Physiological and behavioural consequences of network breakdown in brain injury

Traumatic brain injury (TBI) is a major public health problem with a huge unmet need for effective long-term care. Advances in MRI technology using diffusion tensor imaging (DTI) have demonstrated structural abnormalities in patients with TBI, often not seen on conventional brain imaging. The structural and neuropsychological consequences are described in existing research. The aim of this thesis is to identify whether there are physiological and behavioural consequences of TBI, which may be contributing to the observed problems in daily activities associated with this condition. This will help to understand the devastating functional impact following TBI, and its neurorehabilitation needs. This thesis initially develops a study protocol to investigate the physiology in TBI. Initial work explores physiology in thirty four healthy individuals using transcranial magnetic stimulation (TMS) to produce a study protocol that can be used in the patient group. This examined a selection of pathways, including the assessment of callosal physiology using a twin coil TMS method to assess for interhemispheric inhibition. This protocol was used to assess seventeen TBI patients, and compared to healthy controls, and demonstrated that callosal transfer is physiologically different between the two groups. The behavioural consequences of callosal transfer were then explored through the development of a bimanual tapping task in twenty nine healthy participants. The behavioural consequences were then assessed in the same group of TBI patients, and compared to the control group. The TBI patients had comparable mean performance. However, the variability in performance was the main difference between the two groups. The MRI DTI metrics were then investigated in the TBI and control groups. A relationship between the physiology, behaviour and microstructure was then explored. Through this series of investigations this thesis hopes to increase existing understanding of the consequences of brain injury

GPS analysis of a team competing at a national Under 18 field hockey tournament

The purpose of this study was to utilise global-positioning system (GPS) technology to quantify the running demands of national Under 18 field hockey players competing in a regional field hockey tournament. Ten male players (mean ± SD; age 17.2 ± 0.4 years; stature 178.1 ± 5.2 cm; body mass 78.8 ± 8.8 kg) wore GPS units while competing in six matches over seven days at the 2018 New Zealand national under 18 field hockey tournament. GPS enabled the measurement of total distance (TD), low-speed activity (LSA; 0 -14.9 km/hr), and high-speed running (HSR; ≥ 15 km/hr) distances. Differences in running demands (TD, LSA, HSR) between positions were assessed using effect size and percent difference ± 90% confidence intervals. Midfielders covered the most TD and LSA per game and strikers the most HSR during the 6 matches. There were “very large” differences between strikers and midfielders for TD and LSA, strikers and defenders for LSA and HSR, and defenders and midfielders for LSA. These results suggest that these playing positions are sufficiently different to warrant specialised position-specific conditioning training leading into a field hockey tournament

The effects of morning preconditioning protocols on testosterone, cortisol and afternoon sprint cycling performance [conference presentation]

Opportunities exist for athletes to undertake morning exercise protocols in an attempt to potentate afternoon performance. Four sub elite track sprint cyclists completed a morning cycling (Cyc) or weights-based protocol (WP) prior to an afternoon cycling time trial (500m) in a repeated measures, counterbalance crossover design. Measured variables included heart rate, blood lactate, cycling peak power, salivary testosterone (T) and cortisol levels along with time trial performance. Standardised differences in means via magnitude-based inferences were calculated using paired samples T-tests in SPSS version 24 with statistical significance set at p < 0.05. The WP produced significantly faster times in the final 250m in comparison to CycP. The anticipated circadian decline of T was observed after the CycP but was however mitigated following the WP. While slight decreases in 500m times were experienced during the WP, they were not significant and were considered within the normal variations experienced between performances by elite athletes. The effect of the WP on the circadian rhythm of T could be linked to a greater recruitment of muscle fibres. Results suggest a morning resistance protocol can positively affect testosterone levels for afternoon performance. Possible gender and individual responses from conducting a W over Cyc protocol were observed and require further investigation

Upper limb movement control after stroke and in healthy ageing: does intensive upper limb neurorehabilitation improve motor control and reduce motor impairment in the chronic phase of stroke?

Stroke affects people of all ages, but many are in the elderly population. 75% of stroke survivors have residual upper limb motor impairment and resultant disability. This thesis firstly examines upper limb motor control in chronic stroke. Evidence is emerging that high dose, high intensity complex neurorehabilitation interventions in chronic stroke patients produce unprecedented gains on clinical outcome scores of motor impairment, function and activity. But whether these clinical improvements represent behavioural repair or merely behavioural compensation remains undetermined. To address this question, upper limb movement kinematics, strength and joint range and clinical scores were measured in 52 chronic stroke patients before and after an intensive three-week treatment intervention. 29 chronic stroke patients who had not undergone treatment were similarly assessed, three-weeks apart. Significant improvements in motor control, arm strength and joint range in addition to gains on clinical scores were observed in the impaired arm of the intervention group. Crucially, changes in motor control occurred independently of changes in strength and joint range. Improvements in motor control were retained in a cohort of 28 patients in the intervention group, also assessed 6-weeks and 6-months after treatment had ended, demonstrating persistent changes in motor behaviour. These results suggest that behavioural restitution has occurred. Secondly, knowledge of the effects of normal healthy ageing on upper limb motor control is essential to informing research and delivery of clinical services. To this end, movement kinematics were measured in both arms of 57 healthy adults aged 22 to 82 years. A decline in motor control was observed as age increased, particularly in the non-dominant arm. However, motor control in healthy adults of all ages remained significantly better than in chronic stroke patients pre- and post-intervention. This thesis provides new evidence that treatment-driven improvements in motor control are achievable in the chronic post-stroke upper limb, which strongly suggests that motor control should remain a therapeutic target well beyond the current three to six-month post-stroke window. It will inform the continued development and delivery of high dose, high intensity upper limb neurorehabilitation treatment interventions for stroke patients of all ages

Functional decline in residents living in nursing homes : a systematic review of the literature

Objectives To describe the functional dependence progression over time in older people living in nursing homes (NHs). Design A systematic review of the literature was performed. Studies involving individuals 65 years and older living in NHs, describing their functional decline, improvement or stability in activities of daily living (ADLs), were eligible. The search strategy was applied in MedLine, Cochrane, CINAHL, and SCOPUS databases; aimed at identifying an unbiased and complete list of studies, searching by hand was also performed. The methodological quality of the 27 studies included was assessed. Results Functional trajectories were documented mainly through multicenter study design including sample size ranging from 2 to 9336 NHs, from 1983 to 2011 throughout a single or multiple follow-ups (>20). The average rate of decline was expressed in different metrics and periods of time: from 3 months with a decline of −0.13 points of 28, to 6 months (−1.78 points of 2829) to 1.85 years (−0.5 points of 6). Eating and toileting were the most documented ADLs and the decline is approximately 0.4 points and 0.2 to 0.4 points of 5 a year, respectively. Among the covariates, individual factors, such as cognitive status, were mainly considered, whereas only 13 studies considered facility-level factors. Conclusions Findings report the slow functional decline mainly in women living in US NHs, in years when residents were admitted with a low or medium degree of functional dependence. Considering that in recent years residents have been admitted to NHs with higher-level functional dependence, studies measuring each single ADL, using standardized instruments capable of capturing the signs of decline, stability, or improvement are strongly recommended. Among the covariates, evaluation of both individual and facility-level factors, which may affect functional decline, is also suggested

Characterization of upper limbs movements of healthy and poststroke adults.

Introdução: O comprometimento motor do membro superior afeta muitos sobreviventes pós-AVC em todo o mundo e a sua recuperação é lenta e complexa. A evidência de comprometimento bilateral após AVC está a crescer, levando à necessidade de desenvolver uma referência saudável para a qualidade do desempenho motor, em vez dos dados do membro superior ipsilesional. Objetivos: Caracterizar o movimento dos membros superiores de adultos saudáveis e pós-AVC, através da análise cinemática, durante o desempenho das tarefas "beber" e "acender a luz". Métodos: 63 adultos saudáveis e 5 pacientes pós-AVC foram elegíveis para desempenhar as tarefas "beber" e "acender a luz" com os dois membros superiores. Os pacientes pós-AVC foram avaliados no início da fase sub-aguda e no início da fase crónica. Os movimentos das tarefas foram captados por um sistema de captura de movimento 3D, variáveis cinemáticas da mão e articulares foram analisadas e foram feitas comparações entre tarefas e entre adultos saudáveis e pós-AVC. Resultados: A tarefa beber teve cinco fases com diferentes habilidades motoras e estratégias cinemáticas que foram influenciadas principalmente pela idade e pelo sexo. Acender a luz tem menor exigência manual, quando comparada com o beber. Os formatos diferentes dos alvos e a interação diferente parecem ser responsáveis por diferenças nas estratégias cinemáticas entre as duas tarefas executadas pelos adultos saudáveis. Foram encontradas diferenças entre as estratégias cinemáticas usadas pelos adultos pós-AVC e as usadas pelos adultos saudáveis. Todos os pacientes pós-AVC apresentaram alterações cinemáticas bilaterais em ambas as tarefas. Conclusão: Foi feita uma análise abrangente das estratégias cinemáticas das tarefas beber e acender a luz, de modo a obter uma referência do desempenho de atividades da vida diária com diferentes exigências de manualidade para adultos pós-AVC. Todos os pacientes estudados apresentaram alterações cinemáticas bilaterais, o que suporta a implementação de uma avaliação bilateral e a necessidade de ter uma referência saudável para a qualidade do desempenho motor. A severidade inicial do AVC e a idade dos pacientes parecem ter sido as informações mais importantes para explicar a extensão das alterações cinemáticas, mas a localização do AVC parece ter condicionado a especificidade dos défices, bem como a recuperação.PALAVRAS-CHAVE: ACIDENTE VASCULAR CEREBRAL; MEMBROS SUPERIORES; RECUPERAÇÃO MOTORA; AVALIAÇÃO DA QUALIDADE DA PERFORMANCE MOTORA; ANÁLISE CINEMÁTICA.Introduction: Upper limb (UL) motor impairment affects numerous poststroke survivors worldwide and its recovery is slow and complex. Evidence of bilateral impairment after stroke is growing, which creates the need to have a healthy reference for the quality of motor performance instead of ipsilesional UL data. Currently, kinematic analysis is considered one of the best ways to improve the understanding about the mechanisms that drive motor recovery, but a set of methodological flaws is hampering this knowledge. Aims: To characterize the ULs movement of healthy and poststroke adults, through kinematic analysis, during the performance of drinking and turning on the light tasks. Methods: 63 healthy adults and 5 poststroke patients were eligible to perform drinking and turning on the light tasks with both ULs. Poststroke patients were assessed in early sub-acute phase and in the beginning of chronic phase. Tasks movements were captured by a 3D motion capture system, end-point and joint kinematics were analysed and comparisons between tasks and healthy and poststroke adults were made. Results: Drinking task has five phases with different motor skills and kinematic strategies that were mainly influenced by age and sex. Turning on the light has a lower handling requirement, when compared to drinking. The different target formats and the different interaction with them seemed to be responsible for differences in kinematic strategies between both tasks performed by healthy adults. Differences were found between the kinematic strategies used by poststroke adults and those of healthy adults. All poststroke patients presented bilateral kinematic alterations in both tasks. Conclusion: A comprehensive analysis of kinematic strategies of drinking and turning on the light were made, in order to obtain a reference of the performance of activities of daily living with different handling requirement for poststroke adults. All studied patients showed bilateral kinematic alterations, which supports the implementation of a bilateral assessment and the need to have a healthy reference for the quality of motor performance. Initial severity of stroke and patients' age appear to have been the most important information to explain the extent of kinematic alterations, but stroke location seemed to have conditioned the specificity of deficits as well as the recovery

Backward Walking: A Novel Marker Of Fall Risk, Cognitive Dysfunction, And Myelin Damage In Persons With Multiple Sclerosis

Multiple sclerosis (MS) is a progressive, neurologic disease of the central nervous system that causes debilitating motor, sensory and cognitive impairments. As a result, persons with MS are at an increased risk for falls and falls represent a serious public health concern for the MS population. The current clinical measures used to assess fall risk in MS patients lack sensitivity and predictive validity for falls and are limited in their ability to capture to multiple functional domains (i.e., motor, sensory, cognitive and pathological domains) that are impaired by MS. Backward walking sensitively detects falls in the elderly and other neurologic diseases. However, backward walking and falls has never been explored in the MS population and the underlying reasons as to why backward walking sensitively detects falls remains unknown. Identification of a quick, simply and clinically feasible fall risk measures related to multiple functions impacted by MS and related to fall risk, which can detect falls before they occur is critical for fall prevention and timely and targeted intervention. Therefore, this dissertation examines backward walking as a novel marker of fall risk and its cognitive and pathological underpinnings to support its clinical utility. Our results indicate that backward walking is a sensitive marker of fall risk in the MS population, regardless of co-morbid cognitive deficits, and that examining underlying brain regions likely to contribute to backward walking performance including the corticospinal tract, corpus callosum and cerebellum, with neuroimaging tools sensitive to myelin (i.e., Myelin Water Imaging) demonstrate potential to identify underlying mechanisms of backward walking performance in the MS population. This work is the critical first step in establishing backward walking as a sensitive marker of fall risk for the MS population and leads the way to more personalized fall prevention therapies and interventions to improve clinical outcomes and decrease fall rates in the MS population