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Framework for Biomedical Algorithm Designs
Published in Pietro Salvo, Miguel Hernandez-Silveira, Krzysztof Iniewski, Wireless Medical Systems and Algorithms, 2017
Su-Shin Ang, Miguel Hernandez-Silveira
A highly accurate technique of measuring calorie energy expenditure is achieved through the use of indirect calorimetry (an example of an indirect calorimeter is shown in Figure 6.9). This method is premised on the fact that energy is required for muscular contraction in order for physical activity to occur. The release of energy occurs through the metabolism of fat, carbohydrates, and proteins, which requires oxygen and produces carbon dioxide as one of the by-products. Therefore, by allowing the subject to breathe in air of known concentration (20.9% oxygen, 0.03% carbon dioxide, 79.1% nitrogen), and measuring the concentration of gases in exhaled air by means of a face mask, the oxygen uptake and the expelled carbon dioxide can be determined. The calorie energy expenditure can then be worked out as a function of oxygen uptake and carbon dioxide production (Weir formula [25]). Other accurate techniques for measuring calorie energy expenditure include direct calorimetry [26] and the doubly labeled water technique [27].
The Challenges of Monitoring Physical Activity in Children with Wearable Sensor Technologies
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
Gita Pendhakar, Daniel T.H. Lai, Alistair Shilton, Remco Polman
The doubly labelled water method is used to measure the average metabolic rate, also known as the field metabolic rate. The method involves using heavier isotopes of hydrogen (H-2, also known as deuterium) and oxygen (O-18) to form deuterium oxide (D2O18), which is heavy water. The average elimination of deuterium and O-18 is then measured over a period of time. It turns out that O-18 in the body is lost through carbon dioxide and body water (urine, sweat), while deuterium is lost only through body water. This concept can be used to infer the metabolic rate by computing the ratio of oxygen used in metabolism to carbon dioxide eliminated. Measurements involve taking two body water samples (at the beginning and the end of the measurement period) and carbon dioxide measurements at fixed intervals during the measurement period.
The validity of the commercially-available, low-cost, wrist-worn Movband accelerometer during treadmill exercise and free-living physical activity
Published in Journal of Sports Sciences, 2019
Jacob E. Barkley, Ellen Glickman, Curtis Fennell, Mallory Kobak, Megan Frank, Gregory Farnell
Because of the problems with subjective measures, many researchers rely on objective measures of physical activity. These objective measures typically include: indirect calorimetry, doubly labeled water, accelerometers and pedometers (Hendelman, Miller, Baggett, Debold, & Freedson, 2000; Hills et al., 2014; Holbrook, Barreira, & Kang, 2009; Seale, Conway, & Canary, 1993; Yang & Hsu, 2010). Indirect calorimetry or measuring ventilatory gas exchange, is an accurate measure of energy expenditure but typically requires the individual to be tethered to a metabolic cart (i.e., computer and gas analyzers) not making it an ideal method of assessing physical activity outside of a laboratory setting. Doubly labeled water requires an individual to consume water containing traceable hydrogen (deuterium) and traceable oxygen (oxide-18) and then the elimination rate of the traceable hydrogen and oxygen in the subject is recorded. Doubly labeled water is a high-cost and extremely complex method that, while accurate, is not often utilized because of its impracticality.