Cycling is increasing in popularity which is accompanied with a higher rate of injuries sustained due to collisions, crashes or falls. A high proportion of these events happen when the bicycle rider loses control of the bicycle. In order to improve bicycle rider control, the skill of riding a bicycle needs to be understood. Therefore, the overall aim of this PhD work was to explore bicycle rider control skills and to examine the effects of different constraints on the control of a bicycle. The first part of this thesis focuses on developing a valid and reliable methodology that can be further used for studying bicycle rider control skill. Firstly, a protocol to determine knee angle during cycling is being developed. Secondly, some technical approaches when studying muscle activity during cycling are being questioned. Lastly, a portable device based on a single angular rate sensor to record steering rate and bicycle roll rate was tested for reliability in an outdoor setup. Second part of the thesis examines the effects on bicycle rider control of three different constraints: 1) expertise, 2) body position and 3) cycle lane design. Results overall showed that all three constraints significantly affect steering and bicycle roll rate.

Rheumatoid Arthritis (RA) is a chronic inflammatory disease that can negatively impact people both psychologically and physically. Health benefits of regular physical activity (PA) have been demonstrated for RA patients (Cooney et al., 2011), however people living with RA are more likely to be sedentary (Sokka et al., 2008; Yu et al., 2015). A Self-Determination Theory (SDT) based approach was adopted in this thesis. The validity and reliability of the Behavioural Regulation in Exercise Questionnaire-2 (BREQ-2) was tested (Chapter 2) within RA patients via a mixed method approach. In a second study (Chapter 3), hypothesised relationships based on SDT between autonomy support from the important other (s), basic psychological needs, motivation regulations and RA patients’ subjective vitality and self-reported PA was tested via structural equation modelling. Presumed mediation effects were also examined. As an incongruence between PA measurement has been found previously (Semanik et al., 2011), the agreement with self-reported PA and sedentary time (ST) were determined (Chapter 4) on both objective and subjective PA, then related to the VO2 max test. The next investigation (Chapter 5) assessed the associations between motivation regulations, objectively measured PA/ST and a key indicator of compromised mental health (i.e., depressive symptoms). Overall findings of this thesis were discussed in Chapter 6, and future research directions, practical implication and limitations proposed.

It is commonly believed that with increased age, movement dexterity becomes slower and increasingly clumsy when performing simple every day tasks. In the General Introduction of this PhD thesis (Chapter 1), literature that supports evidence for this relationship was reviewed. In addition, literature that has attempted to understand co-variance factors that may influence the age and dexterity relationship were also presented. From this, the general thesis hypothesis raised was that other factors such as sense of touch, attention ability or strength might also correlate with age and so possibly could also explain the reduced dexterity variable. Five empirical chapters present the experiments conducted to address the hypothesis, and the data from these are discussed in the General Discussion (Chapter 7). The empirical chapters consisted of three main areas of experimentation. That is, Chapter 2 ran preliminary screening data, Chapters 3 and 4 tested the effects of selective attention ability on the age - dexterity relationship and Chapters 5 and 6 tested the effects of strength on the age - dexterity relationship. In more detail, Chapter 2 used standard clinical measurements to assess the effects of age on fine and gross movement dexterity, sense of touch, selective attention and strength. The data showed that all factors declined with increased age, but that strength and selective attention seemed particular relevant to general upper limb dexterity. In Chapter 3, the impact of selective attention ability was assessed using a modified and motion tracked dexterity task. This demonstrated that the age and dexterity relationship was not generalised across all movements, but instead was specific for phases of action that contained a selective attention component. Chapter 4 followed up these data by showing evidence of impaired selective attention and inhibition with increased age. Chapter 5 sought to clarify the impact that strength had on the age and dexterity relationship. The findings showed that while age and strength were related, age explained more of thedata’s variance for steadiness and movement tracking dexterity, whereas strength explained more of the data’s variance for aiming and tapping dexterity. In Chapter 6, the findings of Chapter 5 were tested by directly manipulating hand grip strength and measuring the resultant effects on tapping dexterity. The data supported Chapter 5 and confirmed that hand grip strength had a clear impact on the age and dexterity relationship. Together, the data presented in the PhD thesis suggest that other factors contribute to the effects of age on dexterity, and support the idea that better management of these confounding factors may allow for a better understanding of the age and dexterity relationship and furthermore, help older adults enjoy better movement dexterity.

In the healthy human the primary driver for neuroplastic change is experience, in the form of learning and memory. Visuomotor learning has been shown as an effective experimental paradigm for inducing neuroplasticity, which is expressed as changes in corticospinal excitability (CSE). The present thesis uses the transcranial magnetic stimulation (TMS) stimulus response (SR) curve to assess learning induced changes in CSE. The first study presents a means of rapidly acquiring the TMS SR curve. Study two compares learning induced modulation of CSE between proximal and distal muscles. Study three assesses the influence of hand preference on learning induced changes in CSE. The results of study one indicate that it is possible to acquire the TMS SR curve in under two minutes. Studies two and three suggest distal muscles have a greater capacity for CSE modulation and this modulation of CSE is invariant to hand preference. Importantly, there is considerable variability in learning induced modulation of CSE. This thesis presents a novel paradigm for rapidly acquiring the TMS SR curve. It also highlights an important point for future studies of learning induced neuroplasticity – there is considerable variability in the neuroplastic response to a single session of visuomotor learning.

Understanding brain health is crucial in diagnosing, preventing and treating neurocognitive conditions (e.g., dementia). However, the literature reveals discrepancies around the interpretation of brain health and differences between populations. This thesis investigates brain health measures from different disciplines, including: resting cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) (using transcranial Doppler (TCD) ultrasound and magnetic resonance imaging (MRI)); cognition (including attention and memory); and quality of life (QoL) questionnaires. Differences between age (younger versus older) and cardiorespiratory fitness (fit versus unfit) groups were also investigated. Importantly, these multimodal brain health measures were completed in the same cohort. Declines were observed between younger and older groups in resting CBF measures (derived using TCD and MRI), and cognitive performance measures (attention-switching, learning and memory). In the older group, higher fitness offset declines in resting CBF and improved markers of cognition. In both groups, fitness significantly positively correlated with better QoL. However, no differences between age or fitness groups were observed in CVR measures. Further, CVR differed significantly depending on the imaging and analysis approach used. Future research is required to elucidate the cause of discrepancies and determine differences between groups (i.e., age/fitness/disease). Further, robust approaches to assess brain vascular health are needed.

Current methods used in the diagnosis of coronary artery disease vary in sensitivity and specificity and have a number of limitations. The aim of this thesis investigation was to explore a new technique for inducing hypocapnia in resting subjects and investigate whether this technique has any clinical applications in the diagnosis of coronary artery disease. In 18 healthy subjects, the effects of hypocapnia, induced by mechanical hyperventilation (in 21% or 15% inspired O\(_2\)), on cardiac electrical activity and heart function were investigated using an electrocardiogram (ECG) and echocardiogram. In addition, a pilot study was conducted to examine the effect of hypocapnia on the ECG of four patients suffering from coronary artery disease with stable angina. Experiments using mechanical hyperventilation showed that the most severe hypocapnia tolerable (PetCO\(_2\) = 20 ± 0mmHg) in normal healthy subjects causes a significant increase in T wave amplitude (increase of up to 0.09 ± 0.02mV, P < 0.01) in the anteroseptal leads (V\({_1-3}\)) of 18 normal subjects but these changes do not exceed the clinical thresholds for hyperacute T wave amplitudes. Hypocapnia did not cause any other significant ECG or echocardiographic changes during mechanical hyperventilation. Reducing inspired O\(_2\) to 15% during hypocapnia in nine normal subjects did not accentuate any of the T wave changes seen during hypocapnia, nor did it cause any clinically significant changes to appear. In two patients suffering from coronary artery disease with stable angina, no clinically significant ECG changes were seen during hypocapnia. These patients were taking isosorbide mononitrate medication which could have interfered with the vasoconstrictive effects of hypocapnia. In two patients not taking this type of medication, small increases in T wave amplitude (of up to 0.05 ± 0.01mV) and decreases in ST segment height (of up to 0.05 ± 0.01mV) were observed. These results show that hypocapnia, induced by mechanical hyperventilation, of the greatest severity tolerable in normal subjects, does not induce clinically significant ECG changes in normal healthy subjects as has been previously suggested. Preliminary results from four patients suffering from stable angina suggest that hypocapnia does cause small ECG changes but these are not consistent and are unlikely to be of clinical importance. However, conclusions about the clinical applications of this technique cannot be made until more patients are studied.

Thesis (M. Sc. (Physiotherapy)) -- University of Limpopo, 2011 / Aim of the study To investigate whether the Premier Soccer League Teams (PSL), in South Africa, have an ‘ideal’ medical team structure Objectives of the study Identification of medical professionals involved in the PSL and its leadership, the qualifications and experience of the medical professionals in PSL teams and whether the specialties of the medical professionals were clearly defined in order to avoid conflict within the team. Determination of the protocol that was followed when a player was injured and subsequent management and the influence on a player’s rehabilitation and return to activity. Setting The Premier Soccer League offices were contacted in order to conduct the research. Design The research design for this study was a descriptive survey. Methodology A purposeful sample of team managers and head coaches was chosen from 12 PSL teams. A self-constructed questionnaire was used to collect the data. A questionnaire was faxed to each participant and two follow-ups were made on the questionnaires that were not returned. Results The response rate was 54%. The composition of the medical teams comprised mainly of physiotherapists (85%) followed by sports physicians (77%), massage therapists (62%), dieticians (31%), sports psychologists (15%) and no podiatrist. Eight out of 13 participants reported having a sports physician as the head of the medical team while 4 participants reported the team leader to be a physiotherapist. Four out of 13 participants reported that their medical professionals were not all qualified and experienced in sport. The specialties of the medical professionals were clearly defined and each team had its own protocol for when a player was injured. The medical team had a positive influence on the management of injuries. Conclusion The PSL teams do not have an ‘ideal’ medical team structure. Keywords PSL, Medical team, structure, soccer

Patient noncompliance to treatment regimen is a common problem for health service providers. Five personality variable subscales of the Millon Behavioral Health Inventory were related to trainer-judged adherence to treatment plans of 50 injured athletes. Multiple regression analysis showed only Somatic Anxiety was a significant predictor of adherence (r = -.427); injured athletes with high scores are less likely to adhere to treatment recommendations. Results suggest the promise of the MBHI as a diagnostic instrument for evaluating injured athletes and enhancing their treatment, and provide evidence for construct validity of the Somatic Anxiety subscale using a previously unstudied population.

Thesis (M.S.) -- University of Texas at Arlington, 2008.

Exercising muscle needs a constant supply of oxygen for the aerobic metabolism of carbohydrate and fat, and regulation of the blood supply to muscle during exercise is therefore critical. Heart rate, stroke volume and minute ventilation all increase during exercise, and sympathetic vasoconstriction diverts blood to exercising muscle. It is well recognised that receptors in skeletal muscle play a vital role in the regulation of blood flow, including receptors sensitive to products of anaerobic metabolism such as lactate and hydrogen ions: metaboreceptors. Activation of the muscle metaboreflex signals the need for an increase in blood flow, and leads to an increase in cardiac output, ventilation and sympathetic vasoconstriction to non-essential organs. Exercise intolerance is one of the most disabling symptoms in patients with a range of cardiorespiratory diseases. Abnormalities of skeletal muscle favouring anaerobic metabolism have been documented in both chronic heart failure and chronic obstructive pulmonary disease (COPD), and this is thought to be relevant to exercise limitation in these diseases. Studies looking at patients with chronic heart failure have demonstrated an increase in muscle metaboreflex activity. It is thought that abnormal skeletal muscle generates greater quantities of anaerobic metabolites, leading to increased metaboreceptor activation. This in turn causes an increased sympathetic nervous system and ventilatory response to exercise. Patients with COPD have been shown to demonstrate similar skeletal muscle abnormalities, so we hypothesised that we would also find an increase in muscle metaboreflex activity in this group. It is possible to quantify muscle metaboreflex activity by exercising a small muscle group to fatigue then isolating it from the rest of the circulation with a sphygmomanometer cuff. This traps the metabolic products of exercise in the muscle and leads to prolonged stimulation of metaboreceptors. This can be measured as a sustained increase in blood pressure and ventilation when compared with control recovery without cuff inflation. The aims of this thesis were as follows: (i) to assess if it is possible to quantify the muscle metaboreflex in a group of patients with COPD and to determine whether muscle metaboreflex activity is increased in patients with more severe disease, (ii) to determine whether supplementation with oral creatine monohydrate alters muscle metaboreflex activity, upper limb strength or endurance and respiratory muscle strength in patients with COPD, (iii) to assess the effects of diabetic autonomic neuropathy on muscle metaboreflex function, and (iv) to evaluate whether pulse transit time is of use in the measurement of muscle metaboreflex activity. In our first study, we looked at a group of patients with stable COPD and found that rhythmic forearm exercise followed by post-exercise forearm ischaemia led to a sustained increase in blood pressure and minute ventilation when compared with control recovery. These findings are in keeping with previously published observations in normal subjects and in patients with chronic heart failure. We found that there was no difference in muscle metaboreflex activity between the groups of patients with moderate or severe disease. We then performed a randomised, double-blind, placebo-controlled, crossover trial looking at the effects of loading a group of patients with stable COPD with creatine monohydrate. We demonstrated a small increase in body weight and an increase in peak inspiratory and expiratory mouth pressures, but there were no effects on muscle metaboreflex activity or forearm muscle strength, endurance or recovery. A group of patients with type I diabetes mellitus was then used to study the effects of autonomic neuropathy on muscle metaboreflex function. We found that there was no difference in metaboreflex activity between subjects with diabetic autonomic neuropathy and subjects with diabetes but no evidence of autonomic neuropathy, suggesting that the afferent and efferent limbs of the muscle metaboreflex were intact. Our final study evaluated whether pulse transit time could be used to assess muscle metaboreflex activity. Pulse transit time is defined as the time taken for a pulse wave to travel between two arterial sites, and can be easily and non-invasively measured. It is thought to reflect blood pressure and arterial tone. In a group of healthy subjects, we found that pulse transit time fell with rhythmic handgrip exercise, and post-exercise muscle ischaemia led to a sustained fall in pulse transit time when compared with control recovery. Pulse transit time therefore shows promise in the measurement of muscle metaboreflex activity, but further studies are required. Studies comparing pulse transit time with more invasive measurements such as muscle sympathetic nerve activity would be of particular interest.