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A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand Gauteng, May 2018 / Background The trunk is the centre of the kinetic chain, connecting upper and lower limbs and transferring energy during movement. Proximal stability serves as a base for quality movements distally. Trunk muscle stability and strength-endurance are associated with sporting performance. Asymmetrical sport-specific adaptation in the morphometry of the trunk muscles has been investigated and described in cricket pace bowlers, but not linked to or described in terms of the association with bowling performance. Aim The aim of this study is to investigate the association between bowling performance and trunk muscle stability, strength-endurance and thickness in adolescent pace bowlers. Method In this observational cross-sectional study, bowling performance, namely ball release speed and accuracy, was measured by means of a radar gun and accuracy target in the outdoor nets of the respective schools, where the 46 pace bowlers, aged 13-18 years old, were invited from. Trunk muscle stability was measured as the level passed on the Sahrmann Stability Scale and strength-endurance as the failing time in seconds according to the Bourbon Trunk Muscle Strength Test. Ultrasound imaging measured the thickness of external oblique, internal oblique, transversus abdominis and lumbar multifidus in millimetre. Spearman’s correlations were used to determine associations between individual variables and a multiple linear regression analysis calculated predictors of bowling performance, including independent variables such as age, height and weight. Statistical significance was set at p<0.05. Results No association was found between trunk muscle stability and ball release speed (r=0.278; p=0.061) or accuracy (r=0.026; p=0.866). Stability, however, accounted for a 60.7% variance in ball release speed (p=0.004), increasing ball release speed by 3.570 units per unit increase in stability. Strength-endurance of the trunk muscle chains did not correlate to ball release speed (r=-0.039-0.214; p=0.154-0.796) or accuracy (r=-0.062-0.131; p=0.385-0.801). A moderate and fair relationship was found between ball release speed and transversus abdominis (r=0.543; p=0.0001) at rest and contracted (r=0.440; p=0.002), respectively. Non-dominant transversus abdominis showed a fair relationship with height at rest (r=0.458, p=0.001) and a moderate correlation with weight (r=0.625, p<0.001). On the dominant side, transversus abdominis at rest, showed a moderate relationship to ball release speed (r=0.564; p<0.001), height (r=0.539; p<0.001) and weight (r=0.611; p<0.001). Thickness of bilateral transversus abdominis at rest had an R-square value of .67 and ball release speed increased with 5.133 units for each unit increase in the thickness of the non-dominant transversus abdominis and 4.677 for that on the dominant side. Accuracy did not correlate with any independent variable, but weight (R-square value .207) was found to increase accuracy by .766 units for each unit increase. Bowling performance was found to be predicted by age (R-square value 0.084). Conclusion A direct association between bowling performance and trunk muscle stability and strength-endurance was not found. Trunk muscle stability – as a suppressor variable – was found to be a predictor of ball release speed. Trunk muscle thickness accounted for the variance in ball release speed and weight for that of accuracy. These findings implicate that adolescent pace bowlers may be able to improve ball release speed by increasing trunk muscle stability and bilateral transversus abdominis thickness. However, future research is needed to confirm this statement. / LG2018

MSc, Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand / The Association between Trunk Muscle Endurance and Lumbar-Pelvic Instability in Adolescent Low Back Pain Françoise Lewis Supervisors: Wendy-Anne Wood, Benita Naude. Low back pain (LBP) is a common cause of discomfort in modern society, and the prevalence of LBP in the adolescent population is high and has a predictive value for the occurrence of LBP as an adult. The aim of the study was to investigate the association between adolescent LBP and trunk muscle endurance and lumbar-pelvic instability, as well as the association between trunk muscle endurance and lumbar-pelvic instability. Sports and physical activity participation, sedentary activity participation and a family history were also investigated as they have been identified in previous studies as potential risk factors. The study was a cross sectional study of 80 adolescents in grade 8 to grade 11, aged 12 to 17 year , at three high schools in Gauteng, who agreed to participate in the study. Data was collected by means of a validated questionnaire and a physical examination. The level of significance for as sociated factors was set at 0.05. The results revealed a lifetime prevalence of 82.50%, one year prevalence of 78.80% and point prevalence of 23.80%. Adolescents with LBP have decreased endurance of the trunk extensor muscles but increased endurance of the trunk flexor muscles, which is statistically significant (p=0.044) . Lumbar-pelvic instability is not associated with adolescent LBP. Extensor trunk muscle endurance and poor lumbar pelvic stability show an association (p=0.031), with those adolescents with decreased trunk extensor muscle endurance presenting with poor lumbar-pelvic stability. A family history of LBP is significant for point prevalence of LBP (p=0.012), and one-year prevalence of LBP is marginally significant (p=0.086). Low activity level particpation was reported by a large percentage of all subjects. Sedentary activity participation is moderate in the LBP group, but the results are not statistically significant . There is a need for preventative srategies to decrease the prevalence of adolescent LBP. Increased awareness of LBP and potential risk factors needs to be addressed.

Trunk lean over the stance limb during gait has been linked to a reduction in the knee adduction moment, which is associated with joint loading. Differences were examined in knee adduction moments and frontal plane trunk lean during gait between subjects with knee osteoarthritis and a control group of healthy adults. Additionally, subject variability in human motion data presents a challenge to researchers when trying to detect differences between subject groups. The individual differences in neutral posture between subjects is a source of variation in joint angles. A method was developed using principal component analysis (PCA) to objectively reduce this inter subject variability. Gait analysis was performed on 80 subjects (40 osteoarthritis). Models were developed to define lateral thoracic tilt, as well as pelvic tilt. The trunk and pelvis frontal plane angles were used to describe trunk lean and pelvic tilt. Angles were calculated across the stance phase of gait. We analyzed the data, (i) by extracting discrete parameters (mean and peak) waveform values, and (ii) using principal component analysis (PCA) to extract shape and magnitude differences between the waveforms. Osteoarthritis (OA) subjects had a higher knee adduction moment than the control group (α=0.05). Although the discrete parameters for trunk lean did not show differences between groups, PCA did detect characteristic waveform differences between the control and osteoarthritis groups. The data show that subjects display similar waveform shapes, however waveforms vary in magnitude, suggesting a variation in posture between subjects. The results from the PCA reveal that the first PC, which captures the most variation in the data, represents this variation in magnitude. The second PC describes a significant difference in range of motion between the subject groups. Subjects with knee OA were found to have a different range of motion of their pelvis and trunk than control subjects. These changes are consistent with a strategy to lower the knee adduction moment. As an alternative to conventional subjective methods, PCA should be employed to reduce inter subject variability in order to ensure objective analysis in human motion waveform data. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-08-14 14:43:53.127

Standing at a workbench is required for manual work including sorting and assembly. When work heights and reach distances are not matched to stature or arm length, the trunk assumes a partially bent position, which increases the postural effort required to stand or to reach to far distances. As a result, the biomechanical load on the lumbar spine is raised, which contributes to a higher risk for back pain. In ergonomics, assistive devices are being developed to counter this effect. A new leaning device was tested in the laboratory with forward-bent standing and reaching where the trunk was bent forward and twisted to reach to a far target 45° from the center. This device supported the trunk at the upper chest. With leaning, back muscle activity decreased by ~ 60% with forward-bent standing and ~ 23-30% with the off-center reach, depending on reach height. Because leaning changed how standing remained balanced, ~12° less bending was required to reach the target. Therefore, upper-trunk support may be helpful for benchworkers when ergonomic design is not possible; some product development and testing is still needed to provide the right amount of support at the right time and to ensure there is no rib joint irritation. An interesting outcome from these previous studies was related to workers’ posture when they leaned against a workbench that was adjusted for heavier work (hip height). Low back muscle activity was unchanged with forward-bent standing, but decreased by ~ 23-30% with the off-center reach. This reduction was accompanied by greater twist at the mid back as a way of compensating for a loss of hip rotation. Three different heights for bench leaning were compared in a third study: elbow height, hip height and below hip height. The results showed that leaning at elbow height lowered the work demand by ~16-24% for far reach, partially due to changed motions consistent with greater mid back movement and coincided with ~ 8% increase in work demands at the mid-back and greater scapular recruitment. Therefore, more research is needed to establish work height guidelines for use when leaning against a workbench. / Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2013-01-29 14:32:19.696

ABSTRACT South Africa has a high incidence of violence and death due to unnatural causes. Gunshot and/or multiple stab wounds to the trunk are consequently injuries commonly seen in South African hospitals. Penetrating injuries often necessitate explorative surgical intervention to identify and treat injuries to the internal organs. Patients are managed in the intensive care unit and frequently return to theatre for abdominal lavage prior to eventual wound closure. Critical illness with prolonged mechanical ventilation and immobilization results in some degree of muscle dysfunction. Survivors of critical illness suffer from poor functional capabilities and decreased quality of life. No formal rehabilitation programmes exist in South Africa for these patients following discharge. Purpose: To determine if patients that survived penetrating trunk trauma recover adequately spontaneously following critical illness over the first six months following discharge from the hospital. Methods: A prospective, observational study was conducted. Patients with penetrating trunk trauma were recruited from four intensive care units in Johannesburg. Patients who received mechanical ventilation < 5 days were placed in Group 1 and those who received mechanical ventilation 5 days were placed in Group 2. Lung function tests, dynamometry, quality of life, six-minute walk distance and oxygen uptake tests were performed over six months following discharge from the hospital. The obtained results for dynamometry, exercise capacity and quality of life were compared between groups and to that measured for a healthy (age and sex-matched) control group. Results and Discussion: No pulmonary function abnormalities were detected for subjects in Groups 1 or 2. Distance walked during 6MWD test was significantly reduced for subjects in Group 2 compared to the control group [one-month (p = 0.00), three-months (p = 0.00)]. Morbidity correlated significantly with distance walked by subjects in Group 2 during 6MWD test [three-months (p = 0.03), six-months (p = 0.02)]. No statistically significant differences were found between subjects during the VO2peak test although subjects in Group 1 performed better clinically than those in Group 2. At one-month there was a significant reduction in upper and lower limb strength for subjects in Group 2 compared to those in Group 1 and the controls (p = 0.00 – 0.04). Similar results were detected at the three- and six-month assessments. ICU and hospital length of stay did demonstrate a significant relationship with muscle strength at one and three months following discharge for subjects in Group 2. Severity of illness and morbidity in ICU did not have a significant relation to muscle strength for subjects in Groups 1 or 2 at any of the assessments. Subjects in Group 1 had a significant reduction in right deltoid and triceps strength compared to the controls at one-month (p = 0.00 respectively) only. No significant differences in upper and lower limb muscle strength were detected between the control group and subjects in Group 1 three and six months after discharge. Subjects in both groups had similar limitations in physical and mental aspects of quality of life one-month after discharge. Subjects in Group 1 reported a quality of life comparable to the control group by three-months. Subjects in Group 2 had significant limitations in the physical components of quality of life at three- and six-months compared to those in Group 1 and the controls [p = 0.00 – 0.02]. Conclusion: Subjects in Group 1 recovered adequately on their own within three months after discharge from hospital with regard to muscle strength, exercise capacity and all aspects of quality of life. Subjects in Group 2 presented with significant limitations in exercise capacity, muscle strength and the physical aspects of quality of life even at six months after discharge. Impaired function was related to the duration of critical illness and immobility. A physiotherapist-led rehabilitation programme may be indicated for survivors of penetrating trunk trauma that received prolonged mechanical ventilation to address cardiovascular endurance and peripheral muscle strength retraining between one and three months after discharge to address the physical disabilities observed in these subjects.

This dissertation aimed to investigate the relationship between posture and reaching in both healthy and pathological conditions, approaching the trunk as a multi-segmented structure. For this purpose, neuromuscular and kinematic profiles were recorded from trunk and arm during seated reaches providing mid-rib vs pelvic levels of trunk support. Healthy adults with mature postural and reaching abilities displayed invariant arm kinematics during the reach. However, participants displayed increased anticipatory control and earlier activation of cervical muscles with mid-rib support. Participants also presented increased compensatory responses of paraspinal muscles when responding to the increased trunk balance demands with pelvic support. Children with moderate/severe cerebral palsy (CP) cannot maintain an upright sitting position and thus cannot create a stable postural frame around which upper limb movements are planned and executed. A second set of studies examined postural and reaching characteristics in these children, while applying axillae, mid-rib or pelvic levels of support. Participants were classified according to their intrinsic level of trunk control as mild, moderate and severe. With higher levels of support children with moderate to severe impairments in trunk control showed improvements of head and trunk control along with enhanced reaching performance. Participants with mild trunk dysfunction were able to sit independently and thus did not demonstrate significant changes in postural and reaching proficiency across levels of external trunk support. Electromyographic profiles were more variable depending on the severity of intrinsic trunk control. Overall, participants in the mild group presented more refined timing mechanisms for both anticipatory (closer to reaching onset) and compensatory (reduced latency) postural adjustments during the reach across all levels of support. Participants in the moderate group displayed earlier muscle onsets and more efficient arm/trunk muscle amplitudes with higher levels of support. Participants in the severe group showed very limited capability of anticipatory control of paraspinal muscles, delayed muscle onsets and variable muscle amplitudes across levels of support. These results emphasize the complex neuro-anatomical nature of trunk control during reaching. Also, they highlight that inefficient postural control while sitting significantly impacts children with CP and trunk dysfunction. This dissertation includes previously unpublished co-authored material.

This dissertation aimed to investigate the relationship between posture and reaching in both healthy and pathological conditions, approaching the trunk as a multi-segmented structure. For this purpose, neuromuscular and kinematic profiles were recorded from trunk and arm during seated reaches providing mid-rib vs pelvic levels of trunk support. Healthy adults with mature postural and reaching abilities displayed invariant arm kinematics during the reach. However, participants displayed increased anticipatory control and earlier activation of cervical muscles with mid-rib support. Participants also presented increased compensatory responses of paraspinal muscles when responding to the increased trunk balance demands with pelvic support. Children with moderate/severe cerebral palsy (CP) cannot maintain an upright sitting position and thus cannot create a stable postural frame around which upper limb movements are planned and executed. A second set of studies examined postural and reaching characteristics in these children, while applying axillae, mid-rib or pelvic levels of support. Participants were classified according to their intrinsic level of trunk control as mild, moderate and severe. With higher levels of support children with moderate to severe impairments in trunk control showed improvements of head and trunk control along with enhanced reaching performance. Participants with mild trunk dysfunction were able to sit independently and thus did not demonstrate significant changes in postural and reaching proficiency across levels of external trunk support. Electromyographic profiles were more variable depending on the severity of intrinsic trunk control. Overall, participants in the mild group presented more refined timing mechanisms for both anticipatory (closer to reaching onset) and compensatory (reduced latency) postural adjustments during the reach across all levels of support. Participants in the moderate group displayed earlier muscle onsets and more efficient arm/trunk muscle amplitudes with higher levels of support. Participants in the severe group showed very limited capability of anticipatory control of paraspinal muscles, delayed muscle onsets and variable muscle amplitudes across levels of support. These results emphasize the complex neuro-anatomical nature of trunk control during reaching. Also, they highlight that inefficient postural control while sitting significantly impacts children with CP and trunk dysfunction. This dissertation includes previously unpublished co-authored material.

Non-specific low back pain (LBP) has been associated with alterations in the biomechanical properties and muscle activities of the trunk, but it is unclear how these changes are related to the dynamic stability of the trunk. During sitting, the structures of the trunk stabilise the upper body counterbalancing external moments acting on the trunk. The aim of this research was to evaluate a range of biomechanical variables including the hip and lumbar spine joints range of motions, moments and powers the viscoelastic properties of the trunk, and the role of the muscles while a participant was performing a balancing task in sitting and to compare results between healthy and LBP subjects. A custom-made swinging chair was used to perform the balancing task. It was designed to challenge primarily the trunk and to minimise the effect of the lower limbs so that the role of the trunk could be examined in isolation. Twenty-four participants with LBP and thirty healthy participants were requested to sit on the custom-made swinging chair and to regain the balance after tilting the chair backward for 10° and 20º. Electromagnetic motion track system sensors were placed on the participants’ back, one at the sacrum level and one at the first lumbar vertebral level to measure hip and lumbar kinematics. One further sensor was placed on the chair to track its rotation, which was also the rotation of the lower limbs. Forces data were taken from a force-plate which was mounted at the bottom of the chair. Inverse dynamic equations were used to derive the muscle moment acting at the hip and lumbar spine joints using data from the force platform and the motion tracking system. Muscle power was then calculated by multiplying the muscle moment and the corresponding joint angular velocity. Trunk viscoelastic parameters were derived using a second order linear model combine trunk moment and motion. Chair motion and trial duration were used to evaluate dynamic stability and task performance, in particular, the angular displacement of the chair was fitted in an equation describing the underdamped second-order response to a step input to derive natural frequency and damping ratio and to evaluate possible differences between groups. Activities, reaction times and co-contraction of the trunk muscles were evaluated using surface electromyography (EMG). The surface electrodes were placed bilaterally on the erector spinae , rectus abdominus, external and internal oblique. Kinematic analysis showed that the hip range of motion increased whereas spine range of motion angle decreased in participants with LBP for both tilt angles (p. < 0.05). No significant differences were found in muscle moment and power between healthy and LBP subjects (p > 0.05). The duration of contraction of various trunk muscles and co-contraction were significantly longer in the LBP subjects (p < 0.05) when compared to healthy subjects, and the reaction times of the muscles were also significantly reduced in LBP subjects (p<0.05). Trunk stiffness was found increased for LBP subjects (p < .05) while no difference was found for damping coefficient. There were no significant differences between the 2 subject groups in the time required to regain balance, and in the dynamic stability parameters, the natural frequency and damping ratio. The present study showed LBP was associated with alterations in biomechanical variables; in particular stiffness, hip and lumbar spine joints kinematic and muscle responses were altered in subjects with LBP when compared with healthy group. However, these alterations did not affect dynamic stability and moment developed at joints level, suggesting that LBP subjects adopted a different strategy to maintain balance but with the same effectiveness as the healthy subjects without any worsening of the symptoms. This may suggest to clinicians to encourage patients to remain active rather than to avoid movements. On the other hand, compensatory strategies were achieved with increased co-contraction at the expenses of muscle efficiency. This may lead to muscle fatigue and increase in spinal stress. Future research should clarify if the observed biomechanical alterations in this study are consequences or causes of LBP; or if the biomechanical changes and pain operate in a vicious circle, reinforcing each other leading to chronic conditions. This would help achieve our ultimate goal of developing effective treatment strategies, and it is hoped that the work of this thesis has helped us take a significant forward towards this goal.

No abstract included. / Arts, Faculty of / History, Department of / Graduate