Article Text

Lower limb activity and its determinants in COPD
  1. P P Walker1,2,
  2. A Burnett1,
  3. P W Flavahan1,
  4. P M A Calverley1
  1. 1
    Division of Infection and Immunity, School of Clinical Science, University of Liverpool, Liverpool, UK
  2. 2
    Clinical Science Centre, University Hospital Aintree, Liverpool, UK
  1. Dr P P Walker, Clinical Science Centre, University Hospital Aintree, Lower Lane, Liverpool L9 7AL, UK; ppwalker{at}


Background: Patients with chronic obstructive pulmonary disease (COPD) walk less than healthy older people and their self-reported activity predicts exacerbation risk. The relationship between lower limb activity and total daily activity is not known, nor are there any data which relate objectively assessed daily activity to laboratory assessments made before and after rehabilitation.

Methods: Lower limb activity was measured by leg actigraphy over 3 days in 45 patients with moderate to severe COPD and 18 controls of similar age. Thirty-three patients with COPD entered an 8-week rehabilitation programme in which the change in leg activity was measured and related to other outcomes.

Results: In patients with COPD the mean level of activity measured by whole body and leg activity monitors was closely related (r = 0.92; p<0.001), but leg activity was consistently reduced compared with controls of similar age (p = 0.001). Mean leg activity, mean intensity of leg activity and the time that patients spent mobile at home were all related to forced expiratory volume in 1 s (FEV1) (r = 0.57, p = 0.001; r = 0.5, p = 0.003; and r = 0.51, p = 0.002, respectively), but intensity of activity and time spent mobile were not related. Subjects completing pulmonary rehabilitation showed significant improvements in mean activity (p = 0.001) and spent more time moving (p = 0.014). These changes were unrelated to improvement in muscle strength or walking distance but correlated with baseline FEV1 (r = 0.8, p<0.001).

Conclusions: Total daily activity in patients with COPD is closely related to leg activity which is reduced compared with controls of similar age. Individuals differ in the time spent mobile during the day, but subjective and objectively assessed activity improves after rehabilitation and is predicted by FEV1. The change in activity is unrelated to improvements in corridor walking and health status.

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Supplementary materials


  • See Editorial, page 663

  • Additional Methods and Results data are published online only at

  • Funding: None.

  • Competing interests: None.

  • Ethics approval: All patients provided written informed consent and the protocol was approved by the local research ethics committee.

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