Biomedical subjects

Carol L Richards

Publications and source records attributed to Carol L Richards.

At least 19 recordsLinked to original sources

PubMed2007

Navigational strategies during fast walking: a comparison between trained athletes and non-athletes.

Many common activities such as walking in a shopping mall, moving in a busy subway station, or even avoiding opponents during sports, all require different levels of navigational skills. Obstacle circumvention is beginning to be understood across age groups, but studying trained athletes with greater levels of motor ability will further our understanding of skillful adaptive locomotor behavior. The objective of this work was to compare navigational skills during fast walking between elite athletes (e.g. soccer, field hockey, basketball) and aged-matched non-athletes under different levels of environmental complexity in relation to obstacle configuration and visibility. The movements of eight women athletes and eight women non-athletes were measured as they walked as fast as possible through different obstacle courses in both normal and low lighting conditions. Results showed that athletes, despite similar unobstructed maximal speeds to non-athletes, had faster walking times during the navigation of all obstructed environments. It appears that athletes can process visuo-spatial information faster since both groups can make appropriate navigational decisions, but athletes can navigate through complex, novel, environments at greater speeds. Athletes' walking times were also more affected by the low lighting conditions suggesting that they normally scan the obstructed course farther ahead. This study also uses new objective measures to assess functional locomotor capacity in order to discriminate individuals according to their level of navigational ability. The evaluation paradigm and outcome measures developed may be applicable to the evaluation of skill level in athletic training and selection, as well as in gait rehabilitation following impairment.

Adult↗

PubMed2006

Balance self-efficacy and its relevance to physical function and perceived health status after stroke.

OBJECTIVES: To estimate the level of balance self-efficacy among community-dwelling subjects with stroke and to determine the relative importance of balance self-efficacy compared with functional walking capacity in predicting physical function and perceived health status. DESIGN: Secondary analysis of baseline, postintervention, and 6-month follow-up data from a randomized trial. SETTING: General community. PARTICIPANTS: Ninety-one subjects with a first or recurrent stroke, discharged from rehabilitation therapy with a residual walking deficit. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The Activities-Specific Balance Confidence (ABC) Scale, Medical Outcomes Study 36-Item Short-Form Health Survey physical function scale, and the EQ-5D visual analog scale of perceived health status. RESULTS: Average balance self-efficacy was 59 out of 100 points on the ABC scale (95% confidence interval, 55-64; n=89). After adjusting for age and sex, functional walking capacity explained 32% and 0% of the respective variability in physical function and perceived health status scores obtained 6 months later. After adjustment for age, sex, and functional walking capacity, balance self-efficacy explained 3% and 19% of variation in 6-month physical function and perceived health status scores, respectively. CONCLUSIONS: Subjects living in the community after stroke experience impaired balance self-efficacy. Enhancing balance self-efficacy in addition to functional walking capacity may lead to greater improvement, primarily in perceived health status, but also in physical function, than the enhancement of functional walking capacity alone.

Activities of Daily Living↗

PubMed2006

Psychometric evaluation of the original and Canadian French version of the activities-specific balance confidence scale among people with stroke.

OBJECTIVE: To evaluate the internal and absolute reliability and construct validity of the Activities-Specific Balance Confidence (ABC) scale and a new Canadian French version (ABC-CF) of it among people with stroke. DESIGN: Cross-sectional data from a randomized controlled trial. SETTING: Community. PARTICIPANTS: Ninety-one people with a residual walking deficit between 57 and 386 days poststroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The ABC and ABC-CF scales, Berg Balance Scale (BBS), comfortable and maximum gait speeds, Timed Up & Go (TUG) test, 6-minute walk test (6MWT), Barthel Index, physical function scale of the Medical Outcomes Study 36-Item Short-Form Health Survey, Geriatric Depression Scale (GDS), and the EQ-5D visual analog scale (EQ VAS). RESULTS: Internal consistency (Cronbach alpha) was .94 and .93 and the standard error of measurement was 5.05 and 5.13 for the ABC (n=51) and the ABC-CF (n=35) scales, respectively. Spearman rho values ranged from .30 to .60 for the ABC scale and from .45 to .68 on the ABC-CF scale for associations with scores on the BBS, comfortable and maximum gait speeds, TUG, 6MWT, Barthel Index, physical function scale, GDS, and EQ VAS. CONCLUSIONS: Evidence of internal and absolute reliability and of construct validity of the ABC and the ABC-CF scales supports their use for cross-sectional measurements of balance self-efficacy among community-dwelling people in the first year poststroke.

Adult↗

PubMed2006

A treadmill and motion coupled virtual reality system for gait training post-stroke.

A virtual reality (VR)-based locomotor training system has been developed for gait rehabilitation post-stroke. The system consists of a self-paced treadmill mounted onto a 6-degrees-of-freedom motion platform. Virtual environments (VEs) that are synchronized with the speed of the treadmill and the motions of the platform are rear-projected onto a screen in front of the walking subject. A feasibility study was conducted to test the capability of two stroke patients and one healthy control to be trained with the system. Three VE scenarios (corridor walking, street crossing, and park stroll) were woven into a gait-training program that provided three levels of complexity (walking speed, slopes, collision avoidances), progression criteria (number of successful trials) and knowledge of results. Results show that, with practice, patients can effectively increase their gait speed as demanded by the task and adapt their gait with respect to the change in physical terrain. However, successful completion of tasks requiring adaptation to increasing demands related to speed and physical terrains does not necessarily predict the patient's ability to anticipate and avoid collision with obstacles during walking. This feasibility study demonstrates that persons with stroke are able to adapt to this novel VR system and be immersed in the VEs for gait training.

Computer Simulation↗

PubMed2006

The effect of a task-oriented intervention on arm function in people with stroke: a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy of a task-oriented intervention in enhancing arm function in people with stroke. DESIGN: Two-centre, observer-blinded, stratified, block-randomized controlled trial. SETTING: General community. PATIENTS: Ninety-one individuals within one year of a first or recurrent stroke consented to participate between May 2000 and February 2003. INTERVENTIONS: The experimental intervention involved practice of functional, unilateral and bilateral tasks that were designed to improve gross and fine manual dexterity whereas the control intervention was composed of walking tasks. Members in both groups participated in three sessions a week for six weeks. MAIN OUTCOME MEASURE(S): The primary test of arm function was the Box and Block Test. Secondary tests included the Nine-Hole Peg Test, maximal grip strength, the Test d'Evaluation des Membres supérieurs des Personnes Agées (TEMPA) and the Stroke Rehabilitation Assessment of Movement. RESULTS: Results are for the more affected arm. Baseline performance on the Box and Block Test was an average of 26 blocks (standard deviation (SD) = 16) in the experimental group (n = 47) and 26 blocks (SD = 18) in the control group (n = 44). These values represent approximately 40% of age-predicted values. Values for the postintervention evaluation were an average of 28 (SD = 17) and 28 (SD = 19) blocks for the experimental and control group respectively. No meaningful change on other measures of arm function was observed. CONCLUSIONS: A task-oriented intervention did not improve voluntary movement or manual dexterity of the affected arm in people with chronic stroke.

Activities of Daily Living↗

PubMed2005

The circumvention of obstacles during walking in different environmental contexts: a comparison between older and younger adults.

Avoiding pedestrians is an integral part of our daily activities, yet this locomotor activity has received little attention in gait research. A recent study [Motor Control 2005;9:242] described the motor strategies used by young adults to circumvent an obstruction in different environmental contexts including obstacle movement, certainty about this obstacle movement and auditory distractions. The relationship between normal aging and such locomotor activity within these different environmental contexts, however, is not known. The purpose of this study was thus to compare the walking speed and the personal space-a protective zone preserved around the body-in healthy younger and older adults during obstacle circumvention in the above mentioned environmental contexts. The movements of nine younger adults (24.6+/-4.1 years) and nine older adults (69.7+/-3.2 years) were measured as they circumvented a stationary or moving mannequin with and without initial knowledge of the obstacle's displacements. Participants also had to pay attention to auditory messages, played in half of the trials, and to answer related questions. Results showed that all three environmental factors resulted in decreased gait speed in both groups, but the effect of auditory distractions was greater in older adults. Older adults also increased their personal space more than younger adults while paying attention to messages and they made more mistakes when answering related questions. Therefore, even if such an avoidance task is performed routinely, the increased information processing demanded by the environmental context affected both the motor and cognitive performance of older adults more than that of younger adults.

Adaptation, Physiological↗

PubMed2005

The effect of a task-oriented walking intervention on improving balance self-efficacy poststroke: a randomized, controlled trial.

OBJECTIVES: To evaluate the efficacy of a task-oriented walking intervention in improving balance self-efficacy in persons with stroke and to determine whether effects were task-specific, influenced by baseline level of self-efficacy and associated with changes in walking and balance capacity. DESIGN: Secondary analysis of a two-center, observer-blinded, randomized, controlled trial. SETTING: General community. PARTICIPANTS: Ninety-one individuals with a residual walking deficit within 1 year of a first or recurrent stroke. INTERVENTION: Task-oriented interventions targeting walking or upper extremity (UE) function were provided three times a week for 6 weeks. MEASUREMENTS: Activities-specific Balance Confidence Scale, Six-Minute Walk Test, 5-m walk, Berg Balance Scale, and Timed "Up and Go" administered at baseline and postintervention. RESULTS: The walking intervention was associated with a significantly greater average proportional change in balance self-efficacy than the UE intervention. Treatment effects were largest in persons with low self-efficacy at baseline and for activities relating to tasks practiced. In the walking group, change in balance self-efficacy correlated with change in functional walking capacity (correlation coefficient=0.45, 95% confidence interval=0.16-0.68). Results of multivariable modeling suggested effect modification by the baseline level of depressive symptoms and a prognostic influence of age, sex, comorbidity, time poststroke, and functional mobility on change in self-efficacy. CONCLUSION: Task-oriented walking retraining enhances balance self-efficacy in community-dwelling individuals with chronic stroke. Benefits may be partially the result of improvement in walking capacity. The influence of baseline level of self-efficacy, depressive symptoms, and prognostic variables on treatment effects are of clinical importance and must be verified in future studies.

Adult↗

PubMed2005

The negotiation of stationary and moving obstructions during walking: anticipatory locomotor adaptations and preservation of personal space.

This article introduces a novel, ecological, obstructed walking paradigm. Gait adaptations to circumvent obstacles undergoing uncertain displacements, and the effect of revealing the obstacle's action beforehand, were investigated in young adults. The personal space (PS) maintained during walking was quantified for the first time under different environmental factors including auditory distractions. Obstacle movement and its uncertainty resulted in gait adjustments aimed at gaining time to assess the situation. Early gait adaptations and constant clearances around the obstacle suggest that anticipation and preplanning are involved in such navigational tasks. Participants systematically maintained an elliptical PS during circumvention, but they adjusted its size according to different environmental factors. There was a relationship between the size of PS and level of attention, which suggests that the regulation of PS is used to control locomotion. This novel paradigm has important implications for the assessment and training of locomotor ability within real world environments.

Adaptation, Physiological↗

PubMed2004

Bilateral slowing of mentally simulated actions after stroke.

The ability to mentally simulate motor actions was studied in 25 patients with stroke. The duration of imagined and executed movements of the arm and leg was compared. Both executed and imagined movements took longer with the affected limbs than with the unaffected limbs. For both tasks, the duration of movements with the unaffected limbs was longer in the imagined than in the executed conditions, indicating a lack of temporal congruence on that side. Because the temporal uncoupling was found in the limbs contralateral to the intact hemisphere, we propose that this reflects a general slowing in motor imagery that is an indirect consequence of the lesion, rather than a deficit in movement representation within the unaffected hemisphere per se.

Aged↗

PubMed2004

Working memory and mental practice outcomes after stroke.

OBJECTIVE: To examine the relationship between working memory and motor improvement obtained after a single training session combining mental and physical practice. DESIGN: Before-after trial. SETTING: Laboratory of a university-affiliated research rehabilitation center. PARTICIPANTS: A sample of 12 patients with stroke and 14 age- and gender-matched healthy subjects. INTERVENTION: In a single session, patients were trained with combined mental and physical practice to increase the loading on the affected leg while standing up and sitting down. MAIN OUTCOME MEASURES: Motor improvement as measured by the percentage change in limb loading on the affected limb after training and 24 hours later (follow-up), and the relationship between working memory and percentage motor improvement. RESULTS: The loading on the affected leg was improved after training (P< .01) and at follow-up (P< .05), and working memory scores at follow-up correlated significantly (P< .004 to P< .007) with the level of improvement. The visuospatial domain yielded the strongest correlation (r= .83), followed by the verbal (r= .62) and kinesthetic (r= .59) domains. CONCLUSIONS: These results suggest that the outcome (improved limb loading) of mental rehearsal with motor imagery depends on the ability to maintain and manipulate information in working memory.

Adult↗

PubMed2004

The efficacy of combined physical and mental practice in the learning of a foot-sequence task after stroke: a case report.

OBJECTIVE: To investigate the effect of mental practice on the learning of a sequential task for the lower limb in a patient with a hemiparesis resulting from a stroke. DESIGN: A single-case study. SETTING: Research laboratory of a university-affiliated rehabilitation center. PATIENT: A right-handed 38-year-old man who had suffered a left hemorrhagic subcortical stroke 4 months prior. INTERVENTION: The patient practiced a serial response time task with the lower limb in 3 distinct training phases over a period of 5 weeks: 2 weeks of physical practice, 1 week of combined physical and mental practice, and then 2 weeks of mental practice alone. MAIN OUTCOME MEASURES: Performance on the task measured through errors and response times. Imagery abilities measured through questionnaires. RESULTS: The patient's average response time improved significantly during the 1st 5 days of physical practice (26%) but then failed to show further improvement during the following week of physical practice. The combination of mental and physical practice during the 3rd week yielded additional improvement (10.3%), whereas the following 2 weeks of mental practice resulted in a marginal increase in performance (2.2%). CONCLUSION: The findings show that mental practice, when combined with physical practice, can improve the performance of a sequential motor skill in people who had a stroke, and suggest that mental practice could play a role in the retention of newly acquired abilities.

Adult↗

PubMed2004

Training mobility tasks after stroke with combined mental and physical practice: a feasibility study.

This study examines the potential of using mental practice (MP) to promote the learning of 2 mobility tasks in persons with stroke. Twelve patients were trained with MP to increase the loading of the affected limb while standing up from a chair and sitting down. Vertical forces were recorded using force plates under each foot and the chair. Changes in the loading of the affected limb and in task duration, immediately after 1 training session and 24 h later, served as outcomes. After training, the loading of the affected limb had increased (P < 0.001) during standing up (16.2%) and sitting down (17.9%), and the improvement remained significant 24 h later, indicating a learning effect. In contrast, the duration of the performance did not change with training. The results indicate that, in the early stage of learning with MP, changes in limb-loading strategies are a more sensitive measure of performance than is speed.

Adult↗

PubMed2004

The role of technology in task-oriented training in persons with subacute stroke: a randomized controlled trial.

This trial compares the effects of task-oriented physical therapy (PT) provided with and without the use of rehabilitation technology on locomotor recovery in 63 persons with subacute stroke. Participants in the experimental (EXP) group used a treadmill, a Kinetron isokinetic exerciser, and a limb-load monitor, whereas those in the control (CTL) group did not while engaging in PT 1 h per day, 5 days per week for 2 months. Locomotor recovery was assessed by clinical (gait speed, Fugl Meyer motor leg and arm subscores, the Balance Scale, the Timed Up and Go, and the Barthel ambulation subscore) and laboratory outcomes (gait kinematics and kinetics) pre- and posttherapy and 3 months later. Within groups, gait speed (P < 0.01) and all secondary measures improved posttherapy (P < 0.01-0.05), and improvements in clinical measures were maintained at follow-up, but there was no difference between groups (P > 0.05). When the groups were pooled, the increase in gait speed was associated (r = 0.52, P = 0.003) with an increase in ankle power generation of the affected leg. The results demonstrate that the efficacy of the task-oriented approach is not dependent on rehabilitation technology.

Aged↗

PubMed2003

Brain activations during motor imagery of locomotor-related tasks: a PET study.

Positron emission tomography (PET) was used to study the involvement of supraspinal structures in human locomotion. Six right-handed adults were scanned in four conditions while imagining locomotor-related tasks in the first person perspective: Standing (S), Initiating gait (IG), Walking (W) and Walking with obstacles (WO). When these conditions were compared to a rest (control) condition to identify the neural structures involved in the imagination of locomotor-related tasks, the results revealed a common pattern of activations, which included the dorsal premotor cortex and precuneus bilaterally, the left dorsolateral prefrontal cortex, the left inferior parietal lobule, and the right posterior cingulate cortex. Additional areas involving the pre-supplementary motor area (pre-SMA), the precentral gyrus, were activated during conditions that required the imagery of locomotor movements. Further subtractions between the different locomotor conditions were then carried out to determine the cerebral regions associated with the simulation of increasingly complex locomotor functions. These analyses revealed increases in rCBF activity in the left cuneus and left caudate when the W condition was compared to the IG condition, suggesting that the basal ganglia plays a role in locomotor movements that are automatic in nature. Finally, subtraction of the W from the WO condition yielded increases in activity in the precuneus bilaterally, the left SMA, the right parietal inferior cortex and the left parahippocampal gyrus. Altogether, the present findings suggest that higher brain centers become progressively engaged when demands of locomotor tasks require increasing cognitive and sensory information processing.

Adult↗

PubMed2003

Functional cerebral reorganization following motor sequence learning through mental practice with motor imagery.

The goal of the present study was to examine, via positron emission tomography, the functional changes associated with the learning of a sequence of foot movements through mental practice with motor imagery (MI). Following intensive MI training over several days, which led to a modest but significant improvement in performance, healthy subjects showed an increase in activity restricted to the medial aspect of the orbitofrontal cortex (OFC), and a decrease in the cerebellum. These main results are largely consistent with those found in a previous study of sequence learning performed in our laboratory after physical practice of the same task [NeuroImage 16 (2002) 142]. Further analyses showed a positive correlation between the blood flow increase in the OFC and the percentage of improvement on the foot sequence task. Moreover, the increased involvement of the medial OFC revealed a modality specific anatomo-functional organization, as imagination of the sequential task after MI practice activated a more posterior region than its execution. These results demonstrate that learning a sequential motor task through motor imagery practice produces cerebral functional changes similar to those observed after physical practice of the same task. Moreover, the findings are in accord with the hypothesis that mental practice with MI, at least initially, improves performance by acting on the preparation and anticipation of movements rather than on execution per se.

Adult↗

PubMed2003

[New perspectives of locomotor rehabilitation after stroke].

The task-oriented approach incorporating treadmill walking for retraining gait early after stroke has contributed to promote locomotor recovery. To augment practice, training strategies such as mental practice and training in virtual environments are proposed. While the former offers more practice with less physical exertion, the latter allows safe practice in a variety of challenging environments. Work is under way to assess whether these new strategies can further enhance locomotor recovery.

Gait↗

PubMed2003

Assessing mobility and locomotor coordination after stroke with the rise-to-walk task.

INTRODUCTION: To assess mobility and locomotor coordination after stroke with the rise-to-walk task (RTW) and to examine the construct and concurrent validity of this task. METHODS: Nineteen subjects who had sustained a stroke and 19 healthy subjects performed the RTW task. The performance was recorded simultaneously with 2 clinical methods and 1 instrumented method. The RTW duration and fluidity of the motor strategy (fluid or nonfluid) were compared between groups and between methods. The relationship between RTW duration and 3 locomotor-related disability tests, as well as 1 motor impairment test, was studied. RESULTS: The subjects with stroke took 65% more time to complete the RTW task, and 16/19 separated the tasks of rising and walking (nonfluid strategy). Measures of the RTW duration with clinical methods were strongly correlated (r = 0.84 to 0.98) to those from the instrumented method, and the motor strategy was successfully assessed from video records. The duration was moderately correlated to scores from other locomotor-related tests, but not to the motor impairment test. DISCUSSION: The assessment of mobility and locomotor coordination with the RTW task indicate that both outcomes are impaired after stroke and that clinical methods provide a valid measurement of the task.

Adult↗

PubMed2003

Arm and leg impairments and disabilities after stroke rehabilitation: relation to handicap.

OBJECTIVES: (1) To examine the relationships between measures of impairment and disability for the arm and leg with a measure of handicap and (2) to identify the impairment or disability most strongly related to handicap situations. DESIGN: Prospective cohort study. SETTING: Intensive functional rehabilitation unit and community. PATIENTS: One hundred and two persons who had a stroke. MAIN OUTCOME MEASURES: Arm and leg impairments and disabilities were evaluated with reliable and valid tests at discharge from rehabilitation. Six months later, handicap situations were evaluated with the Assessments of Life Habits (LIFE-H). RESULTS: Arm and leg impairments and disabilities are correlated with handicap situations. Disability of the leg is more strongly associated with handicap than arm disability. Arm and leg disabilities are not statistically more strongly related to handicap than arm and leg impairments. CONCLUSIONS: The high correlations found between handicap situations and the impairment and disability measures of the leg provide new information that support the importance of mobility to promote integration after stroke.

Aged↗