This research assessed the role of Hatha yoga in the modulation of vascular health. In study one, Hatha yoga practitioners were compared to sedentary controls to whom they were matched for age and body mass index. Practitioners of Hatha yoga were no different from sedentary individuals in terms of arterial stiffness or vascular endothelial function. Yoga practitioners possessed lower HbA1c (P < 0.05) levels and lower pulse pressure (P < 0.05) than their sedentary counterparts. Practitioners of Hatha yoga had lower body fat percentages, but this observed trend did not reach statistical significance (P = 0.052). In study two, a 12-week Hatha yoga intervention resulted in reductions in HbA1c levels (P < 0.05) and total cholesterol (P < 0.05) in previously sedentary adults. No changes were observed in carotid artery compliance or brachial artery flow-mediated dilation as a result of the intervention. In study three, obese and lean, apparently healthy adults completed an 8-week Bikram yoga intervention. Reductions in total- and LDL-cholesterol were observed in the lean subjects (P < 0.05), with no changes in lipid profiles in the obese group. The homeostasis model assessment of insulin resistance (HOMA-IR) decreased in the lean subjects, but this trend did not attain statistical significance (P = 0.06). Although an observed trend was shown at 60 minutes during the oral glucose tolerance test (P = 0.07), glucose tolerance remained unchanged in the obese subjects. Brachial artery flow-mediated improved by approximately 2% in the obese subjects, but this observed change did reach statistical significance (P = 0.10). Flexibility increased in both groups as a result of the Bikram yoga intervention. Therefore Hatha yoga improved lipid profiles and glycemic control in sedentary adults, but no effects on vascular health were demonstrated. / text

Core exercise is a staple of many physical training regimens with goals ranging from improving athletic performance to rehabilitation of spine and knee injuries. Traditionally, dynamic movements such as flexion, lateral bending and twisting core exercise maneuvers are used in training programs; an approach consistent with training the distal limbs where muscular effort is mostly devoted to creating motion. However, knowledge of the functional anatomy of core musculature and spine injury mechanisms questions the use of these types of exercises. Alternative core exercises make use of isometric postures and static bracing to create muscular activation while minimizing spine loads and injury mechanisms linked with movement. This study aims to quantify the effect of various core training programs on the change of passive and active stiffness properties of the torso. This study was driven by several curiosities: 1) Isometric core exercises are reported to help some people who have low back pain. Is there a short lasting ???enhanced stiffness??? after performing these exercises? 2) Core training regimens use Isometric and Dynamic core exercises to enhance core bracing properties. Is one method superior to the other in terms of enhancing core stiffness? 3) If adaptations to core stiffness can be achieved with core exercise, do these adaptations differ between beginners and trained individuals? Twenty four healthy male subjects (22.9 ?? 2.7 years, 1.79 ?? 0.06 m, 77.5 ?? 10.8 kg) were recruited for short and long term core training. Of the overall population, twelve subjects (21.7 ?? 1.89 years, 1.80 ?? 0.076 m, 78.3 ?? 12.3 kg) were University students with little to no experience in performing regular core exercise. The other twelve subjects (24.2 ?? 2.89 years, 1.79 ?? 0.047 m, 76.8 ?? 9.71 kg) were athletically trained with at least one year of experience performing regular core exercise (minimum three times per week). This study was a repeated measures design examining short and long term core stiffness (active and passive) and range of motion before and after a single fifteen minute bout of isometric core exercise and a six week core training program. The long term training groups were divided evenly into isometric, dynamic and control groups. The Isometric group received a six week training program consisting of core bracing exercises ranging from basic static bodyweight exercises to weighted exercises with additional challenge of distal limb mobility while maintaining a braced core, while dynamic group exercises consisted of movement and speed based core exercises. The Control group received no further training during this period. All subjects were asked to refrain from any extra core demands not given by the researchers. After the training period was complete all subjects were retested for stiffness and range of motion. Passive stiffness tests were performed using a frictionless bending apparatus for flexion, extension, left and right lateral bend and left and right axial twist directions. Active stiffness was assessed via a ???quick release??? mechanism, preloaded with a 16 kg mass and randomly released to assess active extension. Participants were instrumented with unilateral electromyography (EMG) of selected core musculature and electromagnetic signals for motion capture for lumbar kinematics. To determine if training had an effect on dependent variables a series of repeated measures ANOVAs were performed; short term training utilized a 2x2 Repeated Measures ANOVA using the pre/post condition and training experience (na??ve vs. savvy) as factors. Long term training utilized a 3x2x2 Repeated Measures ANOVA using training group (Isometric vs. Dynamic vs. Control), training experience (na??ve vs. savvy) and pre/post condition as factors. In general, short term isometric core training increased core stiffness in all directions for na??ve and savvy subjects. Comparisons between these two subject groups did not yield any significant differences. After long term training stiffness was increased the greatest in the Isometric training group with both na??ve and savvy subjects. Dynamic training yielded significant increases in stiffness but for only one direction in each subject group (right lateral bend in na??ve subjects and left axial twist in savvy subjects). The Control group did not show any significant changes in stiffness. Comparisons between training groups and training experience did not yield any significant differences. Isometric training lead to significant stiffness increases in all test except for passive and active extension in na??ve subjects, and similar results were found for savvy subjects except for right lateral bend not showing any significant changes. Researchers believe reasons for insignificant changes are related to high variances which may be due to inadequate statistical power and a wide variety of responses within each subject group. Though some analyses showed inadequate statistical power due to small sample sizes it should be noted that this research is the first of its kind investigating the trainability of core stiffness in the short and long term, and thus difficult to establish sample sizes without any baseline values. The findings of this study can be directly applied to core training for rehabilitation and athletic function. Enhancements in core stiffness are thought to subsequently enhance traits such as load bearing ability, pain management and athletic function. The results of short term training give insight into how a short training session performed prior to a load bearing task can make the task safer and easier to perform. The results of long term training show that Isometric training performed over a long duration may induce more permanent enhancements to stiffness and core function.

Suspensions play a crucial role in vehicle comfort and stability. Different types of suspensions have been proposed to fulfill the essential characteristics of vehicle suspensions. A semi-active suspension with adjustable damper improves the performance of a suspension in different conditions and it is better than a passive suspension in terms of ride comfort and handling. Furthermore, it is not as expensive and complicated as an active suspension. Semi-active suspensions rely on adjustable damping coefficient. A new type of air suspension with independent ride height and stiffness tuning has been developed recently. By using two air chambers in the suspension system, ride height of vehicle and stiffness of suspension can be adjusted independently and simultaneously. The conventional air suspension systems use compressor to pump the air into a single flexible rubber airbag and by inflating the air, the chassis will be raised from the axle (ride height control). In this type of suspensions, the stiffness of spring is not under control. In the new air suspension system, by controlling the air pressure on both chambers, one can tune the suspension stiffness and the ride height of the vehicle at the same time for different driving conditions. The air suspension is also able to maintain the vehicle body at the same height and natural frequency for different load or number of passengers. This thesis discusses about the design analysis of an air suspension with ride height and stiffness tuning. The analytical formulation is developed for the optimum design of the new air suspension system. In this thesis, the interconnection between the pressurized chambers of the new air suspension with ride height and stiffness tuning is studied to further improve the performance. Proper interconnection of air springs can help the suspension system to distribute the load between tires more evenly on rough roads or uneven surfaces. Different configurations in air spring interconnection have different impact on the handling and tire load distribution. To study the effect of air spring interconnection configurations on tires load distribution and vehicle handling, a general mathematical model is developed. This model is used to compare various configurations in detail. Results show that interconnection could improve tire load distributions greatly. It is also shown that improving tire load distribution will deteriorate roll stiffness that in turn deteriorate vehicle handling at higher speeds. Since on rough roads, vehicle’s speed is necessarily low, interconnection will not have adverse effects on vehicle handling when activated.

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Master of Science / Department of Kinesiology / Carl Ade / Background – Chemotherapy-induced left ventricular cardiotoxicity is associated with many cancer treatments; however, what is less known is how these treatments affect vascular health and autonomic control of blood pressure. Arterial stiffness and cardiovagal baroreflex sensitivity (BRS) are indicators of cardiovascular health and may provide insight into the adverse effects of anti-cancer chemotherapy. Therefore, the primary aims of the present study were to evaluate carotid artery stiffness and arterial BRS in cancer patients currently being treated with adjuvant chemotherapy. Methods – We performed a cross-sectional, case-control study involving 9 cancer patients and 9 age- and sex-matched controls. Carotid artery stiffness was assess via 2D ultrasonography. Cardiovagal BRS was assessed from the spontaneous changes in beat-to-beat time series of R-R interval and systolic blood pressure via the cross correlation technique. Results – Our findings indicated a significant decrease in cardiovagal BRS in cancer patients compared to controls (4.7 ± 0.6 vs 9.2 ± 1.7 msec mmHg⁻¹ respectively, P = 0.02). Carotid artery β-Stiffness was significantly higher in the cancer patients compared to control participants (9.2 ± 1.2 vs 6.6 ± 0.74 U respectively, P = 0.05). Conclusions – These data suggest that anti-cancer chemotherapy elicits significant decreases in the autonomic control of blood pressure and arterial stiffness, leaving cancer survivors with an increased risk of future cardiovascular disease.

Nonlinearity accompanied with stiffness in atmospheric boundary layer physical parameterizations is a well-known concern in numerical weather prediction (NWP) models. Nonlinear diffusion equations, furthermore, are a class of equations which are extensively applicable in different fields of science and engineering. Numerical stability and accuracy is a common concern in this class of equation. In the present research, a comprehensive effort has been made toward the temporal integration of such equations. The main goal is to find highly stable and accurate numerical methods which can be used specifically in atmospheric boundary layer simulations in weather and climate prediction models, and extensively in other models where nonlinear differential equations play an important role, such as magnetohydrodynamics and Navier-Stokes equations. A modified extended backward differentiation formula (ME BDF) scheme is adapted and proposed at the first stage of this research. Various aspects of this scheme, including stability properties, linear stability analysis, and numerical experiments, are studied with regard to applications for the time integration of commonly used nonlinear damping and diffusive systems in atmospheric boundary layer models. A new temporal filter which leads to significant improvement of numerical results is proposed. Nonlinear damping and diffusion in the turbulent mixing of the atmospheric boundary layer is dealt with in the next stage by using optimally stable singly-diagonally-implicit Runge-Kutta (SDIRK) methods, which have been proved to be effective and computationally efficient for the challenges mentioned in the literature. Numerical analyses are performed, and two schemes are modified to enhance their numerical features and stability. Three-stage third-order diagonally-implicit Runge-Kutta (DIRK) scheme is introduced by optimizing the error and linear stability analysis for the aforementioned nonlinear diffusive system. The new scheme is stable for a wide range of time steps and is able to resolve different diffusive systems with diagnostic turbulence closures, or prognostic ones with a diagnostic length scale, with enhanced accuracy and stability compared to current schemes. The procedure implemented in this study is quite general and can be used in other diffusive systems as well. As an extension of this study, high-order low-dissipation low-dispersion diagonally implicit Runge-Kutta schemes are analyzed and introduced, based on the optimization of amplification and phase errors for wave propagation, and various optimized schemes can be obtained. The new scheme shows no dissipation. It is illustrated mathematically and numerically that the new scheme preserves fourth-order accuracy. The numerical applications contain the wave equation with and without a stiff nonlinear source term. This shows that different optimized schemes can be investigated for the solution of systems where physical terms with different behaviours exist.

Cellular structures are highly evaluated due to their high material efficiency. Both theoretical and experimental studies have done on periodic cellular structures. However, the mechanical performance can be stochastically distributed in the cellular architecture. This thesis presents the design and manufacturing of variable stiffness cellular architecture to achieve optimized topology by changing the unit cell parameters. The author applies image analysis technique to extract and digitize the information from the performance distribution map. Two types of cellular cells are studied for their relationship of stiffness and relative density. The methods of voxelization for both cells are also given in this study. This proposed methodology is then implemented to design a customized mattress and compare with current existing mattress. With the study of the unit cells and voxelization technique, our designed mattress aligns body curve better which provides more recuperation of the body during sleep.

Indiana University-Purdue University Indianapolis (IUPUI) / Leg-Spring Stiffness (LSS) is the measure of the musculoskeletal, neuromuscular, and biomechanical functions of the human body, and an appropriate evaluation metric for changes brought on by Anterior Cruciate Ligament Reconstruction (ACLr). ACLr can lead to flexion and extension loss, resulting in increased stiffness of the musculotendinous units of the ACLr leg and thus changes in LSS. LSS can be measured using Kleg, but little is known about the validity and reliability of the different methods of LSS and Kleg calculations. The purpose of this study was to determine if ACLr leads to a change in LSS (as measured by Kleg) during hopping, and to compare results of the Spring-Mass calculation and knee Joint Torsional stiffness methods in the computation of the overall Kleg. Video data synchronize with GRF were used to compute the kinematic and kinetic variables. Mann-Whitney U tests were used to determine significant differences between the control and experimental group for the Spring-Mass method of calculation (p = 0.004), Joint Torsional method (p =0.44), Kknee (p = 0.29), and Kankle (p = 0.17). Cohen’s effect calculations showed small to medium effects for the KKnee, (d = 0.383) but moderate effect size for the KAnkle, (d = 0.541). Wilcoxon Signed Rank comparison for all the legs and (N=42) between computational methods were significant differences between computational methods (Z = 5.65, p = 0.000), and with a large effect size (Cohen’s d = 3.14). Similar results were found when comparing only the ACLr leg values (p = 0.005, Cohen’s d = 4.88). The comparison between ACL Leg vs Non-ACL leg for experimental group subjects was not significant in either calculation method (Spring-Mass p = 0.20, Z = -1.27; torque calculation p = 0.96, Z = -0.05). The spring-mass method was more stable and able to detect differences between the control and ACLr group. The lack of statistical differences in the joint torsion calculation method, as well as in comparing the unaffected leg to the ACLr leg in the experimental group, suggests that LSS may not be a precise enough measurement to determine the effects of an ACLr.

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Background. Stroke affects over 80 million individuals worldwide. Elevated arterial stiffness has emerged as a novel independent risk marker for stroke. While arterial stiffness is improved after chronic aerobic training, a single bout of aerobic exercise leads to transient increases that typically resolve within 5 minutes of recovery. Elevated arterial stiffness may persist for up to 30 minutes following exercise in populations with cardiovascular disease. However, no study has examined the effect of acute aerobic exercise on arterial stiffness and central hemodynamics in individuals with stroke. Moreover, no study has explored the clinical significance of these responses. Objectives. The primary objective of this thesis was to characterize the response and recovery of arterial stiffness and central hemodynamics to peak aerobic exercise in individuals ≥ 6 months post-stroke. The secondary objective was to explore the relationships between the exercise response and recovery of arterial stiffness and central hemodynamics, with cardiorespiratory fitness and walking ability. Results. This cross-sectional study recruited 10 adults with stroke (mean ± SD age=56.9 ± 11.8; median [IQR]= 2.9 [1.9] years post-stroke; n=4 females). After peak aerobic exercise, cfPWV increased from rest and remained elevated for 20 minutes (p<0.05). Heart rate increased and remained elevated for 10 minutes post-exercise (p<0.05), while systolic blood pressure decreased and remained reduced for 15 minutes (p<0.05). Positive associations were found between cardiorespiratory fitness and heart rate reserve (r=0.74, p=0.02), and with each phase of heart rate recovery (HR60s r=0.80, p=0.005, HR120s r=0.79, p=0.006; HR300s r=0.72, p=0.02; and HR600s r=0.75, p=0.01). There were no relationships between response and recovery of hemodynamic variables with walking ability. Conclusion. Individuals with chronic stroke may have impaired arterial stiffness and heart rate recovery following peak aerobic exercise. Moreover, heart rate reserve and all phases of heart rate recovery were related to cardiorespiratory fitness, but not walking ability. / Thesis / Master of Science Rehabilitation Science (MSc) / Arterial stiffness has been recently identified as an important risk marker for stroke. Aerobic exercise reduces the risk of stroke by lowering arterial stiffness. But during exercise, there is an increase in arterial stiffness that usually subsides by 5 minutes. Lengthy exposure to arterial stiffness can cause damage to organs like the kidneys and liver. The purpose of this thesis was to measure the arterial stiffness and cardiovascular response to exercise in people with stroke. We also studied the relationship between the responses, fitness and walking ability. Ten people with stroke participated in this study. After aerobic exercise, arterial stiffness stayed high above resting levels and did not recover after 20 minutes. Also, heart rate recovery was related to fitness but not walking ability. This study tells us that people with stroke have an weakened ability to recover from aerobic exercise and that higher fitness levels can improve exercise recovery.