The general purpose of this study was to examine factors that may influence acceleration characteristics of the upper body during walking, thereby clarifying the means by which the postural system facilitates dynamic stability of the upper body during walking. Upper body accelerations were measured during a range of straight-line walking tasks. Time domain, frequency domain, signal regularity and coupling analyses were used to 1) provide new insight into gait-related upper body accelerations during walking in normal healthy adults, and 2) determine how the postural system accommodates to perturbations that challenge upper body stability during walking. The specific perturbations to the postural system that were examined in the present study were the normal ageing process, changes in walking speed, and fatigue of the cervical and lumbar erector spinae. In general, the patterns of accelerations measured at the level of the head were an attenuated version of those at the lower trunk during normal walking. Power spectral analysis revealed that both the head and lower trunk in the anterior-posterior (AP) and vertical directions (VT) directions were characterised by a single peak frequency corresponding the step frequency during normal walking. However, the most notable of all attenuation profiles was the difference between accelerations of the head and lower trunk in the mediolateral (ML) direction. ML trunk accelerations were characterised by multiple low amplitude frequency peaks, which were attenuated to a single peak at the head corresponding to stride frequency. The coupling between acceleration directions was greater for the head than the lower trunk, suggesting that the postural system promotes a coordination strategy which enhances global stability of the head. Subdividing the upper body into neck and trunk segments facilitated a more comprehensive description how the gait-related oscillations are prevented from impacting on the motion of the head. Overall, acceleration amplitude, power content, and regularity were predominantly regulated by the trunk segment, especially for the AP and ML directions. This suggests that the trunk segment plays a critical role in modulating the amplitude and structure of gait-related oscillations prior to reaching the neck segment and thus the head. It was envisaged that examining factors that may challenge the individual (the normal ageing process), and the walking task (changes in walking speed, and induced fatigue of the upper body), would provide new insight into the extent to which the postural system prioritises head stability during walking. Regardless of the challenges imposed on the postural system due to the ageing process, upper body movement was organised in a manner which assisted in maintaining a degree of head stability comparable to those observed under normal walking conditions. Similarly, the importance that the postural system places on maintaining head stability was evident in the attenuation characteristics of the trunk and neck segments when walking speed was manipulated, and neuromuscular fatigue induced. Manipulating walking speed highlighted the critical role that the trunk segment has in regulating upper body accelerations arising from gait-related events. Aside from a minor contribution from the neck segment in the direction of travel at preferred and fast walking speeds, regulation of accelerations occurred due to the dynamics of the trunk segment. Inducing neuromuscular fatigue of the cervical and lumbar erector spinae groups (CES and LES) revealed compensatory movement strategies of the upper body, with a view of enhancing head stability. For several variables quantifying attenuation, fatiguing one muscle group, such as the CES, resulted in changes in the dynamics of another level of the upper body, such as the trunk segment. The trunk segment was particularly dominant in regulating upper body accelerations under fatigued conditions, further reinforcing the importance to control accelerations prior to reaching the neck and head. Overall, the results of this study suggest that optimal head stability is reliant on the trunk segment providing a stable base of support for the neck and head. By regulating accelerations via the trunk segment, the postural system is effectively regulating the orientation of the neck and head, and the inclusive sensory organs. It was evident that the postural system prioritises, and in general, maintains head stability during walking despite challenges imposed on upper body stability.

<p>Abstract </p><p>The core is the center of gravity in our body. Injuries and overload in the joints, is the most common reason for not be able to work in Sweden today. A god strength capacity in the core is important for secure and effective movements, as well for active athletes, as for non athletes. The increased number of employees, who report in sick today, has been correlated with psychological bad health. New methods to deal with mental and physical health problems among people can indicate to the fact that Yoga in the western world has increased its members, due its spiritual and physical recognition in favor of well being. The purpose with this study was to examine the effect of yoga practice on isometrics muscular strength endurance in the core, and if the mental and physical general health has been effected after 8 weeks of yoga classes twice a week. The method has a quantitative and qualitative approach. Fourteen health female subjects, ranging in age from 32 to 60 years old, were studied. The subjects were evaluated before and after the training program in three test positions for core isometric endurance. There was improvement for all the subjects, in all three tests positions together. The subject’s isometric endurance average improved with 29 %. All subjects reported improvement in physical and mental function after the yogic practices. These findings indicate that regular yoga practice can elicit improvements in isometric endurance in the core, and facilitate mental and physical well being for the subjects.</p>

Trunk instability is a major problem for people with spinal cord injury (SCI); it not only limits their independence, but also leads to secondary health complications such as kyphosis, pressure sores, and respiratory dysfunction. In exploring mechanisms that may facilitate or compromise postural stability, dynamic models are very useful because the spine dynamics are difficult to study in vivo compared to other structures of the body. Therefore, one objective of this work was to develop a detailed three-dimensional dynamic model of the human trunk as a tool for investigating the neural-mechanical control strategy that healthy people apply to maintain trunk stability during various tasks. Since trunk control is fairly complex, however, another objective of this work was to provide insights into the balance control strategy of a simpler neuro-musculo-skeletal system that may facilitate future studies on trunk control. For this purpose, the control of the ankle joint complex during quiet standing (anterior-posterior degree of freedom) was studied in place of the trunk. The obtained results reveal that a neural-mechanical control scheme using a proportional-derivative controller as the neural control strategy can overcome a large sensory-motor (feedback) time delay and stabilize the ankle joint during quiet standing. Moreover, a detailed dynamic model of the trunk has been developed that is: (1) based on highly accurate geometric models; and (2) universally applicable. Thus, this work also responds to the postulation that structurally more complex models are needed to better characterize the biomechanics of multifaceted systems. Combining the developed biomechanical tools for the trunk with the postural control insights for the ankle joint during standing will be beneficial for: (1) understanding the neural-mechanical control strategy that facilitates trunk stability in healthy people; and for (2) developing neuroprostheses for trunk stability after SCI and other neurological disorders.

Trunk instability is a major problem for people with spinal cord injury (SCI); it not only limits their independence, but also leads to secondary health complications such as kyphosis, pressure sores, and respiratory dysfunction. In exploring mechanisms that may facilitate or compromise postural stability, dynamic models are very useful because the spine dynamics are difficult to study in vivo compared to other structures of the body. Therefore, one objective of this work was to develop a detailed three-dimensional dynamic model of the human trunk as a tool for investigating the neural-mechanical control strategy that healthy people apply to maintain trunk stability during various tasks. Since trunk control is fairly complex, however, another objective of this work was to provide insights into the balance control strategy of a simpler neuro-musculo-skeletal system that may facilitate future studies on trunk control. For this purpose, the control of the ankle joint complex during quiet standing (anterior-posterior degree of freedom) was studied in place of the trunk. The obtained results reveal that a neural-mechanical control scheme using a proportional-derivative controller as the neural control strategy can overcome a large sensory-motor (feedback) time delay and stabilize the ankle joint during quiet standing. Moreover, a detailed dynamic model of the trunk has been developed that is: (1) based on highly accurate geometric models; and (2) universally applicable. Thus, this work also responds to the postulation that structurally more complex models are needed to better characterize the biomechanics of multifaceted systems. Combining the developed biomechanical tools for the trunk with the postural control insights for the ankle joint during standing will be beneficial for: (1) understanding the neural-mechanical control strategy that facilitates trunk stability in healthy people; and for (2) developing neuroprostheses for trunk stability after SCI and other neurological disorders.

The primary purpose of the present study was to determine the acute hemodynamic responses to twenty-three select yoga postures in advanced and novice yoga practitioners. Additionally, we sought to determine if trunk flexibility is related to arterial stiffness. Using a cross-sectional study design, 37 apparently healthy adults (26 females and 11 males; 22-71 years old) were divided into two groups according to level of yoga experience. Beat-to-beat measures of blood pressure, stroke volume, cardiac work-load, cardiac output, and total peripheral resistance were measured using a finger plethysmograph during the yoga routine. Baseline measures of trunk flexibility (sit-and-reach scores and inclinometer measurements) and arterial stiffness (carotid-femoral pulse wave velocity) were also compared. Yoga postures elicited significant increases in heart rate, blood pressure and cardiac output (P<0.05) for both groups. There was no difference in blood pressure responses between the two groups throughout the yoga testing session. Lumbar flexion, as measured by an inclinometer, was significantly (P<0.01) and inversely associated with cfPWV (r=-0.52). / text

Abstract The core is the center of gravity in our body. Injuries and overload in the joints, is the most common reason for not be able to work in Sweden today. A god strength capacity in the core is important for secure and effective movements, as well for active athletes, as for non athletes. The increased number of employees, who report in sick today, has been correlated with psychological bad health. New methods to deal with mental and physical health problems among people can indicate to the fact that Yoga in the western world has increased its members, due its spiritual and physical recognition in favor of well being. The purpose with this study was to examine the effect of yoga practice on isometrics muscular strength endurance in the core, and if the mental and physical general health has been effected after 8 weeks of yoga classes twice a week. The method has a quantitative and qualitative approach. Fourteen health female subjects, ranging in age from 32 to 60 years old, were studied. The subjects were evaluated before and after the training program in three test positions for core isometric endurance. There was improvement for all the subjects, in all three tests positions together. The subject’s isometric endurance average improved with 29 %. All subjects reported improvement in physical and mental function after the yogic practices. These findings indicate that regular yoga practice can elicit improvements in isometric endurance in the core, and facilitate mental and physical well being for the subjects.

The aim of the study was to determine and to compare the trunk extensor and flexor muscles isocinetic contraction properties of adolescent wrestlers and non-athletes. To meet the target set the following tasks have been formulated: 1. To determine the trunk extensor muscles isocinetic contraction indices of wrestlers and non-athletes performing movements at different rate. 2. To determine the trunk flexor muscles isocinetic contraction indices of wrestlers and non-athletes performing movements at different rate. 3. To compare the ratio of trunk extensors and flexors muscles isocinetic contraction indices of wrestlers and non-athletes.. Six 16 years-old Greco-Roman wrestlers and nine non-athletes of the same age participated in the research. By means of the isokinetic dynamometer of the Biodex System 3 Pro type such functional indices of trunk muscles (extensors and flexors), as maximal and mean peak torque (PT), power, time up to developing maximal PT, as well as the ratio of these indices between trunk muscles (extensors and flexors) have been determined, All these indices were established performing trunk extension and flexion at 3 different angular rates, at 60, 90 and 120 degrees/sec. 1. Trunk extension indices (maximal and mean PT, power) of 16 year-old wrestlers are higher than those of non-athletes of the same age, irrespective of trunk extensors rate that was 60, 90 and 120 degrees/sec, except for the values of power indices performing trunk extensor at the rate... [to full text]

Background: It has been reported that the ratio of limb fat to trunk fat (LF/TF) is associated with markers of cardiometabolic risk in elderly men and women. However, it is unknown if LF/TF is associated with cardiometabolic risk beyond that explained by LF and TF independently. Objective: To determine if LF/TF is associated with markers of cardiometabolic risk in elderly men and women after control for LF and TF. A secondary objective was to examine the independent associations of LF and TF with markers of cardiometabolic risk. Methods: Subjects included abdominally obese men (n=58) and women (n=78) between 60 and 80 years of age. Regional adiposity was quantified using magnetic resonance imaging. Insulin resistance, fasting glucose, HDL-cholesterol, plasma triglycerides and adiponectin were determined. Regression analyses and partial correlations were used to assess the independent associations between variables. Results: After control for potential confounders, TF was positively associated with fasting glucose, insulin resistance and plasma triglycerides, and negatively associated with HDL-cholesterol (p<0.05). These associations were strengthened after further control for LF (p<0.05). LF was not associated with any marker of cardiometabolic risk after control for potential confounders (p>0.05). However, after further control for TF, LF was positively associated with HDL-cholesterol and negatively associated with plasma triglycerides (p<0.05). Plasma adiponectin was independently associated with both LF and TF in elderly women (p<0.05) but was not independently associated with either depot in elderly men (p>0.05). LF/TF was not associated with any marker of cardiometabolic risk after control for LF and TF. Conclusions: These results suggest that it is the absolute, rather than relative amounts of LF and TF which have the greatest influence on cardiometabolic risk in elderly men and women. Further, these results suggest that the associations between plasma adiponectin and regional adiposity are significantly influenced by sex in elderly men and women. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2008-12-05 16:08:10.868

The purposes of this study were to: 1) evaluate the effect of walking speed on gait, balance and cognitive task performance and 2) examine the effect of dual task (cognitive load) on gait balance and cognitive task performance. Twenty young healthy adults (24+6 years of age) were recruited and each participant walked on a motorised treadmill at two speeds(0.5m/s and 0.8m/s), first without performing cognitive tasks, then while performing three types of cognitive loaded tasks. The speed had a significant effect on average and coefficient of variation of temporal gait parameters (P<0.001), cognitive task performance (P<0.001) and center of pressure excursion (P<0.001). No statistically significant effect of speed was found ML trunk displacement. However, dual task (cognitive load) had significant effect on COV of temporal gait (P<0.001), cognition (P<0.001) and trunk motion (P<0.001). In conclusion, the speed and dual task had significant effect on locomotors rhythm, balance, and cognitive performances.

Nursing staff have an elevated risk of developing musculoskeletal disorders, in particular in the lower back area. Statistics produced by leading industrial nations show that back problems are the world’s number one work-related health problem, and that healthcare workers suffer from a greater occurrence of such problems than workers in other professions. In this context, many studies have examined manual patient handling activities, which was thought to be the main cause of musculoskeletal disorders of the lower back. But nurses have many other types of work to perform and several reviews have concluded that approaches which only focus on manual patient handling activities do not sufficiently reduce back problems in nursing professions. Other risk factors for musculoskeletal disorders of the lower back discussed in the literature included repeated bending and the high proportion of static trunk postures. The main aim of this doctoral thesis was therefore to examine the influence of stressful trunk postures on the physical workload of nursing staff in hospitals and nursing homes. It focuses on the type, number and extent of stressful postures and on identifying activities that encourage their occurrence. We used our findings to derive strategies for reducing stressful postures in nursing, and examined whether nursing staff regard such a reduction as actually relieving their physical workload. A secondary aim was to consider the older people potentially in need of care. The background to this is that, due to steadily rising costs, many older people are unable to afford care in a nursing home, and additionally that the forecast severe shortage of nursing staff in future gives reason to look for solutions that can reduce the demand for nursing staff. Among older people who still look after themselves, we therefore examined which stressful postures they adopt when carrying out domestic tasks such as cooking and washing laundry. From the results, we provided some examples of a better design of the domestic environment, which reduces stressful postures, when performing these tasks and helps older people to be able to look after themselves in their own homes for longer. / <p>QC 20140324</p>