Abstract
Purpose
Portable methods for assessing energy expenditure outside the laboratory and clinical environments are becoming more widely used. As such, it is important to understand the accuracy of such devices. Therefore, the purpose was to determine the reliability and validity of the COSMED K5 portable metabolic system.
Methods
Reliability and validity were assessed in 27 adults (age: 27 ± 5 years; n = 15 women) using a walking protocol. The protocol consisted of a 5-min walk/2-min rest cycle starting at 1.5 mph and increasing in 0.5-mph increments to 4.0 mph. During visit one, participants wore the K5 to assess oxygen consumption (\({\dot{\text{V}}}\)O2), carbon dioxide production (\({\dot{\text{V}}}\)CO2), and other metabolic variables. Two to seven days later, the protocol was repeated twice with the COSMED K5 and K4b2 systems in a randomized, counterbalanced order.
Results
Intraclass correlation coefficients (ICC) revealed that the K5 reliably measured \({\dot{\text{V}}}\)O2 (ICC 0.64–0.85) and \({\dot{\text{V}}}\)CO2 across all walking speeds (ICC 0.50–0.80), with stronger reliability at faster walking speeds compared with slower speeds. Moderate-to-strong relationships were observed for measured gases between the K5 and K4b2. Specifically, \({\dot{\text{V}}}\)O2 exhibited a moderately high-to-high relationship between devices (r = 0.72–0.82), and a similarly moderately high-to-high relationship was observed for \({\dot{\text{V}}}\)CO2 (r = 0.68–0.82). While there were no differences in \({\dot{\text{V}}}\)O2 measured between devices (p ≥ 0.10), the K5 provided lower \({\dot{\text{V}}}\)CO2 readings than the K4b2 during the 3.0, 3.5, and 4.0 mph walking speeds (p ≤ 0.02).
Conclusions
The K5 provided reliable and valid measures of metabolic variables, with greater reliability and validity at faster walking speeds.
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Availability of data and materials
Data can be made available upon reasonable request.
Abbreviations
- ANOVA:
-
Analysis of variance
- CV:
-
Coefficient of variation
- EE:
-
Energy expenditure
- ICC:
-
Intraclass correlation coefficient
- METs:
-
Metabolic cquivalents
- RER:
-
Respiratory exchange ratio
- \({\dot{\text{V}}}\) e :
-
Minute ventilation
- \({\dot{\text{V}}}\)CO2 :
-
Carbon dioxide production
- \({\dot{\text{V}}}\)O2 :
-
Oxygen consumption
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Acknowledgements
The authors would like to thank the study participants for donating their time and energy to completing the study.
Funding
The study was not funded, however COSMED loaned the K4b2 for the duration of the study.
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JPD, LEW, and TVB conceptualized and designed the study. JPD/LEW collected and analyzed data and drafted the manuscript. TVB provided substantial input/revisions.
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This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted through the Institutional Review Board at Syracuse University (IRB Protocol #18-053).
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Informed consent was obtained from all individual participants in the study.
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All human research participants provided informed consent for data to be used for publication and presentation.
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Communicated by Klaas R Westerterp.
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DeBlois, J.P., White, L.E. & Barreira, T.V. Reliability and validity of the COSMED K5 portable metabolic system during walking. Eur J Appl Physiol 121, 209–217 (2021). https://doi.org/10.1007/s00421-020-04514-2
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DOI: https://doi.org/10.1007/s00421-020-04514-2