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. Maximal Oxygen Consumption (VO 2 max) Time or Intensity VO 2 VO 2 max Cardiorespiratory limitations A.V. Hill V E F E O 2 F E CO 2

3. No universally recommended procedures for processing VO 2 data from breath-by-breath indirect calorimetry, or from time averaged systems. No standardized criteria or recommended methods for detecting either of a VO 2 plateau, the maximal rate of oxygen consumption (VO 2 max), or a peak VO 2 in the absence of a VO 2 plateau (VO 2 peak). 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

4. Challenges How do researchers in exercise physiology currently collect and process data? What causes the “noise” in breath-by-breath VO 2 data? Should this “noise” be reduced? How should this “noise” be reduced? What is a VO 2 plateau? How can a VO 2 plateau be objectively determined? What is VO 2 max? What is VO 2 peak? How can VO 2 max and VO 2 peak 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 VO 2 plateau = 93%

6. VO 2 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%) No distinction between VO 2 max or VO 2 peak = 76%

7. What causes the “noise” in breath-by-breath VO 2 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 FEO 2

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

11. Time Averaging

12. Breath Averaging

13. muscle cardiovascular ventilation Digital Filtering

14. What is a VO 2 plateau?

15. What is VO 2 max or VO 2 peak?

16. Data Example

17. Custom Programming Example

18. Conclusions Clear rationale for processing breath-by-breath VO 2 data to decrease “noise”. Processing best done by digital filtering Still formulating and debating criteria and methods to quantify VO 2 plateau, VO 2 max, VO 2 peak In the absence of a VO 2 plateau, what are valid criteria to use to verify a “true” VO 2 max?

19. Thank you