Abstract
Background: Most recommendations for physical activity (PA) are based on subjective self reported measures, although performance-based accelerometers are already available for many years. To meet PA recommendations, subjects need to be physically active in bouts varying from 5 to 20 minutes. However, the influence of bout length and bout interruptions in objectively measured PA status is not exactly known.
Aim: The aim of the present study is to investigate the effect of different consecutive bout lengths and bout interruptions on the PA status using accelerometers.
Methods: Twenty COPD patients were selected from a larger dataset, based on a large range in PA level. The DynaPort accelerometer (100Hz, ±2g, McRoberts BV, The Hague, the Netherlands) was used for measuring PA during a full week of daily living. Systematically varied bout lengths and interruptions are investigated to examine PA status.
Results: Bout length of 10 versus 1 minute shows a 71% difference in PA status (91 METs·min vs 317 METs·min) (figure 1a). Bout interruption duration of 0 vs 5 minutes shows a 57% difference in PA status (91 METs·min vs 214 METs·min) (figure 1b).
Conclusion: This study shows that varying bout length and interruption duration has large impact on PA status. When applying PA recommendations this should be taken into account, particularly in subjects with a sedentary life style.
- © 2011 ERS
