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- Genre: Masters Thesis
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
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