behaviour is not the same as the opposite of lack of physical exercise: even people who have enough exercise may sit too much during the rest of the day. Recent evidence suggest that it may be prolonged, uninterrupted sitting -rather than total sitting time- that may increase cardiometabolic risk. Prolonged sitting leads to the loss of contractile stimulation in weight-bearing muscles, which suppresses skeletal muscle However, measuring sitting time and sedentary patterns is not as straightforward as it may seem. Sedentary behaviour is maybe best measured with accelerometers, however, no consensus is yet established on such accelerometer data most validly reflect sedentary time or sedentary patterns.
In a study just published in PLOS ONE -with Prof. Mai Chin A Paw as first author- we aimed to establish evidence-based accelerometer data reduction criteria to accurately assess total sedentary time and sedentary patterns in children. More than 1000 children in five countries in Europe wore accelerometersfor at least 6 consecutive days. We explored 1) non-wear time criteria; 2) minimum daily valid wear time; 3) differences between weekday and weekend day; and 4) minimum number of days of accelerometer wear by comparing the effects of commonly used data reduction decisions on total sedentary time, and duration and number of prolonged sedentary bouts.
More than 60 consecutive minutes of zero counts was the optimal criterion for non-wear time. Increasing the definition of a valid day from 8 to 10 hours wear time hardly influenced the sedentary outcomes, while the sample size of children with more than 4 valid days increased from 69 to 81%. On weekdays, children had on average 1 hour more wear time, 50 minutes more total sedentary time, 26 minutes more sedentary time accumulated in bouts, and 1 more sedentary bout. At least 6 days of accelerometer data were needed to accurately represent weekly sedentary time and patterns.
No comments:
Post a Comment