title: Association between peripheral muscle strength and daily physical activity in patients with COPD: a systematic literature review and meta-analysis.
abstract: 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.
authors.affiliation: Department of Physiotherapy, Zurich University of Applied Sciences (ZHAW), Winterthur, Switzerland (Ms Osthoff and Drs Kool, van Gestel, and Marcar); and Bern University of Applied Sciences, Bern, Switzerland (Dr Taeymans).
authors.forename: Anne-Kathrin Rausch
authors.initials: AK
authors.lastname: Osthoff
authors.forename: Jan
authors.initials: J
authors.lastname: Taeymans
authors.forename: Jan
authors.initials: J
authors.lastname: Kool
authors.forename: Valentine
authors.initials: V
authors.lastname: Marcar
authors.forename: Arnoldus J R
authors.initials: AJ
authors.lastname: van Gestel
mesh_terms: D000203:Activities of Daily Living; D017079:Exercise Tolerance / Q000502:physiology*; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D013147:Spirometry