Dear Editor,
I read with interest the paper of Schneider et al. (Citation1) regarding sedentary behavior and physical inactivity among patients with COPD. The level of physical activity is an important factor of morbidity and mortality in COPD patients and the level of sedentarism is associated with worse clinical outcomes in adults (Citation2,Citation3); however there are hardly any data to characterize the pattern of daily activities among COPD patients, so the study of Schneider et al. offers novel information to this literature gap.
The authors have chosen to use the SenseWear Armband, a multisenson PA monitor, which COPD patients wore for at least 12 hours, for two consecutive days. SenseWear is a validated monitor with the ability to capture the variability in activity levels across different days and correlates well with parameters of exercise capacity (Citation4). However, in a previous validating study, it has been found to explain a smaller portion of the Total Energy Expenditure, not related to Total Body Water than other activity monitors. Moreover, 2 days might be a short period of time to study physical activity in COPD patients of various severity, as the authors also mention, so in order to capture daily variability longer time periods (up to a week) have been previously proposed (Citation5). Given these conditions, a systemic bias in the calculation of daily METs might have been produced.
Another important finding in the study is that more sedentary patients have worse respiratory function, with lower Forced Expiratory Volume in 1 second and they present with more severe dyspnea. Although reduced physical activity has been associated with both respiratory and non-respiratory manifestations in COPD, dynamic hyperinflation is a major limitation factor of both exercise capacity and daily activities in these patients (Citation6). Under this scope, a more detailed approach of hyperinflation indices might offer a further insight in the causes of sedentary lifestyle. Moreover, information on bronchodilation usage (Citation7) and especially on the frequency of short-acting bronchodilators use during moderate-to vigorous-activities break might provide important data to this direction.
In conclusion, this is an important study describing the pattern of daily activity in COPD patients. Changing these patterns have proven to be difficult, even after optimal pulmonary rehabilitation (Citation8), thus more studies are needed on the potentially modifiable factors which could alter this unhealthy lifestyle.
References
- Schneider LP, Furlanetto KC, Rodrigues A, et al. Sedentary behaviour and physical inactivity in patients with Chronic Obstructive Pulmonary Disease: two sides of the same coin? COPD. 2018;15(5):432–438. doi: 10.1080/15412555.2018.1548587.
- Waschki B, Kirsten A, Holz O, et al. Physical activity is the strongest predictor of all-cause mortality in patients with COPD: a prospective cohort study. Chest. 2011;140(2):331–342. doi: 10.1378/chest.10-2521.
- Gibbs BB, Hergenroeder AL, Katzmarzyk PT, et al. Definition, measurement, and health risks associated with sedentary behavior. Med Sci Sports Exerc. 2015;47(6):1295–1300
- Langer D, Gosselink R, Sena R, et al. Validation of two activity monitors in patients with COPD. Thorax. 2009;64(7):641–642
- Rabinovich RA, Louvaris Z, Raste Y, et al. Validity of physical activity monitors during daily life in patients with COPD. Eur Respir J. 2013;42(5):1205–1215
- Marco D, Santus P, Sotgiu G, et al. Does improving exercise capacity and daily activity represent the holistic perspective of a new COPD approach? COPD. 2015;12(5):575–581
- Thomas M, Decramer M, O'Donnell DE. No room to breathe: the importance of lung hyperinflation in COPD. Prim Care Respir J. 2013;22(1):101–111. doi: 10.4104/pcrj.2013.00025.
- Shioya T, Sato S, Iwakura M, et al. Improvement of physical activity in chronic obstructive pulmonary disease by pulmonary rehabilitation and pharmacological treatment. Respir Invest. 2018;56(4):292–306. doi: 10.1016/j.resinv.2018.05.002.