Yong Hao Pua

Validity of the Microsoft Kinect for providing lateral trunk lean feedback during gait retraining

Gait retraining programs are prescribed to assist in the rehabilitation process of many clinical conditions. Using lateral trunk lean modification as the model, the aim of this study was to assess the concurrent validity of kinematic data recorded using a marker-based 3D motion analysis (3DMA) system and a low-cost alternative, the Microsoft Kinect™ (Kinect), during a gait retraining session. Twenty healthy adults were trained to modify their gait to obtain a lateral trunk lean angle of 10°. Real-time biofeedback of the lateral trunk lean angle was provided on a computer screen in front of the subject using data extracted from the Kinect skeletal tracking algorithm. Marker coordinate data were concurrently recorded using the 3DMA system, and the similarity and equivalency of the trunk lean angle data from each system were compared. The lateral trunk lean angle data obtained from the Kinect system without any form of calibration resulted in errors of a high (>2°) magnitude (mean error=3.2±2.2°). Performing global and individualized calibration significantly (P<0.001) improved this error to 1.7±1.5° and 0.8±0.8° respectively. With the addition of a simple calibration the anatomical position coordinates of the Kinect can be used to create a real-time biofeedback system for gait retraining. Given that this system is low-cost, portable and does not require any sensors to be attached to the body, it could provide numerous advantages when compared to laboratory-based gait retraining systems.

Concurrent validity of the Microsoft Kinect for assessment of spatiotemporal gait variables

Spatiotemporal characteristics of gait such as step time and length are often associated with overall physical function in clinical populations, but can be difficult, time consuming and obtrusive to measure. This study assessed the concurrent validity of overground walking spatiotemporal data recorded using a criterion reference - a marker-based three-dimensional motion analysis (3DMA) system - and a low-cost, markerless alternative, the automated skeleton tracking output from the Microsoft Kinect™ (Kinect). Twenty-one healthy adults performed normal walking trials while being monitored using both systems. The outcome measures of gait speed, step length and time, stride length and time and peak foot swing velocity were derived using supervised automated analysis. To assess the agreement between the Kinect and 3DMA devices, Bland-Altman 95% bias and limits of agreement, percentage error, relative agreement (Pearsons correlation coefficients: r) overall agreement (concordance correlation coefficients: rc) and landmark location linearity as a function of distance from the sensor were determined. Gait speed, step length and stride length from the two devices possessed excellent agreement (r and rc values >0.90). Foot swing velocity possessed excellent relative (r=0.93) but only modest overall (rc=0.54) agreement. Step time (r=0.82 and rc=0.23) and stride time (r=0.69 and rc=0.14) possessed excellent and modest relative agreement respectively but poor overall agreement. Landmark location linearity was excellent (R(2)=0.991). This widely available, low-cost and portable system could provide clinicians with significant advantages for assessing some spatiotemporal gait parameters. However, caution must be taken when choosing outcome variables as some commonly reported variables cannot be accurately measured.

Gait assessment using the Microsoft Xbox One Kinect: Concurrent validity and inter-day reliability of spatiotemporal and kinematic variables.

The revised Xbox One Kinect, also known as the Microsoft Kinect V2 for Windows, includes enhanced hardware which may improve its utility as a gait assessment tool. This study examined the concurrent validity and inter-day reliability of spatiotemporal and kinematic gait parameters estimated using the Kinect V2 automated body tracking system and a criterion reference three-dimensional motion analysis (3DMA) marker-based camera system. Thirty healthy adults performed two testing sessions consisting of comfortable and fast paced walking trials. Spatiotemporal outcome measures related to gait speed, speed variability, step length, width and time, foot swing velocity and medial-lateral and vertical pelvis displacement were examined. Kinematic outcome measures including ankle flexion, knee flexion and adduction and hip flexion were examined. To assess the agreement between Kinect and 3DMA systems, Bland-Altman plots, relative agreement (Pearsons correlation) and overall agreement (concordance correlation coefficients) were determined. Reliability was assessed using intraclass correlation coefficients, Cronbachs alpha and standard error of measurement. The spatiotemporal measurements had consistently excellent (r≥0.75) concurrent validity, with the exception of modest validity for medial-lateral pelvis sway (r=0.45-0.46) and fast paced gait speed variability (r=0.73). In contrast kinematic validity was consistently poor to modest, with all associations between the systems weak (r<0.50). In those measures with acceptable validity, the inter-day reliability was similar between systems. In conclusion, while the Kinect V2 body tracking may not accurately obtain lower body kinematic data, it shows great potential as a tool for measuring spatiotemporal aspects of gait.

Instrumenting gait assessment using the Kinect in people living with stroke: reliability and association with balance tests

BackgroundThe Microsoft Kinect has been used previously to assess spatiotemporal aspects of gait; however the reliability of this system for the assessment of people following stroke has not been established. This study examined the reliability and additional information that the Kinect provides when instrumenting a gait assessment in people living with stroke.MethodsThe spatiotemporal variables of step length, step length asymmetry, foot swing velocity, foot swing velocity asymmetry, peak and mean gait speed and the percentage difference between the peak and mean gait speed were assessed during gait trials in 30 outpatients more than three months post-stroke and able to stand unsupported. Additional clinical assessments of functional reach (FR), step test (ST), 10xa0m walk test (10MWT) and the timed up and go (TUG) were performed, along with force platform instrumented assessments of center of pressure path length velocity during double-legged standing balance with eyes closed (DLEC), weight bearing asymmetry (WBA) and dynamic medial-lateral weight-shifting ability (MLWS). These tests were performed on two separate occasions, seven days apart for reliability assessment. Separate adjusted multiple regressions models for predicting scores on the clinical and force platform assessments were created using 1) the easily assessed clinically-derived gait variables 10MWT time and total number of steps; and 2) the Kinect-derived variables which were found to be reliable (ICCu2009>u20090.75) and not strongly correlated (Spearman’s ρu2009<u20090.80) with each other (i.e. non-redundant).ResultsKinect-derived variables were found to be highly reliable (all ICCsu2009>u20090.80), but many were redundant. The final regression model using Kinect-derived variables consisted of the asymmetry scores, mean gait velocity, affected limb foot swing velocity and the difference between peak and mean gait velocity. In comparison with the clinically-derived regression model, the Kinect-derived model accounted for >15% more variance on the MLWS, ST and FR tests and scored similarly on all other measures.ConclusionsIn conclusion, instrumenting gait using the Kinect is reliable and provides insight into the dynamic balance capacity of people living with stroke. This system provides a minimally intrusive method of examining potentially important gait characteristics in people living with stroke.

Diminished sub-maximal quadriceps force control in anterior cruciate ligament reconstructed patients is related to quadriceps and hamstring muscle dyskinesia

The aim of this study was to determine the effects of anterior cruciate ligament reconstruction (ACLR) on sub-maximal quadriceps force control with respect to quadriceps and hamstring muscle activity. Thirty ACLR individuals together with 30 healthy individuals participated. With real-time visual feedback of muscle force output and electromyographic electrodes attached to the quadriceps and hamstring muscles, subjects performed an isometric knee extension task where they increased and decreased their muscle force output at 0.128Hz within a range of 5-30% maximum voluntary capacity. The ACLR group completed the task with more error and increased medial hamstring and vastus medialis activation (p<0.05). Moderate negative correlations (p<0.05) were observed between quadriceps force control and medial (Spearmans rho=-0.448, p=0.022) and lateral (Spearmans rho=-0.401, p=0.034) hamstring activation in the ACLR group. Diminished quadriceps sub-maximal force control in ACLR subjects was reflective of medial quadriceps and hamstring dyskinesia (i.e., altered muscle activity patterns and coordination deficits). Within the ACLR group however, augmented hamstring co-activation was associated with better quadriceps force control. Future studies should explore the convergent validity of quadriceps force control in ACLR patients.

Impaired voluntary quadriceps force control following anterior cruciate ligament reconstruction: relationship with knee function

AbstractPurposenImpairments in quadriceps force control and altered quadriceps and hamstring muscle activation strategies have been observed following anterior cruciate ligament reconstruction; however, the functional implications of these impairments are unclear. This study examined the cross-sectional associations between quadriceps force control, quadriceps activation, hamstring coactivation and clinically assessed knee function following anterior cruciate ligament reconstruction with a hamstring graft.MethodsSixty-six patients (18xa0±xa03xa0months following surgery) and 41 uninjured individuals participated. Quadriceps force control was assessed using an isometric knee extension task. Participants cyclically increased and decreased quadriceps force at slow speeds between 5 and 30xa0% maximum voluntary isometric contraction matching a moving target displayed on a screen. Quadriceps activation and hamstring coactivation were assessed concurrently using surface electromyography. Knee function was assessed with the Cincinnati Knee Rating Scale and three single-leg hop tests.ResultsThe reconstructed group completed the task with 48xa0% greater root-mean-square error (RMSE), indicating significantly worse quadriceps force control (pxa0<xa00.001). In a multivariable model adjusted for sex, greater RMSE and greater lateral hamstring coactivation were significantly associated with worse knee function that is greater odds of scoring <85xa0% on one or more knee functional assessment.ConclusionsLess-accurate quadriceps force output and greater hamstring coactivation are associated with worse knee joint function following anterior cruciate ligament reconstruction and may contribute to irregular knee joint loading and the onset or progression of knee osteoarthritis. Impairments in quadriceps force control and altered muscle activation strategies may be modifiable through neuromuscular training, and this is an area for future research.Level of evidenceCase–control study, Level III.

Neck musculature fatigue affects specific frequency bands of postural dynamics during quiet standing

Proprioceptive input from the neck is important for maintenance of upright standing. Although neck musculature fatigue has been demonstrated to impair standing balance, there is limited understanding of the underlying postural mechanisms. This study aimed to further examine the effects of neck musculature fatigue on standing by using modern analysis of center of pressure (CoP) data. Forty-eight young healthy adults stood quietly on a balance board for 1 min before and after performing repeated weight-resisted scapular elevation exercises. In a supplementary study on 20 participants, we examined (i) the effects of visual deprivation and (ii) the test-retest reliability of the traditional and wavelet-based CoP measures. Test-retest reliability of the CoP measures was moderate to good (intraclass correlation coefficients ranged from 0.58 to 0.94). With neck muscle fatigue or without vision, traditional measures of CoP velocity and standard deviation increased monotonically. Wavelet analysis revealed that CoP velocity within the ultralow (<0.10 Hz) and moderate (1.56-6.25 Hz) frequency bands increased post-fatigue. Without vision, CoP velocity increased in all but the ultralow frequency band. Our data suggest that post-fatigue, vision may be the main compensatory postural mechanism for altered neck proprioception. In conclusion, our findings reveal more nuances than the simple assertion that neck musculature fatigue increased postural sway and they advocate the use of wavelet analysis in examining postural mechanisms associated with neck proprioception.

Effects of WiiActive exercises on fear of falling and functional outcomes in community-dwelling older adults: a randomised control trial

BACKGROUNDnthe study compares the effects of a Nintendo Wii exercise programme and a standard Gym-based exercise intervention on fear of falling, knee strength, physical function and falls rate in older adults.nnnMETHODSneighty community-dwelling adults aged 60 years and above with short physical performance battery score of 5-9 points and modified falls efficacy scale (MFES) score of ≤9 points participated in the parallel-group randomised trial. Each intervention arm involved an hour of intervention per week, totalling 12 sessions over 12 weeks. Besides 1-year fall incidence, the participants were evaluated on MFES, knee extensor strength (KES), timed-up-and-go test, gait speed, 6-minute walk test and narrow corridor walk test at weeks 13 and 24.nnnRESULTSnat week 13, between interventions, the effect of MFES changes did not reach statistical significance (differencexa0=xa0-0.07 point, 95% CI -0.56 to 0.42, Pxa0=xa00.78); at week 24, the Wii group showed statistically significant effects over the Gym group (differencexa0=xa00.8 point, 95% CI 0.27 to 1.29, Pxa0<xa00.01). For KES, the two groups did not differ statistically at week 13 (differencexa0=xa0-2.0%, 95% CI -5.6 to -1.7, Pxa0=xa00.29); at week 24, the Gym group had greater strength gains than the Wii group (differencexa0=xa0-5.1%, 95% CI -8.7 to -1.5, Pxa0<xa00.01). No between-group differences were observed for other outcome measures.nnnCONCLUSIONnon completion of a 12-week Nintendo Wii exercise programme, there was no significant benefit seen on fear of falling when compared to a standard Gym-based exercise intervention; however, post-intervention there was an apparent reduction in fear of falling in the group allocated to Wii training, despite knee strength apparently improving more in those allocated to the Gym. It is possible that long-term gains after using the Wii might be due to a carry-over effect.nnnTRIAL REGISTRATIONnAustralian New Zealand Clinical Trials Registry, ACTRN12610000576022.

The minimal clinically important difference of six-minute walk in Asian older adults

BackgroundRehabilitation interventions promote functional recovery among frail older adults and little is known about the clinical significance of physical outcome measure changes. The purpose of our study is to examine the minimal clinically important difference (MCID) for the 6-minute walk distance (6MWD) among frail Asian older adults.MethodsData from the “Evaluation of the Frails’ Fall Efficacy by Comparing Treatments” study were analyzed. Distribution-based and anchor-based methods were used to estimate the MCID of the 6MWD. Participants who completed the trial rated their perceived change of overall health on the Global Rating of Change (GROC) scale. The receiver operating characteristic curve (ROC) was used to analyze the sensitivity and specificity of the cut-off values of 6MWD (in meters) for GROC rating of “a little bit better” (+2), based on feedback from participants.ResultsThe mean (SD) change in 6MWD was 37.3(46.2) m among those who perceived a change (GROCu2009≥u20092), while those who did not was 9.3(18.2) m post-intervention (Pu2009=u20090.011). From the anchor-based method, the MCID value for the 6MWD was 17.8xa0m (sensitivity 56.7% and specificity 83.3%) while distribution-based method estimated 12.9xa0m.ConclusionThe MCID estimate for 6MWD was 17.8xa0m in the moderately frail Asian older adults with a fear of falling. The results will aid the clinicians in goal setting for this patient population.Trial registrationAustralian New Zealand Clinical Trials Registry number: ACTRN12610000576022

Factors Associated With Post-Stroke Physical Activity: A Systematic Review and Meta-Analysis

OBJECTIVEnTo integrate the literature investigating factors associated with post-stroke physical activity.nnnDATA SOURCESnA search was conducted from database inception to June 2016 across 9 databases: Cochrane, MEDLINE, ProQuest, Web of Science, PsycINFO, Scopus, Embase, CINAHL, and Allied and Complementary Medicine Database. The reference lists of included articles were screened for secondary literature.nnnSTUDY SELECTIONnCohort and cross-sectional studies were included if they recruited community-dwelling stroke survivors and measured factors associated with physical activity.nnnDATA EXTRACTIONnRisk of bias was evaluated using the Quality in Prognosis Studies checklist. A meta-analysis was conducted for correlates where there were at least 2 studies that reported a correlation value. Correlation values were used in an effect size measure and converted to a standardized unit with Fisher r to z transformation and conversion back to r method. Results were described qualitatively for studies that could not be pooled.nnnDATA SYNTHESISnThere were 2161 studies screened and 26 studies included. Age (meta r=-.17; P≤.001) and sex (meta r=-.01; P=.02) werexa0the nonmodifiable factors that were found to be associated with post-stroke physical activity. The modifiable factors were physical function (meta r=.68-.73; P<.001), cardiorespiratory fitness (meta r=.35; P≤.001), fatigue (meta r=-.22; P=.01), falls self-efficacy (meta r=-.33; P<.001), balance self-efficacy (meta r=.37; P<.001), depression (meta r=-.58 to .48; P<.001), and health-related quality of life (meta r=.38-.43; P<.001). The effect of side of infarct, neglect, and cognition on post-stroke physical activity was inconclusive.nnnCONCLUSIONSnAge, sex, physical function, depression, fatigue, self-efficacy, and quality of life were factors associated with post-stroke physical activity. The cause and effect of these relations are unclear, and the possibility of reverse causality needs to be addressed.