Kinesiology
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Item ALLOSTATIC LOAD INFLUENCES VASCULAR FUNCTION AND SYMPATHOLYSIS IN YOUNG BLACK ADULTS(2024) Eagan, Lauren Elizabeth; Ranadive, Sushant M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the U.S., Black individuals tend to face a disproportionately higher risk for hypertension. This is largely attributed to chronic sympathetic activation induced by heightened exposure to psychosocial stressors. Allostatic load (AL), an index of cumulative physiological dysfunction from chronic stress, is associated with hypertensive risk and is also heightened in Black adults compared to those of other racial groups. Indeed, increased sympathetic activity is a hallmark characteristic of both hypertension and AL. The inability to blunt sympathetic-induced vasoconstriction during exercise (impaired functional sympatholysis) is also associated with hypertension. This dissertation aimed to investigate whether AL was associated with measures of vascular health in young Black adults, both at rest and during a sympathetic stressor. In our first study, we examined associations between AL and indices of vascular function and structure among young Black adults at rest, finding that higher AL was associated with greater macrovascular dysfunction and amplified wave-reflections. Additionally, we identified significant correlations among greater self-perceived stress with smaller brachial artery diameters and greater wave-reflections. The second aim of this dissertation focused on the associations between AL and the magnitude of functional sympatholysis among this population. Results indicated a positive association between AL and functional sympatholysis, with amplified sympatholytic responses among young Black females, as compared to their male counterparts, when forearm volume was controlled for. Overall, our findings suggest that elevated AL might predict macrovascular dysfunction at rest, with larger arterial diameters potentially compensating for chronic stress. These adaptive mechanisms, commonly observed in aging and diseased states, may also explain the positive correlations between AL and the functional sympatholytic response in young Black adults. Our consistent observations of the redundant vascular mechanisms among young Black adults allowing for adaptation to chronic stress strengthen our findings and further highlight the complex interplay between stress and cardiovascular health in Black adults.Item LOWER LIMB ASYMMETRY AND LOADING IN INDIVIDUALS WITH UNILATERAL TRANSFEMORAL AMPUTATIONS WITH A LIFETIME OF OSSEOINTEGRATED PROSTHESIS USE(2023) Burnett, Jenna K; Shim, Jae Kun; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Individuals with transfemoral amputation commonly develop chronic health problems due to decreased physical activity as a result of the missing musculature and tissue on the amputated side, and the poor imitation of the intact limb provided by the prosthesis. In addition, the indirect and semi-rigid connection of the socket to the body may increase interlimb asymmetries, as well as lead to pain and discomfort on the residual limb. Recent innovations have introduced a bone-anchored or osseointegrated (OI) implant which connects the prosthesis to the skeleton, and removes most of the socket related pain and discomfort complaints, as well as providing a rigid connection which may reduce the interlimb asymmetries. However, the direct bone and prosthesis connection may also introduce longitudinal bone health concerns due to the repetitive loads during walking. This dissertation investigated the effect of walking speed on the loads placed on the lower limbs of 11 individuals who use an OI prosthesis at 3 different anatomical levels, including the whole limb through interlimb ground reaction force, the joints through interlimb joint kinematics and kinetics, and finally the residual limb bone through implant input forces, finite element analysis of bone strain, and the probability of bone injury with a simulated lifetime of use.In study 1, the interlimb ground reaction force asymmetries were found to be moderate to large at all walking speeds, and to have a general increase as individuals walked faster, indicating there is an intact limb reliance strategy which may be used to compensate for the limitations of the amputated limb. Similarly, in study 2, the interlimb joint kinematics and kinetics were found to have moderate to large asymmetries at each joint level, with a general increase in asymmetry at faster walking, with this increase largely due to limitations within the prothesis. In study 3, the abutment force decreased in magnitude with walking speed, but the peak strain on the bone, and the probability of injury was greater for the preferred speed and fast speed walking when compared to slow speed walking. However, the overall probability of injury was low for all speeds, indicating the ability of the bone to repair and adapt with sustained loading likely provides effective protection over a lifetime of simulated OI prothesis use. The findings of this dissertation suggest that the more rigid connection afforded by the OI implant cannot fully remove the interlimb asymmetries which occur as a result of the poor imitation of the intact limb provided by the prosthesis and prosthesis components, but that there is minimal risk to the bone due to a lifetime of sustained walking with an OI prosthesis as a result the inherent ability of the bone to repair and adapt to variable loads over time. Therefore, while an OI prosthesis may not fully mitigate the interlimb asymmetries which occur as a result of the prosthesis limitations, individuals who use an OI prosthesis may feel confident that there is minimal longitudinal risk to the bone as a result of walking over their lifetime.Item RACIAL DIFFERENCES IN VASCULAR FUNCTION FOLLOWING INDUCED ACUTE INFLAMMATION(2020) Chesney, Catalina Anne; Ranadive, Sushant M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)African-Americans (AAs) have higher rates of cardiovascular disease (CVD), including hypertension and stroke, as compared to their Caucasian-American (CA) counterparts. High resting concentrations of systemic inflammatory biomarkers contribute to vascular dysfunction and are predictive of future cardiovascular events; differential resting levels of inflammatory markers between groups may reveal increased potential for CVD in at-risk groups. Additionally, impaired endothelial function and increased arterial stiffness, subclinical measures of CVD progression, have been reported in AA groups. The purpose of this study was to examine race differences between young, healthy AA and CA adults after a systemic inflammatory stimulus and subsequent endothelial responses to inflammation. Endothelial function, arterial stiffness, and hemodynamic variables were measured. The results suggest there were no race differences in vascular function or hemodynamic responses following an acute inflammatory stimulus.Item Understanding and Retraining the Causal Attributions for Exercise Intenders(2019) Singpurwalla, Darius; Iso-Ahola, Seppo E; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Given that ~50% of all exercise intenders will fall into the intention-behavior gap (i.e., a situation where people fail to act on their intentions), it is necessary to identify the constructs and/or theories that can explain the discord between intention and behavior (i.e., the intention-behavior gap). For this purpose, the present research was conducted through two studies that were designed to test the efficacy of causal attributions as a means to reduce the intention-behavior discord. The first study collected information from 952 individuals on their exercise behavior and their associated causal attributions over a six-week period. The findings from this study included: (1) those individuals who fell into the intention-behavior gap made self-serving attributions for their exercise failure; (2) Weiner’s model accurately predicted several of the affective and cognitive responses to exercise behavior for the sample of exercise intenders; and (3) causal attributions were not found to be effective moderators of the intention-behavior relationship. The second study was an experiment that tested whether an attribution retraining intervention could improve exercise behavior for a sample of sedentary, exercise intenders (n=200). Results of this study were mixed as the intervention appeared to have been able to modify one of the targeted attributional dimensions (control), but the effect was not strong enough to change the exercise behavior of the participants in the experimental group. It is suggested that attributions may not be able to reduce the gap because they represent conscious deliberations of the behavior, while sustained exercise is based on nonconscious processing of relevant information to make exercise an automatic behavior.Item TRAINING THE BODY FOR HEALTHISM: REIFYING VITALITY IN AND THROUGH THE CLINICAL GAZE OF THE NEOLIBERAL FITNESS CLUB(2013) Wiest, Amber Lynn; Andrews, David L; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Against the backdrop of changing understandings of (public) `health' and `fitness' in the contemporary United States, and through a nuanced critique of healthism (Crawford, 1980; Kirk & Colquhoun, 1989; Skrabanek, 1994), the aim of this project is to investigate how mediated renditions of `healthiness' are constructed and maneuvered in the for-profit fitness industry--and interrogate the non-necessary interrelationship between health, fitness, and (bio)citizenship in the historical present (Grossberg, 2006). This is examined through a critical explication of Amber's experiences and observations drawn from her period of (ethnographic) employment in the fitness industry. Focusing specifically on personal training as a biotechnological and pedagogical tool, we explicate how personal training becomes complicit in the communication of particular "healthist" understandings, which unerringly benefit private enterprise (as well as corroborate a pervasive political individualism) through the normalization of the individual's moral responsibility to embody, practice, and ultimately consume healthist practices and ideologies.Item Association between increased hepatic lipid storage and impaired hepatic mitochondrial function in ovariectomized mice(2012) Valencia, Ana Patricia; Spangenburg, Espen E; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Reduced ovarian function is associated with development of the metabolic syndrome (MetS). Increased risk for MetS is strongly linked to hepatic metabolic dysfunction. However, at this time few studies have examined metabolic function of hepatic tissue under conditions of reduced ovarian function. The purpose of this study was to determine if ovariectomy (OVX) impaired hepatic mitochondrial function and its potential association with sirtuin (SIRT) function. Female C57BL/6 mice were divided into two groups (SHAM, OVX). Hepatic mitochondrial function was measured by assessing oxygen consumption, reactive oxygen species (ROS) production, and mitochondrial protein content. In addition, mitochondrial acetylation status and SIRT protein content was determined. The OVX group exhibited increased ROS production compared to the SHAM group. However, no differences were detected in oxygen consumption, mitochondrial protein content, acetylation status, or total SIRT content between groups. The data shows that ovariectomy increases mitochondrial ROS production, which suggests a novel mechanism to consider.