title: Does a history of exercise in COPD patients affect functional status? A study using a lifetime physical activity questionnaire investigates a correlation between exercise and functional status as evidenced by six-minute walk distance.
abstract: Recent studies have shown strong associations between chronic exercise and improved spirometric values. Building on these findings, we investigated whether habitual lifetime exercise influences six-minute walk test performance (6MWT) in subjects with at least 10 pack-years smoking history. The 6MWT was chosen for its correlation with performance on activities of daily living and predictive value for inactivity, morbidity and mortality in individuals with chronic obstructive pulmonary disease (COPD) versus spirometric values, which are less adept at predicting functional status. Because COPD is a global cause of disability, therapeutic measures that delay symptom-induced immobility are more cost-effective versus late-stage interventional therapies. Among 49 subjects, we compared lifetime exercise assessed with a validated physical activity questionnaire with six-minute walk distances (6MWD). The American College of Sports Medicine's (ACSM) recommended exercise levels (30 minutes/day, 1000 kcal/week) were used as a benchmark. Among subjects with spirometry-determined lung obstruction (n = 21), those who have not met at least half of ACSM guidelines (500 kcal/week) were classified as "Inactive," while others were "Active." A significant difference in 6MWD was found between Inactive and Active subjects: (1123.86ft vs. 1468.25ft, STDev = 210.07 vs. 240.25, p = 0.0045). This difference was not found in subjects without lung obstruction. Pack-years was a significant covariate: subjects who smoked less walked farther distances. No relation was found between exercise and predicted FEV(1)%. In summary, our case-control study suggests that meeting even half of ACSM exercise guidelines could improve functional status in smokers if habitual exercise is adopted early in life.
authors.affiliation: University of California-San Diego, 1919 S. Grand Blvd., St. Louis, MO 63104, USA. Weiyenzhao@gmail.com
authors.forename: Peter Weiyen
authors.initials: PW
authors.lastname: Chao
authors.forename: Joseph
authors.initials: J
authors.lastname: Ramsdell
authors.forename: Marian
authors.initials: M
authors.lastname: Renvall
authors.forename: Chirag
authors.initials: C
authors.lastname: Vora
mesh_terms: D016022:Case-Control Studies; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012720:Severity of Illness Index; D012907:Smoking / Q000503:physiopathology; D013147:Spirometry; D011795:Surveys and Questionnaires