Brain impairment is defined as a significant loss or abnormality in the brain structure. Brain impairments may be acquired as a result of trauma (e.g., traumatic brain injury or stroke), non-traumatic origins (e.g., tumour) or disease (e.g., Parkinson’s disease or multiple sclerosis) or congenital (e.g., cerebral palsy) and are frequently associated with abnormal brain function (e.g., impaired memory, executive function and/ or impaired motor control). Evidence indicates that physical activity is beneficial for individuals with brain impairment as the subsequent loss of cardiovascular fitness, muscle strength and flexibility that occurs as a result of inactivity can compound the effects of the initial disability. Current cross-sectional evidence indicates that individuals with brain impairment are significantly less active than individuals without brain impairment. In order to address the low levels of physical activity in adults with brain impairment and thereby improve health, fitness and functioning, it is critical to develop interventions which effectively promote physically active behaviour in this population. The overall aim of the program of research described in this thesis is to contribute to the development and implementation of evidence-based physical activity promotion strategies in individuals with brain impairment. This thesis presents studies relating to two major subpopulations of people with brain impairment: adolescents with cerebral palsy (Chapters Three and Four); and adults with brain impairment (Chapters Five and Six).
Chapter Three presents a systematic review of the clinimetric properties of objective and subjective measures of physical activity in adolescents with cerebral palsy. Seven measures were included in this review. Each measure had notable limitations related to the assessment of physical activity intensity and duration and compliance with the physical activity guidelines. The review identified accelerometry as a promising means of measuring physical activity as it is objective and can collect real-time activity data on the frequency, intensity, and duration of activity, allowing for meaningful comparison to the physical activity guidelines.
Chapter Four presents a study that evaluated the validity of the ActiGraph accelerometer for the measurement of physical activity in children and adolescents with cerebral palsy. Results indicated that the ActiGraph is able to differentiate between different intensities of walking and that, for the purpose of classifying activity intensity, the cut-points developed by Evenson et al. for typically developing children had excellent classifaction accuracy for detecting moderate to vigorous physical activity. These findings indicate that the ActiGraph is a suitable device for measuring free-living ambulatory physical activity among children and adolescents with cerebral palsy and that the output can be used to make meaningful comparisons to the physical activity guidelines.
Chapter Five presents a systematic review of the research relating to physical activity and adults with brain impairment mapped against the five phases of a behavioral epidemiological framework. Results indicated that the vast majority of research to date has focused on identifying the benefits of physical activity for people with brain impairment; that measures previously used to evaluate physical activity participation do not allow meaningful comparison to the physical activity guidelines; that the evidence relating to correlates of physical activity has been largely concerned with levels of impairment and self-efficacy and; there is a relative paucity of studies evaluating the efficacy of interventions that promote physically active behaviour in this population. Currently there are no studies that evaluate the translation of physical activity interventions previously shown to be successful in controlled efficacy or effectiveness studies into widespread practice. On the basis of these results, it is concluded that future studies should consider a community-based rehabilitation model of intervention and that the rigor of such studies would be enhanced by the use of objective measures of physical activity. Chapter Six presents the results of a randomised controlled trial to evaluate the efficacy of a physical activity promotion intervention for community-dwelling adults with brain impairment. The intervention utilised elements of a community-based rehabilitation approach to deliver a lifestyle intervention to community-dwelling adults with brain impairment and outcomes were evaluated using an objective measure of physical activity. After the 12-week program, intervention participants exhibited significant increases in average counts per minute (cpm) (60.9 ± 20.7 cpm, p= .004) and daily average time spent in moderate to vigorous physical activity (MVPA) (10.4 ± 4.0 mins MVPA, p= .01). Daily counts per minute and time spent in moderate to vigorous physical activity declined significantly among attention controls (-11.1 ± 22.9 cpm; -2.6 ± 4.5 mins MVPA). Net differences in daily counts per minute and time spent in moderate to vigorous physical activity were 71.9 cpm (p= .02) and 12.9 mins MVPA (p= .03), respectively. Between-condition differences in the physical activity outcomes were not significant at 3-months follow-up. These findings are noteworthy given the particularly low rates of physical activity participation in this population and the significant physical and environmental barriers that individuals with brain impairment face. Given the rigour of the study, the results are sufficiently positive to warrant conducting a larger scale effectiveness trial utilising trained practitioners in clinical practice settings.