Moderate Intense Physical Activity Depends on Selected Metabolic Equivalent of Task MET Cut-Off and Type of Data AnalysisReport as inadecuate




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Background

Accelerometry data are frequently analyzed without considering whether moderate-to-vigorous physical activities MVPA were performed in bouts of >10 minutes as defined in most physical activity guidelines. We aimed i to quantify MVPA by using different commonly-applied physical activity guidelines, ii to investigate the effect of bouts versus non-bouts analysis, and iii to propose and validate a MVPA non-bouts cut-point to classify in- active subjects.

Methods

Healthy subjects n=110;62±6yrs and patients with Chronic Obstructive Pulmonary Disease COPD n=113;62±5yrs wore an activity monitor for 7 days. Three Metabolic Equivalent of Task MET cut-offs and one individual target 50% VO2 reserve were used to define MVPA. First, all minutes of MVPA were summed up NON-BOUTS. Secondly, only minutes performed in bouts of >10 minutes continuous activity were counted BOUTS. Receiver operating characteristic ROC curve analyses were used to propose and cross- validate new MVPA non-bout cut-points based on the criterion of 30 minutes MVPA per day BOUTS. Likelihood ratios sensitivity-1-specificity were used to express the association between the proposed MVPA non-bout target and the MVPA bout target of 30 min*day-1.

Results

MVPA was variable across physical activity guidelines with lowest values for age-specific cut-offs. Selecting a METs cut-point corresponding to 50% VO2 reserve revealed no differences in MVPA between groups. MVPA’s analyzed in BOUTS in healthy subjects were 2 to 4 fold lower than NON-BOUTS analyses and this was even 3 to 12 fold lower in COPD. The MVPA non-bouts cut-point of 80 min*day-1 using a 3 METs MVPA threshold delivered positive likelihood ratios of 5.11.5-19.6 healthy subjects and 2.31.6-3.3 COPD.

Conclusion

MVPA varies upon the selected physical activity guideline-targets and bouts versus non-bouts analysis. Accelerometry measured MVPA non-bouts target of 80 min*day-1, using a 3 METs MVPA threshold, is associated to the commonly-used MVPA bout target of 30 min*day-1.



Author: Hans van Remoortel , Carlos Augusto Camillo , Daniel Langer, Miek Hornikx, Heleen Demeyer, Chris Burtin, Marc Decramer, Rik Gosse

Source: http://plos.srce.hr/



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