First author [ref.] | Design and setting | Subjects n (males/females) | Main objective | Physical activity assessment | Exercise tolerance assessment | Correlation coefficient | p-value | Main results |
Steele [39] | Single-centre convenience sample USA | 47 (44/3) | Feasibility of accelerometer measurement | Accelerometer | 6MWD | 0.74 | <0.001 | Preliminary data suggesting that a triaxial movement sensor is a reliable, valid and stable measure of walking and daily physical activity in COPD patients |
Belza [91] | Single-centre convenience sample USA | 63 (60/3) | Evaluation of correlates of physical activity | Accelerometer | 6MWD | 0.60 | <0.001 | Physical activity is most significantly related to walking abilities |
Pitta [74] | Single-centre convenience sample Belgium | 50 (36/14) | Comparison of physical activity in COPD with healthy subjects | Acclerometer | 6MWD % pred Wmax % pred Peak V′O2 % pred | 0.76 0.64 0.33 | <0.0001 <0.0001 | Patients with COPD are markedly inactive in daily life Functional exercise capacity is the strongest correlate of physical activity |
Eliason [96] | Multicentre convenience sample Sweden | 44 (28/16) | Associations between physical activity and clinical characteristics of COPD | Accelerometer | 6MWD | 0.34#] | 0.03 | Mean physical activity level and physical activity of at least moderate intensity are positively associated with exercise capacity |
Waschki [79] | Multicentre convenience sample UK, the Netherlands | 127 (79/48) | Evaluation of compliance with wearing an accelerometer and the relationship of disease characteristics with physical activity in a multicentre study | Accelerometer | 6MWD | 0.47¶] | <0.001 | Excellent compliance with wearing a physical activity monitor in a multicentre study Consistent associations of physical activity with relevant disease characteristics in a multicentre study |
Watz [65] | Single-centre convenience sample Germany | 163 (122/41) | Various analyses of physical activity and its clinical correlates in COPD | Accelerometer | 6MWD | 0.46 | <0.001 | Relation to clinical outcomes |
Van Gestel [40] | Single-centre convenience sample Switzerland | 70 (49/21) | Predicting physical activity levels from 6MWD | Accelerometer | 6MWD | 0.69 | <0.001 | 6MWD cannot reliably predict physical inactivity |
↵6MWD: 6-min walking distance; COPD: chronic obstructive pulmonary disease; Wmax: maximal workload; V′O2: oxygen uptake. #: standardised regression β-coefficient; ¶: standardised regression β-coefficient adjusted for age, sex, study site and body mass index >30 kg·m−2.