Professional drivers of off-road vehicles, driving on irregular terrain such as in forestry, agriculture and mining, are exposed to whole-body vibration and mechanical shocks. These driver groups have reported severe musculoskeletal problems in the spine, but the association to seated postural reactions is not fully understood. One assumption is that unexpected shocks may create excessive load on spinal joints. The driver’s posture and exposure to mechanical shocks are required to be included in work risk assessments, but muscle activity and body kinematics are not included. The overall aim of this thesis was to describe and analyse seated postural reactions to mechanical shocks and to evaluate measuring of seated postures with relevance for risk assessment and the prevention of musculoskeletal disorders among drivers. The thesis includes four studies, all laboratory-based using a repeated-measures design. Postural reactions were recorded from 23 (Paper I) and 20 (Paper II & III) young, healthy male participants who were seated on a movable platform. The platform delivered mechanical shocks with peak accelerations up to 14 m/s2 in lateral directions during different conditions. Furthermore, twenty participants (Paper IV) were tested by four testers for analysis of test-retest reliability within and between testers measuring seated postures. Kinematics were here detected by means of a motion analysis system (MoLabTM) and described for the spine as angular displacements or range of motion (ROM) using a three-segment model of neck, trunk and pelvis (Paper I–III) and as a more specific model (Paper IV). Surface electromyography (EMG) was recorded bilaterally on the following muscles; trapezius upper part, upper neck, erector spinae and external oblique (Paper I–III). The general findings show that EMG amplitudes normalised to maximum voluntary contractions (MVC) did not exceed 2% in the trapezius, 8% in the upper neck and erector spinae and 18% in the external oblique. The EMG amplitudes and the angular displacements in the neck were significantly reduced from the first compared to the fifth mechanical shock. Adding a cognitive task significantly increased angular displacements. The largest ROM with approximately 20° in each segment was found during a double-sided mechanical shock (shock that changes direction). The reliability within one tester measuring seated postures was mostly considered good and superior to the reliability between several testers, but still insensitive to changes of less than 10°. Exposure to single-sided or double-sided mechanical shocks with accelerations up to 14 m/s2 seem not to cause postural reactions to such an extent that overload of muscles or joint structures should be expected. There seems to be a quick adaptation that causes an improved readiness. The external obliques were most active when restoring equilibrium and seem important for stabilising the whole spinal column. Stability training, in order to improve neuromuscular control of the external obliques could, therefore, be a possible recommendation. The angular displacement in the neck increases if the subject solves a cognitive task of why such activities should be avoided when driving in difficult terrains. Since accurate descriptions of the spinal posture seems difficult even when advanced technical equipment is used, simpler models seem more appropriate. The results show that postural control is maintained even when exposed to considerable mechanical shocks. On the basis of these results, there is no need to change established risk assessment models.

Thesis (MScPhysio (Physiotherapy))--Stellenbosch University, 2008. / The Western Cape Education Department initiated a project that aims to provide all the learners from the province with computer access and to promote computer use in schools. Prolonged sitting in front of computers and psychosocial factors have been associated with musculoskeletal symptoms internationally. However, the impact of computer use on musculoskeletal pain among South African high school learners is yet to be determined. Objective The objective of the study was to determine whether sitting postural alignment and psychosocial factors contribute to the development of upper quadrant musculoskeletal pain in grade ten high school learners working on desktop computers. Study design An observational analytical study was performed on a sample of 104 asymptomatic high school learners. Methodology Six high schools in the Western Cape metropole were randomly selected 322 grade ten learners who are using desktop computers, were screened for upper quadrant musculoskeletal pain. Measurements at baseline were taken of the 104 asymptomatic learners, 49 girls and 55 boys. The sitting postural alignment was measured by using the Portable Posture Analysis Method (PPAM), which measured head tilt; cervical angle; shoulder pro- and retraction angle and thoracic angle in the sagittal plane. Depression and anxiety were described by using the Beck Depression Inventory (BDI) and the Multidimensional Anxiety Scale for Children (MASC) respectively. The exposure to computer use was described in terms of duration and frequency of daily and weekly computer use. At three and six months post baseline, the onset and area of upper quadrant musculoskeletal pain was determined by using the Computer Usage Questionnaire. Results After six months, 27 of the 104 learners developed upper quadrant musculoskeletal pain due to seated or computer-related activities. There was no difference in computer exposure between the learners who developed upper quadrant musculoskeletal pain symptoms and the learners who remained asymptomatic. An extreme cervical angle (<34.75° or >43.95°; OR 2.6; 95% CI: 1.0-6.7) and a combination of extreme cervical and thoracic angle (<63.1° or >71.1°; OR 2.19; 95% CI: 1.0-5.6) were significant postural risk factors for the development of upper quadrant musculoskeletal pain. There was a tendency for boys to be at a greater risk for upper quadrant musculoskeletal pain than the girls (OR 1.94; 95% CI: 0.9-4.9). Weight greater than 54.15kg and a depression score greater than 11 was found to be significantly associated with a poor posture (OR 3.1; 95% CI: 1.0-9.7; OR 1.02; 95% CI: 1.0-1.1). Discussion and conclusion The study concluded that poor posture, relating to extreme cervical and thoracic angles, is a risk factor for the development of upper quadrant musculoskeletal pain in high school learners working on desktop computers. South African boys were at a greater risk of developing upper quadrant musculoskeletal pain than the girls. However the study found no causal relationship between depression, anxiety and upper quadrant musculoskeletal pain among South African high school learners and computer usage.

Thesis (MScPhysio (Physiotherapy))--University of Stellenbosch, 2007. / Objective The objective of this study was to establish the reliability and validity of a Portable Posture Analysis Method (PPAM). Design The design for the reliability section was a repeated measures observational study and the design for the validity section was a correlation study. Background The prevalence of spinal pain among high school learners is high (Murphy et al, 2002). It is also notable that the prevalence of back pain increases across the teenage years (Grimmer & Williams 2000, Burton et al 1996). In South Africa, the preliminary findings of a study conducted by a Physiotherapy masters candidate (Ms L Smith: ethics nr. N05/09/164) indicates that about 74% of high school learners in Cape Town complained of musculoskeletal pain. Posture has been identified by some researchers to be a primary predictor of the development of spinal, particularly upper quadrant pain among computer users (NIOSH 1997, Vieira et al 2004). Measurement of posture poses a real challenge to researchers wanting to accurately evaluate posture in research projects. Considering the practical implications in measuring posture, the validity and reliability of posture measurement are often reported to be poor. Many of these methods of indirect assessment of working posture have been reported on in the literature. These measures include; the goniometer, inclinometer, flexible electrogoniometer, flexicurve and photography (Harrison et al 2005, Christensen 1999, Nitschke et al 1999, Chen & Lee 1997). ...

<p>Constrained optimization is used to derive human postures and movements. In the first study a static 3D model with 30 muscle groups is used to analyse postures. The activation levels of these muscles are minimized in order to represent the individual's choice of posture. Subject specific data in terms of anthropometry, strength and orthopedic aids serve as input. The aim is to study effects from orthopedic treatment and altered abilities of the subject. Initial validation shows qualitative agreement of posture strategies but further details about passive stiffness and anthropometry are needed, especially to predict pelvis orientation. In the second application, the athletic long jump, a problem formulation is developed to find optimal movements of a multibody system when subjected to contact. The model was based on rigid links, joint actuators and a wobbling mass. The contact to the ground was modelled as a spring-damper system with tuned properties. The movement in the degrees of freedom representing physical joints was described over contact time through two fifth-order polynomials, with a variable transition time, while the motion in the degrees of freedom of contact and wobbling mass was integrated forwards in time, as a consequence. Muscle activation variables were then optimized in order to maximize ballistic flight distance. The optimization determined contact time, end configuration, activation and interaction with the ground from an initial configuration. The results from optimization show a reasonable agreement with experimentally recorded jumps, but individual recordings and measurements are needed for more precise conclusions.</p><p> </p>

The home should represent safety and security for the person who lives there, and this is an important factor for independence and autonomy in very old age. With aging populations, the needs for long-term care increase, care provided by spouses and/or from the growing home care sector. Injuries among these groups are common. In this study, an ergonomics perspective was applied in the analysis of some basic daily activities performed by old persons and by home care workers, assisting. The postures and movements of home care staff assisting at toilet visits, and transferring persons from wheelchair to toilet, were measured and analysed. Some daily activities related to making food and washing clothes, performed by a group of persons between the age of 75 and 100, were measured and analysed. The task of getting up from the floor – on your own and with the help of a walker equipped with a lifting device – was analysed with the help of older persons and nursing staff. The design was built on the knowledge gained from analysing how older people get up from floor. Requirements for access with a four-wheeled walker in the local built environment were investigated. Observations were made with the help of video recording. Postures were recorded with the CUELA measurement system. The VIDAR ergonomics evaluation instrument was used to register the participants’ experiences of discomfort and pain during getting up from the floor with or without the walker with a lifting device. Structured interviews were used to find out about older peoples’ experience of using the four-wheel walker. It is concluded that ageing at home requires improved architectural and technical bathroom design and improved access in the local built environment. / <p>QC 20140124</p>

Background: The negative side of rugby participation is the danger it presents to health in the form of injuries. Most school coaches, advocates of talent development and selectors put a high priority on implementing programmes to develop bigger, stronger, faster and more skilful rugby players who can excel at their sport. These programmes however, do not place enough emphasis on the prevention of injuries. Aims: The primary aim of the study was to determine the effect of an approved injury prevention programme on the incidence (injuries per 1000 player hours) of n~gbyin juries (overall, intrinsic and extrinsic injuries) of 15- and 16 year-old schoolboys, over a two-year period. A further aim was to measure the effect of an approved injury prevention programme on the selected anthropometric, physical and motor and biomechanical and postural variables of all the groups involved in this study over a period of two years. Originating from these aims, a sub-aim of this study was to use information from this study to provide modifications - if necessary - to the current prevention programme in order for it to be effectively applied at high-school rugby level. Design: A non-equivalent experimental-control group design with multiple post-tests was used for the investigation. Subjects: The subjects were 120 schoolboy rugby players. The subjects came from two secondary schools in the North West province of South Africa. Both schools were schools wit11 a tradition of excellence in rugby. Players who participated in the experimental injury prevention programme were the year 2004, 15- and 16-year old elite A teams. The B teams acted as controls. Method: Players were tested over a two-year period. During each of the two years there were three testing occasions where all players were tested: pre-season, during the mid-season break and at the end of the season. The results of these tests were used to monitor changes in anthropometric, physical and motor and biomechanical and postural variables in various stages of the training programme. At the end of every evaluation, deficits were identified in the performance of all players in the experimental group and the prevention programmes were planned accordingly. Players in the experimental group received exercises to address the specific deficits identified. Rugby injuries were screened and injury data collected through the use of weekly sports. medical clinics. Results: Differences and changes in extrinsic injury incidences in this study could not be attributed to the effect of the prevention programme, and as a result injury trends related to overall injury incidences were inconsistent when the experimental groups were compared to the matching control groups. However, the prevention programme did have a positive effect on the intrinsic injury incidence of both experimental groups during the study period. The following moderate or highly practically significant anthropometric changes occurred when inter-group comparisons for the two year period were considered: triceps skinfold (d=0.8 among 16-year olds), subscapular skinfold (d=0.5 among 16-year olds, midaxillary skinfold (d=1.3 among 15-year olds), calf skinfold (d=1.3 among 16-year olds), humerus breadth (d=1.4 among 15-year olds), femur breadth (d=0.5 among 15-year olds), fat percentage (d=0.5 among 16-year olds) and mesomorphy (d=1.3 among 15-year olds). However, these anthropometric changes may be due to other factors, such as the natural growth phase of boys, rather than the effect of the prevention programme. During the inter-group comparisons of physical and motor components, moderately or highly practically significant improvements were recorded in the vertical jump (d=0.8 for 15-year olds and d=1.5 for 16year olds), bleep (d=0.7 for 16-year olds), pull-ups (d=0.6 for 15-year olds) and push-up tests (d=1.5 for 15-year olds and d=1.1 for 16 year-olds) of the experimental groups considering the total two year period. From the results it was clear that in practice, the prevention programme significantly improved only four of the 11 physical and motor components over the two-year period and that these improvements often occurred in only one of the age groups involved. The inter-group comparison of biomechanical and postural variables revealed numerous moderately and highly practically significant improvements in both age groups. over the total two-year period. All in all the prevention p r o v e provided the experimental groups with a more balanced (closer to ideal) dynamic mobility, core stability and postural symmetry. Conclusion: It could be concluded that the present prevention programme did not have a practically significant effect on the incidence of overall rugby injuries and extrinsic rugby injuries of 15- and 16-year old schoolboys over a two-year period. However, in practice, the prevention programme did have a significantly positive effect on the incidence of intrinsic rugby injuries of 15- and 16-year old schoolboys over a period of two years. It could be concluded that the prevention programme did not have a practically significant effect on the anthropometric components of 15- and 16-year old schoolboys over a two-year period. Seeing that the prevention programme had a moderately or highly practically significantly effect on only four of 11 physical-and-motor components over the two-year period, and that these improvements often occurred in only one of the age groups involved, it could be concluded that the prevention programme did not significantly affect the physical and motor variables of 15- and 16-year old schoolboys over a two-year period. Finally the conclusion could be drawn that in practice the prevention programme significantly improved the biomechanical and postural variables over a period of two years. This improvement in biomechanical and postural status may be responsible for the decrease in intrinsic injury incidence. Information from this study was used to provide modifications to the tested prevention programme in order for it to be effectively applied at high school rugby level. / Thesis (Ph.D. (Movement Science Education))--North-West University, Potchefstroom Campus, 2006

Elements of an individuals occupational exposure, such as their posture can affect their comfort during work, and also their long term musculoskeletal health. Knowledge as to the extent of the influence of particular aspects of the exposures can help in providing guidance on risk evaluation, and direct future technical design focus. In many situations the exposures interact, and even if the effects of individual exposures are understood, the interactions are often less so. This is certainly the case with off-road driving exposures. Specific investigations have focussed on the effects of vibration exposure, resulting in the development of international standards and guidelines on measurement and evaluation of exposure. Consideration of the posture of the operator can be accomplished through postural assessment tools, although none of the currently available methods are developed specifically for use within a vehicle environment. The issues of both the posture of the operator and the seated vibration exposure are particularly apparent in off-road agricultural driving environments, where the driving task dictates that operator is often required to maintain specific postures whilst also exposed to whole-body vibration. In agriculture, many of the tasks require the operator to maintain axially rotated postures to complete the task effectively. The analysis of the combined effects of the axial rotation of the operator and the whole-body vibration exposure has been limited to a few studies within the literature, and is currently poorly understood. The overall aim of the thesis was to assess the influence of axial rotation and whole-body vibration on the musculoskeletal discomfort of the neck and trunk, in order that the true extent of the exposure risk may be evaluated. A field study was conducted to determine the common characteristics of some typical exposures, to provide a basis for the laboratory studies. A survey of expert opinion was conducted, examining the knowledge and experience of experts in assessing the relative influence of axial rotation and whole-body vibration on operators musculoskeletal health. The main investigations of the thesis are focussed in the laboratory, where the objective and subjective effects of axial rotation (static and dynamic) and whole-body vibration were investigated. Objective measures included the investigation of muscular fatigue in response to exposures. The tasks investigated in the field study indicated that the exposures often exceed the EU Physical Agents Exposure Limit Value, and that the axial rotation is a large component of the postures required. The survey of expert opinion concluded that combined exposure to axial rotation and whole-body vibration would increase the risks of lower back pain, and that acknowledgement of combined exposures should be included when assessing for risk. The results of the laboratory studies indicated that the greatest discomfort was present when subjects were exposed to axial rotation in the neck and shoulders. Out of the 8 muscles investigated, at most 6 of the 8 indicated fatigue during an experimental exposure. The muscle group which was affected most by the exposures was the m. trapezius pars decendens. Findings demonstrated that when subjects were exposed to axial rotation and whole-body vibration they indicated discomfort and their muscles fatigued. However, there was poor correlation between the sites of discomfort and the location of muscular fatigue. The discomfort findings suggest that there is an increased risk of discomfort from experiencing axial rotation together with whole-body vibration. Investigations of muscular fatigue do not substantiate this finding.

Respiratory muscle training (RMT) has been shown to improve exercise tolerance during a wide range of exercise modalities and durations of activity (McConnell & Romer, 2004b). However, there is a limited amount of research characterising the influence of RMT in specific athletic populations, or examining any sport-specific factors that may influence the benefits of RMT. Hence, the purpose of this dissertation was to evaluate the application of RMT in competitive rowers and to explore methods of optimising this to rowing. Results: Inspiratory muscle training (IMT) increased inspiratory muscle strength (~20-29%; p < 0.05) and attenuated inspiratory muscle fatigue (~8-28%; p < 0.05) during time trial performance in club-level and elite rowers. However, only in the club-level oarsmen was IMT associated with a measurable improvement in rowing performance (2.7% increase in mean power; p < 0.05). Expiratory muscle training (EMT) provided no ergogenic effect, and concurrent EMT and IMT did not enhance performance above that seen with IMT alone. IMT loads performed at 60-70% of maximal inspiratory mouth pressure (PImax) were equivalent to the widely used 30 repetition maximum, which is higher than reported for non-rowers (Caine & McConnell, 1998a); further, a load of 60% PImax was sufficient to activate the inspiratory muscle metaboreflex, as evidenced by a time-dependent rise in heart rate (70.1 ± 13.2 to 98.0 ± 22.8 bpm; p < 0.05) and mean arterial blood pressure (92.4 ± 8.5 to 99.7 ± 10.1 mmHg; p < 0.05). Higher and lower inspiratory loads did not activate the metaboreflex. Assessments of flow, pressure and volume in rowing relevant postures revealed no significant impairments, but optimal function occurred in the most upright postures. Conclusions: These data support the application of IMT, but not EMT, in elite and sub-elite rowers, and suggest that a load of 60-70% of PImax provides metaboreflex activation during loading. Further, the data do not support a requirement to undertake IMT in rowing relevant postures.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

An innovative Partially Immersed Approach, based on mixed principles of land and aquatic therapy theories was developed to enhance sitting adaptation and functioning in an Aquatics Therapy environment, thus improving quality of life for children with Cerebral Palsy. The approach aimed to enhance motor adaptation, engendering adaptation in psychosocial domains of quality of life. It employed a specially developed therapeutic treatment chair, in an unloading toward loading strategy, to regulate and control percentage of weight-bearing by manipulation of buoyancy (Archimedes principle). Participants were bilateral spastic hypertonia, Cerebral Palsy children, aged 10-15 years. Mixed-method methodology was used to investigate effectiveness of treatment, employing a small sample in a multiple case study. In conclusion, the developed approach enables aquatic therapy to be employed to improve motor function adaptation on land and consequently enhancing adaptation in other psychosocial domains - perceived competence, empowerment and motivation - thus improving quality of life for children with cerebral palsy, sustained at a one-year post-intervention test.