The effect of salbutamol on performance was studied in 7 male non-asthmatic elite (VO₂max ≥ 60 ml/kg/min) athletes. The subjects entered the study just prior to their competitive season. Salbutamol (2 puffs=200 µg) or placebo was administered by metered-dose inhaler, through a spacer device, 20 minutes prior to testing in a double-blind, randomized crossover design. Pulmonary functions including maximum flow volume curves were performed on the first two visits, at 5 intervals (pre-medication, 20 minutes post-medication, and 5, 10, and 20 minutes post-exercise). The first two sessions combined these pulmonary function measures with an exercise bout consisting of a continuously ramped cycle ergometer ride to exhaustion to determine maximal oxygen uptake (VO₂max), peak power, and maximal heart rate. Pulse oximetry was used to measure the oxygen saturation of hemoglobin. The next sessions involved performing a 45 minute ride at 70% of VO₂max, followed by a timed sprint to exhaustion. Lastly, a Wingate anaerobic test was used to measure total work and peak power. There was a non-significant decrease in VO₂max from a mean of 63.5 ml/kg/min (± 3.2) for the placebo (P) trial, to a mean of 62.6 (± 3.3) with salbutamol (S). No difference was found in peak power (P= 438 Watts ±26.3, S= 438 ±27.9) or maximum heart rate (P=191 beats/min ±5.4, S=191 ±6.0). The performance related variables of endurance sprint time (P=104 seconds ±22.8, S= 97 ±31.4), and Wingate peak power (P= 10.12 Watts/kg ±0.57, S= 9.97 ±0.60) showed a non-significant decrease, while the total work performed on the Wingate test (P= 19.30 kJ ±2.09, S= 19.61 ±1.54) displayed a non-significant increase. The data failed to show significance despite using statistical analysis with a level of significance of p<0.20 to maximize the power of the tests. There was a statistically significant (p<0.05) increase in post medication (pre-exercise) forced expiratory volume (FEV₁) of 4.5% with salbutamol. This baseline increase persisted post-exercise, but there was no interaction effect of salbutamol and placebo over time. This represents an expected effect in non-asthmatic individuals, and although statistical significance was achieved, the magnitude of difference is not considered to be clinically significant. It was concluded that a therapeutic dose of aerosol salbutamol does not have an ergogenic effect in elite non-asthmatic athletes and it is therefore recommended that inhaled salbutamol continue to be permitted in international competition for individuals with exercise induced asthma. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Recently published federal public health initiatives have called for research to “develop better methods for analysis and quantification of (physical) activity” behaviors and to better understand the most important “features of physical activity (total amount, intensity, duration, frequency, pattern, or type) that confers health benefit”. Accordingly, this dissertation examined measurement issues related to the sources of variance in daily physical activity, as well as the types and features (e.g., dose) of physical activity that were associated with the cardiovascular disease risk factors body mass and blood lipids. Three investigations from within the Seasonal Variation of Blood Cholesterol Study (Seasons) cohort were conducted. Seasons was an observational study of 641 healthy adults that collected longitudinal assessments of body mass, blood lipids, physical activity, and dietary intake over 12 months of follow-up. The first investigation found that day-to-day variability was the major source of variance (65–80%) in activity, and that seasonal and day-of-the-week effects were minimal (<2%). Between-subject differences accounted for 20–35% of the variance observed, and 14 to 21 days of assessment were required to reliably measure non-occupational activity. The second investigation found that men increased (0.5 kg, p < 0.05) and women maintained (–0.2 kg, p > 0.05) their body mass levels over follow-up, and that both sexes had lower body mass (0.4 to 0.6 kg, p < 0.09) and higher activity levels (0.7 to 1.1MET-hrs·d–1, p < 0.05) in spring/summer compared to winter months. Total, occupational, and leisure activities were associated with lower cross-sectional body mass levels, and household and leisure activities were associated with longitudinal reductions in body mass. The final investigation revealed that individuals who were below recommended levels of moderate-vigorous physical activity ([special characters omitted]2 MET-hrs·d–1) had lower high-density lipoprotein cholesterol and higher triglyceride levels, placing them at increased risk of coronary heart disease. Additionally, total activity and duration of activity, but not intensity, were associated with lower levels of, or changes in blood lipids, particularly among men. These findings have important implications for the measurement of physical activity in epidemiologic studies, and they underscore the notion that naturally occurring changes in physical activity levels are directly related to disease risk.

The purpose of this dissertation was to investigate, in vivo, the effect of low back pain status on lumbo-sacral (L5S1) joint reaction force and moment profiles, and also on pelvis-trunk coordination during locomotion. We studied three groups of runners: runners with low to moderate LBP (LBP), runners who had recovered from a single bout of acute LBP (RES), and runners who never had LBP (CTRL). We developed an inverse dynamics model to investigate L5S1 mechanics. Results indicated that L5S1 reaction forces increased as stride length increased (p<0.024) in healthy runners, as did peak sagittal L5S1 moments (p=0.078). Subsequently, we used this model to examine L5S1 differences between our three experimental groups at their preferred running speed and at 3.8 m/s. While differences were observed between speeds for many L5S1 variables, and between groups for peak vertical GRF, no differences were found between groups for lumbar angle ROM, peak L5S1 joint reaction force, or L5S1 joint moment. In a further study, pelvis and trunk range of motion (ROM), relative phase coordination (CRP) and coordination variability (CRPvar) were compared between our groups over a range of locomotor speeds. We found increased pelvis-trunk CRP in the frontal plane for the LBP group as compared to the CTRL group during walking (p=0.029). During running, we observed increased pelvis axial ROM for the LBP group as compared to CTRL (p=0.010), and increased CRP for CTRL as compared to both RES (p=0.021) and LBP group (p=0.025), and increased CRPvar for CTRL as compared to LBP group (p=0.019). Findings from the second and third studies demonstrated differences between clinical groups despite the relative low levels of disability (mean Modified Oswestry Disability Questionnaire score = 7.9±6.2%), and suggest that mechanical and coordinative differences exist between those with and without LBP. Further, our RES group demonstrated characteristics common to both extreme groups (CTRL and LBP), supporting previous literature regarding residual performance effects. Our findings further suggest that the RES group represented a transition stage between the CTRL and LBP groups.

The aim of this dissertation was to develop, demonstrate and evaluate a tendon adaptation model (TAM), which predicts the relative tendon damage incurred by wrist muscles during repetitive wrist motion. This research was divided into three major goals. The first goal was to adapt the muscle model of Loren and Lieber (1995) with an optimization routine in order to predict muscle forces during dynamic motions. The muscle model was combined with the cumulative strain model of Goldstein (1981) and the tendon healing and damage models of Wren, Beaupre and Carter (1998) and Liao and Belkoff (1993) respectively. TAM predicts the amount of tendon adaptation given job/worker specific force, repetition, duration, and anthropometry and wrist posture. Individual components and the entire model were subjected to benchmark tasks to demonstrate how TAM produces muscle forces, tendon strains and damages for a given task. Results showed that the TAM reproduced results found in animal studies. The second goal was to demonstrate the model's capabilities. The first of three experiments was designed to collect maximal contractions at the wrist to determine the maximal strength (PST) of five wrist muscles. The second experiment was designed to evaluate the muscle model under dynamic situations. TAM predicted muscle stimulation patterns were compared to those recorded from subject electromyograms. Predicted stimulation patterns synchronized well with electromyograms but did not match as well in amplitude. The third experiment was designed to collect necessary data over the course of one hour while subjects performed a repetitive wrist flexion task to determine tendon strain parameters K1, K2 and α. The results suggest that subjects change their kinematic and kinetic profiles over the course of an hour to minimize the effects of fatigue and damage. The third goal was to perform a sensitivity analysis on the model by varying the estimated parameters and subject specific measurements. The muscle model was found to be sensitive to the parameter PST. The cumulative strain model was hardly sensitive to the parameter K1 while changes in the parameter α were found to have little effect on ending damage levels for simulations lasting approximately 1 hour.

Eccentric muscle contractions induce ultrastructural disruption, prolonged loss of maximal strength (MVC) and range of motion (ROM), increase in muscle soreness (SOR) and muscle proteins, and secondary damage by inflammation. The overall purpose of this dissertation research was to further examine the relationship between blood glutathione (GSH) levels and the blood creatine kinase (CK) response to eccentric exercise, and the inflammatory response, specifically neutrophil function. Study I examined the effect of resting GSH levels on CK activity after eccentric muscle contractions, and Study II examined the effect of α-lipoic acid (LA) supplementation on resting GSH levels in plasma. Study III examined the effect of eccentric muscle contractions on neutrophil function by examining gene expression of neutrophils after eccentric muscle contractions to determine which genes are up-regulated or down-regulated during initiation of inflammation. It was concluded from Study I that subjects in the low GSH group experienced less muscle damage than subjects in the high GSH group, and these changes for the low GSH group were consistent with less secondary damage due to inflammation. Study II concluded that LA supplementation for 4 weeks may not be enough to increase GSH levels in low GSH group. Study III concluded that neutrophils initiate several processes including inflammation, cytoskeletal regulation, transcription, and metabolism in response to eccentric muscle contractions with the evidence of up- or down-regulation of genes.

This 60-minute interactive seminar going over the “Hot Topics” of musculoskeletal education for residency programs including hands-on skills training is sponsored by the STFM Group on Musculoskeletal Education and Sports Medicine. The mission is to encourage, empower, and teach musculoskeletal and sports medicine skills to faculty for educating other faculty, residents, and medical students in the PCMH. The seminar will review diagnosis, management, and treatment options of “Hot Topics” in musculoskeletal and sports medicine conditions seen routinely in primary care. The seminar will provide both hands-on skills training and introduce teaching methods of these musculoskeletal skills to participants. The seminar will review recent updates in musculoskeletal medicine and sports medicine to the family medicine residency curriculum.

Abstract available through the Clinical Journal of Sport Medicine.

A spinal cord injury (SCI) is life-altering, resulting in neurological deficits and a multitude of secondary complications. South Africa holds one of the highest traumatic SCI incidence rates in the world, where the social need for SCI prevention and rehabilitation is immense. Robotic locomotor training (RLT) is a novel rehabilitation technique that may improve health and wellbeing after SCI. A systematic review was conducted across 27 studies and 308 participants to explore the systemic effects of RLT. This review demonstrated that RLT shows promise as a tool for improving neurological rehabilitation outcomes; providing individuals with a SCI the ability to walk safely while improving their walking performance, as well as potentially improving cardiovascular outcomes and psychosocial factors. However, the studies reviewed were non-controlled with small, heterogenous sample sizes. Further high-powered, randomised controlled trials, with homogenous samples, are required to investigate these effects. If widespread adoption of these new technologies is to occur, sound evidence demonstrating efficacy and long-term cost saving is required. This dissertation aimed to explore some of these under-researched areas in a sample of sixteen persons with incomplete tetraplegia. Areas of focus included, 1) rehabilitation feasibility, adherence, and research challenges in an under-resourced environment 2) cardiovascular functioning and adaptation to a rehabilitation programme, and 3) psychological well-being. We implemented two interventions, robotic locomotor training (RLT) and activity-based training (ABT), over a 24-week pilot randomised control trial. Adherence to the interventions was high (93.9 ± 6.2%). Challenges to the study's feasibility included: ethical approval, medical clearance, transport and limited human/financial resources. Cardiovascular parameters demonstrated that efficiency of exoskeleton walking improved during the intervention. RLT may be more effective than ABT in improving cardiac responses to orthostatic stress, with standing heart rate at 24-weeks being significantly lower in the RLT group (75.1 ± 15.0 beats/min) compared to the ABT group (95.6 ± 12.6 beats/min). Standing and RLT had similar effects on the parasympathetic nervous system, whilst both interventions were limited in their effect on brachial and ankle blood pressure. Despite experiencing past trauma, participants possessed psychological resources including resilience, self-efficacy and post-traumatic growth which contributed to high perceptions of quality of life. The use of an exoskeleton may have had a greater positive impact on subjective psychological well-being. Expectations of participants entering the study centred around regaining the ability to walk again, despite past experiences and medical advice suggesting otherwise. Hope aids in buffering against negative emotions, however, a thin line exists between supporting high expectations and confronting unrealistic hope. Initial high expectations of recovery decreased and became more realistic during the intervention. This dissertation demonstrates potential physiological and psychological benefits that RLT provides. Despite this potential, barriers exist in the use of RLT in low- and middle-income countries such as South Africa, primarily due to a lack of financial and human resources. The development of lower-cost exoskeletons would lessen the burden of conducting large-scale trials and increase the likelihood of adopting these innovative rehabilitation tools into current standard of care practices.

No description available.

No description available.