title: Correlations between gait speed, 6-minute walk distance, physical activity, and self-efficacy in patients with severe chronic lung disease.
abstract: BACKGROUND
  Four-meter gait speed (4MGS) has been associated with functional capacity and overall mortality in elderly patients, and may easily be translated to daily practice. We evaluated the association of 4MGS with meaningful outcomes.
  
  
  METHODS
  In 70 subjects we conducted the 4MGS, 6-min walk test (6MWT), objectively measured physical activity, and assessed dyspnea, quality of life, and self-efficacy for walking and routine physical activity. 4MGS was measured in 3 separate time epochs during the 6MWT, to explore 4MGS variability.
  
  
  RESULTS
  Diagnoses included COPD (51.4%), interstitial lung disease (38.6%), and other pulmonary conditions (10%). The mean ± SD values were: 4MGS 0.85 ± 0.21 m/s, 6-min walk distance (6MWD) 305 ± 115 m, and physical activity level 1.28 ± 0.17, which is consistent with severe physical inactivity. The gait speeds within the time epochs 1-2, 3-4, and 5-6 min during the 6MWT were not significantly different: 1.01 ± 0.29 m/s, 0.98 ± 0.31 m/s, and 1.00 ± 0.31 m/s, respectively. 4MGS had a significant correlation with 6MWD (r = 0.70, P < .001). 6MWD was the dominant variable for predicting 4MGS. Other significant predictors of 4MGS included dyspnea, self-efficacy, quality of life, and objectively measured physical activity.
  
  
  CONCLUSIONS
  4MGS is significantly and independently associated with 6MWD, and may serve as a reasonable simple surrogate for 6MWD in subjects with chronic lung disease. Gait speed was remarkably stable throughout the 6MWT, which supports the validity of an abbreviated walk test such as 4MGS.
authors.affiliation: Division of Pulmonary and Critical Care Medicine.
authors.forename: Zachary S
authors.initials: ZS
authors.lastname: DePew
authors.forename: Craig
authors.initials: C
authors.lastname: Karpman
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Novotny
authors.forename: Roberto P
authors.initials: RP
authors.lastname: Benzo
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D002908:Chronic Disease; D004417:Dyspnea / Q000503:physiopathology; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005684:Gait; D006801:Humans; D016015:Logistic Models; D008171:Lung Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D008297:Male; D062527:Meaningful Use; D008875:Middle Aged; D009043:Motor Activity; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D020377:Self Efficacy; D012720:Severity of Illness Index; D013223:Statistics as Topic; D016138:Walking
keywords: 6-min walk test; COPD; exercise capacity; gait speed; interstitial lung disease