Matching Items (9)
Filtering by
- All Subjects: Exercise
- All Subjects: Physiology
- Creators: Gaesser, Glenn
Description
Eccentric muscle action (ECC) occurs when the force exerted by a working muscle is less than that of an outside resistance. This is characterized by muscle lengthening, despite actin-myosin crossbridge formation. Research has indicated that muscles acting eccentrically are capable of producing more force when compared to muscles acting concentrically. Further, research has shown ECC muscle actions may have different fatigue patterns that CON actions. The purpose of this study was to determine if a) ECC bench press yields greater strength than concentric (CON) as measured by one-repetition maximum (1RM), b) there is a difference between the number of repetitions that can be completed concentrically and eccentrically under the same relative intensities of 1RM (90%, 80%, 70%, 60%), c) a prediction model may be able to predict ECC 1RM from CON 1RM or CON repetitions to fatigue. For this study, 30 healthy males (age = 24.63 + 5.6 years) were tested for 1RM in CON and ECC bench press, as well as the number of repetitions they were able to complete at various intensities of mode-specific 1RM. A mechanical hoist was affixed to a gantry crane and placed over a standard weightlifting bench. The hoist was connected to 45lb plates that were loaded on a standard barbell, which allowed for mechanical raising and lowering of the barbell. For CON repetitions, the weight was mechanically lowered to the chest and the participant pressed it up. For ECC repetitions, the weight was mechanically raised and the participant lowered it. Paired t-tests showed that ECC 1RM was significantly (p < 0.05) greater than CON 1RM (ECC =255.17 + 68.37lbs, CON = 205.83 + 58.43lbs). There was a significant difference (p < 0.05) between the number of repetitions completed at 90% 1RM (CON = 4.57 + 2.21 repetitions, ECC = 7.67 + 3.24 repetitions). There were no differences in repetitions completed at any other intensity 1RM. CON 1RM and the number of repetitions completed with two different absolute loads (130-150lbs and 155-175lbs) concentrically and eccentrically were valid predictors of ECC 1RM. These data indicate that ECC actions yield increased force capabilities than CON actions, there is no difference in the rate of the fatigue, and ECC 1RM may be predicted from various CON tests.
ContributorsKelly, Stephen B., Jr (Author) / Hooker, Steven (Thesis advisor) / Brown, Lee (Committee member) / Buman, Matthew (Committee member) / Gaesser, Glenn (Committee member) / Swan, Pamela (Committee member) / Arizona State University (Publisher)
Created2013
Description
Birds have plasma glucose levels that are 1.5-2 times greater than mammals of similar body mass in addition to higher free fatty acid concentrations, both of which would typically impair endothelium-dependent vasodilation if observed in mammals. Endothelium-dependent vasodilation can be stimulated in mammals through the use of acetylcholine (ACh), which primarily acts through nitric oxide (NO) and cyclooxygenase (COX)-mediated pathways, with varying reliance on endothelial-derived hyperpolarizing factors (EDHFs). Very few studies have been conducted on small resistance systemic arteries from birds. The hypothesis was that because birds have naturally high glucose and free fatty acid concentrations, ACh-induced vasodilation of isolated arteries from mourning doves (Zenaida macroura) would be independent of endothelial-derived factors and resistant to high glucose-mediated vascular dysfunction. Small resistance mesenteric and cranial tibial (c. tibial) arteries were pre-constricted to 50% of resting inner diameter with phenyleprine then exposed to increasing doses of ACh (10-9 to 10-5 μM) or the NO donor, sodium nitroprusside (SNP; 10-12 to 10-3 μM). For both vessel beds, ACh-induced vasodilation occurred mainly through the activation of potassium channels, whereas vasodilation of mesenteric arteries additionally occurred through COX. Although arteries from both vessel beds fully dilated with exposure to sodium nitroprusside, ACh-mediated vasodilation was independent of NO. To examine the effect of high glucose on endothelium-dependent vasodilation, ACh dose response curves were conducted following exposure of isolated c. tibial arteries to either a control solution (20mM glucose) or high glucose (30mM). ACh-induced vasodilation was significantly impaired (p = 0.013) when exposed to high glucose, but normalized in subsequent vessels with pre-exposure to the superoxide dismutase mimetic tiron (10 mM). Superoxide concentrations were likewise significantly increased (p = 0.0072) following exposure to high glucose. These findings indicate that dove arteries do not appear to have endogenous mechanisms to counteract the deleterious effects of oxidative stress. Additional studies are required to assess whether endogenous mechanisms exist to protect avian vascular reactivity from systemic hyperglycemia.
ContributorsJarrett, Catherine Lee (Author) / Sweazea, Karen L (Thesis advisor) / Johnston, Carol (Committee member) / Gaesser, Glenn (Committee member) / Arizona State University (Publisher)
Created2012
Description
This study examines the effect of exercise therapy on a stationary bike on cognitive function, specifically inhibition and set-switching, in adolescents with Down syndrome. 44 participants were randomly divided between the voluntary cycling therapy group (VCT) (i.e., self-selected cadence), assisted cycling therapy group (ACT) (i.e., 30% faster than self-selected cadence accomplished by a motor), and a control group (NC) in which the participants did not undergo any exercise therapy. Both cycling groups rode a stationary bicycle, for 30 minutes, three times a week, for eight-weeks. At the beginning (i.e., pretest) and end (i.e., posttest) of the eight-week session the participants completed tasks to evaluate their cognitive function. They completed three trials of the card sort test (i.e., set-switching) and three trials of the knock-tap test (i.e, inhibition) before and after eight-weeks of cycling therapy. The scores of these tests were analyzed using one-way ANOVA between groups and paired samples t-tests. The results showed that after eight-weeks of cycling therapy the participants in the VCT group performed worse in the knock-tap test, but improved in two trials of the card sort test. The results also showed that the participants in the ACT group performed worse after eight-weeks of exercise therapy in one trial of the card sort test. No significant changes were seen for the control group. Due to the fact that on average the participants in the VCT group cycled with a higher heart rate, our results suggest exercise that significantly elevates heart rate can improve cognitive function, specifically set-switching, in adolescents with Down syndrome.
ContributorsBenson, Alicia Meigh (Author) / Ringenbach, Shannon (Thesis director) / Amazeen, Eric (Committee member) / Maraj, Brian (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
The purpose of this study was to investigate the effects of high intensity interval exercise (HIIE) on postprandial fat and carbohydrate oxidation after a high carbohydrate and fat meal in healthy adults. It was hypothesized that the HIIE would result in greater postprandial fat oxidation than the control condition. Three subjects, all non-obese (BMI<30) from the ages of 21-24, underwent a 3 visit protocol. The first visit was to establish a VO2 max (on a cycle ergometer) and the following two were randomized between a control and exercise condition. The exercise condition was comprised of one hour rest to provide baseline data, followed by a 1 minute on (90-95% HR max), one minute off high intensity interval protocol on a cycle ergometer. This was conducted until the same amount of kcal as the standard meal (490 kcal. 250 kcal snickers and 240 kcal sprite) was expended. After the exercise, the participant waited for one hour to minimize the effects of the excess post-exercise oxygen consumption (EPOC) period, and then consumed the meal. Once this was completed, VO2 was measured for the last 10 minutes of every 30 minutes for a full 5 hours postprandial. The same methodology was employed in the control condition except for the exercise protocol. Results showed a significantly greater fat oxidation in the HIIE condition, oxidizing 28 grams, 32 grams, and 27 grams of fat in each of the 3 subjects compared to 14, 16, and 17 grams in the control condition respectively. This supports the notion that HIIE results in greater postprandial fat oxidation compared to seated rest.
ContributorsSeroka, Zachary Steven (Author) / Gaesser, Glenn (Thesis director) / Angadi, Siddhartha (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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
PURPOSE: Lean hypertension (HTN) is characterized by a mechanistically different HTN when compared to obese HTN. The purpose of this study is to assess whether body phenotype influences blood pressure (BP) responses following both acute and chronic exercise. METHODS: Obese (body mass index (BMI) > 30 kg/m2) and lean (BMI < 25 kg/m2) men with pre-hypertension (PHTN) (systolic BP (SBP) 120 - 139 or diastolic BP (DBP) 80 - 89 mm Hg) were asked to participate in a two-phase trial. Phase 1 assessed differences in post-exercise hypotension between groups in response to an acute exercise bout. Phase 2 consisted of a two-week aerobic exercise intervention at 65-70% of heart rate (HR) max on a cycle ergometer. Primary outcome measures were: brachial BP, central (aortic) BP, cardiac output (CO), and systemic vascular resistance (SVR) measured acutely after one exercise session and following two weeks of training. RESULTS: There were no differences between groups for baseline resting brachial BP, central BP, age, or VO2 peak (all P > 0.05). At rest, obese PHTN had greater CO compared to lean PHTN (6.3 ± 1 vs 4.7 ± 1 L/min-1, P = 0.005) and decreased SVR compared to lean PHTN (1218 ± 263 vs 1606 ± 444 Dyn.s/cm5, P = 0.003). Average 60-minute post-exercise brachial and central SBP reduced by 3 mm Hg in Lean PHTN in response to acute exercise (P < 0.005), while significantly increasing 4 mm Hg for brachial and 3 mm Hg for central SBP (P < 0.05). SVR had a significantly greater reduction following acute exercise in lean PHTN (-223 Dyn·s/cm5) compared to obese PHTN (-75 Dyn·s/cm5, P < 0.001). In lean subjects chronic training reduced brachial BP by 4 mm Hg and central BP by 3 mm Hg but training had no effect on the BP’s in obese subjects. Resting BP reduction in response to training was accompanied by reductions in SVR within lean (-169 Dyn·s/cm5, P < 0.001), while obese experienced increased SVR following training (47 Dyn·s/cm5, P < 0.001). CONCLUSION: Hemodynamic response to both acute and chronic exercise training differ between obese and lean individuals.
ContributorsZeigler, Zachary (Author) / Swan, Pamela (Thesis advisor) / Gaesser, Glenn (Committee member) / Buman, Matthew (Committee member) / Angadi, Siddhartha (Committee member) / Farouk, Mookadam (Committee member) / Arizona State University (Publisher)
Created2016
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
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
Estimates indicate that in the United States 1 in 8 women will develop breast cancer in their lifetime. Improved cancer screenings, early detection, and targeted treatments have increased breast cancer survival rates. However, breast cancer patients treated with chemotherapy are at an increased risk for cardiovascular disease, functional impairments, and loss of cardiorespiratory fitness. These negative outcomes have implications for early morbidity and mortality. The purpose of this thesis was to test the hypothesis that high-intensity exercise preconditioning (exercise commenced prior to initiating chemotherapy and continued throughout treatment cycles) preserves health-related outcomes in breast cancer patients treated with anthracycline-containing chemotherapy. Here, we present a subset of preliminary data from an ongoing trial (NCT02842658) that is focused on VO2peak and skeletal muscle outcomes from the first 10 participants that have enrolled in the trial. Breast cancer patients (N=10; 50 ± 11 y; 168 ± 4 cm; 92 ± 37 kg; 32.3 ± 12.3 kg/m2) scheduled to receive anthracycline-containing chemotherapy were randomly assigned to one of two interventions: 1) exercise preconditioning, (3 days per week of supervised exercise throughout treatment) or 2) standard of care (attention-control). Pre-testing occurred 1-2 week prior to chemotherapy. The interventions were initiated 1 week prior to chemotherapy and continued throughout anthracycline treatment. Post-testing occurred 3-7 days following the last anthracycline treatment. VO2peak (L/min) was reduced by 16% in the control group (P < 0.05), whereas VO2peak was preserved in the exercise preconditioning group. Trends for greater preservation and/or improvement in the exercise preconditioning group were also observed for lean body mass and peak heart rate. Hand grip strength was not changed in either group (P > 0.05). Both groups demonstrated an increase in ultrasound-derived echogenicity measures of the vastus lateralis (P < 0.05), indicating changes in the composition of the skeletal muscle during treatment. These preliminary data highlight that exercise preconditioning may serve as a strategy to preserve cardiorespiratory fitness and perhaps lean mass during anthracycline treatment of breast cancer. There remains a need for larger, definitive clinical trials to identify strategies to prevent the array of chemotherapy-induced toxicities that are observed in breast cancer patients treated with anthracyclines.
ContributorsCasey, Kathleen (Author) / Angadi, Siddhartha (Thesis director) / Gaesser, Glenn (Committee member) / Dickinson, Jared (Committee member) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05