateau = 93%

  6. No distinction between VO2max or VO2peak = 76% • VO2 Plateau criteria • < 150 mL/min (34%) • < 2 mL/kg/min (27%) • subjective visual (18%) • other (19%) • Secondary criteria = attainment of age predicted HRmax (53%), RER > 1.10 (49%) or RER > 1.15 (27%), RPE > 17, 18 or 19 (20%) • Why these methods used? = own beliefs (32%), what they were taught (26%), what they read in research articles (22%), tradition (13%) and the influence of their colleagues (7%)

  7. 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

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

  9. Should this “noise” be reduced? SIM How should this “noise” be reduced?

  10. Time Averaging

  11. Breath Averaging

  12. muscle Digital Filtering cardiovascular ventilation

  13. What is a VO2 plateau?

  14. What is VO2max or VO2peak?

  15. Data Example

  16. Custom Programming Example

  17. 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?

  18. Thank you

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