Abstract
Thirty minutes of MVPA in bouts of at least 10 minutes is a commonly-used target to distinguish active from inactive subjects. Since MVPA data are frequently analyzed without bouts, we aimed to propose a MVPA non-bout target equivalent to 30 min. (bouts) and to validate this target in subjects with and without COPD.
Hundred-thirteen subjects with (62±6 yrs, FEV1 65±27%) and 110 without COPD (62±5 yrs, FEV1 111±18%) wore an activity monitor for 7 days. MVPA was defined as the time spent >3 METs. We randomly divided our healthy population into a calibration sample (CS, n=73) and a cross-validation sample (CV-S, n=37). Receiver operating characteristic (ROC) curve analyses were used to determine a MVPA non-bout target (CS) and to (cross-)validate this target by comparing sensitivity and specificity in subjects with and without (CV-S) COPD.
Using the criterion of 30 minutes MVPA per day (bouts), a daily target of 80 min. MVPA provided the best combination of sensitivity (83(58 to 96)%) and specificity (85(73 to 93)%) with an area under the ROC curve of 0.89 (0.81 to 0.98). This target revealed a high balance of sensitivity and specificity in both the healthy CV-S sample (n=37) and patients with COPD (n=113).
Accelerometry measured MVPA (non-bouts) of 80 min. per day corresponds to 30 min. of MVPA per day in bouts and is valid to discriminate active from inactive subjects.
- © 2013 ERS