Matching Items (22)
Description
Most studies that explored the health benefits of interrupting sitting time focused on using different modalities (i.e., comparing walking vs standing breaks)33,36,59. However, experimental studies that directly compare patterns of interrupting sitting time through standing only are needed to advance the field. This study aimed to (i) determine if there is a difference in glucose response between continuous sitting (CS) and two intermittent standing regimes (high frequency, low duration breaks (HFLD) and low frequency, high duration breaks (LFHD)) and (ii) to determine if there is a difference in glucose response between the two strategies (HFLD vs. LFHD).
Ten sedentary employees (mean±SD age 46.8±10.6 years; 70% female) with impaired fasting glucose (mean glucose= 109.0±9.8 mg/dL) participated. Eligible participants were invited to three 7.5 hour laboratory visits where they were randomized to perform each study conditions: (i) CS, (ii) HFLD and (iii) LFHD. Standardized meals (breakfast and lunch) were given with each meal providing 33% of the participant’s total daily caloric needs following a typical American diet (50-60% carbohydrates, 25-30% fat, and 10-20% protein). Participants wore an activPAL device to measure compliance with the sit-stand condition and a continuous glucose monitor to measure post-prandial glucose response. Post-prandial mean glucose, incremental area under the curve and mean amplitude glycemic excursion between conditions were evaluated using linear mixed models.
Participants demonstrated high compliance with the study condition. The results indicated that the mean glucose of the HFLD condition were significantly lower (p< .01) than the CS condition with mean difference of -7.70 (-11.98, -3.42) mg/dL·3.5h and -5.76 (-9.50, -2.03) mg/dL·7h for lunch and total time, respectively. Furthermore, the mean post-prandial glucose during lunch and total time were significantly lower in the HFLD condition compared to the LFHD condition with mean difference of -9.94 (-14.13, -5.74) mg/dL·3.5h and -6.23 (-9.93, -2.52) mg/dL·7h, respectively. No differences were found between the CS and LFHD conditions.
This study provides evidence favoring the use of frequent interruptions in sitting time to improve glycemic control of prediabetic individuals. In contrast, less frequent, although longer bouts of standing resulted in similar post-prandial glucose profile to that of the continuous sitting condition despite total standing time being equal to the LFHD condition.
Ten sedentary employees (mean±SD age 46.8±10.6 years; 70% female) with impaired fasting glucose (mean glucose= 109.0±9.8 mg/dL) participated. Eligible participants were invited to three 7.5 hour laboratory visits where they were randomized to perform each study conditions: (i) CS, (ii) HFLD and (iii) LFHD. Standardized meals (breakfast and lunch) were given with each meal providing 33% of the participant’s total daily caloric needs following a typical American diet (50-60% carbohydrates, 25-30% fat, and 10-20% protein). Participants wore an activPAL device to measure compliance with the sit-stand condition and a continuous glucose monitor to measure post-prandial glucose response. Post-prandial mean glucose, incremental area under the curve and mean amplitude glycemic excursion between conditions were evaluated using linear mixed models.
Participants demonstrated high compliance with the study condition. The results indicated that the mean glucose of the HFLD condition were significantly lower (p< .01) than the CS condition with mean difference of -7.70 (-11.98, -3.42) mg/dL·3.5h and -5.76 (-9.50, -2.03) mg/dL·7h for lunch and total time, respectively. Furthermore, the mean post-prandial glucose during lunch and total time were significantly lower in the HFLD condition compared to the LFHD condition with mean difference of -9.94 (-14.13, -5.74) mg/dL·3.5h and -6.23 (-9.93, -2.52) mg/dL·7h, respectively. No differences were found between the CS and LFHD conditions.
This study provides evidence favoring the use of frequent interruptions in sitting time to improve glycemic control of prediabetic individuals. In contrast, less frequent, although longer bouts of standing resulted in similar post-prandial glucose profile to that of the continuous sitting condition despite total standing time being equal to the LFHD condition.
ContributorsToledo, Meynard John Lapore (Author) / Buman, Matthew P (Thesis advisor) / Ainsworth, Barbara (Committee member) / Gaesser, Glenn (Committee member) / Hooker, Steven (Committee member) / Pereira, Mark (Committee member) / Arizona State University (Publisher)
Created2019
Description
Obesity is highly prevalence in United States. Obesity can be seen as a positive energy balance, especially a positive fat balance. This may be due in part to how the human body uses energy sources. When a person overconsumes a meal that contains high amounts of both carbohydrate and fat, carbohydrate will stimulate its own oxidation and suppress fat oxidation. This can result in a positive fat balance, which could eventually lead to obesity. Also, it has been shown that after consuming a meal endothelial function is frequently impaired for several hours during the postprandial period. Long-term endothelial dysfunction is a major cause of different types of cardiovascular disease. Exercise has been shown to stimulate fat oxidation and, when performed the day before meal ingestion, precondition arteries by enhancing endothelial function in the basal state. However, the acute effect of exercise on postprandial period is unknown. The purpose of this study is to examine the effect of high intensity interval exercise (HIIE) on the substrate oxidation and endothelial function in the postprandial period after consumption of “meal” consisting of a sugar-sweetened beverage (SSB) and a candy bar (480 kcal; ~75% sugar). Five subjects (4 males, 1 female; age=25yr, BMI=25 kg/m2) completed two conditions in random order: 1) no exercise control; 2) high-intensity interval exercise on a cycle ergometer: alternating 1-min intervals at 90-95% HRmax separated by 1-min of active recovery at 50W, for a duration sufficient to expend ~480 kcal. Endothelial function was measured by flow-mediated dilation (FMD) at baseline, and at 1, 2 and 4 hours postprandial. Substrate oxidation was measured by indirect calorimetry during the entire first hour postprandial and then during the last 20 min of hours 2-5 postprandial. Absolute postprandial fat oxidation (g/5 hours) was higher in HIIE (exercise: 5.47 ± 9.97, control: -9.78 ± 3.80; p<0.011). Absolute postprandial carbohydrate oxidation (g/5 hours) was higher in control group (control: 27.79 ± 6.20, exercise: -1.48 ± 7.75; p<0.019). Therefore, these results show that HIIE results in greater fat oxidation during the postprandial period in comparison to a no-exercise control condition. For FMD, there was no significant difference between groups, and no group x time interaction. However, there was a significant time effect (p<0.046), with both groups demonstrating a reduction in FMD during the postprandial period. FMD in the control condition decreased from 12% to 7.5% during the first 2 hours postprandial, and from 11.4% to 7.3% in the HIIE condition. These results indicate that HIIE performed 1 hour prior to ingestion of a SSB and candy bar does not prevent postprandial endothelial dysfunction.
ContributorsLin, Chia Yu (Author) / Gaesser, Glenn (Thesis advisor) / Whisner, Corrie (Committee member) / Angadi, Siddhartha (Committee member) / Arizona State University (Publisher)
Created2020