Qualisys Motion Capture System Research Articles

Immediate effects of a single treadmill session with additional ankle loading on gait in children with hemiparetic cerebral palsy.

Children with hemiparetic cerebral palsy are often characterized by reduced speed progression, shorter step length, and increased support base. These kinematic alterations result in inefficient gait. To assess the immediate effects of treadmill training with additional lower limb loading on kinematic gait parameters in children with Cerebral Palsy (CP). This cross-sectional, observational study, involved 20 children with hemiparetic CP that underwent single treadmill session with ankle loading. Kinematic gait data were collected by the Qualisys Motion Capture System during baseline (PRE), immediately after training (POST) and 5 minutes after post session (FOLLOW UP). The results demonstrated increase in knee (p = 0.001) and hip (p = 0.005) range of motion, maximum knee (p <.0.001) and hip (p =.001) flexion in swing and paretic foot height during swing (p <0.001) when PRE x POST were compared. Treadmill gait training with additional lower limb loading was a disturbance capable of modifying the locomotor strategy of these population. The increase in hip flexion during swing phase allowed higher paretic foot clearance which may favor the improvement of gait function.

Does functional mobility vary among individuals with up to one year after stroke? An analysis using the TUG-ABS

The Timed “Up and Go” Assessment of Biomechanical Strategies (TUG-ABS) analyses functional mobility activities of Timed “Up and Go” (TUG) test, showing to be valid and reliable for individuals with stroke. The aim of this study was to evaluate if the performance of functional mobility activities varies between subjects within the first year poststroke. Thirty-eight stroke subjects (mean age 56.5 years) of both genders and with up to one year of first stroke that caused gait deficits (gait speed < 0.8 m/s) participated in the study. Participants were instructed to perform the following activities: standing up from a chair without armrests, walking and circling (180° turns) a cone placed at the 1.35-m mark, walking back and sitting down. The performances of these activities were registered by the Qualisys Motion Capture System. By analyzing the images, TUG-ABS was applied to evaluate: sit-to-stand (STSt), walking (W), turn (T) and stand-to-sit (STSi). For statistical analysis, participants were divided into: one group with up to 3 months poststroke ( n = 21), and another group with 4 to 12 months poststroke ( n = 17). Study groups were compared with Mann Whitney test for TUG-ABS activities and total TUG-ABS score (TS). The groups were homogeneous with regard to middle age, cognitive level (Mini-Mental State Examination), neurological status (National Institute of Health Stroke Scale) and walking ability (Functional Ambulatory Category). For TUG-ABS, there was also no difference between groups for the activities: STSt: P = 0.161; W: P = 0.383; T: P = 0.052; STSi: P = 0.542, and for TS: P = 0.144. Although motor recovery can be influenced by lesion time, the performance of functional mobility activities did not appear to be different among subjects in the first year poststroke. This suggests that biomechanical strategies for performing these activities are developed within the first three months following stroke, indicating the importance of early intervention for rehabilitation.

Posture and discomfort assessment in computer users while using touch screen device as compared with mouse-keyboard and touch pad-keyboard.

Touch screen computers require significant arm and hand movements. This can result to body discomfort and biomechanical load in users. This study was carried out to examine posture and users' discomfort while using touch screen device as compared with mouse-keyboard and touch pad-keyboard. Twenty three (23) students participated in this experimental study. The subjects completed pre-defined tasks in three 15 min trials by means of touch screen, touch pad-keyboard and mouse-keyboard as input devices. Postural angles were measured by Qualisys motion capture system. Body discomfort was assessed by a 10-cm visual analog scale. Rating scale was employed to assess the perception of subjects on the posture of body parts while utilizing the three devices. There was no significant difference in head inclination when using the three types of devices. Nevertheless, the mean of neck (p = 0.005) and trunk (p < 0.0001) inclinations as well as arm angle (p < 0.0001) while using touch screen, differed significantly from the two other devices and were more deviated from neutral posture. The type of input device was found to have significant effect on the right shoulder (p = 0.017), right elbow (p = 0.031), right wrist/hand (p = 0.004) and whole body discomfort (p = 0.026). Touch screen caused more discomfort in the mentioned regions when compared to the other two devices. Friedman test showed that differences of mean ratings for perceived shoulder and elbow postures in the 3 trials were significant (p = 0.005 and p = 0.011, respectively). Touch screen was the most unfavorable input device based on the subjects' judgment. Touch screen caused more deviated postural angles, increased body discomfort and unfavorable postures.

An Automatic Gait Feature Extraction Method for Identifying Gait Asymmetry Using Wearable Sensors.

This paper aims to assess the use of Inertial Measurement Unit (IMU) sensors to identify gait asymmetry by extracting automatic gait features. We design and develop an android app to collect real time synchronous IMU data from legs. The results from our method are validated using a Qualisys Motion Capture System. The data are collected from 10 young and 10 older subjects. Each performed a trial in a straight corridor comprising 15 strides of normal walking, a turn around and another 15 strides. We analyse the data for total distance, total time, total velocity, stride, step, cadence, step ratio, stance, and swing. The accuracy of detecting the stride number using the proposed method is 100% for young and 92.67% for older subjects. The accuracy of estimating travelled distance using the proposed method for young subjects is 97.73% and 98.82% for right and left legs; and for the older, is 88.71% and 89.88% for right and left legs. The average travelled distance is 37.77 (95% CI ± 3.57) meters for young subjects and is 22.50 (95% CI ± 2.34) meters for older subjects. The average travelled time for young subjects is 51.85 (95% CI ± 3.08) seconds and for older subjects is 84.02 (95% CI ± 9.98) seconds. The results show that wearable sensors can be used for identifying gait asymmetry without the requirement and expense of an elaborate laboratory setup. This can serve as a tool in diagnosing gait abnormalities in individuals and opens the possibilities for home based self-gait asymmetry assessment.

Maximum striking velocities in strikes with steel rods-the influence of rod length, rod mass and volunteer parameters.

In blunt force trauma to the head caused by attacks with blunt instruments, contact forces can be estimated based on the conservation of momentum if impact velocities are known. The aims of this work were to measure maximum striking velocities and to examine the influence of rod parameters such as rod mass and length as well as volunteer parameters such as sex, age, body height, body mass, body mass index and the average amount of physical exercise. Steel rods with masses of 500, 1000 and 1500g as well as lengths of 40, 65 and 90cm were exemplarily tested as blunt instruments. Twenty-nine men and 22 women participated in this study. Each volunteer performed several vertical strikes with the steel rods onto a passive immobile target. Maximum striking velocities were measured by means of a Qualisys motion capture system using high-speed cameras and infrared light. Male volunteers achieved maximum striking velocities between 14.0 and 35.5m/s whereas female volunteers achieved values between 10.4 and 28.3m/s. Results show that maximum striking velocities increased with smaller rod masses and less consistently with higher rod lengths. Statistically significant influences were found in the volunteers' sex and average amount of physical exercise.

Performance analysis of a generalized motion capture system using microsoft kinect 2.0

Abstract This work presents a fine-grained analysis of the performance and limitations of the Microsoft Kinect sensor for tracking human movement in the context of biomechanical research and clinical applications. Earlier work in this field has focused on scalar summary measures or ad-hoc metrics with respect to specific movements that do not generalize well across clinical applications. In this work, the performance of the Microsoft Kinect is compared to motion tracking from a concurrently sampled professional grade Qualisys motion capture system. Subjects performed a range of clinically relevant tasks such as Sit-to-Stand and Timed Up-and-Go. Captured data included both three-dimensional joint center displacements and joint angles as recorded from both systems. Kinect performance was measured using cross correlation coefficients (CCR), root mean squared error (RMSE) relative to the Qualisys gold-standard and a new summary metric (SM) that combines both. Our results show that the Kinect-based system provides adequate performance when tracking joint center displacements in time, with overall CCR = 0.78, RMSE = 3.35 cm and SM = 1.21. On the contrary, lower accuracy was measured when tracking joint angles, with CCR = 0.58, RMSE = 24.59°, and SM = 3.76. Although performance differences for various movements and motion planes have been found, the results suggest that the Kinect is a viable tool for general biomechanical research, with specific limits on what levels of performance can be expected under various conditions.

23 - Romiplostim in Low/INT-1-Risk MDS Results in Reduced Bleeding without Impacting Leukemic Progression: Final Results from a Randomized, Double-Blind, Placebo-Controlled Study

This preliminary study sought to analyze the effects of a training program based on the Proprioceptive Neuromuscular Facilitation (PNF) method on motor recovery of individuals with chronic post-stroke hemiparesis. Eleven individuals with chronic hemiparesis (mean lesion time of 19.64 months) after unilateral and non-recurrent stroke underwent training based on PNF method for twelve sessions, being evaluated for motor function - using the Stroke Rehabilitation Assessment of Movement (STREAM) instrument; functionality, by the Functional Independence Measure (FIM); and gait kinematic (using the Qualisys Motion Capture System), at baseline and post-training. Significant changes in FIM (from median 67 to median 68; P = .043) and STREAM scores (from median 47 to median 55; P = .003) were observed. Data showed significant changes in motor function and functionality after training, suggesting that this program can be useful for rehabilitation of chronic stroke survivors.

Evaluation of a Gait Assessment Module Using 3D Motion Capture Technology.

Gait analysis is the study of human locomotion. In massage therapy, this observation is part of an assessment process that informs treatment planning. Massage therapy students must apply the theory of gait assessment to simulated patients. At Humber College, the gait assessment module traditionally consists of a textbook reading and a three-hour, in-class session in which students perform gait assessment on each other. In 2015, Humber College acquired a three-dimensional motion capture system. The purpose was to evaluate the use of 3D motion capture in a gait assessment module compared to the traditional gait assessment module. Semester 2 massage therapy students who were enrolled in Massage Theory 2 (n = 38). Quasi-experimental, wait-list comparison study. The intervention group participated in an in-class session with a Qualisys motion capture system. The outcomes included knowledge and application of gait assessment theory as measured by quizzes, and students' satisfaction as measured through a questionnaire. There were no statistically significant differences in baseline and post-module knowledge between both groups (pre-module: p = .46; post-module: p = .63). There was also no difference between groups on the final application question (p = .13). The intervention group enjoyed the in-class session because they could visualize the content, whereas the comparison group enjoyed the interactivity of the session. The intervention group recommended adding the assessment of gait on their classmates to their experience. Both groups noted more time was needed for the gait assessment module. Based on the results of this study, it is recommended that the gait assessment module combine both the traditional in-class session and the 3D motion capture system.

Influence of a virtual reality-based exercise protocol on the sit-to-stand activity kinematic variables in pregnant women: a randomized controlled trial

Abstract AIMS Changes resulting from the gestational period may lead to changes in the biomechanics of women, which can alter the performance of functional activities such as sit-to-stand. Thus, the objective of this study was to investigate the influence of a virtual reality-based exercise protocol on the kinematic variables of the sit-to-stand movement in women in their second and third gestational trimesters. METHODS The sample consisted of 44 women selected according to the eligibility criteria, allocated into 4 groups: control group, 2nd trimester (CG2T); experimental group, 2nd trimester (EG2T); control group, 3rd trimester (CG3T); and experimental group, 3rd trimester (EG3T). All the volunteers answered the identification and evaluation form and were sent to the kinematic evaluation through the Qualisys Motion Capture System®. An intervention with game therapy was performed in 12 sessions of 30 minutes each, three times a week. RESULTS No statistically significant differences were found intra- (P> 0.54) and inter-groups (P> 0.059) for kinematic variables. However, there was a tendency for improvement in the analyzed variables after the proposed protocol. CONCLUSIONS The data obtained suggest that the use of the Nintendo Wii Fit Plus® was not able to influence sit-to-stand kinematic variables in the analyzed women.

Sensor node acceleration signatures and electromyography in synchronisation and sequencing analysis in sports: A rowing perspective

Following a review of the key determinants of successful rowing, a wireless body sensor network was developed to monitor boat and body segment acceleration and surface electromyography in major muscles recruited during the rowing stroke cycle. Its design was optimised to yield maximum information about the rowing stroke cycle from fewest sensors and minimise the power consumption of the nodes. The system was validated against the Qualisys motion capture and high-speed camera system with most Pearson correlation coefficients in excess of r = 0.8. On-land ergometer experimentation allowed muscle recruitment over the stroke cycle to be studied, with data from multiple experiments combined using correlation of the acceleration signatures of back and thigh nodes (r = 0.95). It was demonstrated that it was possible to identify one of the common rowing errors of ‘shooting-the-slide’ from the data collected, and that a marked decrease in correlation of good-to-bad technique over the drive phase of the stroke (0.95 reducing to 0.34 in the experiment undertaken) could be used to indicate the presence of this error. Extension of the wireless body sensor network to encompass boat and two oarsmen was demonstrated, allowing correlation of their rowing signatures to be studied, indicating their cohesion as a crew.

Adaptive Body Gesture Representation for Automatic Emotion Recognition

We present a computational model and a system for the automated recognition of emotions starting from full-body movement. Three-dimensional motion data of full-body movements are obtained either from professional optical motion-capture systems (Qualisys) or from low-cost RGB-D sensors (Kinect and Kinect2). A number of features are then automatically extracted at different levels, from kinematics of a single joint to more global expressive features inspired by psychology and humanistic theories (e.g., contraction index, fluidity, and impulsiveness). An abstraction layer based on dictionary learning further processes these movement features to increase the model generality and to deal with intraclass variability, noise, and incomplete information characterizing emotion expression in human movement. The resulting feature vector is the input for a classifier performing real-time automatic emotion recognition based on linear support vector machines. The recognition performance of the proposed model is presented and discussed, including the tradeoff between precision of the tracking measures (we compare the Kinect RGB-D sensor and the Qualisys motion-capture system) versus dimension of the training dataset. The resulting model and system have been successfully applied in the development of serious games for helping autistic children learn to recognize and express emotions by means of their full-body movement.

Infants' prospective control during object manipulation in an uncertain environment.

This study investigates how infants use visual and sensorimotor information to prospectively control their actions. We gave 14-month-olds two objects of different weight and observed how high they were lifted, using a Qualisys Motion Capture System. In one condition, the two objects were visually distinct (different color condition) in another they were visually identical (same color condition). Lifting amplitudes of the first movement unit were analyzed in order to assess prospective control. Results demonstrate that infants lifted a light object higher than a heavy object, especially when vision could be used to assess weight (different color condition). When being confronted with two visually identical objects of different weight (same color condition), infants showed a different lifting pattern than what could be observed in the different color condition, expressed by a significant interaction effect between object weight and color condition on lifting amplitude. These results indicate that (a) visual information about object weight can be used to prospectively control lifting actions and that (b) infants are able to prospectively control their lifting actions even without visual information about object weight. We argue that infants, in the absence of reliable visual information about object weight, heighten their dependence on non-visual information (tactile, sensorimotor memory) in order to estimate weight and pre-adjust their lifting actions in a prospective manner.

Electromyography of symmetrical trunk movements and trunk position sense in chronic stroke patients

[Purpose] To explore the differences in bilateral trunk muscle activation between chronic stroke patients and healthy controls, this study investigated the symmetry index and cross-correlation of trunk muscles during trunk flexion and extension movements. This study also assessed the differences in trunk reposition error between groups and the association between trunk reposition error and bilateral trunk muscle activation. [Subjects and Methods] Fifteen stroke patients and 15 age- and gender-matched healthy subjects participated. Bilateral trunk muscle activations were collected by electromyography during trunk flexion and extension. Trunk reposition errors in trunk flexion and extension directions were recorded by a Qualisys motion capture system. [Results] Compared with the healthy controls, the stroke patients presented lower symmetrical muscle activation of the bilateral internal oblique and lower cross-correlation of abdominal muscles during trunk flexion, and lower symmetry index and cross-correlation of erector spinae in trunk extension. They also showed a larger trunk extension reposition error. A smaller trunk reposition error was associated with higher cross-correlation of bilateral trunk muscles during trunk movements in all subjects. [Conclusion] Trunk muscle function during symmetrical trunk movements and trunk reposition sense were impaired in the chronic stroke patients, and trunk position sense was associated with trunk muscle functions. Future studies should pay attention to symmetrical trunk movements as well as trunk extension position sense for patients with chronic stroke.

Mobile Sensor Application for Kinematic Detection of the Knees.

ObjectiveTo correctly measure the knee joint angle, this study utilized a Qualisys motion capture system and also used it as the reference to assess the validity of the study's Inertial Measurement Unit (IMU) system that consisted of four IMU sensors and the Knee Angle Recorder software. The validity was evaluated by the root mean square (RMS) of different angles and the intraclass correlation coefficient (ICC) values between the Qualisys system and the IMU system.MethodsFour functional knee movement tests for ten healthy participants were investigated, which were the knee flexion test, the hip and knee flexion test, the forward step test and the leg abduction test, and the walking test.ResultsThe outcomes of the knee flexion test, the hip and knee flexion test, the forward step test, and the walking test showed that the RMS of different angles were less than 6°. The ICC values were in the range of 0.84 to 0.99. However, the leg abduction test showed a poor correlation in the measurement of the knee abduction-adduction movement.ConclusionThe IMU system used in this study is a new good method to measure the knee flexion-extension movement.

Effect of Rope Skipping Techniques on Kinematics and Dynamics of Motion

Rope skipping is a simple practice which provides strength and stamina and also enhance athlete’s performance. Identifying the optimum rope skipping techniques to boost athlete’s performance and minimize risk of injuries is crucial. In this study, the effect of various skipping techniques on the dynamic of human body motion during landing and jumping phase was investigated. Sixth teen male and female subjects performed three types of skipping techniques; bounce, alternate step and bell jump. Vertical ground reaction force, knee joint kinematics and kinetics were recorded during exercise by using the Qualisys motion capture system. There were no significant differences between gender in knee flexion angle, but significant in different types of skipping techniques. However, a significant difference in peak vertical ground reaction force was shown between gender and types of skipping. A linear relationship is shown between taking off velocity, jump height and percentage of ground reaction force per body weight. These findings suggest that the alternate step jump is the best skipping technique for all to practice which may prevent anterior cruciate ligament risk injury with a consistent landing posture.

Influence of treadmill training in dual-task gait in people with Parkinson's Disease: a case report

The loss in the automaticity of gait hinders the performance of concurrent activities - Dual Task (DT) - in individuals with Parkinson's disease (PD). One hypothesis for the negative interference of DT on gait is related to the limitation of attention resources in the brain for different activities. When the automation of a task occurs, the negative interference of DT on the gait can be minimized. Because the treadmill promotes automaticity of a better locomotion pattern, due to the repetition that promotes motor learning, the study sought to investigate whether treadmill training can improve the performance of gait on DT in people with PD. Three individuals were evaluated in the on-phase of the antiparkinsonian medication regarding the kinematics (Qualisys Motion Capture System) while in gait, simultaneously performing cognitive activities. Subsequently, the subjects performed a 20-minute workout on the treadmill and were reassessed during gait in cognitive activities. There were increases in the length of the cycle (p=0.01), the length of the step (p=0.01) and in total swing time (p=0.03), and a decrease in the total length of support (p=0.03). These results indicate that treadmill training can promote improvement in the performance of DT on gait in individuals with PD. Longitudinal studies with this focus of research are needed.

Visual feedback and target size effects on reach-to-grasp tasks in children with autism.

This study explores the effects of visual condition and target size during four reach-to-grasp tasks between autistic children and healthy controls. Twenty children with autism and 20 healthy controls participated in the study. Qualisys motion capture system and kinematic measures were used to record movement. Autistic group showed significantly longer movement time, larger normalized jerk score, more movement unit than controls, especially in non-visual feedback and small target blocks. Autistic group also showed significantly larger maximal grip aperture and normalized maximal grip aperture in visual feedback condition than controls. Autistic children demonstrate motor coordination problems and also depend on more visual cuing in high accuracy tasks. Autistic children develop other compensatory skills while performing tasks.

Effects of a training program based on the Proprioceptive Neuromuscular Facilitation method on post-stroke motor recovery: A preliminary study

This preliminary study sought to analyze the effects of a training program based on the Proprioceptive Neuromuscular Facilitation (PNF) method on motor recovery of individuals with chronic post-stroke hemiparesis. Eleven individuals with chronic hemiparesis (mean lesion time of 19.64 months) after unilateral and non-recurrent stroke underwent training based on PNF method for twelve sessions, being evaluated for motor function - using the Stroke Rehabilitation Assessment of Movement (STREAM) instrument; functionality, by the Functional Independence Measure (FIM); and gait kinematic (using the Qualisys Motion Capture System), at baseline and post-training. Significant changes in FIM (from median 67 to median 68; P = .043) and STREAM scores (from median 47 to median 55; P = .003) were observed. Data showed significant changes in motor function and functionality after training, suggesting that this program can be useful for rehabilitation of chronic stroke survivors.

Effects of Gait Training with Added Load on Children with Hemiparetic Cerebral Palsy

The study aimed to evaluate the immediate effects of treadmill training with leg load on kinematic parameters of gait in children with spastic hemiparetic cerebral palsy (SHCP). Quasi-experimental study. Laboratory of Intervention and Movement Analysis on Federal University of Rio Grande do Norte (UFRN). 20 children with SHCP clinical diagnosis (mean age was 8.8 years ± 2.39), and independent walk (GMFCS I-II). Children walked with added load on ankles in a single treadmill training session during 5 minutes. Kinematic parameters were evaluated using the Qualisys Motion Capture System in three phases: before training (FBT); immediately after training (FPT); and 5 minutes after the end of training (FET). Significant increase in range of motion on knee (F=8.654; P =.001) and hip joint (F=6.053; P=.005), maximum flexion in swing phase of knee (F=16.252; P<.001) and hip joint (F=7.876; P=.001) and the maximum height of the paretic leg during the swing phase (F=12.309; P<.001) were observed when comparing FBT versusFPT versus FET. The Bonferroni test identified that difference occurred when comparing phases FBTversus FPT and FPTversus FET. Gait training with leg load seems modifies the locomotor strategy for children with SHCP, suggesting that this therapy may benefit the gait of these children.

Construction of an instrumented roller ski and validation of three-dimensional forces in the skating technique

The purposes of the present investigation were to construct an instrumented roller ski, validate the force measurements and resolve the forces into three dimensions. To demonstrate the practical applications of the system, this study aimed to distinguish cycle characteristics and kinetics between skiers with different technical characteristics and between skating with and without poling while roller ski skating on a treadmill. It was shown that a roller ski with full bridge strain gauges could provide valid measurements of one-dimensional forces. By recording the orientation of the skis in space using the Qualisys motion capture system, the one-dimensional forces were converted into three dimensions according to the global coordinate system. However, some corrections are still required to obtain valid three-dimensional forces. It was possible to distinguish clear differences in cycle characteristics and roller ski forces between the two skiers with different characteristics and between skating with and without poling. Overall, this instrumented roller ski can be useful for future research and when monitoring elite athletes’ technical development.