Data Processing From Indirect Calorimetry: Recommendations and Guidelines

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

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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?

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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

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• 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)

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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
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Variability 96 explained by a two-factor model
of VE and FEO2
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(No Transcript)
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Should this noise be reduced?
SIM
How should this noise be reduced?
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Time Averaging
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Breath Averaging
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muscle
Digital Filtering
cardiovascular
ventilation
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What is a VO2 plateau?
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What is VO2max or VO2peak?
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Data Example
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Custom Programming Example
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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?

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Thank you