Emerging methods for measuring physical activity using accelerometry in children and adolescents with neuromotor disorders: a narrative review.

BACKGROUND: Children and adolescents with neuromotor disorders need regular physical activity to maintain optimal health and functional independence throughout their development. To this end, reliable measures of physical activity are integral to both assessing habitual physical activity and testing the efficacy of the many interventions designed to increase physical activity in these children. Wearable accelerometers have been used for children with neuromotor disorders for decades; however, studies most often use disorder-specific cut points to categorize physical activity intensity, which lack generalizability to a free-living environment. No reviews of accelerometer data processing methods have discussed the novel use of machine learning techniques for monitoring physical activity in children with neuromotor disorders. METHODS: In this narrative review, we discuss traditional measures of physical activity (including questionnaires and objective accelerometry measures), the limitations of standard analysis for accelerometry in this unique population, and the potential benefits of applying machine learning approaches. We also provide recommendations for using machine learning approaches to monitor physical activity. CONCLUSIONS: While wearable accelerometers provided a much-needed method to quantify physical activity, standard cut point analyses have limitations in children with neuromotor disorders. Machine learning models are a more robust method of analyzing accelerometer data in pediatric neuromotor disorders and using these methods over disorder-specific cut points is likely to improve accuracy of classifying both type and intensity of physical activity. Notably, there remains a critical need for further development of classifiers for children with more severe motor impairments, preschool aged children, and children in hospital settings.

Correction to: Advanced Robotic Therapy Integrated Centers (ARTIC): an international collaboration facilitating the application of rehabilitation technologies.

The original article [1] contains a small mistake concerning the ARTIC Team members mentioned in the Acknowledgements. The team member, Rocco Salvatore Calabrò had their name presented incorrectly. This has now been corrected in the original article.

Ten-dimensional anthropomorphic arm control in a human brain-machine interface: difficulties, solutions, and limitations.

OBJECTIVE: In a previous study we demonstrated continuous translation, orientation and one-dimensional grasping control of a prosthetic limb (seven degrees of freedom) by a human subject with tetraplegia using a brain-machine interface (BMI). The current study, in the same subject, immediately followed the previous work and expanded the scope of the control signal by also extracting hand-shape commands from the two 96-channel intracortical electrode arrays implanted in the subject's left motor cortex. APPROACH: Four new control signals, dictating prosthetic hand shape, replaced the one-dimensional grasping in the previous study, allowing the subject to control the prosthetic limb with ten degrees of freedom (three-dimensional (3D) translation, 3D orientation, four-dimensional hand shaping) simultaneously. MAIN RESULTS: Robust neural tuning to hand shaping was found, leading to ten-dimensional (10D) performance well above chance levels in all tests. Neural unit preferred directions were broadly distributed through the 10D space, with the majority of units significantly tuned to all ten dimensions, instead of being restricted to isolated domains (e.g. translation, orientation or hand shape). The addition of hand shaping emphasized object-interaction behavior. A fundamental component of BMIs is the calibration used to associate neural activity to intended movement. We found that the presence of an object during calibration enhanced successful shaping of the prosthetic hand as it closed around the object during grasping. SIGNIFICANCE: Our results show that individual motor cortical neurons encode many parameters of movement, that object interaction is an important factor when extracting these signals, and that high-dimensional operation of prosthetic devices can be achieved with simple decoding algorithms. ClinicalTrials.gov Identifier: NCT01364480.

State of the Science in Spinal Cord Injury Rehabilitation 2011: informing a new research agenda.

STUDY DESIGN: This manuscript summarizes recommendations from the State of the Science Conference in Spinal Cord Injury Rehabilitation 2011. OBJECTIVES: To develop an agenda for spinal cord injury (SCI) rehabilitation research in the next decade. SETTING: Participants scheduled planning meetings and then gathered at the 2011 joint meeting of the American Spinal Injury Association and International Spinal Cord Society in Washington DC. METHODS: Recommendations were made by an international, multidisciplinary team that met in large plenary sessions and breakout groups during the meeting. RESULTS: Recommendations are organized by conference track, including neurological and functional recovery; technology issues; aging with spinal cord injury; and employment, psychosocial and quality of life issues. CONCLUSION: A number of themes emerged across the conference tracks, including the need for improved measures of process and outcome constructs, application of qualitative and quantitative research designs, and use of contemporary statistical analytic approaches. Participants emphasized the value of collaborative research that uses the latest methods, techniques and information.

Technology for mobility in SCI 10 years from now.

OBJECTIVES: To identify technological advances and that are likely to have a great impact on the quality of life and participation in individuals with spinal cord injury (SCI). METHODS: In this paper we use the International Classification of Function to frame a discussion on how technology is likely to impact SCI in 10 years. In addition, we discuss the implication of technological advances on future research. RESULTS/CONCLUSION: Although technology advances are exciting, a large challenge for the research community will be how to effectively apply and deploy this technology. Advances occurring in the next 10 years that reduce cost of technology may be more important to the population with SCI than brand new technologies. Social context is everything. As a research community we must advocate for better systems of care. Advocating now for better care will lead to a world in 2020 that is ready to adopt new technologies that are truly transformative.

Comparison of skin perfusion response with alternating and constant pressures in people with spinal cord injury.

STUDY DESIGN: Two-way factorial mixed design, the between-subjects factor as the spinal cord injury (SCI) status (SCI and non-SCI) and the within-subjects factor as the pressure pattern (alternating and constant pressures). OBJECTIVES: To compare the effects of alternating and constant pressures on weight-bearing tissue perfusion in people with SCI, with application for improving alternating pressure support surface usage. SETTING: University research laboratory. SUBJECTS: A total of 28 participants were studied, 7 participants with cervical injury, 7 participants with injury below T6 and 14 healthy controls. METHODS: Sacral skin perfusion was continuously measured using laser Doppler flowmetry under 10 min preloading, 20 min loading (alternating or constant pressures) and 10 min postloading. Alternating pressure was applied with low-interface pressure at 0 mm Hg and high-interface pressure at 60 mm Hg with a cycle time of 5 min; constant pressure was applied with interface pressure at 30 mm Hg. RESULTS: The results showed that pressure pattern affects skin perfusion responses in weight-bearing tissues (P < 0.01). Alternating pressure stimulates an increase in skin perfusion (1.21 ± 0.08 au) as compared with constant pressure (0.74 ± 0.07 au) in people with SCI (P < 0.01). There was no overall difference in the skin perfusion responses of patients with SCI as compared with non-SCI patients (P > 0.05). CONCLUSION: This study has shown that alternating pressure enhances the skin perfusion of weight-bearing tissues as compared with constant pressure in people with SCI. The protocol tested in this study may be used to guide the selection of parameters of commercial alternating pressure support surfaces for preventing pressure ulcers in people with SCI.

A fuzzy logic model for hand posture control using human cortical activity recorded by micro-ECog electrodes.

This paper presents a fuzzy logic model to decode the hand posture from electro-cortico graphic (ECoG) activity of the motor cortical areas. One subject was implanted with a micro-ECoG electrode array on the surface of the motor cortex. Neural signals were recorded from 14 electrodes on this array while Subject participated in three reach and grasp sessions. In each session, Subject reached and grasped a wooden toy hammer for five times. Optimal channels/electrodes which were active during the task were selected. Power spectral densities of optimal channels averaged over a time period of 1/2 second before the onset of the movement and 1 second after the onset of the movement were fed into a fuzzy logic model. This model decoded whether the posture of the hand is open or closed with 80% accuracy. Hand postures along the task time were decoded by using the output from the fuzzy logic model by two methods (i) velocity based decoding (ii) acceleration based decoding. The latter performed better when hand postures predicted by the model were compared to postures recorded by a data glove during the experiment. This fuzzy logic model was imported to MATLABSIMULINK to control a virtual hand.

Human motor cortical activity recorded with Micro-ECoG electrodes, during individual finger movements.

In this study human motor cortical activity was recorded with a customized micro-ECoG grid during individual finger movements. The quality of the recorded neural signals was characterized in the frequency domain from three different perspectives: (1) coherence between neural signals recorded from different electrodes, (2) modulation of neural signals by finger movement, and (3) accuracy of finger movement decoding. It was found that, for the high frequency band (60-120 Hz), coherence between neighboring micro-ECoG electrodes was 0.3. In addition, the high frequency band showed significant modulation by finger movement both temporally and spatially, and a classification accuracy of 73% (chance level: 20%) was achieved for individual finger movement using neural signals recorded from the micro-ECoG grid. These results suggest that the micro-ECoG grid presented here offers sufficient spatial and temporal resolution for the development of minimally-invasive brain-computer interface applications.

Manual wheelchair stroke characteristics during an extended period of propulsion.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: The purpose of this study was to examine stroke characteristics of long-term manual wheelchair users during an extended manual wheelchair propulsion trial and the extent to which changes in propulsion biomechanics occurred. SETTING: Human Engineering Research Laboratories, VA Rehabilitation Research and Development Center, VA Pittsburgh Healthcare Systems, Pittsburgh, PA, USA. METHODS: Kinetic data were recorded from 21 subjects with paraplegia at four time points over the course of a 10-min propulsion trial at a steady state speed of 1.4 m s(-1). Upper extremity kinetic parameters were recorded using Smartwheels, force and torque sensing pushrims. RESULTS: Subjects for propulsion biomechanics changed from early to late during the 10-min trial. Individuals displayed decreased maximum rate of rise of resultant force (P=0.0045) with a simultaneous increase in push time (P=0.043) and stroke time (P=0.023), whereas stroke frequency remained static. In addition, there was a decrease in out of plane moment application (P=0.032). CONCLUSION: Individuals seemed to naturally accommodate their propulsive stroke, using less injurious propulsion biomechanics over the course of a 10-minute trial on a dynamometer. The findings may have occurred as a result of both biomechanical compensations to a challenging propulsion trial and accommodation to propelling on a dynamometer. These results suggest that subjects may be capable of independently incorporating favorable biomechanical strategies to meet the demands of a challenging propulsion scenario.

Wheelchair racing efficiency.

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.

Development and consumer validation of the Functional Evaluation in a Wheelchair (FEW) instrument.

PURPOSE: The purpose of the study is to develop an outcome measurement tool to investigate functional performance of consumers using seating and wheelchair systems as their primary seating and mobility device. The instrument is undergoing systematic development in three phases. The results of Phase 1 will be reported. METHOD: Manual and power wheelchair users were interviewed using a modified version of a client-centred outcome measure. An item bank was derived based on the interview data. Subjects were then asked to validate item categories of the new instrument, and finally to self-administer the first version of the instrument. RESULTS: Subjects reported 154 self-care, productivity, and leisure occupational performance issues related to their current seating-mobility system. Based on their input, 10 categories (i.e. transfers, reach, accessing task surfaces, transportation-portability, human-machine interface, architectural barriers, transportation-accessibility, transportation-securement, natural barriers and accessories) were validated for inclusion in the new outcome measure, Functional Evaluation in a Wheelchair (FEW). CONCLUSION: The items on the FEW focus on the interaction between the consumer, the technology, and the milieu. Consumers viewed the overall importance of FEW categories for seating-mobility system users differently than when they self-administered the FEW.

Comparison of fatigue life for 3 types of manual wheelchairs.

OBJECTIVES: To examine 3 types of manual wheelchairs-ultralight wheelchairs (UWs), lightweight wheelchairs (LWs), and depot wheelchairs (DWs)-and to compare the fatigue life between the wheelchair types. DESIGN: A database of different manual wheelchairs tested according to the International Organization for Standardization (ISO). Fatigue life was determined by using standards that define methods accepted internationally using double-drum and curb-drop testing equipment. SETTING: A rehabilitation engineering center. SPECIMENS: Sixty-one manual wheelchairs: 25 DWs, 22 UWs, and 14 LWs. MAIN OUTCOME MEASURES: Wheelchairs were examined for differences in fatigue life based on equivalent cycles. Unique survival curves were fit and compared for each wheelchair type. RESULTS: The UWs lasted the longest, with a mean of 309,362 equivalent cycles. The DWs faired the worst, with a mean of 117,210 equivalent cycles. The Kaplan-Meier survival curves were significantly different (p < .001), with the UWs having the longest fatigue life. CONCLUSION: Fatigue life for UWs is significantly greater (p < .05) than LWs and DWs, indicating wheelchairs differ in durability.

Predictive factors for successful early prosthetic ambulation among lower-limb amputees.

OBJECTIVE: To predict successful prosthetic ambulation for patients immediately transferred to an inpatient rehabilitation facility after amputation surgery. METHODS: Seventy-five individuals with lower-limb amputation were studied at a tertiary acute care and rehabilitation facility. Successful prosthetic ambulation, defined as the ability to ambulate with a prosthesis at least 45 m, was measured in addition to other key demographic and medical factors. RESULTS: Sixty-eight percent were successful prosthetic ambulators at rehabilitation discharge. The absence of residual-limb contracture and a longer length of stay during rehabilitation showed a significant relationship to successful prosthetic ambulation with regression analysis. Younger age was modestly correlated to outcome. There were no significant differences when comparing success of the early rehabilitation program with surgical level or etiology of amputation. For successful prosthetic users, mean wear time at rehabilitation discharge was 5.7 hours with a mean distance walked of 67 m. Of those who failed this approach, 70% were related to a failure of wound healing. CONCLUSIONS: In this cohort, 68% of patients who were selected for a trial of early prosthetic rehabilitation ambulated using a prosthesis at rehabilitation discharge. This approach appears to be more effective for younger patients without contractures who are medically stable to participate in the rehabilitation process.

Analysis of vibrations induced during wheelchair propulsion.

Little is known about how dynamic acceleration affects wheelchair-rider comfort. The current study was to test both the operation of an instrumented wheelchair by a wheelchair user over a Simulated Road Course (SRC) and the operation of the same instrumented wheelchair during normal daily activities (a field test) by test subjects. Sixteen subjects participated in the protocol. A SRC allowed collection of data from wheelchair users traversing obstacles similar to those experienced by a typical wheelchair user. The SRC consisted of eight obstacles fixed rigidly to a flat concrete surface. The field test began after the conclusion of the SRC test. Transfer functions were derived for all 16 subjects. It is clear from the results that for the SRC, the acceleration at the wheelchair frame exceeded the 8-h "fatigue-decreased performance boundary." A vertical acceleration resonant peak was evident for eight of the subjects. The average for these peaks, when present, was 8.1 Hz. This frequency is higher than the 4-6 Hz resonant peak presented in the literature for a seated human subject. This discrepancy could be due to different levels of trunk control between wheelchair users in this study and ambulatory subjects used in the literature. Subjects and their wheelchairs were exposed to a few, high-acceleration events rather than consistent, small-magnitude accelerations during the field test. This study indicates that vibration may be a contributing factor to fatigue among manual wheelchair users, which could lead to injury.

Shoulder imaging abnormalities in individuals with paraplegia.

Shoulder pain and rotator cuff tears are highly prevalent in individuals with paraplegia (PP). The purpose of this study was to use magnetic resonance imaging (MRI), plain radiographs, questionnaires, and physical examination to gain insight into the prevalence of shoulder disorders in individuals with PP. A total of 28 individuals with PP was recruited (mean age=35; mean year from injury=11.5). Each subject completed a questionnaire designed to identify arm pain, had a standard physical examination focusing on the shoulder, and underwent imaging studies (radiographic and MRI). Nine of the thirty-two subjects (36 percent) experienced shoulder pain in the month prior to testing. The MRI studies documented only one rotator cuff tear. Five subjects showed osteolysis of the distal clavicle by plain radiographic study. In two subjects this was seen bilaterally. Although no relationship was seen between pain and imaging abnormalities, stepwise linear regressions found a statistically significant positive relationship between imaging abnormalities and body mass index (BMI) (radiographic: beta= 0.56, p<0.01; MRI: beta=0.52, p<0.01). This study found a low prevalence of rotator cuff tears and a high prevalence of distal clavicle osteolysis in a sample of relatively young individuals with PP. Although there was only one tear identified by MRI, a number of subclinical abnormalities were seen and found to correlate with BMI.

Comparison of three different models to represent the wrist during wheelchair propulsion.

Due to the high incidence of secondary wrist injury among manual wheelchair users, recent emphasis has been placed on the investigation of wheelchair propulsion biomechanics. Accurate representation of wrist activity during wheelchair propulsion may help to elucidate the mechanisms contributing to the development of wrist injuries. Unfortunately, no consensual wrist biomechanical model has been established. In order to determine if different methodologies obtain similar results, this investigation created and compared three different wrist models: 1) a fixed joint center placed between the styloids (midstyloid joint center); 2) a joint center with 2 degrees of freedom computed from de Leva's joint center data; and 3) a floating joint center. Results indicate that wrist flexion and extension angles are highly consistent between models, however, radial and ulnar deviation angles vary considerably. Mean maximum right flexion angles were found to be 3.5 degrees, 2.2 degrees, and 5.0 degrees for the midstyloid, de Leva, and floating joint center models, respectively. Extension angles were 22.3 degrees, 23.6 degrees, and 23.6 degrees, respectively. Mean maximum right radial deviation angles for the midstyloid, de Leva, and floating joint center models were 26.0 degrees, 26.9 degrees, and 45.1 degrees, respectively, and ulnar deviation angles were found to be 30.5 degrees, 38.8 degrees, and 10.2 degrees, respectively. This information is useful when comparing kinematic studies and further supports the need for consensual methodology.

Resident research education in physical medicine and rehabilitation: a practical approach.

The Accreditation Council for Graduate Medical Education includes training in research as a required component of physical medicine and rehabilitation residency programs. Unfortunately, there is a lack of practical information on how to meet this requirement. In this paper, information is provided for individuals involved in resident education on how to teach residents about research.

Kinematic comparison of Hybrid II test dummy to wheelchair user.

Hybrid test dummies provide a safe alternative to human subjects when investigating mechanisms of wheelchair tips and falls. The data that researchers acquire from these test dummies are more useful if the test dummy represents the population being studied. The goal of this study was to measure the validity of a 50th percentile Hybrid II test dummy (HTD) as an accurate representation of a wheelchair user. A test pilot with T8 paraplegia due to traumatic spinal cord injury served as a basis for validation. Simple modifications were made to the HTD to approximate the trunk stability characteristics of a person with a spinal cord injury. An HTD, a modified HTD, and a human test pilot were seated in an electric-powered wheelchair and several braking tests performed. The standard HTD underestimated the kinematics when compared to the test pilot. The modified HTD had less trunk stability than the standard HTD during all braking methods. The modified HTD and wheelchair test pilot had similar trunk stability characteristics during kill switch and joystick full-reverse braking conditions. The modified HTD is a satisfactory representation of a wheelchair user with a spinal cord injury; however, the modified test dummy underestimates the trunk dynamics during the less extreme joystick release braking. Work should continue on the development of a low-speed, low-impact test dummy that emulates the wheelchair user population.

Does computer game play aid in motivation of exercise and increase metabolic activity during wheelchair ergometry?

GAME(Wheels) is an interface between a portable roller system and a computer that enables a wheelchair user to play commercially available computer video games. The subject controls the game play with the propulsion of their wheelchair's wheels on the rollers. The purpose of this study was to investigate whether using the GAME(Wheels) System during wheelchair propulsion exercise can help increase the individual's physiological response and aid in the motivation to exercise. Fifteen subjects participated in this study. The subjects propelled their wheelchairs on a portable roller that was equipped with the GAME(Wheels) System. There were two exercise trials consisting of 2 min of warm-up, 16 min of exercise and 2 min of cool-down. Physiological data (ventilation rate, oxygen consumption, heart rate) were collected. A significant difference (P<0.05) was found between exercise with GAME(Wheels) versus without GAME(Wheels) for average ventilation rate and average oxygen consumption. The differences were found during time periods of transition from warm-up to exercise, and before and after the midpoint of exercise. Written questionnaires showed that 87% of the individuals tested reported the system would help them work out on a regular basis. Playing the video game helped these individuals to reach their exercise training zone faster and maintain it for the entire exercise trial.