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Whitney A. Welch, Ann M. Swartz, Chi C. Cho and Scott J. Strath

The purpose of the study was to evaluate the accuracy of direct observation (DO) to estimate MET level and intensity category during laboratory-based and free-living activity in older adults. Older adults engaged in unstructured laboratory and free-living activity. Participants wore a portable metabolic system to measure energy expenditure and were directly observed. DO recorded MET-level point estimates. 32,401 in-laboratory and 87,715 free-living data points (9 participants, 67% male, 71.0 ± 6.9 years, 27.1 ± 4.3 kg·m–2) were included in final analysis. Results revealed 45.4% of in-laboratory and 61.1% of free-living mean DO activities fell within 0.5 METs of the measured MET values. DO accurately classified intensity category 45.0% of the time in-laboratory and 50.9% of free-living observations. DO-estimated activity cost resulted in low point estimate accuracy however there was low variability between the mean measured and estimated METs. This suggests, dependent on the desired outcome, DO could provide a viable option for activity assessment, however, the low point estimate accuracy presents a need for further research to continue to refine the approach to increase accuracy.

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Whitney A. Welch, Scott J. Strath, Michael Brondino, Renee Walker and Ann M. Swartz

Background: Older adults spend 30% of their day in light-intensity physical activity (LPA). This study was designed to determine if increasing the proportion of time spent in LPA would affect glucose control. Methods: Older adults (N = 9) completed four 3-hour treatment conditions consisting of a seated control and 3 randomized conditions: (1) 20% time spent in continuous LPA, 80% seated; (2) 40% time spent in continuous LPA, 60% seated; and (3) 60% time spent in continuous LPA, 40% seated. Energy expenditure was measured continuously, and glucose was measured prior to mixed-meal ingestion and hourly thereafter. Glucose area under the curve was compared between conditions using Friedman test. Results: There was a significant difference in glucose area under the curve by time spent in LPA (P < .001); specifically, between the seated and 60% LPA (mean difference = 35.0 [24.6] mg/dL, P = .01), seated and 40% LPA (mean difference = 25.2 [11.8] mg/dL, P = .03), seated and 20% LPA (mean difference = 17.8 [22.5] mg/dL, P = .03), 20% LPA and 60% LPA (mean difference = 17.2 [22.5] mg/dL, P = .01), and 40% LPA and 60% LPA (mean difference = 9.8 [7.3] mg/dL, P = .01). Conclusion: These results provide experimental evidence to the importance LPA has on metabolic health. If older adults who already spend, on average, about 3 hours per day in LPA, further increase their LPA, they could see benefit to glucose control.