Characteristics of physical activities in daily life in chronic obstructive pulmonary disease

Quantification of physical activities in daily life in patients with chronic obstructive pulmonary disease has increasing clinical interest. However, detailed comparison with healthy subjects is not available. Furthermore, it is unknown whether time spent actively during daily life is related to lung function, muscle force, or maximal and functional exercise capacity. We assessed physical activities and movement intensity with the DynaPort activity monitor in 50 patients (age 64 +/- 7 years; FEV1 43 +/- 18% predicted) and 25 healthy elderly individuals (age 66 +/- 5 years). Patients showed lower walking time (44 +/- 26 vs. 81 +/- 26 minutes/day), standing time (191 +/- 99 vs. 295 +/- 109 minutes/day), and movement intensity during walking (1.8 +/- 0.3 vs. 2.4 +/- 0.5 m/second(2); p < 0.0001 for all), as well as higher sitting time (374 +/- 139 vs. 306 +/- 108 minutes/day; p = 0.04) and lying time (87 +/- 97 vs. 29 +/- 33 minutes/day; p = 0.004). Walking time was highly correlated with the 6-minute walking test (r = 0.76, p < 0.0001) and more modestly to maximal exercise capacity, lung function, and muscle force (0.28 < r < 0.64, p < 0.05). Patients with chronic obstructive pulmonary disease are markedly inactive in daily life. Functional exercise capacity is the strongest correlate of physical activities in daily life.