Shaw Bronner

Comparative abilities of Microsoft Kinect and Vicon 3D motion capture for gait analysis

Abstract Biomechanical analysis is a powerful tool in the evaluation of movement dysfunction in orthopaedic and neurologic populations. Three-dimensional (3D) motion capture systems are widely used, accurate systems, but are costly and not available in many clinical settings. The Microsoft Kinect™ has the potential to be used as an alternative low-cost motion analysis tool. The purpose of this study was to assess concurrent validity of the Kinect™ with Brekel Kinect software in comparison to Vicon Nexus during sagittal plane gait kinematics. Twenty healthy adults (nine male, 11 female) were tracked while walking and jogging at three velocities on a treadmill. Concurrent hip and knee peak flexion and extension and stride timing measurements were compared between Vicon and Kinect™. Although Kinect measurements were representative of normal gait, the Kinect™ generally under-estimated joint flexion and over-estimated extension. Kinect™ and Vicon hip angular displacement correlation was very low and error was large. Kinect™ knee measurements were somewhat better than hip, but were not consistent enough for clinical assessment. Correlation between Kinect™ and Vicon stride timing was high and error was fairly small. Variability in Kinect™ measurements was smallest at the slowest velocity. The Kinect™ has basic motion capture capabilities and with some minor adjustments will be an acceptable tool to measure stride timing, but sophisticated advances in software and hardware are necessary to improve Kinect™ sensitivity before it can be implemented for clinical use.

Injuries in a Modern Dance Company Effect of Comprehensive Management on Injury Incidence and Time Loss

Background Professional dancers experience high rates of musculoskeletal injuries. Objective To analyze the effect of comprehensive management (case management and intervention) on injury incidence, time loss, and patterns of musculoskeletal injury in a modern dance organization. Study Design Retrospective/prospective cohort study. Methods Injury data were analyzed over a 5-year period, 2 years without intervention and 3 years with intervention, in a modern dance organization (42 dancers). The number of workers’ compensation cases and number of dance days missed because of injury were compared across a 5-year period in a factorial design. Results Comprehensive management significantly reduced the annual number of new workers’ compensation cases from a high of 81% to a low of 17% and decreased the number of days lost from work by 60%. The majority of new injuries occurred in younger dancers before the implementation of this program. Most injuries involved overuse of the lower extremity, similar to patterns reported in ballet companies. Benefits of comprehensive management included early and effective management of overuse problems before they became serious injuries and triage to prevent overutilization of medical services. Conclusions This comprehensive management program effectively decreased the incidence of new cases and lost time. Both dancers and management strongly support its continuance.

Comparison of steps and energy expenditure assessment in adults of Fitbit Tracker and Ultra to the Actical and indirect calorimetry

Abstract Epidemic levels of inactivity are associated with chronic diseases and rising healthcare costs. To address this, accelerometers have been used to track levels of activity. The Fitbit and Fitbit Ultra are some of the newest commercially available accelerometers. The purpose of this study was to determine the reliability and validity of the Fitbit and Fitbit Ultra. Twenty-three subjects were fitted with two Fitbit and Fitbit Ultra accelerometers, two industry-standard accelerometers and an indirect calorimetry device. Subjects participated in 6-min bouts of treadmill walking, jogging and stair stepping. Results indicate the Fitbit and Fitbit Ultra are reliable and valid for activity monitoring (step counts) and determining energy expenditure while walking and jogging without an incline. The Fitbit and standard accelerometers under-estimated energy expenditure compared to indirect calorimetry for inclined activities. These data suggest the Fitbit and Fitbit Ultra are reliable and valid for monitoring over-ground energy expenditure.

Parietal and temporal activity during a multimodal dance video game: An fNIRS study

Using functional near infrared spectroscopy (fNIRS) we studied how playing a dance video game employs coordinated activation of sensory-motor integration centers of the superior parietal lobe (SPL) and superior temporal gyrus (STG). Subjects played a dance video game, in a block design with 30s of activity alternating with 30s of rest, while changes in oxy-hemoglobin (oxy-Hb) levels were continuously measured. The game was modified to compare difficult (4-arrow), simple (2-arrow), and stepping conditions. Oxy-Hb levels were greatest with increased task difficulty. The quick-onset, trapezoidal time-course increase in SPL oxy-Hb levels reflected the on-off neuronal response of spatial orienting and rhythmic motor timing that were required during the activity. Slow-onset, bell-shaped increases in oxy-Hb levels observed in STG suggested the gradually increasing load of directing multisensory information to downstream processing centers associated with motor behavior and control. Differences in temporal relationships of SPL and STG oxy-Hb concentration levels may reflect the functional roles of these brain structures during the task period. NIRS permits insights into temporal relationships of cortical hemodynamics during real motor tasks.

Frontotemporal oxyhemoglobin dynamics predict performance accuracy of dance simulation gameplay: Temporal characteristics of top-down and bottom-up cortical activities

We utilized the high temporal resolution of functional near-infrared spectroscopy to explore how sensory input (visual and rhythmic auditory cues) are processed in the cortical areas of multimodal integration to achieve coordinated motor output during unrestricted dance simulation gameplay. Using an open source clone of the dance simulation video game, Dance Dance Revolution, two cortical regions of interest were selected for study, the middle temporal gyrus (MTG) and the frontopolar cortex (FPC). We hypothesized that activity in the FPC would indicate top-down regulatory mechanisms of motor behavior; while that in the MTG would be sustained due to bottom-up integration of visual and auditory cues throughout the task. We also hypothesized that a correlation would exist between behavioral performance and the temporal patterns of the hemodynamic responses in these regions of interest. Results indicated that greater temporal accuracy of dance steps positively correlated with persistent activation of the MTG and with cumulative suppression of the FPC. When auditory cues were eliminated from the simulation, modifications in cortical responses were found depending on the gameplay performance. In the MTG, high-performance players showed an increase but low-performance players displayed a decrease in cumulative amount of the oxygenated hemoglobin response in the no music condition compared to that in the music condition. In the FPC, high-performance players showed relatively small variance in the activity regardless of the presence of auditory cues, while low-performance players showed larger differences in the activity between the no music and music conditions. These results suggest that the MTG plays an important role in the successful integration of visual and rhythmic cues and the FPC may work as top-down control to compensate for insufficient integrative ability of visual and rhythmic cues in the MTG. The relative relationships between these cortical areas indicated high- to low-performance levels when performing cued motor tasks. We propose that changes in these relationships can be monitored to gauge performance increases in motor learning and rehabilitation programs.

Occupational Musculoskeletal Disorders in Dancers

Abstract Professional dancers are a medically under-served occupational group at high risk for work-related musculoskeletal disorders. Historically, a sports medicine approach has been used in the treatment of dancers and dance companies. Recently, health care providers have also applied occupational medicine concepts to the dance organisation. Consideration of risk factors and the application of organisational programmes to prevent work-related musculoskeletal disorders in dancers are discussed. Deficiencies in our understanding of the contribution of risk factors towards injury are outlined for future consideration. The majority of dance organisations are non-profit and have no injury prevention strategies in place, viewing medical programmes as an unaffordable luxury. The application of a customised sports-occupational medicine approach shows promise in reducing the human and financial costs of work-related musculoskeletal disorders.

Reliability and validity of electrogoniometry measurement of lower extremity movement

Objectives: To establish the reliability, accuracy and concurrent validity of electrogoniometers for measuring extreme lower extremity movements. Study design: Reliability, accuracy and validity study. Methods: This project employed two experiments. Investigation I determined electrogoniometer accuracy compared to a digital protractor. Investigation II compared electrogoniometers to a criterion measure, motion analysis, in sagittal plane dance movements in 17 dancers. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated for hip, knee, and ankle sagittal plane angular displacements. Results: In Investigation I, electrogoniometer to protractor correlations were high (r ≥ 0.998, SEM ≤3.65°). In Investigation II, instrument and intra-rater reliability correlations were high (r ≥ 0.983 and r ≥ 0.972, SEM ≤ 3.49° and ≤4.48°), as were concurrent validity correlations (r ≥ 0.949, SEM ≤6.80°) to motion analysis. Conclusions: This error may be acceptable for lower extremity studies with extreme movements when motion capture is unavailable.

fMRI Validation of fNIRS Measurements During a Naturalistic Task

We present a method to compare brain activity recorded with near-infrared spectroscopy (fNIRS) in a dance video game task to that recorded in a reduced version of the task using fMRI (functional magnetic resonance imaging). Recently, it has been shown that fNIRS can accurately record functional brain activities equivalent to those concurrently recorded with functional magnetic resonance imaging for classic psychophysical tasks and simple finger tapping paradigms. However, an often quoted benefit of fNIRS is that the technique allows for studying neural mechanisms of complex, naturalistic behaviors that are not possible using the constrained environment of fMRI. Our goal was to extend the findings of previous studies that have shown high correlation between concurrently recorded fNIRS and fMRI signals to compare neural recordings obtained in fMRI procedures to those separately obtained in naturalistic fNIRS experiments. Specifically, we developed a modified version of the dance video game Dance Dance Revolution (DDR) to be compatible with both fMRI and fNIRS imaging procedures. In this methodology we explain the modifications to the software and hardware for compatibility with each technique as well as the scanning and calibration procedures used to obtain representative results. The results of the study show a task-related increase in oxyhemoglobin in both modalities and demonstrate that it is possible to replicate the findings of fMRI using fNIRS in a naturalistic task. This technique represents a methodology to compare fMRI imaging paradigms which utilize a reduced-world environment to fNIRS in closer approximation to naturalistic, full-body activities and behaviors. Further development of this technique may apply to neurodegenerative diseases, such as Parkinson’s disease, late states of dementia, or those with magnetic susceptibility which are contraindicated for fMRI scanning.

Gender and limb differences in healthy elite dancers: passé kinematics.

Symmetry of skill development is emphasized in dance training, and many movements are well learned by both genders. The authors conducted a 2-dimensional kinematic analysis of a complex dance movement, the passé, in 12 healthy professional male and female dancers to determine whether there are differences between genders or limbs during the performance of that task. Only peak hip angular displacement differed in men and women. No differences were found between limbs in any of the dependent variables. Dancers displayed consistent temporal and spatial proximal-to-distal sequencing of movement coordination. Despite an indication of limb preference, as defined by gesture or stance limb, there were no differences in proficiency.

Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: An fMRI approach

BackgroundThe Kana Pick-out Test (KPT), which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out) and continuous (reading) dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC), and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test.MethodsWe used functional magnetic resonance imaging (fMRI) to evaluate changes in the blood oxygenation level-dependent (BOLD) signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels) and compared it to its single task components (reading or vowel pick-out alone).ResultsBehavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmanns areas 45, 46) was present only in the KPT.ConclusionsOur results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.