Comparison of Weekend and Weekday Physical Activity Patterns in Chronic Obstructive Pulmonary Disease (COPD) and Non-COPD Participants by Daily Activity Level

Rationale: Physical activity endpoints are of interest in chronic obstructive pulmonary disorder (COPD), but in considering what constitutes a “valid” wear time for activity monitors, there is still debate whether monitors should be worn over a period incorporating both weekdays and weekends. We explored whether activity patterns differ significantly between weekdays and weekend and by activity level, using a cohort where subjects were encouraged to wear an activity monitor continuously throughout the 3-week observation period.

Methods: 151 (70 COPD, 81 non-COPD) of the 183 participants from a single center at National Jewish Health from the COPDGene cohort provided complete activity data (minimum 8 hours/day) during the 3-week observation period. Each subject used a wrist-worn physical activity monitor (ActiGraph). Daily summary and 24-hour profiles were analyzed based on their overall step counts throughout the study. A k-means clustering algorithm (k=3) was used on the raw data to categorize participants into low, medium, and high levels of activity.

Results: Activity was normalized based on overall wear time into steps/minute throughout the day (0-24 hours represents midnight to midnight on the graph’s x-axis), with lines representing weekend and weekday means for the three activity clusters.

Conclusion: Despite some individual variation, weekday/weekend activity was similar at the population level for each cluster, although it is possible that our findings may not be applicable to other geographical or cultural settings. Additionally, low activity individuals concentrated their activity in the morning hours, while medium/high activity individuals had more consistent activity patterns throughout waking hours.