Association between peripheral muscle strength and daily physical activity in patients with COPD : a systematic literature review and meta-analysis

Background: Patients with chronic obstructive pulmonary disease have skeletal muscle dysfunction and reduced daily physical activity (PA). Whether the reduction in quadriceps strength (QS) is directly linked to physical inactivity remains to be elucidated. Methods: A systematic review and a meta-analysis were conducted to determine the potential relationship between QS and the level of PA. The overall estimate of the correlation coefficient (r *) was calculated, and a subgroup analysis was conducted to analyze the association between QS and indices of PA separately. Results: A total of 8 studies were included in the meta-analysis. The overall association between QS and PA was low but highly significant (r * = 0.288, 95% CI = 0.180–0.389; P < .001). In the subgroup analysis, the association between QS and the number of steps per day was low (r = 0.260; 95% CI = 0.060–0.440) and the association between QS and the time spent walking was moderate (r = 0.418; 95% CI = 0.229–0.576). Conclusions: Peripheral muscle strength is associated with PA as assessed by the number of steps per day and the time spent walking in patients with chronic obstructive pulmonary disease. The overall association between QS and PA was low to moderate and highly significant