These studies indicate that analysis of the data using 60-s epochs and a vertical magnitude cut-point < 200 cpm or using 30- or 60-s epochs with a machine learning algorithm provides the most valid estimates of SB .
Conclusions Few studies have examined the reliability and validity of accelerometers for measuring SB  in older adults .
Studies to date suggest that the criteria research ers use for classifying an epoch as sedentary instead of as non-wear time ( e.g. , the non-wear algorithm used ) may need to be different for older adults than for younger adults .
The required number of hours and days of wear for valid estimates of SB in older adults was not clear from studies to date .
Background The evidence showing the ill health effects of prolonged sedentary behaviour ( SB ) is growing .
Most studies of  SB in older adults have relied on self-report measures of SB .
However , SB is difficult for older adults to recall and objective measures that combine accelerometry with inclinometry are now available for more accurately assessing SB .
The aim of this systematic review was to assess the validity and reliability of these accelerometers for the assessment of  SB in older adults .
Comparison of accelerometer cut points for predicting activity intensity in youth.
UNLABELLED The absence of comparative validity studies has prevented research ers from reaching consensus regarding the application of intensity-related accelerometer cut points for children and adolescents . PURPOSE This study aim ed to evaluate the classification accuracy of five sets of independently developed ActiGraph cut points using energy expenditure , measured by indirect calorimetry , as a criterion reference st and ard . METHODS A total of 206 participants between the ages of 5 and 15 yr completed 12 st and ardized activity trials . Trials consisted of sedentary activities ( lying down , writing , computer game ) , lifestyle activities ( sweeping , laundry , throw and catch , aerobics , basketball ) , and ambulatory activities ( comfortable walk , brisk walk , brisk treadmill walk , running ) . During each trial , participants wore an ActiGraph GT1 M , and V˙O2 was measured breath-by-breath using the Oxycon Mobile portable metabolic system . Physical activity intensity was estimated using five independently developed cut points : Freedson/Trost ( FT ) , Puyau ( PU ) , Treuth ( TR ) , Mattocks ( MT ) , and Evenson ( EV ) . Classification accuracy was evaluated via weighted κ statistics and area under the receiver operating characteristic curve ( ROC-AUC ) . RESULTS Across all four intensity levels , the EV ( κ=0.68 ) and FT ( κ=0.66 ) cut points exhibited significantly better agreement than TR ( κ=0.62 ) , MT ( κ=0.54 ) , and PU ( κ=0.36 ) . The EV and FT cut points exhibited significantly better classification accuracy for moderate- to vigorous-intensity physical activity ( ROC-AUC=0.90 ) than TR , PU , or MT cut points ( ROC-AUC=0.77 - 0.85 ) . Only the EV cut points provided acceptable classification accuracy for all four levels of physical activity intensity and performed well among children of all ages . The widely applied sedentary cut point of 100 counts per minute exhibited excellent classification accuracy ( ROC-AUC=0.90 ) . CONCLUSIONS On the basis of these findings , we recommend that research ers use the EV ActiGraph cut points to estimate time spent in sedentary , light- , moderate- , and vigorous-intensity activity in children and adolescents
These studies indicate that analysis of the data using 60-s epochs and a vertical magnitude cut-point < 200 cpm or using 30- or 60-s epochs with a machine learning algorithm provides the most valid estimates of SB .
Conclusions Few studies have examined the reliability and validity of accelerometers for measuring SB  in older adults .
Studies to date suggest that the criteria research ers use for classifying an epoch as sedentary instead of as non-wear time ( e.g. , the non-wear algorithm used ) may need to be different for older adults than for younger adults .
The required number of hours and days of wear for valid estimates of SB in older adults was not clear from studies to date .
Background The evidence showing the ill health effects of prolonged sedentary behaviour ( SB ) is growing .
Most studies of  SB in older adults have relied on self-report measures of SB .
However , SB is difficult for older adults to recall and objective measures that combine accelerometry with inclinometry are now available for more accurately assessing SB .
The aim of this systematic review was to assess the validity and reliability of these accelerometers for the assessment of  SB in older adults .