PURPOSE: For individuals with disabilities exercise, such as wheelchair racing, can be an important modality for community reintegration, as well as health promotion. The purpose of this study was to examine selected parameters during racing wheelchair propulsion among a sample of elite wheelchair racers. It was hypothesized that blood lactate accumulation and wheeling economy (i.e. oxygen consumed per minute) would increase with speed and that gross mechanical efficiency would reach an optimum for each athlete. METHOD: Twelve elite wheelchair racers with paraplegia participated in this study. Nine of the subjects were males and three were females. Each subject used his or her personal wheelchair during the experiments. A computer monitored wheelchair dynamometer was used during all testing. The method used was essentially a discontinuous economy protocol. Mixed model analysis of variance (ANOVA) was used to compare blood lactate concentration, economy (minute oxygen consumption), and gross mechanical efficiency across the stages. RESULTS: The results of this study show that both economy and blood lactate concentration increase linearly with speed if resistance is held constant. The subjects in this study had gross mechanical efficiencies (gme) of about 18%, with the range going from 15.222.7%. The results indicate that at the higher speeds of propulsion, for example near race speeds, analysis of respiratory gases may not give a complete energy profile. CONCLUSION: While there is a good understanding of training methods to improve cardiovascular fitness for wheelchair racers, little is known about improving efficiency (e.g. technique, equipment), therefore methods need to be developed to determine efficiency while training or in race situations.

Adult↗

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Upper limb nerve entrapments in elite wheelchair racers.

The prevalence of upper limb nerve injuries has been reported to be as high as 73% in individuals who rely on manual wheelchairs for mobility. Many authors hypothesize that the repetitive trauma to carpal canal structures caused by propelling a wheelchair is the reason for this high prevalence. The purpose of this study was to determine the prevalence of nerve conduction abnormalities in a group of elite wheelchair racers whose wrists are exposed to additional propulsion-related trauma during training and competition. We performed bilateral upper limb nerve conduction studies on each athlete (n = 12). The racers pushed their chairs an average of 56 miles a week for training purposes. Fifty percent of the athletes (n = 6) had evidence of median mononeuropathy by nerve conduction. Of these 6 racers, 5 had evidence of mononeuropathy bilaterally, making a total of 11 positive hands of the 23 tested. Twenty-five percent of the athletes had evidence of ulnar mononeuropathy at the wrist, and 25% had evidence of ulnar mononeuropathy at the elbow. Seventeen percent of athletes had evidence of radial nerve injury. Years with a disability accounted for a significant amount of the variance in the mean median sensory amplitude (R2 = 0.511; P = 0.020) and the mean ulnar palmar amplitude (R2 = 0.605; P = 0.008). Variables not correlated with nerve conduction studies include age, hours per day in a wheelchair not spent training, years competing, and number of miles pushed in training. Despite the amount of time spent training these wheelchair athletes have a similar or lower prevalence of median mononeuropathy then reported in the general wheelchair-using population.

Adult↗

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Three-dimensional pushrim forces during two speeds of wheelchair propulsion.

Upper limb pain frequently occurs in manual wheelchair users. Analyzing the pushrim forces and hub moments occurring during wheelchair propulsion is a first step in gaining insight into the cause of this pain. The objectives of this study were as follows: to describe the forces and moments occurring during wheelchair propulsion; to obtain variables that characterize pushrim forces and are statistically stable; and to determine how these variables change with speed. Convenience samples (n = 6) of paralympic athletes who use manual wheelchairs for mobility and have unimpaired arm function were tested. Each subject propelled a standard wheelchair on a dynamometer at 1.3 and 2.2 m/s. Biomechanical data were obtained using a force- and moment-sensing pushrim and a motion analysis system. A number of variables that describe the force and moment curves were evaluated for stability using Cronbach's alpha. Those measures found to be stable (alpha > 0.8) at each speed were then examined for differences associated with speed. The tangential, radial, and medial-lateral forces were found to comprise approximately 55, 35, and 10% of the resultant force, respectively. In addition to duration of stroke and propulsion, the following variables were found to be stable and to differ with speed (1.3 m/s +/- SD; 2.2 m/s +/- SD): peak force tangential to the pushrim (45.9 +/- 17.9 N; 62.1 +/- 30 N), peak moment radial to the hub (9.8 +/- 4.5 N x m 13.3 +/- 6 N x m), maximum rate of rise of the tangential force (911.7 +/- 631.7 N/sec; 1262.3 +/- 570.7 N/sec), and maximum rate of rise of the moment about the hub (161.9 +/- 78.3 N x m/s; 255.2 +/- 115.4 N x m/s). This study found stable parameters that characterize pushrim forces during wheelchair propulsion and varied with speed. Almost 50% of the forces exerted at the pushrim are not directed toward forward motion and, therefore, either apply friction to the pushrim or are wasted. Ultimately, this type of investigation may provide insight into the cause and prevention of upper limb injuries in manual wheelchair users.

Adult↗

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Gait analysis in rehabilitation medicine: a brief report.

Gait analysis can be a powerful tool for rehabilitation research and clinical practice. However, there has been little coordinated effort to set goals for the application of gait analysis in rehabilitation. Therefore, a priority setting process was engaged to obtain the opinions of a diverse pool of experts related to human motion analysis. The primary goal of this process was to develop priorities for future research, development, and standardization in gait analysis. A multistep approach was used that included expert testimony, group discussions, individually developed priorities, and a ranking process. Several important priorities emerged from this activity. The highest priority was assigned to research on the efficacy, outcomes, and cost-effectiveness of gait analysis.

Cost-Benefit Analysis↗

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Glenohumeral joint kinematics and kinetics for three coordinate system representations during wheelchair propulsion.

The shoulder plays a very important role during manual wheelchair propulsion. Unfortunately, substantial numbers of manual wheelchair users eventually develop shoulder injury or pain. Recently, studies have begun to investigate the etiology of wheelchair user shoulder injuries. This study compared three coordinate systems used to represent the shoulder during wheelchair propulsion. Our results show statistically significant differences between the three shoulder representations analyzed. Differences are seen for individuals and for the subjects as a group. Based upon our results, the fixed-z model appears preferable over the other representations due to its simplicity, low hardware requirements, and the similarity of the results to the free representation. This article also provides some insight into maximal shoulder joint forces and moments recorded during manual wheelchair propulsion. Future work should include more sophisticated models of the shoulder complex.

Acceleration↗

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The efficacy of honey in inhibiting strains of Pseudomonas aeruginosa from infected burns.

Because there is no ideal therapy for burns infected with Pseudomonas aeruginosa, there is sufficient need to investigate the efficacy of alternative antipseudomonal interventions. Honey is an ancient wound remedy for which there is modern evidence of efficacy in the treatment of burn wounds, but limited evidence for the effectiveness of its antibacterial activity against Pseudomonas. We tested the sensitivity of 17 strains of P. aeruginosa isolated from infected burns to two honeys with different types of antibacterial activity, a pasture honey and a manuka honey, both with median levels of activity. All strains showed similar sensitivity to honey with minimum inhibitory concentrations below 10% (vol/vol); both honeys maintained bactericidal activity when diluted more than 10-fold. Honey with proven antibacterial activity has the potential to be an effective treatment option for burns infected or at risk of infection with P. aeruginosa.

Anti-Bacterial Agents↗

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A unified method for calculating the center of pressure during wheelchair propulsion.

The measurement of the center of pressure (COP) has been and continues to be a successful tool for gait analysis. The definition of a similar COP for wheelchair propulsion. however, is not straightforward. Previously, a COP definition similar to that used in force plate analysis had been proposed. Unfortunately, this solution has the disadvantage of requiring a separate COP definition for each plane of analysis. A definition of the generalized center of pressure (GCOP) which is consistent in all planes of analysis is derived here. This definition is based on the placement of a force-moment system, equivalent to the force-moment system at the hub, on a line in space where the moment vector (wrench moment) is parallel to the force vector. The parallel force-moment system is then intersected with three planes defined by anatomical landmarks on the hand. Data were collected using eight subjects at propulsion speeds of 1.34 m/s and 2.24 m/s (1.34 m/s only for subject 1, 0.894 m/s and 1.79 m/s for subject 8). Each subject propelled a wheelchair instrumented with a SMARTwheel. A PEAK 5 video system was used to determine the position of anatomical markers attached to each subject's upper extremity. The GCOP in the transverse plane of the wrist formed clusters for all subject's except subject 2 at 1.34 m/s. The clustering of the GCOP indicates that the line of action for the force applied by the hand is approximately perpendicular to the transverse plane through the wrist. When comparing the magnitude of the moment vector part of the wrench with the moment of the force vector of the wrench about the hub, the wrench moment is approximately an order of magnitude smaller. This indicates that the role of the wrist for wheelchair propulsion is primarily to stabilize the force applied by the arm and shoulder.

Biomechanical Phenomena↗

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Encouraging students with disabilities to pursue careers in bioengineering.

Explore the source record for details and available documents.

Biomedical Engineering↗