ORIGINAL RESEARCH article
Front. Physiol.
Sec. Exercise Physiology
Volume 16 - 2025 | doi: 10.3389/fphys.2025.1583703
This article is part of the Research TopicEmerging technologies in sports performance: data acquisition and analysisView all 3 articles
Comparison of Two Portable Metabolic Systems in Measuring Energy Expenditure during Resting and Exercise in Untrained Women
Provisionally accepted
Feng Gao1,2
Yujing Chan-Yu1,2Zhi Li1,2Yongfu Liu1Fei Liu1Di Liu1
Feng Gao1,2Weiwei Chen3Junhua Wang1,2
Shenglong Le1,3*- 1Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
- 2Hubei University of Medicine, Shiyan, Hubei, China
- 3Shanghai Jiao Tong University, Shanghai, China
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Purpose: Portable metabolic systems are used as "gold standard" for measuring energy expenditure (EE) in the development and validation of wearable devices. This study aimed to compare EE measurements obtained using the COSMED K5 (K5) and CORTEX METAMAX 3B (M3B) during resting state and submaximal-intensity exercise in women without self-reported regular exercise training.Methods: Twenty women aged 21.4 ± 1.5 years completed two measurements, including resting in a seated position and cycling on a simple upright ergometer at 30W, 40W, 50W, and 60W. Average EE and other metabolic parameters were compared between K5 and M3B. Differences between K5 and M3B were assessed using the paired-samples t-test and the effect size was calculated as Cohen's d. Agreement between the two systems was evaluated by calculating Pearson correlation coefficients and visually examining Bland-Altman plots.The number of participants who completed resting measurements and exercise measurements was 18 and 19, respectively. For resting EE, the mean values measured using K5 was 33.4% higher than those measured using M3B (P < 0.001, Cohen's d = 1.47). Similar differences were observed for cycling at 30W (15.8%, P < 0.001, Cohen's d = 1.50), 40W (16.1%, P < 0.001, Cohen's d = 1.68), 50W (14.8%, P < 0.001, Cohen's d = 1.28), and 60W (14.6%, P < 0.001, Cohen's d = 1.29). Pearson correlation coefficients between EE measured using K5 and M3B was 0.66 for 30 W cycling (P = 0.002) and 0.62 for 40W cycling (P = 0.005).Conclusions: K5 and M3B show significant differences in EE measurements during resting and exercise among untrained females, indicating systematic bias in EE measurement between the two systems. Thus, careful consideration is essential when interpreting the results of wearable device studies that using different portable automated metabolic systems.
Keywords: COSMED K5, CORTEX METAMAX 3B, Energy Expenditure, indirect calorimetry, Metabolic measurement, wearable metabolic systems
Received: 26 Feb 2025; Accepted: 09 Jun 2025.
Copyright: © 2025 Gao, Chan-Yu, Li, Liu, Liu, Liu, Gao, Chen, Wang and Le. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Shenglong Le, Shanghai Jiao Tong University, Shanghai, China
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