The ability to pinch an object precisely is an essential function of the hand. The primary objective of this experiment was to examine the effect of aging on the perception of a pinch-grip force exerted by the thumb and index finger. Twelve young (25.3 +/- 2.4 yr.) and twelve older (71.4 +/- 3.3 yr.) healthy adults executed unilateral and bilateral pinch-grip tasks with and without visual feedback. The performance of the older group was worse than that of the younger individuals when asked to reproduce a pinch force. Specifically, the older adults tended to produce an initial overshoot in force which then decreased towards the required force. However, no difference existed between the two age groups when they were asked to produce a same force with both hands simultaneously. These results suggest that the normal aging process has a more significant effect on sensorimotor memory than on the output of descending motor commands.

Injury to the central nervous system as a result of cerebrovascular accidents (CVA) often leads to impairment in balance and mobility. Very little is known about the strategies that patients with CVA employ to prevent falls during unexpected changes of a support surface while patients are standing and walking. Previous studies showed that light touch increases postural stability in healthy subjects. However, it is not known whether patients with CVA would benefit from light touch in the same way as the healthy subjects do. Three studies in this research were conducted to examine the impact of stroke on postural responses triggered by surface rotations (Triggered Postural Responses; TPRs) during standing and walking and to investigate the effect of light touch on the control of TPRs during both tasks. Pitch and roll surface rotations (amplitude:5o; peak velocity:32o/s) were randomly presented to 11 stroke and 8 healthy age-matched subjects during quiet stance and walking, with similar limb geometry in double limb support. Light touch (<4N) was provided by a load sensor strip mounted on a rail along the walkway. Body kinematics was captured at 120 Hz by a 6-camera Vicon 512 system. Ground reaction forces were acquired at 1080Hz by 2 AMTI force plates. Surface EMGs were recorded at 1080 Hz from 4 bilateral lower limb muscles. Results showed that TPRs in healthy subjects were functionally appropriate to the direction of perturbations and task demands, such that TPRs were tuned down during walking, as compared to standing, suggesting that postural requirements are less during walking. In contrast, CVA disrupts equilibrium control such that TPRs in the stroke subjects were delayed and not modulated as the perturbed directions and task demands changed, possibly due to problems in sensorimotor integration. Asymmetry was characterized by under-activated muscle responses and force generations of the paretic side and hyperactivity of the non-paretic upper and lower extremit / Les lésions du système nerveux central suite à un accident vasculaire cérébral (AVC) affectent fréquemment l'équilibre et la mobilité. Peu d'information est disponible sur les stratégies utilisées par les patients ayant survécu à un AVC pour prévenir les chutes lorsque des changements inattendus de la surface de support se produisent pendant la marche et la position debout. Des études ont établi que des sujets sains voient leur stabilité posturale améliorée avec l'ajout d'information tactile. Cependant, il n'a pas été démontré si les sujets ayant eu un AVC peuvent aussi bénéficier de ces informations tactiles. Cette recherche inclut trois études visant à examiner, en premier lieu, l'impact d'un AVC sur les ajustements posturaux réactifs (APR) déclenchés par des rotations de la surface de support et, en deuxième lieu, l'effet des informations tactiles sur le contrôle de ces APR pendant deux tâches, soit la marche et la position debout. Onze sujets ayant eu un AVC et huit sujets sains, appariés pour le genre et l'âge, ont participé à ces études. Des rotations de la surface de support dans les plans sagittal et frontal (amplitude: 5°; vélocité maximale: 32°/s) étaient présentées aléatoirement aux sujets lors de la marche (phase de double appui) et en position debout (position des membres inférieurs simulant la phase de double appui). Le toucher léger (< 4N) d'une rampe fournissait l'information tactile aux sujets. Un système à six caméras d'analyse tridimensionnelle du mouvement (Vicon 512 system) a été utilisé pour acquérir les données cinématiques du corps à une fréquence de 120 Hz. L'électromyographie de surface de quatre muscles du membre inférieur a été enregistrée bilatéralement à une fréquence de 1080 Hz. Les forces de réaction du sol ont été acquises par deux plate-formes de force (AMTI) à la même fréquence. Les sujets sains ont présenté des APR fonctionnels et modulés par la directio

This prospective observational study examined whether baseline self-efficacy can predict health status, post-rehabilitation and whether changes in self-efficacy are associated with changes in health status. Thirty-one subjects with fibromyalgia were recruited consecutively from referrals to rehabilitation programs in Montreal area centers. Assessments, including the Arthritis Self-Efficacy Scale and the Medical Outcomes Study 36-Item Short-Form Health Survey, were done before and after completion of the program, to provide baseline and outcome measures of self-efficacy and health status. Baseline correlations showed a mild-to-moderate association of self-efficacy with physical and mental health status. Baseline self-efficacy for function (FSE) showed a trend towards predicting physical functioning and bodily pain. Baseline self-efficacy for other symptoms (OSE) also showed a trend towards being predictive of bodily pain and mental health. Correlations of the changes showed that FSE and OSE were associated with physical functioning, vitality, social functioning and role-functioning emotional. This research contributes to the understanding of fibromyalgia patients' responses to rehabilitation.

The purpose of the present study was to establish the prevalence of sensory, neurological and systemic impairments in the Inuit pediatric population (0-18 years) in 13 communities of the Baffin region of the Northwest Territories, Canada. / A data collection instrument (DCI) was developed to obtain clinical data from medical files in each of the Community Health Centres. Impairments rather than disabilities were described and possible causal factors were identified. Data collection took place during the month of June, 1989. / Nearly 13% of Inuit children living in the Baffin area have impairments. Of this group, 15.9% have multiple impairments. The prevalence of children with sensory impairments is 49.4/1000, with neurological impairments is 28.7/1000, with systemic impairments is 30.2/1000 and with multiple impairments is 20.5/1000 children. Over 50% of the impairments reported were due to infectious diseases such as meningitis and chronic otitis media. / The results of this study provide a basis for the development of community based programs which emphasize prevention of impairments in children. / Recommendations for the development of appropriate rehabilitation programs are discussed in the context of the policies of the Canadian government pertaining to the needs of Aboriginal persons with disabilities.

Botulinum A toxin (BTX) has become increasingly recognized as a treatment option in the management of spasticity in children with cerebral palsy (CP). Preliminary evidence suggests that certain baseline characteristics of the child may affect responsiveness to BTX. However, the contribution of these factors has not been fully elucidated. / The primary objective of the study was to examine whether specific intrinsic and extrinsic characteristics of the child were associated with responsiveness to BTX. The results indicate that age, number of treatments, parenting stress and child's motivation were associated with the degree of change in gait pattern, level of ambulation, gross motor function and functional independence. The findings suggest that the contribution of contextual factors (personal and environmental) on responsiveness to BTX is underappreciated in children with mild CP. Identification of potential factors contributing to responsiveness to BTX will assist clinicians in identifying children who would benefit most from this procedure.

The main objectives of this prospective cohort study were to examine the construct and predictive validity of the STREAM, and estimating its responsiveness. Sixty three acute stroke patients were evaluated on the STREAM and other measures of impairment and disability during the first week post-stroke, four weeks later, and three months post-stroke. The results of the study showed that STREAM scores were associated with measures of impairment and disability, and could discriminate subjects based on Balance Scale and Barthel Index scores. Moreover, the STREAM during the first week post-stroke was found to be an independent predictor of discharge destination after the acute care hospital, and of gait speed and the Barthel Index at three months post stroke. In addition, the total and subscale STREAM scores were able to mirror changes in motor performance between each evaluation. The utility and measurement properties of STREAM warrant its use in clinical practice and research.

Reduced levels of health-related quality of life (HRQL) post-stroke are an important issue to address in rehabilitation. Despite improvement in function over time, HRQL remains poor for many stroke survivors. This longitudinal study is aimed at estimating the extent to which physical performance, social, and psychological functioning influence HRQL. / Forty-three community-living persons with stroke were recruited to participate in a six-week intervention preceded and followed by a performance- and interview-based evaluation assessing different levels of disability and functioning. HRQL was measured by the VAS of the EQ-5D. / Regression models generated cross-sectionally demonstrated that physical performance, social, and psychological functioning explained up to 90% of the variation in HRQL. A GEE model revealed that, over time, only upper extremity functioning had a significant relationship with HRQL. / Much attention has already been focused on increasing physical performance in rehabilitation. However, clinicians should consider other components that affect HRQL directly or indirectly through physical performance. Only by treating the different components of functioning at various levels can HRQL be ultimately increased.

This research project investigated locomotor and postural strategies to adapt to uphill and downhill treadmill walking in healthy and spinal cord injured (SCI) subjects. In the first experiment, subjects from both groups walked uphill at three different inclinations (5, 10 and 15º) while holding on to the handrails on the treadmill. The goal of this first experiment was to characterize changes in lower limb movements and muscle activity patterns required for up-slope walking. The results showed that the key mechanism when adapting to uphill walking in healthy subjects was to lift up the swinging limb by performing a simultaneous increase in hip and knee flexion of that limb. An increase in ankle dorsiflexion was also required to place the foot properly on the inclined surface. Modifications in lower limb movements were accompanied by progressive increases in the peak amplitude of electromyographic activity of lower limb muscles as the treadmill grade went steeper. The most important increase was observed in the plantarflexor muscles during push off. This increase in muscle activity was necessary to propel the body forward and upward and counteract the resistance due to gravity in uphill conditions. In SCI subjects, a similar trend of adaptation was found only at the hip during uphill walking. Furthermore, the majority of lower limb muscles, including ankle plantarflexors, showed very limited adaptation during uphill walking. The limited changes observed in lower limb movements and muscle activity suggest that SCI subjects have to used different strategies than healthy subjects to adapt to uphill walking. These strategies could involve movements from the trunk and pelvis to compensate for lower limb deficits. / The second experiment specifically focused on the role of the trunk and pelvis in the strategies of adaptation to uphill and downhill treadmill walking in healthy and SCI subjects. Results from healthy subjects showed that walking on an inclined surface required modifications in trunk and pelvic vertical alignment in the sagittal plane. Uphill walking induced a progressive forward inclination of both trunk and pelvis whereas the opposite trend was found in downhill conditions. These modifications in trunk and pelvic alignment are necessary to counteract the effects of gravity on forward momentum at different slope conditions. In contrast to healthy subjects, SCI subjects with minor deficits in lower limb kinematic patterns showed a greater forward inclination of both trunk and pelvis during level and inclined walking, especially in downhill conditions where both segments were maintained at similar inclination as in level gait. SCI subjects with major deficits revealed analogous (but more pronounced) feature in trunk and pelvic orientation during walking. The whole group of subjects with SCI seemed to adopt this anterior posture to benefit from greater stability during level and inclined walking. Results from frontal and transverse plane motions revealed that compensatory movements from trunk and pelvis were performed only by subjects with SCI showing severe mobility dysfunctions. These compensatory movements were maintained similar across treadmill grades. Results from subjects with SCI and healthy subjects did not show any significant changes in trunk and pelvic total angular excursions in the three planes of motion when comparing level and inclined walking. This absence of changes suggests that lower limbs are mainly responsible for generating or absorbing more energy during uphill and downhill walking in these two groups of subjects.

This thesis reports two studies which compared the effects between a feedforward gait training and a standard exercise protocols on parkinsonian (PD) gait and choice reaction times (CRTs). The feedforward treatment consisted of training PD subjects to walk to preparatory signals, in the form of visual and auditory cues. Firstly, we compared the effects of 45 min of feedforward gait training, administered to 9 randomly selected PD subjects, to those of the exercise program, given to 7 PD subjects. Secondly, the effects of 3 weeks of feedforward gait training (n = 5) were compared to those of the exercises (n = 4). Gait and CRT measures were obtained at pre-test, at 45 min and 3 weeks post-treatment. Contrarily to the exercises, 45 min of feedforward gait training increased significantly the mean gait velocity, stride length and decreased the double limb support time (p $<$ 0.01). Neither of the two treatments produced significant effects on the CRTs. Three weeks of feedforward gait training did not produce any additional changes on gait and CRTs. Three weeks of exercises exerted no effects on gait and CRTs. These findings indicated that the 45 min feedforward gait training effect cannot be carried over from gait to CRTs in PD, at least under our present gait training paradigm. The role of preparatory cues in the amelioration of certain PD gait parameters may be related to the improvement of the deficiencies in the parkinsonian motor preparatory process, at the level of the motor basal ganglia.

Due to advances in medical technology, the incidence of incomplete spinal cord injury versus complete paralysis in spinal cord injury is increasing. However, little is known about the interactions between crutch use and gait in the incomplete spinal cord injured population. This thesis presents a quantitative description of five incomplete spinal cord injured subjects who use Canadian crutches, representing a wide spectrum of gait speeds, with respect to several kinetic and kinematic factors, and focuses on describing observed interactions. Results indicate that Canadian crutches are used primarily for support, balance and braking. Peak loading on the crutches in the axial direction was observed to be between 10 and 38 percent of subjects' body weight, and seemed to be related to the magnitude of lower limb loading during the gait cycle. Peak braking forces ranged from 0.13 to 0.58 percent of body weight, where the highest braking forces were seen in the subjects with the lowest gait speeds. The use of crutches for balance was observed consistently throughout the single limb support phase in the contralateral crutch in all subjects. The relationship between vertical ground reaction forces and axial forces on the crutches is supported by kinematic data and moment analysis. It is suggested that due to common factors among all subjects in the spectrum, that there may be prerequisites such as balance or lower limb strength for assisted gait with Canadian crutches. Strategies aimed at improving these requirements may aid in efficient and successful crutch walking.