Effects of pulmonary rehabilitation on activity levels in patients with chronic obstructive pulmonary disease

The purpose of this study was to determine whether patients with chronic obstructive pulmonary disease (COPD) increase physical activity immediately after a short course (8 weeks) of pulmonary rehabilitation (PR). Activity levels in patients with COPD were also compared with those in healthy controls.

Consecutive patients with COPD (n = 24, aged 71.9 ± 7.7 years, forced expiratory ventilation in 1 second 44.1 ± 17.9% predicted, who completed PR) and 8 aged-matched controls (aged 66.6 ± 7.2 years) were studied. Activity was monitored with a triaxial accelerometer for 5 days before and after PR. Activity was expressed as vector magnitude units (VMU) per minute and time spent at VMU above 250 and 500, respectively.

Overall activity was significantly less in patients with COPD compared with that in controls (117 ± 63 compared with 242 ± 103 VMU/min, P = .0003). Time spent at VMU above 250 and 500 was also less in patients with COPD (166 ± 71 vs 227 ± 37 min, P = .028 and 39 ± 43 vs 124 ± 26 min, P < .0001, respectively). After PR, overall VMU activity was not significantly increased (117 ± 63 vs 120 ± 63 VMU/min). Time spent at VMU above 250 and 500 was also not significantly increased after PR. Increases in activity levels after PR did not correlate with improvements in exercise performance, quality of life, or quadriceps strength.

Despite significant improvements in exercise capacity and quality of life after PR, this did not translate into a significant increase in activity level. Improving function in patients with copd may not translate into behavioral change.