| 1. |
- Al-Hammadi, Mustafa, 1995-, et al.
(författare)
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Machine Learning Approaches for Dementia Detection Through Speech and Gait Analysis : A Systematic Literature Review
- 2024
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 100:1, s. 1-27
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Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: Dementia is a general term for several progressive neurodegenerative disorders including Alzheimer's disease. Timely and accurate detection is crucial for early intervention. Advancements in artificial intelligence present significant potential for using machine learning to aid in early detection.OBJECTIVE: Summarize the state-of-the-art machine learning-based approaches for dementia prediction, focusing on non-invasive methods, as the burden on the patients is lower. Specifically, the analysis of gait and speech performance can offer insights into cognitive health through clinically cost-effective screening methods.METHODS: A systematic literature review was conducted following the PRISMA protocol (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The search was performed on three electronic databases (Scopus, Web of Science, and PubMed) to identify the relevant studies published between 2017 to 2022. A total of 40 papers were selected for review.RESULTS: The most common machine learning methods employed were support vector machine followed by deep learning. Studies suggested the use of multimodal approaches as they can provide comprehensive and better prediction performance. Deep learning application in gait studies is still in the early stages as few studies have applied it. Moreover, including features of whole body movement contribute to better classification accuracy. Regarding speech studies, the combination of different parameters (acoustic, linguistic, cognitive testing) produced better results.CONCLUSIONS: The review highlights the potential of machine learning, particularly non-invasive approaches, in the early prediction of dementia. The comparable prediction accuracies of manual and automatic speech analysis indicate an imminent fully automated approach for dementia detection.
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| 2. |
- Burenius, Magnus, 1983-, et al.
(författare)
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Human 3D Motion Computation from a varying Number of Cameras
- 2011
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Ingår i: Image Analysis. - Berlin, Heidelberg : Springer Berlin / Heidelberg. ; , s. 24-35
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Konferensbidrag (refereegranskat)abstract
- This paper focuses on how the accuracy of marker-less human motion capture is affected by the number of camera views used. Specifically, we compare the 3D reconstructions calculated from single and multiple cameras. We perform our experiments on data consisting of video from multiple cameras synchronized with ground truth 3D motion, obtained from a motion capture session with a professional footballer. The error is compared for the 3D reconstructions, of diverse motions, estimated using the manually located image joint positions from one, two or three cameras. We also present a new bundle adjustment procedure using regression splines to impose weak prior assumptions about human motion, temporal smoothness and joint angle limits, on the 3D reconstruction. The results show that even under close to ideal circumstances the monocular 3D reconstructions contain visual artifacts not present in the multiple view case, indicating accurate and efficient marker-less human motion capture requires multiple cameras.
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| 3. |
- Cedervall, Ylva, et al.
(författare)
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A longitudinal study of gait function and characteristics of gait disturbances in individuals with Alzheimer's disease
- 2014
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 39:4, s. 1022-1027
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Tidskriftsartikel (refereegranskat)abstract
- Walking in daily life places high demands on the interplay between cognitive and motor functions. A well-functioning dual-tasking ability is thus essential for walking safely. The aims were to study longitudinal changes in gait function during single- and dual-tasking over a period of two years among people with initially mild AD (n = 21). Data were collected on three occasions, twelve months apart. An optical motion capture system was used for three-dimensional gait analysis. Gait parameters were examined at comfortable gait speed during single-tasking, dual-tasking naming names, and naming animals. The dual-task cost for gait speed was pronounced at baseline (names 26%, animals 35%), and remained so during the study period. A significant (p < 0.05) longitudinal decline in gait speed and step length during single- and dual-tasking was observed, whereas double support time, step width and step height showed inconsistent results. Systematic visual examination of the motion capture files revealed that dual-tasking frequently resulted in gait disturbances. Three main characteristics of such disturbances were identified: Temporal disturbance, Spatial disturbance and Instability in single stance. These aberrant gait performances may affect gait stability and increase the risk of falling. Furthermore, the observed gait disturbances can contribute to understanding and explaining previous reported gait variability among individuals with AD. However, the role that dual-task testing and aberrant dual-task gait performance play in the identification of individuals with early signs of cognitive impairment and in predicting fall risk in AD remains to be studied.
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| 4. |
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| 5. |
- Cedervall, Ylva, et al.
(författare)
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Timed Up-and-Go Dual-Task Testing in the Assessment of Cognitive Function : A Mixed Methods Observational Study for Development of the UDDGait Protocol
- 2020
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 17:5
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Tidskriftsartikel (refereegranskat)abstract
- New methods to screen for and identify early-stage dementia disorders are highly sought after. The purpose of this pilot study is to develop a study protocol for a dual-task test aimed at aiding the early detection of dementia disorders. We used the Timed Up-and-Go (TUG) test, which is a mobility task involving starting in a sitting position, standing up, walking three meters to cross a line on the floor, turning around, walking back and sitting down again. We combined TUG with the verbal task of naming different animals. Pilot study participants were 43 individuals with and without established dementia diagnoses who attended a clinic for memory assessment. Video-recorded test performances were systematically analysed. Deviant test performances concerning the interplay between test administration and participants' responses to the assessment instructions were revealed and led to refinements being made to the final study protocol. Exploration of the dual-task test outcome measures in a sub-sample of 22 persons, ten with and twelve without dementia, indicated that step-length and number of named animals after the turning point of the dual-task test might constitute appropriate measures for examining this kind of sample. We concluded that the refined study protocol is feasible for testing individuals undergoing initial memory assessments and healthy controls. Follow-up studies with larger samples are being carried out and will bring new knowledge to this area of research. It may also provide an opportunity for further studies exploring possibilities for broad clinical implementation.
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| 6. |
- Crommert, Martin Eriksson, 1974-, et al.
(författare)
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Trunk muscle activation at the initiation and braking of bilateral shoulder flexion movements of different amplitudes
- 2015
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate if trunk muscle activation patterns during rapid bilateral shoulder flexions are affected by movement amplitude. Eleven healthy males performed shoulder flexion movements starting from a position with arms along sides (0°) to either 45°, 90° or 180°. EMG was measured bilaterally from transversus abdominis (TrA), obliquus internus (OI) with intra-muscular electrodes, and from rectus abdominis (RA), erector spinae (ES) and deltoideus with surface electrodes. 3D kinematics was recorded and inverse dynamics was used to calculate the reactive linear forces and torque about the shoulders and the linear and angular impulses. The sequencing of trunk muscle onsets at the initiation of arm movements was the same across movement amplitudes with ES as the first muscle activated, followed by TrA, RA and OI. All arm movements induced a flexion angular impulse about the shoulders during acceleration that was reversed during deceleration. Increased movement amplitude led to shortened onset latencies of the abdominal muscles and increased level of activation in TrA and ES. The activation magnitude of TrA was similar in acceleration and deceleration where the other muscles were specific to acceleration or deceleration. The findings show that arm movements need to be standardized when used as a method to evaluate trunk muscle activation patterns and that inclusion of the deceleration of the arms in the analysis allow the study of the relationship between trunk muscle activation and direction of perturbing torque during one and the same arm movement.
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| 7. |
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| 8. |
- Elmgren Frykberg, Gunilla, 1957-, et al.
(författare)
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Impact of stroke on anterior-posterior force generation prior to seat-off during sit-to-walk
- 2012
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 35:1, s. 56-60
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Tidskriftsartikel (refereegranskat)abstract
- Force generation during sit-to-walk (STW) post-stroke is a poorly studied area, although STW is a common daily transfer giving rise to a risk of falling in persons with disability. The purpose of this study was to describe and compare strategies for anterior-posterior (AP) force generation prior to seat-off during the STW transfer in both subjects with stroke and in matched controls. During STW at self-selected speed, AP force data were collected by 4 force plates, beneath the buttocks and feet from eight subjects with stroke '(>6 months after onset) and 8 matched controls. Subjects with post-stroke hemiparesis and matched controls generated a similar magnitude of total AP force impulses (F-1.71 = 0.67; p = 0.42) beneath buttocks and feet prior to seat-off during STW. However, there were significant group differences in AP force impulse generation beneath the stance buttock (i.e. the non-paretic buttock in the stroke group), with longer duration (F-1.71 = 8.78; p <0.005), larger net AP impulse (F-1.71 = 6.76; p < 0.05) and larger braking impulse (F-1.71 = 7.24; p <0.05) in the stroke group. The total braking impulse beneath buttocks and feet was about 4.5 times larger in the stroke group than in the control group (F-1.71 = 8.84; p < 0.005). An intra-and inter-limb dys-coordination with substantial use of braking impulses was demonstrated in the stroke group. This motor strategy differed markedly from the smooth force interaction in the control group. These results might be important in the development of treatment models related to locomotion post-stroke.
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| 9. |
- Elmgren Frykberg, Gunilla, 1957-, et al.
(författare)
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Temporal coordination of the sit-to-walk task in subjects with stroke and in controls
- 2009
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Ingår i: Archives of Physical Medicine and Rehabilitation. - : Elsevier BV. - 0003-9993 .- 1532-821X. ; 90:6, s. 1009-1017
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To explore events and describe phases for temporal coordination of the sit-to-walk (STW) task, within a semistandardized set up, in subjects with stroke and matched controls. In addition, to assess variability of STW phase duration and to compare the relative duration of STW phases between the 2 groups.Design: Cross-sectional.Setting: Research laboratory.Participants: A convenience sample of persons with hemiparesis (n=10; age 50–67y), more than 6 months after stroke and 10 controls matched for sex, age, height, and body mass index.Interventions: Not applicable.Main Outcome Measures: Relative duration of STW phases, SE of measurement in percentage of the mean, and intraclass correlation coefficients (ICCs).Results: Four STW phases were defined: rise preparation, transition, primary gait initiation, and secondary gait initiation. The subjects with stroke needed 54% more time to complete the STW task than the controls did. ICCs ranged from .38 to .66 and .22 to .57 in the stroke and control groups, respectively. SEs of measurement in percentage of the mean values were high, particularly in the transition phase: 54.1% (stroke) and 50.4% (controls). The generalized linear model demonstrated that the relative duration of the transition phase was significantly longer in the stroke group.Conclusions: The present results extend existing knowledge by presenting 4 new phases of temporal coordination of STW, within a semistandardized set-up, in persons with stroke and in controls. The high degree of variability regarding relative STW phase duration was probably a result of both the semistandardized set up and biological variability. The significant difference in the transition phase across the 2 groups requires further study.
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| 10. |
- Eriksson, Martin, et al.
(författare)
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Immediate effect of visual and auditory feedback to control the running mechanics of well-trained athletes
- 2011
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 29:3, s. 253-262
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Tidskriftsartikel (refereegranskat)abstract
- The correlation between mechanical factors of running and running economy as measured by metabolic cost is a subject of much interest in the study of locomotion. However, no change in running technique has been shown to result in an immediate improvement in running economy on an intra-individual basis. To evaluate the effect of a modified running technique, it is probably necessary that the individual trains with the new technique for a longer period using a feedback system to control the new kinematics. In this study, we examine the feasibility of using visual and auditory feedback to adapt running technique according to a simplistic model of the mechanical cost of running. The model considers only the mechanical work against gravity, which is the product of the magnitude of the vertical displacement of the runner's centre of mass and the step-frequency. In the experiments reported here, 18 trained runners, running at 16km center dot h-1 on a treadmill, were given feedback on these parameters together with indicated target levels. In almost all cases, the runners were able to adjust their technique accordingly.
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| 11. |
- Eriksson, Martin, et al.
(författare)
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Wireless Vertical Displacement Measurement during Running using an Accelerometer and a Mobile Phone
- 2011
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to investigate in the usability of a wireless accelerometer linked to a mobile phone via Bluetooth radio for measuring vertical displacement in running athletes. Five experienced runners were monitored during lactate threshold testing at three to five different velocities. Accelerometer data was received, processed and stored on the phone to be compared to simultaneous position transducer (ground truth) recordings after data collection. A paired t-test and statistical analysis show no significant differences in the reliability of the recordings. While further investigations are encouraged, the accelerometer and algorithm (running in J2ME on the mobile phone) proof as aflexible, easy-to-use tool for out-of-the-lab monitoring and to provide real-time feedback for running technique experiments.
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| 12. |
- Forsell, Caroline, et al.
(författare)
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A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum
- 2009
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 42:3, s. 361-365
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Tidskriftsartikel (refereegranskat)abstract
- A new method is proposed for finding small sets of points on the body giving sufficient information for estimating the whole body center of mass (CoM), as well as the linear momenta (LM) and angular momenta (AM). In the underlying model each point (whose trajectory is tracked by a marker) is a point mass: Hence the body is represented by a simple system of point masses. The first step is to determine the appropriate set of points and the mass of each point, which is assumed to be specific for the movement performed. The distribution of the mass to each marker is determined from training data for which the true (or reference) trajectories of the CoM, LM or AM are known. This leads to a quadratic optimization problem with inequality constraints. The use of the method is demonstrated on data from discus throw. Results indicate reasonably small errors, considering the magnitude of other error Sources, in CoM position (average magnitude of estimation error 1-2 cm), and moderate errors in AM (13-20% of peak Value).
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| 13. |
- Frohm, Anna, et al.
(författare)
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A new device for controlled eccentric overloading in training and rehabilitation
- 2005
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 94:1-2, s. 168-174
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to evaluate a device that allows for eccentric overload to be applied under controlled and safe conditions and it is applicable in exercises commonly used in training and rehabilitation. The machine contains a barbell, which is lowered and raised by a motor, following a predetermined velocity profile. It is capable of handling heavy loads (> 500 kg) and is instrumented with a sensor to measure the velocity of the barbell and two scales to measure the vertical component of the ground reaction force. The velocity recordings of the built-in displacement sensor were found to correspond well with those obtained using a motion-capture system. Applying known weights on each scale demonstrated linearity with respect to magnitude and independence regarding location of application. The velocity of the barbell was found to be dependent on the load on the barbell and on the resisting force produced by the individual training in the machine. The combined man-machine reliability was tested using a group of habitually active males (n = 13, 2855 years) performing squats. Peak voluntary resisting force and position at peak resistance were recorded on two occasions, showing no significant differences and a coefficient of variation of 9% and 22%, respectively. Preliminary observations from training in the machine have been positive both for increasing performance in top athletes and for causing pain relief in patients with diffuse knee problems. The possibility of feedback of the force under each foot makes individual dosage of training load possible, which is valuable, e.g. in rehabilitation of a unilateral injury.
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| 14. |
- Frohm, Anna, et al.
(författare)
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Eccentric treatment for patellar tendinopathy : a prospective randomised short-term pilot study of two rehabilitation protocols.
- 2007
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Ingår i: British Journal of Sports Medicine. - : BMJ. - 0306-3674 .- 1473-0480. ; 41:7, s. e7-
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare the efficacy and safety of two eccentric rehabilitation protocols for patients with symptomatic patellar tendinopathy. A new eccentric overload training device was compared with the present standard eccentric rehabilitation programme on a decline board. DESIGN: Prospective, randomised clinical trial. SETTING: Sports rehabilitation clinic, university sports laboratory, supplemented with home exercises. PATIENTS: 20 competitive and recreational athletes, all with clinical diagnosis of patellar tendinopathy, verified by MRI or ultrasound imaging. INTERVENTIONS: A 12-week rehabilitation period, either with bilateral eccentric overload strength training using the Bromsman device twice a week or with unilateral eccentric body load training using a decline board twice a week, supplemented with daily home exercises. OUTCOME MEASURES: The primary outcome was pain and function, assessed by the Swedish Victorian Institute of Sport Assessment for Patella (VISA-P) score. Secondary outcome measures were isokinetic muscle torque, dynamic function and muscle flexibility, as well as pain level estimations using visual analogue scale (VAS). Side effects were registered. RESULTS: Both treatment groups improved in the short term according to the VISA-P scores during the 12-week rehabilitation period. However, there were no significant differences between the groups in terms of pain and function. After a 3-month rehabilitation period, most patients could be regarded as improved enough to be able to return to training and sports. No serious side effects were detected in either group. CONCLUSION: In patients with patellar tendinopathy pain, two-legged eccentric overload training twice per week, using the new device (Bromsman), was as efficient and safe as the present standard daily eccentric one-legged rehabilitation-training regimen using a decline board.
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| 15. |
- Frohm, Anna, et al.
(författare)
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Patellar tendon load in different types of eccentric squats
- 2007
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 22:6, s. 704-711
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Tidskriftsartikel (refereegranskat)abstract
- Background. Differences in mechanical loading of the patellar tendon have been suggested as a reason for varying effects in rehabilitation of patellar tendinopathy using different eccentric squat exercises and devices. The aim was to characterize the magnitude and pattern of mechanical load at the knee and on the patellar tendon during four types of eccentric squat. Methods. Subjects performed squats with a submaximal free weight and with maximal effort in a device for eccentric overloading (Bromsman), on a decline board and horizontal surface. Kinematics was recorded with a motion-capture system, reaction forces with force plates, and electromyography from three leg muscles with surface electrodes. Inverse dynamics was used to calculate knee joint kinetics. Findings. Eccentric work, mean and peak patellar tendon force, and angle at peak force were greater (25-30%) for squats on decline board compared to horizontal surface with free weight, but not in Bromsman. Higher knee load forces (60-80%), but not work, were observed with Bromsman than free weight. Angular excursions at the knee and ankle were larger with decline board, particularly with free weight, and smaller in Bromsman than with free weight. Mean electromyography was greater on a decline board for gastrocnemius (13%) and vastus medialis (6%) with free weight, but in Bromsman only for gastrocnemius (7%). Interpretation. The results demonstrated clear differences in the biomechanical loading on the knee during different squat exercises. Quantification of such differences provides information that could be used to explain differences in rehabilitation effects as well as in designing more optimal rehabilitation exercises for patellar tendinopathy.
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| 16. |
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| 17. |
- Frykberg, Gunilla, 1957-, et al.
(författare)
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Locomotor coordination during the sit-to-walk transfer is different in subjects with stroke and controls
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: To describe and to compare coordination of centre of mass (COM) horizontal and vertical momenta, and fluidity during the sit-to-walk (STW) transfer in subjects with stroke and in matched controls. Design: Cross-sectional. Setting: Research laboratory. Participants: Ten subjects with stroke in the post-acute phase (> 6 months) and ten control subjects, matched for sex, age, height and weight, were recruited through a convenience sample. Interventions: Not applicable. Main Outcome Measures: Magnitudes and timing of COM peak horizontal and peak vertical momenta, scores on the Fluidity Scale (FS) and values of the Fluidity Index (FI). Results: The stroke subjects generated significantly less COM peak horizontal and peak vertical momenta. Latencies from STW-onset and seat-off to the peaks differed significantly between the two groups. The subjects with stroke displayed significantly lower scores on the FS as well as lower percentages of the FI. Conclusions: While rising to walk, scaling and timing parameters of COM horizontal and vertical momenta differed significantly between subjects with stroke and matched controls. This atypical motor strategy needs to be further investigated before it is possible to make clinical recommendations.
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| 18. |
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| 19. |
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| 20. |
- Gullstrand, Lennart, et al.
(författare)
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Measurements of vertical displacement in running, a methodological comparison
- 2009
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 30:1, s. 71-75
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Tidskriftsartikel (refereegranskat)abstract
- The aim was (1) to evaluate measurements of vertical displacements (V-disp) of a single point on sacrum as an estimate of the whole body centre of mass (CoM) V-disp during treadmill running and (2) to compare three methods for measuring this single point. These methods were based on a position transducer(PT), accelerometers (AMs) and an optoelectronic motion capture system. Criterion method was V-disp of the whole body CoM measured with the motion capture system. Thirteen subjects ran at 10, 12, 14, 16. 18, 20 and 22 km h(-1) with synchronous recordings with the three methods. Four measurements of the (V-disp) were derived: (1) V-disp of CoM calculated from a segment model consisting of 13 segments tracked with 36 reflective markets, (2) V-disp of the sacrum recorded with the PT, (3) V-disp of the sacrum Calculated from the AM, and (4) V-disp of the sacrum calculated as the mid point of two reflective markets (sacrum marker, SM) attached at the level of the sacral bone. The systematic discrepancy between the Measurements of sacrum V-disp and CoM V-disp varied between 0 and 1.5 mm and decreased with increasing running velocity and decreasing step duration. PT and SM measurements showed strong correlation, whereas the AM showed a variability increasing with velocity. The random discrepancy within each Subject was 7 mm for all three methods. In conclusion single-point recordings of the sacrum V-disp may be used to monitor changes in V-disp of CoM during treadmill running.
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| 21. |
- Halvorsen, Kjartan, et al.
(författare)
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Acute Effects Of Reducing Vertical Displacement And Step Frequency On Running Economy
- 2012
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Ingår i: Journal of Strength and Conditioning Research. - 1064-8011 .- 1533-4287. ; 26:8, s. 2065-2070
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Tidskriftsartikel (refereegranskat)abstract
- This work studies the immediate effects of altering the vertical displacement of CoM (VD) and step frequency (SF) on the metabolic cost of level treadmill running at 16 km·h on sixteen male runners. Alterations of VD, SF and the product VD SF was induced using a novel feedback system which presents target and current values to the runner by visual or auditory display. Target values were set to 5 and 10% reductions from individual baseline values. Results were expressed as relative changes from baseline values.Alterations led to an increase in metabolic cost in most cases, measured as VO2 uptake per minute and kg body mass. Correlations were weak. Still, linear multiple regression revealed a positive coefficient (0.28) for the relationship between VD SF and VO2. Separate rank correlation tests showed negative correlation (τ = -0.19) between SF and VO2 and positive correlation (τ = -0.16) between VD and VO2. There is a coupling between VD and SF caused by the mechanics of running, hence isolated reduction of either factor was hard to achieve. The linear model also showed a negative coefficient for the relationship between the height of center of mass above ground (CoMh) and VO2.The effect size was small (multiple R-squared 0.07 and 0.12). Still the results indicate that reducing VD SF by reducing vertical displacement can have a positive effect on running economy, but a concurrent reduction in CoMh may reduce or diminish the positive effect. Mid- and long-term effects of altering the technique should also be studied.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Halvorsen, Kjartan, et al.
(författare)
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Minimal marker set for center of mass estimation in running
- 2009
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 30:4, s. 552-555
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to study the validity of a recently proposed method [Forsell C, Halvorsen K. A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum. journal of Biomechanics 2009;42(3):361-5] for estimating the trajectory of the whole-body center of mass (CoM) in the case of running at: velocities ranging from 10 to 22 km h(-1). The method gives an approximation to the CoM using the position of fewer markers on the body than the standard method of tracking each segment of the body. Fourteen male athletes participated. A standard method for determining the CoM from a model of 13 segments and using the position of 36 markers was used as reference method. Leave-one-out cross-validation revealed errors that decreased with increasing number of markers used in the approximative method. Starting from four markers, the error in absolute position of the CoM decreased from 15 mm to 3 mm in each direction. For the velocity of the CoM the estimation bias was neglectable, and the random error decreased from 0.15 to 0.05 m s(-1). The inter-subject and intra-subject variability in the estimated model parameters increased with increasing number of markers. The method worked well also when applied to running at velocities outside the range of velocities in the data used to determine the model parameters. The results indicate that a model using 10 markers represents a good trade-off between simplicity and accuracy, but users must take into account requirements of their specific applications.
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| 27. |
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| 28. |
- Halvorsen, Kjartan
(författare)
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Model-based Methods in Motion Capture
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the use of kinematic models and shape models to solve the problem of estimating the motion of articulated objects from image data. The data considered in the first part of the thesis are trajectories of 3D feature points (markers). In the second part, image sequences are considered. In the first part of the thesis, the problems of estimating 1) the pose of single rigid body, and 2) the configuration of a system of connected rigid bodies, are treated in a unifying manner. An extended Kalman filter is applied to the problem of tracking the pose/configuration, and is shown to give accurate estimates. The Kalman filter framework also provides an improved solution to the common problem of temporary missing marker data. The method is applied to the case of estimating the motion of the distal limb of the horse, and provides the first ever non-invasive \invivo{} estimates of the detailed 3D motion of the distal limb. The estimation of the average center of rotation and axis of rotation is also treated. Four alternative methods are analyzed and contrasted. The methods are found to be biased, and a bias compensation algorithm is derived for one of the methods. Simulation tests show that the bias-compensated method gives a substantial improvement in accuracy. In the second part, a 3D shape model and a framework for tracking the motion of body segments from multi-view image sequences are developed. The novel shape model, which consists of a stack of circular or elliptic discs, gives a good approximation to the shape of human segments, at a moderate computational cost. The tracking is based on minimizing a measure of the distance between the model contours and the set of edges extracted from the images. A differentiable model and distance measure are derived, which improve the rate of convergence of the algorithm, and enable the pose to be tracked using an extended Kalman filter. The extended Kalman filter is shown to give reasonable estimates and eliminates the time-consuming minimization step. The thesis concludes with the development of a method for estimating the inertial parameters (mass, center of mass and moments of inertia) of body segments using the proposed stack-of-discs shape model.
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| 29. |
- Halvorsen, Kjartan, et al.
(författare)
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Pose estimation of cyclic movement using inertial sensor data
- 2016
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Ingår i: Proc. 19th Statistical Signal Processing Workshop. - : IEEE Signal Processing Society. - 9781467378031
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Konferensbidrag (refereegranskat)abstract
- We propose a method for estimating the rotation and displacement of a rigid body from inertial sensor data based on the assumption that the movement is cyclic in nature, meaning that the body returns to the same position and orientation at regular time intervals. The method builds on a parameterization of the movement by sums of sinusoids, and the amplitude and phase of the sinusoids are estimated from the data using measurement models with Gaussian noise. The maximum likelihood estimate is then equivalent to a weighted nonlinear least squares estimate. The performance of the method is demonstrated on simulated data and on experimental data.
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| 30. |
- Halvorsen, Kjartan, et al.
(författare)
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Robust Tracking of Periodic Motion in the Plane using Inertial Sensor Data
- 2017
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Ingår i: Proceedings of IEEE Sensors 2017. - Glasgow, Scotland : IEEE. - 9781509010127 ; , s. 1041-1043
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Konferensbidrag (refereegranskat)abstract
- We propose a robust method for estimating the orientation and displacement of an inertial measurement unit undergoing planar periodic motion. Such movements is a common approximation to human gait and running. We formulate the problem introducing a sparse vector of outlier errors and l1-regularization. The problem thus becomes robust to outliers in the data. The problem can be rewritten as a quadratic programming problem which can be solved efficiently using existing software for convex optimization.
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| 31. |
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| 32. |
- Halvorsen, Kjartan, et al.
(författare)
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The concept of mobility in single- and double handed manipulation.
- 2014
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 47:14, s. 3569-3573
-
Tidskriftsartikel (refereegranskat)abstract
- The concept of mobility describes an important property of the human body when performing manipulation tasks. It describes, in a sense, how easy it is to accelerate a link or a point on the manipulator. Most often it is calculated for the end-link or end-point of the manipulator, since these are important for the control objective of the manipulator. Mobility is the inverse of the inertia experienced by a force acting on the end-point, or a combined force and torque acting on the end-link. The concept has been used in studies of reaching tasks with one arm, but thus far not for bi-manual manipulation. We present here the concept for both single-handed and double-handed manipulation, in a general manner which includes any type of grip of the hands on the object. The use of the concept is illustrated with data on the left and right arm in a golf swing.
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| 33. |
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| 34. |
- Halvorsen, Kjartan, et al.
(författare)
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Tracking the Motion of Hidden Segments Using Kinematic Constraints and Kalman Filtering
- 2008
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Ingår i: Journal of Biomechanical Engineering. - : ASME International. - 0148-0731 .- 1528-8951. ; 130:1, s. 011012:1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Motion capture for biomechanical applications involves in almost all cases sensors or markers that are applied to the skin of the body segments of interest. This paper deals with the problem of estimating the movement of connected skeletal segments from 3D position data of markers attached to the skin. The use of kinematic constraints has been shown previously to reduce the error in estimated segment movement that are due to skin and muscles moving with respect to the underlying segment. A kinematic constraint reduces the number of degrees of freedom between two articulating segments. Moreover, kinematic constraints can help reveal the movement of some segments when the 3D marker data otherwise are insufficient. Important cases include the human ankle complex and the phalangeal segments of the horse, where the movement of small segments is almost completely hidden from external observation by joint capsules and ligaments. This paper discusses the use of an extended Kalman filter for tracking a system of connected segments. The system is modeled using rigid segments connected by simplified joint models. The position and orientation of the mechanism are specified by a set of generalized coordinates corresponding to the mechanism’s degrees of motion. The generalized coordinates together with their first time derivatives can be used as the state vector of a state space model governing the kinematics of the mechanism. The data collected are marker trajectories from skin-mounted markers, and the state vector is related to the position of the markers through a nonlinear function. The Jacobian of this function is derived. The practical use of the method is demonstrated on a model of the distal part of the limb of the horse. Monte Carlo simulations of marker data for a two-segment system connected by a joint with three degrees of freedom indicate that the proposed method gives significant improvement over a method, which does not make use of the joint constraint, but the method requires that the model is a good approximation of the true mechanism. Applying the method to data on the movement of the four distal-most segments of the horse’s limb shows good between trial consistency and small differences between measured marker positions and marker positions predicted by the model.
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| 35. |
- Halvorsen, Kjartan, et al.
(författare)
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Using an extended kalman filter for rigid body pose estimation.
- 2005
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Ingår i: Journal of Biomechanical Engineering. - : ASME International. - 0148-0731 .- 1528-8951. ; 127:3, s. 475-83
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Tidskriftsartikel (refereegranskat)abstract
- Rigid body pose is commonly represented as the rigid body transformation from one (often reference) pose to another This is usually computed for each frame of data without any assumptions or restrictions on the temporal change of the pose. The most common algorithm was proposed by Söderkvist and Wedin (1993, "Determining the Movements of the Skeleton Using Well-configured Markers," J. Biomech., 26, pp. 1473-1477), and implies the assumption that measurement errors are isotropic and homogenous. This paper describes an alternative method based on a state space formulation and the application of an extended Kalman filter (EKF). State space models are formulated, which describe the kinematics of the rigid body. The state vector consists of six generalized coordinates (corresponding to the 6 degrees of freedom), and their first time derivatives. The state space models have linear dynamics, while the measurement function is a non-linear relation between the state vector and the observations (marker positions). An analytical expression for the linearized measurement function is derived. Tracking the rigid body motion using an EKF enables the use of a priori information on the measurement noise and type of motion to tune the filter. The EKF is time variant, which allows for a natural way of handling temporarily missing marker data. State updates are based on all the information available at each time step, even when data from fewer than three markers are available. Comparison with the method of Söderkvist and Wedin on simulated data showed a considerable improvement in accuracy with the proposed EKF method when marker data was temporarily missing. The proposed method offers an improvement in accuracy of rigid body pose estimation by incorporating knowledge of the characteristics of the movement and the measurement errors. Analytical expressions for the linearized system equations are provided, which eliminate the need for approximate discrete differentiation and which facilitate a fast implementation.
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| 36. |
- Harringe, M L, et al.
(författare)
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Postural control measured as the center of pressure excursion in young female gymnasts with low back pain or lower extremity injury.
- 2008
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 28:1, s. 38-45
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Tidskriftsartikel (refereegranskat)abstract
- Gymnasts are known to practice and compete although suffering from injuries and pain. Pain may change strategies for postural control. The primary aim of the present study was to investigate how center of pressure (COP) measurements are influenced by low back pain and lower extremity injury in top-level female gymnasts. A secondary aim was to study the reliability of these measurements using a test-retest design, and how this depends on the duration of the test. Fifty-seven top-level gymnasts were included in four groups: non-injured (NI, n=18), low back pain (LBP, n=11), lower extremity injury (LEI, n=17) and a multiple injury group (MI, n=11). COP excursion during quiet stance was measured on a force platform, during 120s: (1) hard surface/eyes open, (2) hard surface/eyes closed, (3) foam surface/eyes open and (4) foam surface/eyes closed. The COP excursion increased, for all groups, during the foam surface/eyes closed measurement compared to the other three tests. Furthermore, the LBP group showed a 49% (p=0.01) larger COP area compared to the LEI group in the foam surface/eyes closed condition. Measurements on foam surface were in general more reliable than tests on hard surface and tests with eyes closed were more reliable than tests with eyes open. Tests during 120s were in most cases more reliable than tests during 60s. In conclusion the COP excursion is influenced by injury location. Quiet stance measurements on foam surface with eyes closed seems to be reliable and sensitive in young female gymnasts.
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| 37. |
- Jönhagen, Sven, et al.
(författare)
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Muscle activation and length changes during two lunge exercises : implications for rehabilitation
- 2009
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 19, s. 561-568
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Tidskriftsartikel (refereegranskat)abstract
- Eccentric exercises are commonly used as a treatment for various muscle and tendon injuries. During complex motions such as the forward lunge, however, it is not always clear which muscles may be contracting eccentrically and at what time. Because this exercise is used during rehabilitation, the purpose of this investigation was to determine what type of contractions take place during two different types of forward lunge and assess the implications for rehabilitation. Five experienced athletes performed five cycles for each of the walking and jumping forward lunges. Motion analysis was used to calculate the shortening or elongation of each muscle based on the change of position of their origin and insertion points during the lunge. Electromyography of the lateral hamstrings, rectus femoris and lateral gastrocnemius was combined with the muscle length change data to determine when isometric, concentric and eccentric activations occur during the lunge. Eccentric contractions in both the quadriceps and gastrocnemius were observed during the lunge. No hamstring eccentric contractions were found; however, the hamstrings showed isometric contractions during the first part of the stance phase.
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| 38. |
- Kaphle, Manindra, 1979-
(författare)
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Simulations of human movements through temporal discretization and optimization
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Study of physical phenomena by means of mathematical models is common in various branches of engineering and science. In biomechanics, modelling often involves studying human motion by treating the body as a mechanical system made of interconnected rigid links. Robotics deals with similar cases as robots are often designed to imitate human behavior. Modelling human movements is a complicated task and, therefore, requires several simplifications and assumptions. Available computational resources often dictate the nature and the complexity of the models. In spite of all these factors, several meaningful results are still obtained from the simulations. One common problem form encountered in real life is the movement between known initial and final states in a pre-specified time. This presents a problem of dynamic redundancy as several different trajectories are possible to achieve the target state. Movements are mathematically described by differential equations. So modelling a movement involves solving these differential equations, along with optimization to find a cost effective trajectory and forces or moments required for this purpose. In this study, an algorithm developed in Matlab is used to study dynamics of several common human movements. The main underlying idea is based upon temporal finite element discretization, together with optimization. The algorithm can deal with mechanical formulations of varying degrees of complexity and allows precise definitions of initial and target states and constraints. Optimization is carried out using different cost functions related to both kinematic and kinetic variables. Simulations show that generally different optimization criteria give different results. To arrive on a definite conclusion on which criterion is superior over others it is necessary to include more detailed features in the models and incorporate more advanced anatomical and physiological knowledge. Nevertheless, the algorithm and the simplified models present a platform that can be built upon to study more complex and reliable models.
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| 39. |
- Lindh, Jacob, 1971, et al.
(författare)
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Blended learning through global network and interdisciplinary live distance experiments at human performance laboratories.
- 2009
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Ingår i: Learning in the Synergy of Multiple Disciplines, 4th European Conference on Technology Enhanced Learning, EC-TEL 2009, Nice, France, September 29 - October 2, 2009.. - : Springer. - 9783642046353 ; 5794 Springer 2009
-
Tidskriftsartikel (refereegranskat)abstract
- Under a previous grant (2005-2008) we designed an interdisciplinary inquiry-based laboratory course in sports kinesiology, taught simultaneously over the Internet for undergraduate students at the University of Gothenburg and at Stanford University. Student groups developed their own research questions, conducted online distance experiments, processed their unique data with support from an interdisciplinary global network of expert consultants, and presented original scientific results. We will demonstrate one virtual experiment that is central to the course to conference attendees and present a unique set of interactive learning tools for the scientific process. This student-conducted experiment was first tested in a laboratory in Stockholm in 2007, and broadcasted live to three universities, with experts and students actively taking part via Polycom and Marratech. Real-time communication was possible in all directions through a moderator in Stockholm. Our course model seems to improve student learning outcomes while advancing the field of sports science.
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| 40. |
- Melander-Wikman, Anita, et al.
(författare)
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Project: e-Balance
- 2014
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Annan publikation (populärvet., debatt m.m.)
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| 41. |
- Nilsson, Johnny, et al.
(författare)
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Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing
- 2013
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 113:6, s. 1385-1394
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Tidskriftsartikel (refereegranskat)abstract
- This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h(-1). In a second set of recordings, horizontal resistance was added by weights (0.4-1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h(-1). Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (+/- SD) horizontal force components ranged between 1.7 (+/- 1.3) and 2.8 (+/- 1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (+/- 0.6) and 4.0 (+/- 1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.
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| 42. |
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| 43. |
- Norrbrand, Lena, et al.
(författare)
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Metabolic Demands and Kinematics During Level Walking in Darkness With No Vision or With Visual Aid
- 2022
-
Ingår i: Military medicine. - : Oxford University Press (OUP). - 0026-4075 .- 1930-613X. ; 188:7-8, s. e2010-e2017
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Uniformed services commonly perform foot-borne operations at night, while using visual aid in terms of night vision goggles (NVG). During slow-level walking, complete lack of visual input alters kinematics and markedly increases the metabolic demand, whereas the effect on kinematics and energy expenditure of restricting the peripheral visual field by wearing NVG is still unknown. The purpose was to evaluate whether metabolic demands and kinematics during level walking are affected by complete darkness with and without visual aid.MATERIALS AND METHODS: Eleven healthy men walked on a treadmill (inclination: +2.3°, velocity: 4 km/h) with full vision in a lighted laboratory (Light), and in complete darkness wearing either a blindfold (Dark), or restricting the visual field to about 40° by wearing monocular (Mono) or binocular (Bino) NVG. Oxygen uptake ($\dot{\text{V}}$O2) was measured to evaluate metabolic demands. Inertial measurement units were used to estimate kinematics, and the outcome was validated by using a motion capture system. Ratings of perceived exertion, discomfort, and mental stress were evaluated after each condition using a Borg ratio scale. Physiologic and kinematic variables were evaluated using repeated measures analysis of variance (ANOVA), whereas ratings were evaluated using non-parametric Friedman ANOVA.RESULTS: $\dot{\text{V}}$ O2 was 20% higher in the Dark (1.2 ± 0.2 L/min) than the Light (1.0 ± 0.2 L/min) condition. Nominally, $\dot{\text{V}}$O2 in the Mono (1.1 ± 0.2 L/min) and Bino (1.1 ± 0.2 L/min) conditions fell in between those in the Light and Dark conditions but was not statistically different from either the Light or the Dark condition. Step length was shorter in the Dark (-9%, 1.22 ± 0.16 m) and Mono (-6%, 1.27 ± 0.09 m) conditions than in the Light condition (1.35 ± 0.11 m), whereas the Bino (1.28 ± 0.08 m) condition was not statistically different from either the Light or the Dark condition. The three conditions with no or limited vision were perceived more physically demanding, more uncomfortable, and more mentally stressful than the Light condition, and the Dark condition was perceived more mentally stressful than both NVG conditions.CONCLUSIONS: The study confirms that complete lack of visual cues markedly reduces the mechanical efficiency during level walking, even under obstacle-free and highly predictable conditions. That $\dot{\text{V}}$O2 and step length values for the NVG conditions fell in between those of the Light and Dark conditions suggest that both foveal and peripheral vision may play important roles in optimizing the mechanical efficiency during level walking.
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| 44. |
- Olsson, Fredrik, et al.
(författare)
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Accelerometer calibration using sensor fusion with a gyroscope
- 2016
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Ingår i: Proceedings of the IEEE Workshop on Statistical Signal Processing. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781467378024 - 9781467378031 ; , s. 660-664
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a calibration method for a triaxial accelerometer using a triaxial gyroscope is presented. The method uses a sensor fusion approach, combining the information from the accelerometers and gyroscopes to find an optimal calibration using Maximum likelihood. The method has been tested by using real sensors in smartphones to perform orientation estimation and verified through Monte Carlo simulations. In both cases, the method is shown to provide a proper calibration, reducing the effect of sensor errors and improving orientation estimates.
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| 45. |
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| 46. |
- Olsson, Fredrik, et al.
(författare)
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Identification of Nonlinear Feedback Mechanisms Operating in Closed Loop using Inertial Sensors
- 2018
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Ingår i: IFAC-PapersOnLine. - : Elsevier B.V.. - 2405-8963. ; 51:15, s. 473-478
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we study the problem of identifying linear and nonlinear feedback mechanisms, or controllers, operating in closed loop. A recently developed identification method for nonlinear systems, the LAVA method, is used for this purpose. Identification data is obtained from inertial sensors, that provide information about the movement of the system, in the form of linear acceleration and angular velocity measurements. This information is different from the information that is available to the controller to be identified, which makes use of unknown internal sensors instead. We provide two examples, a simulated neuromuscular controller in standing human balance, and a lead-filter controlling a physical position servo using a DC motor. Both linear and nonlinear controllers are used in the examples. We show that the LAVA method is able to identify sparse, parsimonious models of the controllers.
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| 47. |
- Olsson, Fredrik, 1988-
(författare)
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Inertial motion capture for ambulatory analysis of human movement and balance
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inertial sensors (accelerometers and gyroscopes) are ubiquitous in today’s society, where they can be found in many of our everyday mobile devices. These sensors are capable of recording the movement of the device, and by extension, the movement of humans carrying or interacting with the device. Human motion capture is frequently used for medical purposes to assess individual balance performance and movement disorders. Accurate and objective assessment is important in the design of individualized interventions and rehabilitation strategies.The increasing availability of inertial sensors, combined with their mobility and low cost, has made inertial motion capture highly relevant as a more accessible alternative to the laboratory based gold standard. However, mobile solutions need to be adopted for plug-and-play use with the end user in mind. Methods that automatically calibrate the sensors, and methods that detect and record relevant motions are required.This thesis contributes to the development of human inertial motion capture as a plug-and-play technology. A method for accelerometer calibration, which allows for compensation of systematic sensor errors, is proposed. The method fuses accelerometer and gyroscope data to allow dynamic rotation of the sensor during the calibration procedure. Other proposed methods handles sensor-to-segment calibration in a biomechanical model. The position of a joint center and the direction of a hinge joint’s rotation axis, are identified in each sensor’s intrinsic coordinate system. This is done by fitting recorded motions to the kinematic constraints of the underlying biomechanical model. The methods are evaluated on real sensor data collected from mechanical joint systems that mimics human limbs.The state of the current knowledge regarding objective human balance assessment isstudied in the form of a systematic review, that includes methods for modeling and identifying neuromuscular control of human balance. A similar modeling framework is then applied to identify feedback controllers in physical and artificial (simulated) systems. Finally, inertial sensors are applied in tremor quantification in Parkinson’s disease (PD) and essential tremor (ET). The method uses only the inertial sensors in a standard smart phone, and is applied on data from human subjects with PD or ET.
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| 48. |
- Olsson, Fredrik, et al.
(författare)
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Joint Axis Estimation for Fast and Slow Movements Using Weighted Gyroscope and Acceleration Constraints
- 2019
-
Ingår i: 2019 22th International Conference on Information Fusion (FUSION). - 9780996452786 - 9781728118406
-
Konferensbidrag (refereegranskat)abstract
- Sensor-to-segment calibration is a crucial step in inertial motion tracking. When two segments are connected by a hinge joint, for example in human knee and finger joints as well as in many robotic limbs, then the joint axis vector must be identified in the intrinsic sensor coordinate systems. There exist methods that identify these coordinates by solving an optimization problem that is based on kinematic joint constraints, which involve either the measured accelerations or the measured angular rates. In the current paper we demonstrate that using only one of these constraints leads to inaccurate estimates at either fast or slow motions. We propose a novel method based on a cost function that combines both constraints. The restrictive assumption of a homogeneous magnetic field is avoided by using only accelerometer and gyroscope readings. To combine the advantages of both sensor types, the residual weights are adjusted automatically based on the estimated signal variances and a nonlinear weighting of the acceleration norm difference. The method is evaluated using real data from nine different motions of an upper limb exoskeleton. Results show that, unlike previous approaches, the proposed method yields accurate joint axis estimation after only five seconds for all fast and slow motions.
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| 49. |
- Olsson, Fredrik
(författare)
-
Modeling and assessment of human balance and movement disorders using inertial sensors
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inertial sensors and magnetometers are abundant in today's society, where they can be found in many of our everyday electronic devices, such as smart phones or smart watches. Their primary function is to measure the movement and orientation of the device and provide this information for the apps that request it.This licenciate thesis explores the use of these types of sensors in biomedical applications. Specifically, how these sensors can be used to analyze human movement and work as a tool for assessment of human balance and movement disorders. The methods presented in this thesis deal with mathematical modeling of the sensors, their relationship to the biomechanical models that are used to describe the dynamics of human movement and how we can combine these models to describe the mechanisms behind human balance and quantify the symptoms of movement disorders.The main contributions come in the form of four papers. A practical calibration method for accelerometers is presented in Paper I, that deals with compensation of intrinsic sensor errors that are common for relatively cheap sensors that are used in e.g. smart phones. In Paper II we present an experimental evaluation and minor extension of methods that are used to determine the position of the joints in the biomecanical model, using inertial sensor data alone. Paper III deals with system identification of nonlinear controllers operating in closed loop, which is a method that can be used to model the neuromuscular control mechanisms behind human balance. In Paper IV we propose a novel method for quantification of hand tremor, a primary symptom of neurological disorders such as Parkinson's disease (PD) or Essential tremor (ET), where we make use of data collected from sensors in a smart phone. The thesis also contains an introduction to the sensors, biomechanical modeling, neuromuscular control and the various estimation and modeling techniques that are used throughout the thesis.
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| 50. |
- Olsson, Fredrik, et al.
(författare)
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Neuromuscular Controller Models for Quantifying Standing Balance in Older People : A Systematic Review
- 2023
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Ingår i: IEEE Reviews in Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 1941-1189 .- 1937-3333. ; 16, s. 560-578
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Forskningsöversikt (refereegranskat)abstract
- Objective quantification of the balancing mechanisms in humans is strongly needed in health care of older people, yet is largely missing among current clinical balance assessment methods. Hence, the main goal of this literature review is to identify methods that have the potential to meet that need. We searched in the PubMed and IEEE Xplore databases using predefined criteria, screened 1064 articles, and systematically reviewed and categorized methods from 73 studies that deal with identification of neuromuscular controller models of human upright standing from empirical data. These studies were then analyzed with the particular aim to understand to what degree such methods would be useful solutions for assessing the balance of older individuals aged above 60 years. The 16 studies that included an older subject population were especially examined with this in mind. The majority of the reviewed articles focused on research questions related to the general function of human balance control rather than clinical applicability. Further efforts need to be made to adapt these methods for more accessible and mobile technologies and to ensure that the outcomes are valid for balance assessment of a general older population.
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