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 .
Sitting-time and 9-year all-cause mortality in older women
Background Studies of mid-aged adults provide evidence of a relationship between  sitting-time  and all-cause mortality , but evidence in older adults is limited . The aim is to examine the relationship between  total sitting-time  and all-cause mortality  in older women . Methods The prospect i ve cohort design involved 6656 participants in the Australian Longitudinal Study on Women 's Health who were followed for up to 9 years ( 2002 , age 76–81 , to 2011 , age 85–90 ) .  Self-reported total sitting-time was linked to all-cause mortality data from the National Death Index from 2002 to 2011 . Cox proportional hazard models were used to examine the relationship between  sitting-time and all-cause mortality , with adjustment for potential sociodemographic , behavioural and health confounders . Results There were 2003 ( 30.1 % ) deaths during a median follow-up of 6 years . Compared with participants who sat < 4 h/day , those who sat 8–11 h/day had a 1.45 times higher risk of death and those who sat ≥11 h/day had a 1.65 times higher risk of death . These risks remained after adding sociodemographic and behavioural covariates , but were attenuated after adjustment for health covariates . A significant interaction ( p=0.02 ) was found between sitting-time and physical activity ( PA )  , with increased mortality risk for prolonged sitting only among participants not meeting PA guidelines ( HR for sitting ≥8 h/day : 1.31 , 95 % CI 1.07 to 1.61 ) ; HR for sitting ≥11 h/day : 1.47 , CI 1.15 to 1.93 ) . Conclusions  Prolonged sitting-time  was positively associated with all-cause mortality . Women who reported sitting for more than 8 h/day and did not meet PA guidelines had an increased risk of dying within the next 9 years
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 .