Browsing by Subject "Rehabilitation Science"

Now showing 1 - 10 of 10
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    Beneficial effects of estradiol on murine skeletal muscle function.
    (2011-01) Greising, Sarah Marie
    Aging is a multidimensional physiological process that affects all people. Biological systems age at various rates with declines in structure and function of up to 3% per year due to a number of different mechanism (90). Many systems have well defined pathologies related to aging; cardiovascular disease, diabetes, osteoporosis, and dementia. The age-related pathology of skeletal muscle is sarcopenia. Sarcopenia is primarily characterized by muscle atrophy and weakness and is highly associated with functional impairment and immobility of the elderly (45). With age, both absolute force production and that normalized to the size of the muscle, or specific force, have noted decrements compared to younger individuals. It is likely that numerous mechanisms with various contributions of each account for the pathology of sarcopenia; such as physical (in)activity, hormonal changes, nutrition, oxidative stress, inflammation, and mitochondrial dysfunction. The main focus in this dissertation is on hormonal changes in females and secondary changes in physical (in)activity.
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    Effects of occupational therapy task-oriented approach in upper extremity post-stroke rehabilitation.
    (2011-08) Almhdawi, Khader
    There is a need for effective Upper Extremity (UE) post-stroke rehabilitation approaches. The Occupational Therapy Task-Oriented (TO) approach was described early in the nineties of the past century. Many of the TO principles were supported in the literature. However, the TO as a whole was only evaluated in case studies. This study aimed to evaluate the functional and the impairment effects of this approach and to refine its treatment protocol. Twenty participants with stroke of three months or more fulfilled the minimal affected UE active movements of at least 10° of shoulder flexion and abduction and elbow flexion-extension and volunteered for this study. Participants were randomized into two order groups. The immediate group got 3 hours of TO treatment per week for six weeks and then got six weeks of no treatment control while the delayed intervention group underwent the reversed order. Participants were evaluated before the first phase, at the cross over, and after the second phase by trained, blinded evaluators. The treatment change scores from both groups were compared with those of the control. The results supported the TO functional superiority as indicated by significant and clinically meaningful changes in the Canadian Occupational Performance Measure (COPM), the Motor Activity Log (MAL), and the time scale of the Wolf Motor Function Test (WMFT). The result failed to support hypothesis of the impairment effects superiority of the TO. We conclude that the TO approach is an effective UE post-stroke rehabilitation approach in improving the UE functional abilities. More studies are needed to provide more evidence for this approach and to illuminate more of its therapeutic abilities with different stroke severity and chronicity levels.
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    Enhancement of learning: Does sleep benefit motor skill memory consolidation?
    (2010-12) Borich, Michael Robert
    Purpose: It remains unclear how the brain best recovers from neurologic injury and how to optimally focus rehabilitation approaches to maximize this recovery. Recent research has indicated that sleep may augment this recovery. Sleep has been shown to benefit memory consolidation for certain motor skills, but it remains unclear if this relationship exists for explicit, continuous, goal-directed motor skills with rehabilitation applications. We aimed to determine the neurobehavioral relationship between finger-tracking skill development and sleep following skill training in young, healthy subjects. Methods: Forty subjects were recruited to receive motor skill training in the morning (n=20) or the evening (n=20). Measures of skill and cortical excitability were collected before and after training. Following training, each group had a post-training interval consisting of waking activity or an interval containing sleep. After this twelve-hour interval, skill performance and cortical excitability were reassessed. Subjects underwent another twelve-hour interval containing either waking activity or a sleep episode and came back for a second assessment, twenty-four hours after training. A subset of subjects (n=10) underwent the same procedures except the training period involved simple, repeated movement of the finger. Results: Skill performance improved after training and then continued to improve offline during the first post-training interval. Improvement was not enhanced by sleep during this interval. Cortical excitability was not substantially altered by training but was related to level of skill performance at follow-up assessment. Sleep quality was also found to be related to level of skill at follow-up assessments. The skilled training period did not lead to significantly improved performance compared to simple movement activity. Discussion: These data suggest that sleep is not required for offline memory enhancement for a continuous, visuospatial finger-tracking skill. These findings are in agreement with recent literature indicating the type of motor skill trained may determine the beneficial effect of sleep on post-training information processing. These results, combined with related studies in patient populations, provide a foundation to evaluate the relationship between sleep, changes in neural activity, and the time course of continuous visuospatial motor skill learning in individuals following neurologic insult.
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    Evoked human cutaneous reflexes during standing and step initiation.
    (2010-07) Hajela, Nupur
    Cutaneous reflexes have been shown to be task dependent, phase dependent and stimulus intensity dependent in movement tasks (e.g. walking and obstacle avoidance). We have demonstrated previously that cutaneous input can reduce reaction times and alter anticipatory postural adjustments that precede a step. It is not known how cutaneous input produces these changes. The influence of cutaneous reflexes during step initiation and standing was assessed in young, healthy subjects (n=15). Two sets of experiments were conducted. In the first experiment subjects stood on a force platform, then initiated three steps as fast as possible, to either a visual or sural go cue. For each "go" cue, a sural stimulation (2 Radiating Threshold) was delivered at two phases, loading and unloading phase of step initiation. Fifteen trials were acquired for each go cue during each of the two phases. Average reflex responses were determined from tibialis anterior (TA) muscle. This task was again repeated after the second experiment. In the second experiment subjects stood for 40 sec on a wooden platform and reflexes were evoked for varying stimulus intensities. Average evoked responses from TA were obtained. During step initiation, the primary effect in TA was a long latency excitation (70 - 90 ms). The results obtained demonstrate (1) Effect of cueing- reflexes were modulated during visual cueing vs. reversed signs during sural cueing. (2) Effect of phase of step initiation- greater amplitude for the loading than the unloading phase for both go cues. (3) Effect of task- net reflex response was primarily excitatory during step initiation but primarily inhibitory during standing. The cutaneous reflex responses for step initiation suggest behaviorally appropriate modulation of the reflexes which may play a role in the earlier release of the step and enhancement of APAs that we have previously reported (Kukulka et al, 2009).
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    Movement Control And Cortical Activation In Functional Ankle Instability
    (2008-07) Anderson, Kathleen Marie
    Background: Functional ankle instability (FI) is a common development following first-time lateral ankle sprain, resulting in functional limitations. Local tissue damage has not been a satisfactory explanation. Evidence exists of changes in motor control within the central nervous system in individuals with FI. Further investigation of the nature of these changes is warranted. Methods: Twenty subjects with FI and twenty healthy control subjects allowed comparisons between ankles within groups and between groups. Two primary methods of investigation were used. A kinematic analysis using electromagnetic motion capture was used during a step down task to assess repeatability and variation in patterns of ankle dorsiflexion/plantarflexion and inversion/eversion motion and speed and phase timing characteristics. A normalized coefficient of multiple correlations was used for motion cycle comparisons, and means and variance were compared for discreet time variables. Motor control was measured with an accuracy index from an ankle tracking task. A sub-group of 8 right-involved FI subjects and 10 control subjects underwent functional magnetic resonance imaging to detect cortical activation in sensorimotor areas while performing the tracking task. Results: With the step down task no between-group differences in the repeatability of ankle motions were found, although both groups showed greater variability in inversion/eversion than dorsiflexion/plantarflexion. Increased ankle instantaneous angular speed when contacting the step was found in the FI subjects, with trends to reversing instantaneous linear velocity and more rapid weight acceptance also noted. No differences in tracking accuracy were identified; however, differential patterns of lateralization of cortical activation were found within groups between ankles during the task, with greater contralateral hemisphere activity in the primary motor area and more symmetrical activity in the primary sensory cortex (S1) and supplementary motor areas in FI subjects tracking with the involved ankle than was observed in control subjects tracking with the right ankle. Between-group comparisons found areas of greater activation in left S1, premotor cortex, and anterior cingulate gyrus compared to control subjects. Conclusions: The results of this study support that processing differences exist at the cortical level between FI and healthy control subjects. Motor performance differences are also present.
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    Movement velocity effect on cortical reorganization and finger function in stroke.
    (2012-08) Deng, Huiqiong
    Paralysis of limb movement after stroke is a major cause of disability. Recovery of function is linked to favorable brain reorganization. The brain is primed for neuroplastic reorganization after stroke but the rehabilitation interventions must be well designed. Forced use of the paretic limb as a training regimen has been shown to be effective; however, the optimal kinematic parameters are not known. Studies in primates have shown that motor cortical neurons are coded for velocity of limb movement. Studies in healthy humans have shown a relationship between velocity of limb movement and cortical activation. Thus, we hypothesize that higher-velocity finger movement training will be significantly more effective than lower-velocity and that the improved finger function will correlate significantly with brain reorganization. Multiple data points were collected using single-subject cross over design with functional magnetic resonance imaging (fMRI), transcranial magnetic stimulation (TMS), and function tests. Subjects were trained at home, assisted by telerehabilitation devices supervised by a remote physical therapist. Subjects performed 28,800 repetitions of finger extension and flexion movements at lower-velocity and 28,800 at higher-velocity separated by a 3-week baseline phase. Fast-velocity training had significantly greater functional improvement compared to the slow-velocity training in the Box and Block Test, but not consistently in the Jebsen-Taylor and finger force tests. Fast-velocity training did not show significantly greater cortical reorganization compared to the slow-velocity training by TMS or fMRI testing. Further studies are indicated to conclude the impact of movement velocity on behavioral function and brain reorganization in stroke.
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    Oxidative Stress: aging and disuse.
    (2009-05) Chen, Chiao-nan
    Sarcopenia, the age-related decline of muscle mass and strength, is one major risk factor for frailty and mobility disability of the elderly. Muscle disuse due to bed rest or surgery (such as joint replacements) exacerbates the ongoing decline of muscle function in the elderly. The decline of muscle function with disuse is greater in aging muscles. However, the cellular mechanism responsible for the greater functional decline of aging muscles with disuse is unknown. Oxidative stress, a condition where the balance between oxidant production and removal is disrupted, is a shared mechanism of age and disuse related muscle dysfunction. Thus, the overall aim of my dissertation is to understand the role of oxidative stress in the age-related muscle dysfunction with disuse.Using an animal model of muscle disuse (hindlimb unloading), I tested the hypothesis that the ability of aging muscles to cope with the increased oxidative stress associated with muscle disuse is compromised. There are three major findings: (1) the regulation of glutathione (GSH), an essential endogenous antioxidant, is impaired in aging muscles with disuse; (2) the decline of GSH levels in aging muscles with disuse is associated with the decrease of glutamate cysteine ligase (GCL) activity and the reduction of the catalytic subunit of GCL content; (3) using proteomic techniques, I identified two proteins (carbonic anhydrase III and four-and-a-half LIM protein1, FHL1), which show changes in the oxidation levels with disuse and aging. The changes in the oxidation levels of these two proteins with disuse occur in adult rats but not old rats. However, old rats have greater baseline levels of oxidized FHL1.In summary, the series of studies demonstrate that the response of muscles with disuse is age-dependent. The ability to maintain GSH levels with disuse is compromised in aging muscles. In addition, the changes of protein oxidation with muscle disuse occur in specific proteins and that the changes are age-related.
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    Shoulder joint and muscle exposure in violin musicians: a three dimensional kinematic and electromyographic exposure variation analysis.
    (2009-05) Reynolds, Jonathan F.
    Subacromial impingement syndrome is a common disorder in the right shoulders of orchestral violinists. Studies performed to date on this population have been limited in terms of kinematic methods used, resulting in inability to relate recorded motions to clinically relevant motions. They have also used temporal EMG analysis, which can be misleading in terms of exposure. Previous kinematic research on non-musician populations, and using non-occupational tasks, have indicated that subacromial impingement is associated with reduced posterior tilting and upward rotation of the scapula, as well as increased upper trapezius and decreased serratus anterior activation.This study compared 20 violinists (3 males and 17 females) with right sided SIS to 30 normal controls (11 males and 19 females) in the performance of 30-second, randomized performances of slow and fast standardized musical repertoire (each score being played 4 times). Surface EMG of upper trapezius and serratus anterior were sampled at 1,000 Hz using pre-amplified electrodes and signals were further amplified and RMS processed at 100 ms to improve signal to noise ratio. Signals were normalized to resting EMG and relative voluntary electrical activity (RVE). Three-dimensional kinematic data were captured in a standardized fashion by mathematically embedding local coordinate systems within the trunk, scapula and humerus, and rotations of these segments about the embedded axes were sampled at 100 Hz. EMG and 3-D kinematic data were then analyzed using Exposure Variation Analysis (EVA) methods, which expresses 3 amplitudes of the EMG or kinematic signal in terms of time spent at each amplitude level. EVA arrays were expressed in 3X3 graphs and were analyzed in terms of speed effects (fast and slow), and injury effects (injured and uninjured) using Mixed-Effects Multinomial Logistic Regression statistical methods. The reliability of the EVA method was evaluated by calculating intraclass correlation coefficients (ICC) and standard error of the measurement (SEM) statistics for all EVA cells and for all dependent variables. The EVA methods used in this study were found to have moderate to high levels of reliability (moderate to high ICC and low SEM). The EVA method was able to discern differences in terms of speed and injury in both injured and uninjured participants. Musicians in both groups were observed to play in positions of increased glenohumeral internal rotation compared to non-musician subjects participating in other research studies at similar humeral elevation angles. Injured musicians were noted to play in positions characterized by increased posterior scapular tilting for longer durations of time, increased scapular upward rotation for longer durations of time, and increased scapular internal rotation at slow speeds. Injured musicians were also noted to adopt positions of increased scapular posterior tilting, increased scapular upward rotation for longer durations of time, and increased scapular internal rotation at fast speeds. When compared to their uninjured counterparts, injured musicians were also noted to perform with reduced amplitude but more static (longer duration) glenohumeral flexion, as well as with slightly increased glenohumeral external rotation compared to uninjured musicians. Injured musicians were noted to perform with increased short duration, low amplitude upper trapezius activity at slow speeds, while they played with reduced long duration, high amplitude recruitment at fast speeds. Lastly, injured musicians were noted to demonstrate increased amplitude of recruitment of serratus anterior at both slow and fast speeds. The EVA method of data reduction employed in this study was instrumental in identifying these differences where more traditional methods (also attempted in this study) failed to identify group differences with respect to injury. This study has therefore identified a reliable kinematic and EMG data reduction technique that can be used to assess the kinematics of shoulder motion, as well as the upper trapezius and serratus anterior muscle activation in violin musicians. The findings of this study suggest that violinists develop SIS because of the positions they adopt in playing the violin, and that the injured musicians may have developed compensatory strategies to avoid discomfort.
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    Study of scapular muscle latency, shoulder kinematics and muscle activity in people with and without shoulder impingement.
    (2009-08) Phadke, Vandana
    Background and significance: Shoulder impingement is a common shoulder pathology which is associated with changes in kinematics and muscle activity around the shoulder joint. The changes in muscle activity are theorized to be caused by changes in motor program strategies controlling the smooth and coordinated movements at the joints. Changes in muscle latencies, especially feed forward contractions, indicate alterations in these motor control programs. The purpose of the study was to assess for differences in the latencies and deactivation times of scapular muscles between subjects with and without shoulder impingement. Research Methods: Twenty five healthy subjects and 24 subjects with impingement were recruited. Scapulothoracic and glenohumeral kinematic data were collected using an electromagnetic system. Simultaneously myoelectric activities using surface electrodes from upper trapezius, lower trapezius, serratus anterior and anterior fibers of deltoid were collected as subjects raised and lowered their arm in response to a light cue. Data was collected during unloaded, loaded and after performing repetitive arm raising motion conditions. Analysis: The ratios of the number of feedforward contractions during trials were compared by chi square analysis across groups and conditions. The other variables were analyzed using 2 or 3 way mixed model ANOVAs. Results: The percentage of trials showing feed forward contractions was higher for upper trapezius and lower trapezius in the unloaded condition and lower for serratus anterior in the condition after repetitive motion for the subjects with impingement as compared to healthy subjects. Subjects with impingement also demonstrated significantly earlier contraction of upper trapezius and an earlier deactivation of serratus anterior during lowering of the arm as compared to the healthy subjects. All subjects exhibited an earlier activation and delayed deactivation of lower trapezius and serratus anterior in conditions with a weight held in hand. The study found decreased scapular upward rotation, decreased posterior tilt and a less anterior plane of elevation in combination in subjects with impingement using logistic regression analysis. No significant group differences were found for muscle activity as a percentage of the reference contraction. Discussion and conclusions: The subjects with impingement showed some significant differences for muscle activation and deactivation times to indicate differences in motor control strategies. Rehabilitation measures should incorporate appropriate training measures in tandem with strengthening and stretching exercises to focus on improving movement patterns and muscle control.
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    Task-related variations in the surface EMG of human first dorsal interosseous.
    (2010-12) Whitford, Maureen
    Results from animal and human studies question the traditional view of a homogeneous organization of the motorneuron pool. Single muscles may be organized topographically into task groups that correspond with an intraspinal somatotopic organization. The aims of this study were to determine if: i.) there was differential activation in different locations of the first dorsal interosseous (FDI) muscle during a given task, ii.) the differential activation related to directional requirements and/or end goal of the task, and iii.) there was an anatomical pattern to the differential activation. Twenty-six healthy right-handed participants carried out 48 isometric finger/hand contractions [8 tasks x (3 M waves + 3 active contractions)] in sitting while surface EMG was collected from 4 bipolar sites on the FDI muscle simultaneously. Index finger abduction and flexion forces were collected using 2 orthogonally placed load cells. The tasks were: abduction pre, flexion, diagonal, 30% abduction + 30% flexion, 30% flexion + 30% abduction, pinch, power, and abduction post. Mean peak integrated EMG (IEMG; smoothed over 100ms and integrated over contraction period) for each task was normalized to site and task specific mean M waves. We found differential IEMG across sites for all tasks, which further differed based on task direction and end goal. The anatomical pattern of the differential IEMG was such that there was always greatest activation in the distal ulnar site. We conclude that there are task-related variations in activation across locations of the human FDI muscle. The organization of the nervous system at the level of the muscle is not necessarily an "all-or-none" phenomenon.