Sedentary patients with COPD: differences by physical activity level

Sedentary behaviour (SB) and low physical activity (PA) are independently associated with worse health outcomes in COPD. Population studies show better outcomes for physically active than inactive sedentary people; factors distinguishing active/inactive sedentary COPD patients are unclear. This cross-sectional study explored differences between these groups and identified PA predictors. Categories from Bakrania et al.¹ were used: high SB ≥8.5h/day; sufficient PA ≥5000 steps/day (Actigraph GT3X+). Differences in age, sex, comorbidities, FEV₁, GOLD ABE, symptoms (mMRC; CAT), Exercise Motivations Inventory 2 and functional capacity (6MWD) were analysed using (non-)parametric tests and PA predictors by logistic regression. 92 patients were included (67±8yrs; 84% male; 47% GOLD-B; 6MWD 427±98m; 4486[2825–6925] steps/day; 11[9–12] h/day SB). 88% had high SB: 54% were inactive (<italic>couch potatoes</italic>), 46% were active (<italic>sedentary exercisers</italic>). <italic>Sedentary exercisers</italic> were younger (65±7/70±7yrs, p<.001), had fewer symptoms(mMRC≥2:37%/73%, p=.003; CAT≥10:57%/79%, p=.032), higher lung function(FEV₁ 1.4±0.5/1.2±0.5L, p=.014) and functional capacity (6MWD 480±79/383±98m, p<.001) than <italic>couch potatoes</italic>. No other differences were found. In high-SB patients, 6MWD significantly predicted sufficient PA(R²Nagelkerke=.543, R²Cox-Snell=.405; p<.001), adjusting for age(OR=0.901; 95%CI 0.822–0.987) and daylight time(OR=1.662; 95%CI 1.144–2.413). The odds of being active increased by 1.5% per additional 6MWD-meter(OR=1.015; 95%CI 1.007–1.024). High SB patients are more likely to be active if younger, less symptomatic, and with better functional capacity, but only functional capacity predicts sufficient PA. ¹Brakania et al. BMC Public Health 16,25 (2015)