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- Creators: Gaesser, Glenn
Description
Purpose: Exercise interventions often result in less than predicted weight loss or even weight gain in some individuals, with over half of the weight that is lost often being regained within one year. The current study hypothesized that one year following a 12-week supervised exercise intervention, women who continued to exercise regularly but initially gained weight would lose the weight gained, reverting back to baseline with no restoration of set-point, or continue to lose weight if weight was initially lost. Conversely, those who discontinued purposeful exercise at the conclusion of the study were expected to continue to gain or regain weight. Methods: 24 women who completed the initial 12-week exercise intervention (90min/week of supervised treadmill walking at 70%VO2peak) participated in a follow-up study one year after the conclusion of the exercise intervention. Subjects underwent Dual-energy X-Ray Absorptiometry at baseline, 12-weeks, and 15 months, and filled out physical activity questionnaires at 15 months. Results: A considerable amount of heterogeneity was observed in body weight and fat mass changes among subjects, but there was no significant overall change in weight or fat mass from baseline to follow-up. 15 women were categorized as compensators and as a group gained weight (+ 0.94±3.26kg) and fat mass (+0.22±3.25kg) compared to the 9 non-compensators who lost body weight (-0.26±3.59kg) and had essentially no change in fat mass (+0.01±2.61kg) from 12-weeks to follow-up. There was a significant between group difference (p=.003) in change in fat mass from 12-weeks to follow-up between subjects who continued to regularly vigorously exercise (-2.205±3.070kg), and those who did not (+1.320±2.156kg). Additionally, energy compensation from baseline to 12-weeks and early body weight and composition changes during the intervention were moderate predictors of body weight and composition changes from baseline to follow-up. Conclusion: The main finding of this study is that following a 12-week supervised exercise intervention, women displayed a net loss of fat mass during the follow-up period if regular vigorous exercise was continued, regardless of whether they were classified as compensators or non-compensators during the initial intervention.
ContributorsCabbage, Clarissa Marie (Author) / Gaesser, Glenn (Thesis advisor) / Chisum, Jack (Committee member) / Campbell, Kathryn (Committee member) / Arizona State University (Publisher)
Created2013
Description
INTRODUCTION: Exercise performed at moderate to vigorous intensities has been shown to generate a post exercise hypotensive response. Whether this response is observed with very low exercise intensities is unclear. PURPOSE: To compare post physical activity ambulatory blood pressure (ABP) response to a single worksite walking day and a normal sedentary work day in pre-hypertensive adults. METHODS: Participants were 7 pre-hypertensive (127 + 8 mmHg / 83 + 8 mmHg) adults (3 male, 4 female, age = 42 + 12 yr) who participated in a randomized, cross-over study that included a control and a walking treatment. Only those who indicated regularly sitting at least 8 hours/day and no structured physical activity were enrolled. Treatment days were randomly assigned and were performed one week apart. Walking treatment consisted of periodically increasing walk time up to 2.5 hours over the course of an 8 hour work day on a walking workstation (Steelcase Company, Grand Rapids, MI). Walk speed was set at 1 mph. Participants wore an ambulatory blood pressure cuff (Oscar 2, SunTech Medical, Morrisville, NC) for 24-hours on both treatment days. Participants maintained normal daily activities on the control day. ABP data collected from 9:00 am until 10:00 pm of the same day were included in statistical analyses. Linear mixed models were used to detect differences in systolic (SBP) and diastolic blood pressure (DBP) by treatment condition over the whole day and post workday for the time periods between 4 -10 pm when participants were no longer at work. RESULTS:BP was significantly lower in response to the walking treatment compared to the control day (Mean SBP 126 +7 mmHg vs.124 +7 mmHg, p=.043; DBP 80 + 3 mmHg vs. 77 + 3 mmHg, p = 0.001 respectively). Post workday (4:00 to 10:00 pm) SBP decreased 3 mmHg (p=.017) and DBP decreased 4 mmHg (p<.001) following walking. CONCLUSION: Even low intensity exercise such as walking on a walking workstation is effective for significantly reducing acute BP when compared to a normal work day.
ContributorsZeigler, Zachary (Author) / Swan, Pamela (Thesis advisor) / Buman, Matthew (Committee member) / Gaesser, Glenn (Committee member) / Arizona State University (Publisher)
Created2013
Description
Dietary protein is known to increase postprandial thermogenesis more so than carbohydrates or fats, probably related to the fact that amino acids have no immediate form of storage in the body and can become toxic if not readily incorporated into body tissues or excreted. It is also well documented that subjects report greater satiety on high- versus low-protein diets and that subject compliance tends to be greater on high-protein diets, thus contributing to their popularity. What is not as well known is how a high-protein diet affects resting metabolic rate over time, and what is even less well known is if resting metabolic rate changes significantly when a person consuming an omnivorous diet suddenly adopts a vegetarian one. This pilot study sought to determine whether subjects adopting a vegetarian diet would report decreased satiety or demonstrate a decreased metabolic rate due to a change in protein intake and possible increase in carbohydrates. Further, this study sought to validate a new device called the SenseWear Armband (SWA) to determine if it might be sensitive enough to detect subtle changes in metabolic rate related to diet. Subjects were tested twice on all variables, at baseline and post-test. Independent and related samples tests revealed no significant differences between or within groups for any variable at any time point in the study. The SWA had a strong positive correlation to the Oxycon Mobile metabolic cart but due to a lack of change in metabolic rate, its sensitivity was undetermined. These data do not support the theory that adopting a vegetarian diet results in a long-term change in metabolic rate.
ContributorsMoore, Amy (Author) / Johnston, Carol (Thesis advisor) / Appel, Christy (Thesis advisor) / Gaesser, Glenn (Committee member) / Arizona State University (Publisher)
Created2012
Description
Walking interventions focused on increasing step counts are typically associated with salutary effects on glycemia, fasting insulin, insulin resistance and blood lipids which may be in turn associated with improvements in cardiorespiratory fitness (peak oxygen uptake – VO2peak) and vascular stiffness. We hypothesized that a novel 4-month, behavioral economics-based walking intervention would have favorable effects on glucose homeostasis and blood lipids and that these in turn would be related to VO2peak and vascular stiffness (carotid femoral pulse wave velocity – cfPWV).
We carried out secondary analyses on a subsample of sedentary, overweight/obese adults who participated in a 4-month, 2x2, randomized-controlled walking intervention examining the effects of goal setting (static v. adaptive goals) and rewards (immediate v. delayed) on steps/day (N=96). Fasting blood samples (n=58) were collected from participants before and after the intervention. Premenopausal females were in the follicular phase of their menstrual cycles. Lipid and glucose levels were measured using an automated chemistry analyzer, while insulin was measured using radio-immunoassay. Homeostatic model of insulin resistance (HOMA-IR) was calculated using the following formula (HOMA-IR=glucose x insulin / 405). We examined associations [partial correlations (adjusted for age)] between changes in blood biomarkers and VO2peak and cfPWV, irrespective of group, and we used linear mixed models to examine between-group differences in levels of and change in biomarker outcomes.
Groups did not differ in overall levels of, or degree of change in, biomarker outcomes (all p>0.05). Mean changes, irrespective of group, in biomarkers were as follows: glucose Δ= 0.74± 4.5mg/dl; insulin Δ= 0.09 ± 4.1 µU/ml; total cholesterol Δ= 0.24 ± 20.6 mg/dl; HDL-C Δ= 0.27 ± 5.1 mg/dl; LDL-C Δ= 1.3 ± 19.9 mg/dl; triglycerides Δ= 1.7 ± 27.2 mg/dl; HOMA-IR Δ = -.0548 ± 1.05). We found no significant associations between change in biomarker levels and change in VO2peak or change in cfPWV (all correlation coefficients < 0.15; p > 0.05).
A 4-month, behavioral economics-based mHealth intervention focused on increasing steps/day did not bring about favorable changes on markers of glycemia, insulin resistance and blood lipids.
We carried out secondary analyses on a subsample of sedentary, overweight/obese adults who participated in a 4-month, 2x2, randomized-controlled walking intervention examining the effects of goal setting (static v. adaptive goals) and rewards (immediate v. delayed) on steps/day (N=96). Fasting blood samples (n=58) were collected from participants before and after the intervention. Premenopausal females were in the follicular phase of their menstrual cycles. Lipid and glucose levels were measured using an automated chemistry analyzer, while insulin was measured using radio-immunoassay. Homeostatic model of insulin resistance (HOMA-IR) was calculated using the following formula (HOMA-IR=glucose x insulin / 405). We examined associations [partial correlations (adjusted for age)] between changes in blood biomarkers and VO2peak and cfPWV, irrespective of group, and we used linear mixed models to examine between-group differences in levels of and change in biomarker outcomes.
Groups did not differ in overall levels of, or degree of change in, biomarker outcomes (all p>0.05). Mean changes, irrespective of group, in biomarkers were as follows: glucose Δ= 0.74± 4.5mg/dl; insulin Δ= 0.09 ± 4.1 µU/ml; total cholesterol Δ= 0.24 ± 20.6 mg/dl; HDL-C Δ= 0.27 ± 5.1 mg/dl; LDL-C Δ= 1.3 ± 19.9 mg/dl; triglycerides Δ= 1.7 ± 27.2 mg/dl; HOMA-IR Δ = -.0548 ± 1.05). We found no significant associations between change in biomarker levels and change in VO2peak or change in cfPWV (all correlation coefficients < 0.15; p > 0.05).
A 4-month, behavioral economics-based mHealth intervention focused on increasing steps/day did not bring about favorable changes on markers of glycemia, insulin resistance and blood lipids.
ContributorsHook, Benjamin E. (Author) / Angadi, Siddhartha (Thesis director) / Gaesser, Glenn (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Background: Despite the reported improvements in glucose regulation associated with flaxseeds (Linum usitatissimum) few clinical trials have been conducted in diabetic participants. Objective: To evaluate the efficacy of ground flaxseed consumption at attenuating hyperglycemia, dyslipidemia, inflammation, and oxidative stress as compared to a control in adults with non-insulin dependent type 2 diabetes (T2D). Design: In a randomized parallel arm controlled efficacy trial, participants were asked to consume either 28 g/d ground flaxseed or the fiber-matched control (9 g/d ground psyllium husk) for 8 weeks. The study included 17 adults (9 male, 8 females; 46±14 y; BMI: 31.4±5.7 kg/m2) with a diagnosis of T2D ≥ 6 months. Main outcomes measured included: glycemic control (HbA1c, fasting plasma glucose, fasting serum insulin, and HOMA-IR), lipid profile (total cholesterol, LDL-C, HDL-C, total triglycerides, and calculated VLDL-C), markers of inflammation and oxidative stress (TNF-alpha, TBARS, and NOx), and dietary intake (energy, total fat, total fiber, sodium). Absolute net change for measured variables (week 8 values minus baseline values) were compared using Mann-Whitney U non-parametric tests, significance was determined at p ≤ 0.05. Results: There were no significant changes between groups from baseline to week 8 in any outcome measure of nutrient intake, body composition, glucose control, or lipid concentrations. There was a modest decrease in TNF-alpha in the flaxseed group as compared to the control (p = 0.06) as well as a mild decrease in TBARS in the flaxseed as compared to the control group (p = 0.083), though neither were significant. Conclusions: The current study did not detect a measurable association between 28 g/d flaxseed consumption for 8 weeks in T2D participants and improvements in glycemic control or lipid profiles. There was a modest, albeit insignificant, decrease in markers of inflammation and oxidative stress in the flaxseed group as compared to the control, which warrants further study.
ContributorsRicklefs, Kristin (Author) / Sweazea, Karen L (Thesis advisor) / Johnston, Carol S (Committee member) / Gaesser, Glenn (Committee member) / Vega-Lopez, Sonia (Committee member) / Gonzales, Rayna (Committee member) / Arizona State University (Publisher)
Created2015
Description
It is broadly accepted that physical activity provides substantial health benefits. Despite strong evidence, approximately 60% to 95% of US adults are insufficiently active to obtain these health benefits. This dissertation explored five projects that examined the measurement properties and methodology for a variety of physical activity assessment methods. Project one identified validity evidence for the new MyWellness Key accelerometer in sixteen adults. The MyWellness Key demonstrated acceptable validity evidence when compared to a criterion accelerometer during graded treadmill walking and in free-living settings. This supports the use of the MyWellness Key accelerometer to measure physical activity. Project two evaluated validity (study 1) and test-retest reliability evidence (study 2) of the Global Physical Activity Questionnaire (GPAQ) in a two part study. The GPAQ was compared to direct and indirect criterion measures including object and subjective physical activity instruments. These data provided preliminary validity and reliability evidence for the GPAQ that support its use to assess physical activity. Project three investigated the optimal h.d-1 of accelerometer wear time needed to assess daily physical activity. Using a semi-simulation approach, data from 124 participants were used to compare 10-13 h.d-1 to the criterion 14 h.d-1. This study suggested that a minimum accelerometer wear time of 13 h.d-1 is needed to provide a valid measure of daily physical activity. Project four evaluated validity and reliability evidence of a novel method (Movement and Activity in Physical Space [MAPS] score) that combines accelerometer and GPS data to assess person-environment interactions. Seventy-five healthy adults wore an accelerometer and GPS receiver for three days to provide MAPS scores. This study provided evidence for use of a MAPS score for future research and clinical use. Project five used accelerometer data from 1,000 participants from the 2005-2006 National Health and Nutrition Examination Study. A semi-simulation approach was used to assess the effect of accelerometer wear time (10-14 h.d-1) on physical activity data. These data showed wearing for 12 h.d-1 or less may underestimate time spent in various intensities of physical activity.
ContributorsHerrmann, Stephen (Author) / Ainsworth, Barbara (Thesis advisor) / Gaesser, Glenn (Committee member) / Der Ananian, Cheryl (Committee member) / Kang, Minsoo (Committee member) / Vega-Lopez, Sonia (Committee member) / Arizona State University (Publisher)
Created2011
Description
Sedentary behavior and excessive weight gain have been proven to deteriorate many characteristics of muscle. Low muscular power and mass with excess fat mass are risk factors for a multitude of chronic conditions and functional disabilities. Resistance training (RT) has long been accepted as a rehabilitative method of maintaining or enhancing muscular performance and composition. There are various methods of determining lower extremity muscular power; however, isokinetic dynamometry has emerged as one of the most accurate and reliable methods in clinical and research settings. Likewise, various methods exist for determining muscle thickness; however, many of those methods are expensive and can expose individuals to radiation. Ultrasonography has emerged as an accurate and reliable alternative to measuring lower extremity muscle thickness. The objective of this study was to assess the effects of high-load/low-volume (HLLV) and low-load/high-volume (LLHV) RT on isokinetic knee extensor and flexor peak power in sedentary, RT naïve, overweight or obese men and women (Body Mass Index ≥ 25 kg/m2). Twenty-one subjects (n = 21) completed this study and were randomized into one of the following groups: control, a HLLV group that performed three sets of 5 repetitions for all exercises until volitional fatigue, and LLHV which performed three sets of 15 repetitions for all exercises until volitional fatigue. Subjects randomized to the RT groups performed full-body exercises routines on three non-consecutive days per week. Changes in isokinetic knee extensor and flexor peak power, quadriceps ultrasound muscle thickness, and right leg segment of dual-energy X-ray absorptiometry (DEXA) scans were measured before and after the 12-week RT intervention. There were no significant differences found in group, time or, group by time interactions for knee extensor and flexor peak power using isokinetic dynamometry. Other than a group interaction for vastus intermedius muscle thickness (P=0.008), no significant interactions or differences were observed for any of the other variables tested. Based on the results of this study, neither high- nor low-load RT resulted in significant differences between intervention groups in peak power of the knee extensors and flexor, muscle thickness changes of the vastus intermedius, and vastus lateralis and, in the right lower extremity segmented body composition measures using DEXA.
ContributorsSarellis, Sofoklis Demetrios (Author) / Ofori, Edward (Thesis advisor) / Angadi, Siddhartha (Committee member) / Gaesser, Glenn (Committee member) / Arizona State University (Publisher)
Created2020
Description
Cardiovascular disease has long been one of the leading causes of morbidity in the world and places a large burden on the health care system. Exercise has been shown to reduce the risk of developing cardiovascular disease and the risk factors associated with it. Much of the focus of research has been on aerobic exercise modalities and their effect on these risk factors, and less is known in regard to the effect of resistance training. One novel risk factor for cardiovascular disease is arterial stiffness, specifically aortic stiffness. Aortic stiffness can be measured by carotid-femoral pulse wave velocity (PWV) and central pressure characteristics such as central blood pressures and augmentation index. The objective of this study was to assess the effect that two different 12-week long resistance training interventions would have on these measurements in sedentary, overweight and obese men and women (BMI ≥ 25 kg/m2). Twenty-one subjects completed the study and were randomized into one of the following groups: control, a low repetition/high load (LRHL) group which performed 3 sets of 5 repetitions for all exercises, and a high repetition/low load (HRLL) group which performed 3 sets of 15 repetitions for all exercises. Those in the resistance training groups performed full-body exercise routines on 3 nonconsecutive days of the week. Changes in arterial stiffness, central blood pressures, and brachial blood pressures were measured before and after the 12-week intervention period. PWV showed significant group by time interaction (p= 0.024) but upon post hoc testing no significant differences were observed due to the control group confounding (control: 7.6 ± 0.8 vs. 7.1 ± 0.8, LRHL: 6.7 ± 0.5 vs. 6.9 ± 0.5, HRLL: 7.03 ± 0.67 vs. 6.59). No other significant interactions or differences were observed for any of the variables tested. Based on the results of this study a 12-week long resistance intervention training, neither high nor moderate-intensity resistance training, resulted in improvements in indices of vascular stiffness or central and peripheral blood pressures.
ContributorsWeeldreyer, Nathan (Author) / Angadi, Siddhartha (Thesis advisor) / Gaesser, Glenn (Committee member) / Lee, Chong (Committee member) / Arizona State University (Publisher)
Created2020
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