Open-circuit respirometry: a historical review of portable gas analysis systems

Abstract

Scientists such as physiologists, engineers, and nutritionists have often sought to estimate human metabolic strain during daily activities and physical pursuits. The measurement of human metabolism can involve direct calorimetry as well as indirect calorimetry using both closed-circuit respirometry and open-circuit methods that can include diluted flow chambers and laboratory-based gas analysis systems. For field studies, methods involving questionnaires, pedometry, accelerometery, heart rate telemetry, and doubly labelled water exist, yet portable metabolic gas analysis remains the gold standard for most field studies on energy expenditure. This review focuses on research-based portable systems designed to estimate metabolic rate typically under steady-state conditions by critically examining each significant historical innovation. Key developments include Zuntz's 1906 innovative system, then a significant improvement to this purely mechanical system by the widely adopted Kofranyi-Michaelis device in the 1940s. Later, a series of technical improvements: in electronics lead to Wolf's Integrating Motor Pneumotachograph in the 1950s; in polarographic O cells in 1970-1980's allowed on-line oxygen uptake measures; in CO cells in 1990s allowed on-line respiratory exchange ratio determination; and in advanced sensors/computing power at the turn of the century led to the first truly breath-by-breath portable systems. Very recent significant updates to the popular Cosmed and Cortex systems and the potential commercial release of the NASA-developed 'PUMA' system show that technological developments in this niche area are still incrementally advancing.

Assessment of maximal fat oxidation during exercise: A systematic review

“…It seems clear that to reach a steady-state gaseous exchange (oxygen consumption and carbon dioxide production), a key requirement is to accurately measure substrate metabolism through indirect calorimetry. 50,51 In this context, previous studies have suggested that individuals with low cardiorespiratory fitness need longer time periods to reach the steadystate gaseous exchange. 52,53 Thus, the application of a 3-minute stage duration or less could not be enough to attain the steady-state gaseous exchange in specific populations.…”

Magnitude and duration of excess of post‐exercise oxygen consumption between high‐intensity interval and moderate‐intensity continuous exercise: A systematic review

“…Indirect calorimetry is employed to determine EE because the heat released during the process of energy generation is directly proportional to the rate of oxygen uptake. Thus, measuring pulmonary gas exchange is a non‐invasive method to measure energy expended from processes that depend upon oxygen 41 …”

Box-Jenkins Transfer Function Modelling for Reliable Determination of VO2 Kinetics in Patients with COPD

“…BJ-TF, however, are able to estimate kinetic feature values with multiple input transitions, e.g., for time-domain analyses of pseudo-random binary sequences of the cycling load [30], or during unsupervised physical activities. As physical activity and VO 2 can nowadays be measured with wearable devices [31,32], combining these measurements with BJ-TF modelling can produce frequent estimates of kinetic feature values during standard unsupervised training sessions, without the need for elaborate testing procedures. Similar models have already been successfully used to model heart rate responses during road cycling [33].…”