Browsing by Subject "autonomic nervous system"
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Item Autonomic nervous control of cardiovascular function during prolonged exercise in humans(2014-05-01) White, Daniel W.; Peter B. RavenThe importance of physical activity is well established as a means to maintain good health. However, under certain conditions and in some individuals, heavy exercise leads to catastrophic failure of the cardiovascular system. This is especially true during early recovery from exercise. This may be due in part to an improper response of the autonomic nervous system; that is, an imbalance of the sympathetic and parasympathetic nervous systems. The purpose of the investigations presented in this dissertation was to: i) re-evaluate the commonly accepted model of autonomic influence on control of heart rate during exercise; ii) study the effects of posture on recovery from heavy exercise; and iii) determine the effect of muscle pump activity on cardiorespiratory control of the cardiovascular system during the transition from active to inactive recovery following heavy dynamic two legged cycling. In the first investigation we examined previously reported and newly collected data and determined a fine balance exists between the sympathetic and parasympathetic nervous systems throughout all intensities of exercise. Our conclusions led to the development of a new model of autonomic balance during exercise. In the second investigation we concluded that unloading of the cardiopulmonary baroreceptors by upright posture significantly increases baroreflex control of heart rate during rest and during recovery from heavy dynamic leg cycling exercise. We also show that steady-state blood pressure and the baroreflex control of blood pressure is not significantly different based on orthostatic posture before or after exercise. In the third investigation we concluded that loading of the cardiopulmonary baroreceptors by muscle pump activity during active recovery from heavy exercise diminishes the respiratory induced changes in cardiovascular function observed during inactive recovery. Overall, these investigations highlight the importance of the autonomic nervous system during exercise and during recovery from heavy exercise. Collectively, these conclusions should influence the decision making process regarding mode of recovery from heavy exercise, especially in an “at risk” population, because recovery is the time when most adverse events take place.Item Effects of Cervical Manipulation on Cardiac Autonomic Control(2006-05-01) Giles, Paul David; Michael Smith; Scott Stoll; Walter WitryolGiles, Paul David, Effects of Cervical Manipulation on Cardiac Autonomic Control. Master of Science (Clinical Research and Education – OMM), May 2006, pp, 1 table, 8 figures, references. Objective: Osteopathic Manipulative Medicine treatment (OMT) regimes often focus on treating the Autonomic Nervous System (ANS) in addition to biomechanics. Techniques focused on the upper cervical spine are theorized to affect the function of the vagus nerve and thereby influence the parasympathetic branch of the ANS. This study was conducted to observe the effect of upper cervical spine manipulation on cardiac autonomic control as measured by heart rate variability (HRV). Methods: Nineteen healthy, young adult subjects were randomly assigned an order in which they would undergo three different experimental protocols: OMT, Sham, and a time control. Six minutes of electrocardiographic data was collected before and after each intervention to be analyzed by power spectral analysis. Results: All baseline data for each protocol and all parameters studied were the same. The OMT protocol and all parameters studied were the same. The OMT protocol caused a change in the standard deviation of the normal-to-normal (SDNN) intervals (0.121 +/- 0.0822 sec, p=0.005) and the change in the high frequency HRV was different from the changes caused by other interventions (p=0.038). Conclusions: This preliminary data supports the hypothesis that under cervical spine manipulation affects the parasympathetic nervous system; however, more data on more subjects needs to be collected in order to clarify some points, and to reach statistical significance in certain measures.Item Inhibitory Rib-Raising and Microneurographic Measurement of Sympathetic Nervous System Activity(2007-05-01) Kinzler, Damien W.; Michael Smith; Russell Gamber; Hollis KingThe clinical effectiveness of osteopathic manipulative therapy (OMT) techniques that are designed to address the autonomic nervous system (ANS) are untested to current research standards. As the concept of “autonomic imbalance” is frequently ascribed as the etiology of various pathologic conditions, it is paramount to undertake basic research into not only efficacy but also possible mechanistic actions and origins. Osteopathic physicians often utilize treatment regimens and techniques for which the given mechanism of action is simply attributed to “balancing the autonomics”. This intuitive concept may finally be at the threshold where enough basic science exists to justify clinical investigations. Osteopathic manual manipulative techniques have shown effectiveness in the treatment of various musculoskeletal conditions and have been shown to lower perceived pain; supporting the use of manual therapy as an effective treatment modality. A brief review yields the following within just the last four years: Eisenhart showed positive range-of-motion outcomes after ankle sprain in the emergency department. Biondi reviews the usefulness of cervical manipulation for tension headache and McReynolds demonstrated an equivalent decrease in acute neck with OMT versus intramuscular ketolac in an emergency department setting, although the dosing was not maximal. German researchers have shown effectiveness in chronic epicondylopathia humeri radialis and research has led to the demonstration of lowered post-operative pain in hip or knee arthroplasty. There has also been decreased post-operative pain medication reported in hysterectomy when compared with a control group. OMT has demonstrated a decrease in fibromyalgia symptoms when used with standard care over standard care alone. Low back pain, perhaps the most extensively studied diagnosis in which OMT has been evaluated, has reported numerous positive outcomes including lower levels of narcotic use and decreased pain in both double-blinded and meta-analysis studies, although there is still considerable debate within this area. There has also been favorable outcomes associated with the management of gain in Parkinson’s disease and preliminary work has shown the efficacy in treatment of carpal tunnel syndrome. Most of the aforementioned musculoskeletal conditions are not amenable to traditional therapies and have a high-cost burden on the economy. Traditional treatments generally have a “wait and see” approach combined with analgesics which may not cause harm, but hampers quality of life and income in the interim. The cost effectiveness of OMT is still in the preliminary stages, but there is evidence supporting a superior cost benefit ratio when compared to standard care and since many of these conditions have no other proven treatment modality available patients will often try anything over nothing. The evaluation of OMT addressing clear autonomic dysfunction is limited. This study closes a small part of that gap by examining the proposed physiologic mechanism of OMT and its’ interaction with the ANS. Small studies have documented changes, namely heart rate variability, in autonomic processes in healthy individuals while other, older studies have found benefit in clinical variables. With few exceptions however, most of these studies lacked a particular technique protocol. Operators were free to use whatever intervention that they chose and most of these studies were not performed under rigorous testing methods with a randomized design. The technique that was evaluated (inhibitory rib-raising) has a documented history from the origins of osteopathic medicine in the United States, and is currently taught to students in osteopathic medical schools as part of their medical education curriculum. Rib-raising is most often taught to enhance the mechanical motion of the ribs, but other paradigms utilize this technique to either enhance or inhibit sympathetic nervous system (SNS) activity. The evaluation of inhibitory rib-raising or its’ proposed mechanism of action has never been rigorously scrutinized to modern scientific standards. The current study was designed to address that gap with both direct and indirect measurement of SNS variable in healthy individuals with the hypothesis that there would be a time-dependent, graded reduction in measured sympathetic nervous system activity (MSNA) in healthy individuals undergoing cold-pressor stimulus.