A comparison of methods used to quantify the work of breathing during exercise

Abstract

The measurement of the work of breathing (Wb) during exercise provides us with deep insights into respiratory (patho)physiology, and sheds light on the putative factors which lead to respiratory muscle fatigue. There are 4 popular methods available to determine the Wb. Our study demonstrates that no two of these methods produce identical values of Wb during exercise. This paper also discusses the practical and theoretical limitations of each method.

Physiological aspects of cardiopulmonary dysanapsis on exercise in adults born preterm

“…Utilizing modified Campbell diagrams, which allow the work required to overcome airway resistance and tissue elasticity during inspiration and expiration to be quantified (Cross et al . 2021; Gideon et al . 2021), would provide substantive information about how dynamic respiratory mechanics of adults born preterm differ from term‐born individuals.…”

“…alveolar simplification, which could reduce lung recoil. In humans, there are a variety of methods that could provide direct (measurement of oesophageal pressure during quasi-static relaxations (Cross et al 2021;Gideon et al 2021)) and/or indirect (CT and/or forced oscillation technique) evidence of altered lung/chest wall compliance/elastance in adults born preterm. Previous research using CT, however, does not support the hypothesis that adults born preterm have impaired lung compliance (Margraf et al 1991;Wong et al 2008;Aukland et al 2009;Caskey et al 2016;Simpson et al 2017).…”

“…To date, the mechanical work of breathing has not been measured in adults born preterm, but the presence of one or more mechanical ventilatory constraint would result in an excessive work of breathing for a given ventilation. Utilizing modified Campbell diagrams, which allow the work required to overcome airway resistance and tissue elasticity during inspiration and expiration to be quantified (Cross et al 2021;Gideon et al 2021), would provide substantive information about how dynamic respiratory mechanics of adults born preterm differ from term-born individuals. Likewise, quantifying maximum effective expiratory pressure, and determining whether it is met or exceeded during exercise, would provide additional insight.…”

“…In humans, there are a variety of methods that could provide direct (measurement of oesophageal pressure during quasi‐static relaxations (Cross et al . 2021; Gideon et al . 2021)) and/or indirect (CT and/or forced oscillation technique) evidence of altered lung/chest wall compliance/elastance in adults born preterm.…”

Physiological impact of load carriage exercise: Current understanding and future research directions

“…Under normal conditions (no chest wall restriction), the respiratory system utilizes pressure and flow gradients during a standard respiratory cycle (inspiration and expiration) to match the metabolic demands, both at rest and during physical activity, to facilitate the delivery of oxygen to tissue. Early work from the 1950 s outlined this respiratory system phenomenon as a balance between the mechanical work performed by the respiratory muscles to overcome elastic forces of the thoracic cavity (Otis et al, 1950 ) and the total energy cost per breath, which derives a value of work of breathing ( W b , the mechanical work per breath [Joules]) and power of breathing ( P b , the power generated by the respiratory muscles [Joules min −1 ]) (Cross et al, 2021 ; Otis, 1954 ).…”