Assessing Heart Rate Variability as a Surrogate Measure of Cardiac Autonomic Function in Chronic Traumatic Spinal Cord Injury

Individuals with a spinal cord injury (SCI) are at greater risk of cardiovascular disease (CVD) than able-bodied individuals. A major CVD contributing factor is the presence of autonomic disturbances, but the SCI-related changes in cardiac autonomic function are poorly understood. Heart rate variability (HRV) has been reported to non-invasively assess the cardiac autonomic nervous system (ANS). The following thesis involves investigating resting HRV in 56 subjects with a traumatic chronic SCI with the aim to 1) describe the overall distribution of HRV in SCI; 2) determine whether there are HRV differences based on level and/or severity of injury; and, 3) determine whether there is a relationship between parasympathetic and sympathetic frequency measures. The results revealed that HRV is variable between-subjects, there were no significant HRV differences based on level and/or severity of impairment, and the low frequency-to-high frequency ratio (LF:HF), may not be an applicable measure in traumatic chronic SCI.M.Sc

Considerations for Designing and Managing Resistance Training Intervention Studies

Background: Osteoporosis is a bone disease characterized by low bone mineral density (BMD) which is strongly associated with an increase in fracture risk. People with a spinal cord injury (SCI) experience rapid decline in BMD during the acute phase of injury, but the prospective bone changes are yet to be determined in the chronic phase. Resistance training (RT) is a common non-pharmaceutical intervention for treating osteoporosis. However, we are unsure if the benefits of RT outweigh the harms because adverse events (AEs) are not consistently monitored or reported in RT trials involving the healthy and clinical population. Objectives: The purpose of this thesis was to examine considerations for designing and managing RT intervention studies involving the general adult population as well as people with chronic health conditions (e.g., SCI, osteoporosis). The specific objectives were: 1) to determine if there are any prospective bone changes in people with a chronic SCI which can be used to assess the timing of exercise interventions; 2) to determine the benefits and harms of RT on health outcomes in adults aged 18 years or older, compared to not participating in RT; 3a) to explore the experiences and perspectives of individuals with chronic health conditions who had an AE as a result of RT; 3b) to understand researchers' current practices and perspectives on AE reporting in RT, and identify barriers and facilitators of AE reporting; and 3c) to adapt AE reporting guidelines to exercise which can be used to increase the quality of published research with respect to safety of RT interventions. Overall, the objective of this thesis was to inform RT interventions with respect to timing, benefits and the proper reporting of harms. Methods: To address the above objectives, this thesis consisted of three separate studies. Study 1 was a secondary data analysis of a two-year prospective, observational study that assessed bone variables at the tibia sites among a diverse population of individuals with chronic SCI (n=70). Peripheral quantitative computed tomography scans were taken at the 4% (distal tibia) and 38% (diaphyseal tibia) tibia site by measuring from the distal to proximal tibia starting at the inferior border of the medial malleolus. Study 2 was a review of systematic reviews exploring the effect of RT on health outcomes among community dwelling healthy adults (total of 11 systematic reviews, representing 364 primary studies and 382,627 unique participants). Study 3 was a qualitative study involving a multimethod approach. Interviews were conducted with people who have chronic health conditions and had an AE as a result of RT (n=12), and researchers who published RT studies (n=14). Interview data were analyzed using the thematic framework method. AE-reporting recommendations were generated based on interview data and were turned into an electronic survey to perform a modified Delphi consensus process involving 19 international researchers who published RT studies. Results: Study 1 demonstrated no changes in trabecular bone (trabecular volumetric BMD at the 4% tibia site), but reported a decline in cortical bone (cortical volumetric BMD, cortical thickness and cross-sectional area at the 38% tibia site) in people with a chronic SCI. Study 2 showed that RT was associated with a reduction in all-cause mortality and cardiovascular disease incidence, and an improvement in physical functioning. However, AEs were not being consistently monitored or reported in RT studies. For study 3, we learned that despite participant awareness of the value and benefits of RT, there is concern about experiencing exercise-related AEs. Furthermore, the perceived risks of RT influenced the participants’ decision to engage or return to RT. Within the exercise community, there is suboptimal implementation of existing AE reporting standards, or the perception that the available guidelines do not apply to exercise trials. The barriers identified were that researchers lack guidance, resources, or motivation for rigorous AE reporting. To facilitate AE reporting, researchers educate and value participants, use trained personnel, and implement standardized guidelines. An exercise-specific AE-reporting toolkit (i.e., checklist, template form, and decision tree) was developed based on the consensus results (3 rounds; minimum 74% agreement on each recommendation)

Pilot and feasibility studies in exercise, physical activity, or rehabilitation research

Abstract Background Clinical trials of physical activity and rehabilitation interventions can be challenging. Pilot or feasibility studies can be conducted prior to a definitive randomized controlled trial (RCT), to improve the chances of conducting a high-quality RCT of a physical activity intervention. Main body Physical activity interventions or trials present unique challenges at the population, intervention, comparator and outcome levels. At each level, we present guidance for researchers on the design considerations for pilot or feasibility studies of physical activity interventions. When it comes to defining study population, physical activity trials often exclude participants with certain health conditions or other characteristics (e.g., age, gender) because of uncertainty of the safety of the exercise intervention or presumed differences in responsiveness, at the expense of trial generalizability. A pilot trial could help investigators determine refined inclusion and exclusion criteria to balance safety, adequate recruitment, and generalizability. At the intervention level, because exercise can be a complex intervention, pilot trials allow investigators to evaluate participant adherence and instructor fidelity to the intervention and participant experience. At the comparator level, control group dissatisfaction and post-randomization drop-out can occur, because of the desire to be randomized to the exercise group, and the difficulty with blinding to group allocation; an active control or deception could be used. Finally, at the outcome level, there should be an emphasis on the pilot or feasibility outcomes such as recruitment rate, adherence to exercise, and retention or fidelity, than the efficacy of the exercise intervention. Conclusion Physical activity and rehabilitation researchers can use pilot and feasibility studies to enhance the rigor of future trials, while also publishing the results of their pilot work to move the field forward. Researchers in this field are encouraged to use published reporting guidelines for pilot and feasibility studies and to consider the challenges discussed in this paper