BACKGROUND: Quantification of sedentary time still remains a challenge.
OBJECTIVES: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.
