Energy expenditure per minute in different activities and body positions and its association with the classification as physically active or inactive in daily life in individuals with COPD

Abstract

Objective: To describe and compare energy expenditure (EE)/minute walking and in different body postures in individuals with COPD; and to investigate if EE/minute walking is a predictor of their classification as physically active or inactive. Methods: Physical activity (PA) in daily life was objectively assessed using two PA monitors for 7 days and data were analyzed on a minute-by-minute basis. Predominant minutes were separated into walking, standing, sitting, and reclined, and EE/minute (a reflection of PA intensity) was then calculated in each of these four activities and postures. Participants were classified as active and inactive according to the criteria proposed by the American College of Sports Medicine (ACSM). Results: 43 individuals were evaluated (65±8 years; FEV1 50±14% predicted). A binary logistic regression model yielded that, regardless of the time spent walking/day, EE/minute walking was a significant predictor of the classification as physically active (OR=18.2 [2 – 165]; p=0.01), together with BMI (OR=0.68 [0.5 - 0.9]; p=0.008) (model: Chi-square = 22.431, p< 0.05; R2 [Nagelkerke] = 0.556). In the active group, significantly higher EE/minute was observed for walking and standing in comparison both to sitting and reclined. However, in the inactive group, there were significant differences in EE/minute only when comparing walking versus reclined and standing versus reclined. Conclusion: In individuals, with COPD, EE/minute walking is a significant predictor of being classified as physically active, independently of the time spent walking/day. Each additional kilocalorie/minute spent walking increases in 18 times the chances to be classified as physically active in daily life.

Energy expenditure as a marker of physical activity intensity in chronic obstructive pulmonary disease

“…By highlighting the potential usefulness of relative intensity PA and combining this with postures, the work of Brito et al 4 may also inspire the field to expand the interpretation of sedentary behaviours (SBs; reclining and sitting in this study). Indeed, the minute-by-minute data collected by the SWA (with higher resolutions possible with other devices) offers the potential for further insight into the different types of SB.…”

“…This speaks to the value of expanding the assessment of PA beyond variables such as steps/day or time spent walking. Brito et al 4 perform an interesting coupling of data (posture and EE) to dig deeper into intensities of different postures and behaviours. The authors report higher EE/minute values for walking and standing compared with sitting and reclining for patients classified as physical active; while physically inactive patients presented similar EE/ minute values across postures.…”

“…Whilst Brito et al 4 are modest in their justification of examining EE as a reflection of PA intensity, the premise of relative intensity matches the familiar notion of individually-tailoring exercise training, such as during pulmonary rehabilitation to ensure patients walk at a prescribed pace. The evaluation of objectively-measured PA intensity during daily life is limited to a ‘one size fits all’ approach, with little acknowledgement of influencing characteristics, such as exercise capacity or body composition, to data interpretation.…”

“…For those involved in the measurement of PA in COPD, Brito et al 4 provide an interesting approach to evaluating PA intensity; considering the suitability of relative PA intensity in line with the personalised care provided by clinical services such as pulmonary rehabilitation. Overall, Brito et al 4 present a thought-provoking study which could help progress PA and SB research in COPD.…”

CRD Editor’s corner archive: October-December

“…For people with COPD, low intensity PA might actually incur significant energy cost because of truncated physical capacity and high respiratory effort. In the journal this month, Brito et al 9 account for this by comparing the readouts from two contemporaneously worn monitors providing information about time spent walking relative to energy expenditure during walking in a cohort of patients with COPD. They show that both time spent walking and energy expended during walking determine whether an individual is deemed “physically active” but energy expenditure (ie intensity) was more predictive.…”