Dose-Response of Light Intensity Physical Activity and Glucose Dynamics in Older Adults

Abstract

National data reports older adults spend about 30% of their day in light intensity physical activity (LPA). This study was designed to examine how increasing the proportion of the day spent in LPA would affect glucose control. PURPOSE: To determine the duration-response of proportion of time spent in LPA on post-prandial glucose response in older adults in a controlled environment. METHODS: Older adults (N=9), 60 y and older, completed four, three-hour treatment conditions, a seated control condition, and three subsequent randomized conditions 1) 20% (36 min) of the condition spent in continuous LPA, the remaining time seated, 2) 40% (72 min) of the condition spent in continuous LPA, the remaining time seated, and 3) 60% (108 min) of the condition spent in continuous LPA, the remaining time seated. Energy expenditure was measured continuously and glucose was measured at baseline following mixed meal ingestion and each hour thereafter. Glucose AUC was calculated and compared between conditions using RMANOVA. RESULTS: A significantly greater amount of energy was expended during all activity conditions when compared to the seated condition (p<0.05). There was a significant difference between proportion of time spent in LPA and glucose AUC (F=11.601, p<0.001). Post-hoc analysis showed a significant difference between the seated condition and 60% LPA condition (AUC mean difference (Seated-60%): 35.0 mg/dL, p=0.016), 20% LPA condition and 60% LPA condition (AUC mean difference (20%-60%): 17.3 mg/dL, p=0.010), and 40% LPA condition and 60% LPA condition (AUC mean difference (40%-60%): 9.8 mg/dL, p=0.023) CONCLUSION: These results provide experimental evidence to the importance LPA may play in the overall metabolic health of an older adult population. According to national data, LPA constitutes about 30% of the active day in older adults. Therefore, the translation of the current results suggest that if older adults, who spend on average about three hours per day in LPA, increase LPA by 36 min/d they could significantly benefit glucose control.