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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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LACK OF AGREEMENT BETWEEN GAS EXCHANGE VARIABLES MEASURED BY TWO METABOLIC SYSTEMS |
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DjordjeG. Jakovljevic1  ,
David Nunan1, Gay Donovan1, Lynette D. Hodges2, Gavin R.H. Sandercock3 and
David A. Brodie1 |
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1Research Centre for Society and Health, Buckinghamshire New University, Buckinghamshire, UK 2Department of Sport and Exercise Science, University of Bedfordshire, Bedfordshire, UK 3Centre for Sports and Exercise Science, University of Essex, Colchester, UK |
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© Journal of Sports Science and Medicine (2008) 7, 15 - 22 Search Google Scholar for Citing Articles |
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| ABSTRACT | |||
| The purpose of this study was to assess the agreement and consistency
between gas exchange variables measured by two online metabolic systems
during an incremental exercise test. After obtaining local ethics approval
and informed consent, 15 healthy subjects performed an incremental exercise
test to volitional fatigue using the Bruce protocol. The Innocor (Innovision,
Denmark) and CardiO2 (Medical Graphics, USA) systems were placed
in series, with the Innocor mouthpiece attached to the pneumotach of the
CardiO2. Metabolic data were analysed during the last 30 seconds
of each stage and at peak exercise. There were non- significant differences
(p > 0.05) between the two systems in estimation of oxygen consumption
(VO2) and in minute ventilation (VE). Mean Cronbach's alpha for
VO2 and VE were 0.88 and 0.92. The Bland-Altman analysis revealed
that limits of agreement were -0.52 to 0.55 l.min-1 for VO2,
and -8.74 to 10.66 l.min-1 for VE. Carbon dioxide production
(VCO2) and consequently respiratory exchange ratio (RER) measured
by the Innocor were significantly lower (p < 0.05) through all stages.
The CardiO2 measured fraction of expired carbon dioxide (FeCO2)
significantly higher (p < 0.05). The limits of agreement for VO2
and VE are wide and unacceptable in cardio-pulmonary exercise testing. The
Innocor reported VCO2 systematically lower. Therefore the Innocor
and CardiO2 metabolic systems cannot be used interchangeably
without affecting the diagnosis of an individual patient. Results from the
present study support previous suggestion that considerable care is needed
when comparing metabolic data obtained from different automated metabolic
systems.
Key words: Metabolic system, oxygen consumption, minute ventilation, carbon dioxide production, Bruce protocol. |
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