Portable gas analyser Cosmed K4b(2) compared to a laboratory based mass spectrometer system

L. R. McNaughton, R. Sherman, S. Roberts, D. J. Bentley

Research output: Contribution to journalArticle (journal)peer-review


Aim: The purpose of this study was to systematically test the accuracy of an automated, portable, gas analysis system, the Cosmed K4b(2) with a laboratory based mass spectrometer system, the Morgan EX670 across a number of gas and ventilation parameters.

Methods: Eight subjects (mean SE) age, 23.7 +/- 1.1 y, height, 1.78 +/- 0.01 m, mass, 74.4 +/- 2.1 kg performed a VO2max test and a submaximal exercise test at 150, 200, 250 and 300 Watts (W), on an SRM cycle ergometer. The Morgan EX670 system and the K4b(2) were randomly connected in series, using the same breath for the calculation of gas and ventilatory parameters.

Results: The K4b2 system reads siginificantly higher than the Morgan EX 670 for both VO2 md VCO2 at 250 (VO2/VCO2: p < 0.05, p < 0.002), and 300 W (VO2/VCO2: p < 0.002, p < 0.005). Unsystematic bias between the 2 analysers; varies between 1% and 16% and systematic bias between 3% and 8%.

Conclusion: There are some significant unsystematic and systematic differences between these 2 systems and laboratories should endeavour to utilise either one or the other piece of equipment to test their subjects.

Original languageUndefined/Unknown
JournalJournal of Sports Medicine and Physical Fitness
Issue number3
Publication statusPublished - 1 Sept 2005


  • oxygen
  • Carbon dioxide
  • portability
  • correlation
  • log/log transformation
  • systematic bias

Cite this