Data Processing From Indirect Calorimetry: Recommendations and Guidelines - PowerPoint PPT Presentation

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Data Processing From Indirect Calorimetry: Recommendations and Guidelines

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Title: Data Processing From Indirect Calorimetry: Recommendations and Guidelines


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 (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
  • lt 150 mL/min (34)
  • lt 2 mL/kg/min (27)
  • subjective visual (18)
  • other (19)
  • Secondary criteria attainment of age predicted
    HRmax (53), RER gt 1.10 (49) or RER gt 1.15
    (27), RPE gt 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
(No Transcript)
10
Should this noise be reduced?
SIM
How should this noise be reduced?
11
Time Averaging
12
Breath Averaging
13
muscle
Digital Filtering
cardiovascular
ventilation
14
What is a VO2 plateau?
15
What is VO2max or VO2peak?
16
Data Example
17
Custom Programming Example
18
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?

19
Thank you
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