Effects of wheelchair mass on the physiologic responses, perception of exertion, and performance during various simulated daily tasks.

OBJECTIVE: To verify whether additional manual wheelchair mass above a critical level would produce, during many daily tasks, an increase in physiologic parameters, an increase in the perceived exertion, and a decrease in performance. DESIGN: A repeated-measurement design. SETTING: Six standardized tests thought to mimic daily activities. PARTICIPANTS: Volunteers (N=21), 8 men with spinal cord injuries (SCIs; mean age, 34+/-12y; range, 19-56y) and 13 able-bodied persons (11 men and 2 women; mean, 24+/-5y; range, 18-37y). INTERVENTIONS: Random additional masses ("0", 1, 2, 5kg) were placed under the seat of a multisport manual wheelchair (mass approximately 10kg) out of the subject's field of vision. MAIN OUTCOME MEASURES: Energy expenditure (EE; total o(2) consumed), heart rate (total number of beats), perceived exertion (visual analog scale), and performance (seconds to execute a sprint test) were measured. RESULTS: For all tests, there was no significant effect of mass found for either group for the EE, heart rate, and performance. In addition, for all tests, no significant effect of mass was found for the SCI group for the visual analog perceived exertion. However, for the able-bodied group, the added mass had a significant effect for the visual analog perceived exertion (F=6.11; P=.02) in the Stop-and-Go test. A post hoc Tukey test showed a significant difference between the 0kg and 5kg mass conditions (P<.01; d=.8), between 1kg and 5kg (P=.02; d=.6), and between 2kg and 5kg (P=.01; d=.6). CONCLUSIONS: Based on these findings, it can be concluded that, under the conditions of this study, additional mass (up to 5kg) loaded on a multisport manual wheelchair does not seem have any effect on EE, heart rate, or performance and has a minor effect on the visual analog perceived exertion evaluated in many activities of daily living.

Upper limb joint dynamics during manual wheelchair propulsion.

BACKGROUND: Inverse dynamic methods have been widely used to estimate joint loads during manual wheelchair propulsion. However, the interpretation of 3D net joint moments and powers is not always straightforward. It has been suggested to use joint coordinate systems (expression of joint moment on anatomical axes) and the 3D angle between joint moment and angular velocity vectors (propulsion, resistance or stabilization joint configuration) for a better understanding of joint dynamics. METHODS: Nine spinal cord injured subjects equipped with reflective markers propelled in a wheelchair with an instrumented wheel. Inverse dynamic results were interpreted using joint coordinate systems, 3D joint power and the 3D angle between the joint moment and joint angular velocity vectors at the three upper limb joints. The 3D angle was used to determine if the joints were predominantly driven (angle close to 0 or 180 degrees) or stabilized (angle close to 90 degrees ). FINDINGS: The wrist and elbow joints are mainly in a stabilization configuration (angle close to 90 degrees ) with a combination of extension and ulnar deviation moments and an adduction moment respectively. The shoulder is in a propulsion configuration, but close to stabilization (angle hardly below 60 degrees ) with a combination of flexion and internal rotation moments. INTERPRETATION: Stabilization configuration at the joints could partly explain the low mechanical efficiency of manual wheelchair propulsion and could give insight about injury risk at the wrist, elbow and shoulder joints.

Using EMGs and kinematics data to study the take-off technique of experts and novices for a pole vaulting short run-up educational exercise.

This study attempts to characterise the electromyographic activity and kinematics exhibited during the performance of take-off for a pole vaulting short run-up educational exercise, for different expertise levels. Two groups (experts and novices) participated in this study. Both groups were asked to execute their take-off technique for that specific exercise. Among the kinematics variables studied, the knee, hip and ankle angles and the hip and knee angular velocities were significantly different. There were also significant differences in the EMG variables, especially in terms of (i) biceps femoris and gastrocnemius lateralis activity at touchdown and (ii) vastus lateralis and gastrocnemius lateralis activity during take-off. During touchdown, the experts tended to increase the stiffness of the take-off leg to decrease braking. Novices exhibited less stiffness in the take-off leg due to their tendency to maintain a tighter knee angle. Novices also transferred less energy forward during take-off due to lack of contraction in the vastus lateralis, which is known to contribute to forward energy transfers. This study highlights the differences in both groups in terms of muscular and angular control according to the studied variables. Such studies of pole vaulting could be useful to help novices to learn expert's technique.

Demographics of wheelchair users in France: results of national community-based handicaps-incapacités-dépendance surveys.

OBJECTIVE: To highlight the prevalence of manual and/or powered wheelchair use within the general French population living at home or in institutions, to describe the users and to identify factors determining wheelchair use. METHODS: Data were obtained from national community-based Handicaps-Incapacités-Dépendance surveys on disability and dependency carried out on 2 representative samples of the French population in institutions (n = 15,288) and at home (n = 16,945). RESULTS: The prevalence of wheelchair use is 62 per 10,000 people living in France. Forty-three percent of users live in institutions. They frequently show multiple impairments and severe disabilities. They have a mean age of 70 years and 64% are women. After taking confounding factors into account, results show that wheelchair use is not sex-related and decreases slightly with age. On the other hand, wheelchair use is related to widowhood, to the extent of impairments and disabilities, to confinement, to exposure to environmental obstacles and to institutional life. CONCLUSION: Sociodemographic studies on the use of wheelchairs need to pay greater attention to people living in institutions. The prevalence of wheelchair use in France appears to be far lower than in other western countries, and this observation needs to be examined further with intercultural comparisons.

Linking clinical measurements and kinematic gait patterns of toe-walking using fuzzy decision trees.

Toe-walking is one of the most prevalent gait deviations and has been linked to many diseases. Three major ankle kinematic patterns have been identified in toe-walkers, but the relationships between the causes of toe-walking and these patterns remain unknown. This study aims to identify these relationships. Clearly, such knowledge would increase our understanding of this gait deviation, and could help clinicians plan treatment. The large quantity of data provided by gait analysis often makes interpretation a difficult task. Artificial intelligence techniques were used in this study to facilitate interpretation as well as to decrease subjective interpretation. Of the 716 limbs evaluated, 240 showed signs of toe-walking and met inclusion criteria. The ankle kinematic pattern of the evaluated limbs during gait was assigned to one of three toe-walking pattern groups to build the training data set. Toe-walker clinical measurements (range of movement, muscle spasticity and muscle strength) were coded in fuzzy modalities, and fuzzy decision trees were induced to create intelligible rules allowing toe-walkers to be assigned to one of the three groups. A stratified 10-fold cross validation situated the classification accuracy at 81%. Twelve rules depicting the causes of toe-walking were selected, discussed and characterized using kinematic, kinetic and EMG charts. This study proposes an original approach to linking the possible causes of toe-walking with gait patterns.

Identification and classification of toe-walkers based on ankle kinematics, using a data-mining method.

A database of 1,736 patients and 2,511 gait analyses was reviewed to identify for trials where the first rocker was absent. A fuzzy c-means algorithm was used to identify sagittal ankle kinematic patterns and three groups were identified. The first showed a progressive dorsiflexion during the stance phase, while the second had a short-lived dorsiflexion, followed by a progressive plantarflexion. The third group exhibited a double bump pattern, moving successively from a short-lived dorsiflexion to a short-lived plantarflexion and then returning to a further short-lived dorsiflexion before ending with plantarflexion until toe-off. The three patterns were linked to different neurological conditions. Myopathy, neuropathy and arthogryposis essentially revealed group 1 patterns, whereas idiopathic toe-walkers mainly displayed group 2 patterns. Cerebral palsy patients, however, were relatively homogeneously distributed amongst the three groups. Able-bodied subjects walking on their toes showed a high proportion of unclassifiable ankle patterns, due to a variable gait whilst toe walking. Despite the variety of neurological conditions included in this meta-analysis repeatable biomechanical patterns appeared that could influence therapeutic management.

Variability of video-based clinical gait analysis in hemiplegia as performed by practitioners in diverse specialties.

OBJECTIVE: Clinical gait analysis is widely used by different therapists working with hemiplegic patients. The purpose of this study was to assess the reliability of video-based clinical gait assessment, as performed by practitioners in diverse specialties. DESIGN: Five neurologists, 5 physiotherapists, and 5 doctors of physical medicine and rehabilitation (physiatrists) were asked to study a videotape of 6 patients with hemiplegia in the act of walking. This activity was chosen due to the wide use of gait information for therapeutic prescription and medical decision-making during medical consultations, at conventions, or in exchanges between therapists. RESULTS: Results highlighted a certain inconsistency in the use of the gait description indicators. The 15 therapists used 396 different locutions to describe the gaits of the 6 patients. These locutions yielded 60 general indicators, or gait disorders, which were grouped in 5 categories. Eleven of them were classified as "controversial" due to the significant inter-subject variability of the evaluations. CONCLUSION: The study identified a large number of indicators that were used relatively inconsistently by the 3 specialties studied. The results of this study would appear to indicate that greater caution is needed when dealing with some of the "controversial" indicators, as well as with the "unusual" gait patterns observed in some patients.

A 3D analysis of hindlimb motion during treadmill locomotion in rats after a 14-day episode of simulated microgravity.

This study describes the effect of simulated microgravity in rat on kinematics and electromyographic activity during treadmill locomotion. The analysis was performed in rats submitted to 14 days of hindlimb unloading (HU), in rats submitted to hindlimb unloading and then authorized to recover for 7 days (REC), and in aged-matched control rats (CON). Movements of the right hindlimb were measured with a 3D-optical analyzer (SAGA3 system) and five small infrared-reflective disks positioned on the skin, recorded by three CCD cameras. Results showed that HU rats exhibited hyperextensions at the end of the stance phase. By contrast, during the major part of the step, the ankle was less extended than CON. Possible origins of the changes are discussed. This leads to the question of how important is sensory input in the regulation of the locomotor pattern after HU. Data obtained in REC animals showed that 1 week of recovery allowed the restoration of a good locomotor performance. However, the limb motion remained abnormal, and at contrary to HU rats: higher extension during the step, except at push-off when the limb was in hyperflexion. We concluded that simulated microgravity involves a dual adaptive process: a first one during unloading, and a second one during the period of recovery, which is not a simple return to initial characteristics of the locomotor pattern.

Comparison of clinical gait analysis strategies by French neurologists, physiatrists and physiotherapists.

Clinical and functional gait analysis is used widely by different professionals dealing with patients with hemiplegia. The aim of this study was to examine the gait analysis strategies of neurologists, specialists in physical and rehabilitation medicine (physiatrists) and physiotherapists. Differences in global analysis strategy and choice of indicators between different clinicians have not previously been studied precisely, and we believe that a standardized approach would enhance the training of young practitioners. The knowledge acquisition phase (specialists' expertise identification) was completed by an identified expert with a subject groups of 5 neurologists, 5 specialists in physical and rehabilitation medicine and 5 physiotherapists, who were asked to comment on a videotape of patients with hemiplegia walking, followed by a semi-directed interview. The results show that specialists use a wide variety of gait indicators. The total number of different medical vocabulary and expressions used to describe gait was 396, semantically grouped as 60 general indicators. Specialists highlighted an analysis strategy (order, type and number of indicators) typical to each professional specialty. The neurologists tried to identify the elements allowing localization of lesions and characterized the hemiplegia globally,while the specialists in physical and rehabilitation medicine conducted a bio-mechanical analysis and the physiotherapists were highly descriptive. The differences in strategies adopted by each specialty contribute to an enrichment of gait analysis. This should be taken into account in teaching and determining gait assessment scales.

Contribution of accelerated body masses to able-bodied gait.

OBJECTIVE: The objectives of this study were to demonstrate that data from a video-based system could be used to estimate the net effect of the external forces during gait, to determine the contribution of the trunk and upper and lower limbs using their accelerated body masses, and to test the hypothesis that the thigh mainly assumed lower limb propulsion during able-bodied locomotion. METHODS: The gait of 16 able-bodied subjects was assessed using an eight-camera video-based system and two force plates. The right limb was the leading limb, and there were two trials per subject. Although data from all the body segments were used to answer the first two objectives, only right limb information was used to address the third objective. RESULTS: Pearson's coefficients of correlation and root mean square errors were calculated to determine the difference between the curves obtained from the sum of the external forces and that of the accelerated masses. These were >0.85, and the mean root mean square error was <4 N. Analyses of variance were performed on the peak forces developed by the trunk and the upper and lower limbs along each axis. Tukey's posthoc tests (P < 0.05) revealed that the trunk was the principal contributor of external forces in the frontal and transverse planes, whereas the lower limbs were found to be more important in the plane of progression. Analyses of variance and Tukey's posthoc tests (P < 0.05) were performed on the peak forces developed by each segment of the right limb. In decreasing order, the thigh, shank, and foot displayed the highest mass-acceleration products in the right limb during gait. CONCLUSIONS: A video-based system was able to determine the net effect of the external forces with the summation of the mass-acceleration products during able-bodied gait. The trunk and lower limbs were the dominant body segments responsible for the production of external forces during able-bodied gait, whereas the thighs contributed more to the ground reaction force than the foot and shank for forward progression in able-bodied gait.