Determination of young adults' sedentary time with a multisensory activity monitor and activity log diary

Quantification of sedentary time still remains a challenge.This study examined: 1) whether a multisensory activity monitor could accurately measure sedentary activities and discriminate them from light intensity activities; and 2) the validity of activity log diary (AL) in estimating sedentary time using the monitor as a criterion measure.Thirty healthy individuals performed sedentary and light intensity activities in a laboratory while being equipped with a metabolic measurement cart (MMC) and the multisensory monitor. Subsequently, a subset of 19 participants completed AL while wearing the monitor for three days under free-living conditions.Metabolic equivalents (METs) measured by the multisensory monitor during sedentary activities were similar to those measured by MMC and were significantly lower than light-intensity activities (p < 0.001). Relative criterion validity of AL assessed by Pearson's correlation coefficient was high (r = 0.68, p < 0.01). Absolute criterion validity examined by Bland-Altman plots showed small mean difference between AL and the monitor (36.9 minutes ⋅ day(-1)) with its limits of agreement ranging from -103.3 to 177.1 minutes ⋅ day(-1).The multisensory monitor is capable of accurately measuring sedentary activities and distinguishing them from light-intensity activities. Compared to the multisensory monitor, our results showed that AL provides valid estimate of overall sedentary time.