Publications by authors named "Kamiar Aminian"

142 Publications

Running Speed Estimation Using Shoe-Worn Inertial Sensors: Direct Integration, Linear, and Personalized Model.

Front Sports Act Living 2021 18;3:585809. Epub 2021 Mar 18.

Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

The overground speed is a key component of running analysis. Today, most speed estimation wearable systems are based on GNSS technology. However, these devices can suffer from sparse communication with the satellites and have a high-power consumption. In this study, we propose three different approaches to estimate the overground speed in running based on foot-worn inertial sensors and compare the results against a reference GNSS system. First, a method is proposed by direct strapdown integration of the foot acceleration. Second, a feature-based linear model and finally a personalized online-model based on the recursive least squares' method were devised. We also evaluated the performance differences between two sets of features; one automatically selected set (i.e., optimized) and a set of features based on the existing literature. The data set of this study was recorded in a real-world setting, with 33 healthy individuals running at low, preferred, and high speed. The direct estimation of the running speed achieved an inter-subject mean ± STD accuracy of 0.08 ± 0.1 m/s and a precision of 0.16 ± 0.04 m/s. In comparison, the best feature-based linear model achieved 0.00 ± 0.11 m/s accuracy and 0.11 ± 0.05 m/s precision, while the personalized model obtained a 0.00 ± 0.01 m/s accuracy and 0.09 ± 0.06 m/s precision. The results of this study suggest that (1) the direct estimation of the velocity of the foot are biased, and the error is affected by the overground velocity and the slope; (2) the main limitation of a general linear model is the relatively high inter-subject variance of the bias, which reflects the intrinsic differences in gait patterns among individuals; (3) this inter-subject variance can be nulled using a personalized model.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fspor.2021.585809DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8014039PMC
March 2021

Editorial: Health and Performance Assessment in Winter Sports.

Front Sports Act Living 2021 9;3:628574. Epub 2021 Mar 9.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fspor.2021.628574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7985436PMC
March 2021

Robustness of In-Laboratory and Daily-Life Gait Speed Measures over One Year in High Functioning 61- to 70-Year-Old Adults.

Gerontology 2021 Mar 22:1-10. Epub 2021 Mar 22.

Department of Human Movement Sciences, @AgeAmsterdam, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands,

Introduction: Gait speed is a simple and safe measure with strong predictive value for negative health outcomes in clinical practice, yet in-laboratory gait speed seems not representative for daily-life gait speed. This study aimed to investigate the interrelation between and robustness of in-laboratory and daily-life gait speed measures over 12 months in 61- to 70-year-old adults.

Methods: Gait speed was assessed in laboratory through standardized stopwatch tests and in daily life by 7 days of trunk accelerometry in the PreventIT cohort, at baseline, and after 6 and 12 months. The interrelation was investigated using Pearson's correlations between gait speed measures at each time point. For robustness, changes over time and variance components were assessed by ANOVA and measurement agreement over time by Bland-Altman analyses.

Results: Included were 189 participants (median age 67 years [interquartile range: 64-68], 52.2% females). In-laboratory and daily-life gait speed measures showed low correlations (Pearson's r = 0.045-0.455) at each time point. Moreover, both in-laboratory and daily-life gait speed measures appeared robust over time, with comparable and smaller within-subject than between-subject variance (range 0.001-0.095 m/s and 0.032-0.397 m/s, respectively) and minimal differences between measurements over time (Bland-Altman) with wide limits of agreement (standard deviation of mean difference range: 0.12-0.34 m/s).

Discussion/conclusion: In-laboratory and daily-life gait speed measures show robust assessments of gait speed over 12 months and are distinct constructs in this population of high-functioning adults. This suggests that (a combination of) both measures may have added value in predicting health outcomes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1159/000514150DOI Listing
March 2021

Gait speed in clinical and daily living assessments in Parkinson's disease patients: performance versus capacity.

NPJ Parkinsons Dis 2021 Mar 5;7(1):24. Epub 2021 Mar 5.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.

Gait speed often referred as the sixth vital sign is the most powerful biomarker of mobility. While a clinical setting allows the estimation of gait speed under controlled conditions that present functional capacity, gait speed in real-life conditions provides the actual performance of the patient. The goal of this study was to investigate objectively under what conditions during daily activities, patients perform as well as or better than in the clinic. To this end, we recruited 27 Parkinson's disease (PD) patients and measured their gait speed by inertial measurement units through several walking tests in the clinic as well as their daily activities at home. By fitting a bimodal Gaussian model to their gait speed distribution, we found that on average, patients had similar modes in the clinic and during daily activities. Furthermore, we observed that the number of medication doses taken throughout the day had a moderate correlation with the difference between clinic and home. Performing a cycle-by-cycle analysis on gait speed during the home assessment, overall only about 3% of the strides had equal or greater gait speeds than the patients' capacity in the clinic. These strides were during long walking bouts (>1 min) and happened before noon, around 26 min after medication intake, reaching their maximum occurrence probability 3 h after Levodopa intake. These results open the possibility of better control of medication intake in PD by considering both functional capacity and continuous monitoring of gait speed during real-life conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41531-021-00171-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7935857PMC
March 2021

A Novel Macro-Micro Approach for Swimming Analysis in Main Swimming Techniques Using IMU Sensors.

Front Bioeng Biotechnol 2020 14;8:597738. Epub 2021 Jan 14.

Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

Inertial measurement units (IMU) are proven as efficient tools for swimming analysis by overcoming the limits of video-based systems application in aquatic environments. However, coaches still believe in the lack of a reliable and easy-to-use analysis system for swimming. To provide a broad view of swimmers' performance, this paper describes a new macro-micro analysis approach, comprehensive enough to cover a full training session, regardless of the swimming technique. Seventeen national level swimmers (5 females, 12 males, 19.6 ± 2.1 yrs) were equipped with six IMUs and asked to swim 4 × 50 m trials in each swimming technique (i.e., frontcrawl, breaststroke, butterfly, and backstroke) in a 25 m pool, in front of five 2-D cameras (four under water and one over water) for validation. The proposed approach detects swimming bouts, laps, and swimming technique in macro level and swimming phases in micro level on all sensor locations for comparison. Swimming phases are the phases swimmers pass from wall to wall (wall push-off, glide, strokes preparation, swimming, and turn) and micro analysis detects the beginning of each phase. For macro analysis, an overall accuracy range of 0.83-0.98, 0.80-1.00, and 0.83-0.99 were achieved, respectively, for swimming bouts detection, laps detection and swimming technique identification on selected sensor locations, the highest being achieved with sacrum. For micro analysis, we obtained the lowest error mean and standard deviation on sacrum for the beginning of wall-push off, glide and turn (-20 ± 89 ms, 4 ± 100 ms, 23 ± 97 ms, respectively), on shank for the beginning of strokes preparation (0 ± 88 ms) and on wrist for the beginning of swimming (-42 ± 72 ms). Comparing the swimming techniques, sacrum sensor achieves the smallest range of error mean and standard deviation during micro analysis. By using the same macro-micro approach across different swimming techniques, this study shows its efficiency to detect the main events and phases of a training session. Moreover, comparing the results of both macro and micro analyses, sacrum has achieved relatively higher amounts of accuracy and lower mean and standard deviation of error in all swimming techniques.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fbioe.2020.597738DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7841373PMC
January 2021

Falls Efficacy Is Associated With Better Gait and Functional Outcomes After Rehabilitation in Older Patients.

Arch Phys Med Rehabil 2021 Jan 23. Epub 2021 Jan 23.

Service of Geriatric Medicine and Geriatric Rehabilitation, Department of Medicine, University of Lausanne Medical Center (CHUV), Lausanne.

Objective: To examine the relationship between falls efficacy and the change in gait speed and functional status in older patients undergoing postacute rehabilitation.

Design: Prospective cohort study.

Setting: Postacute rehabilitation facility.

Participants: Patients (N=180) aged 65 years and older (mean age ± SD, 81.3±7.1y).

Interventions: Not applicable.

Main Outcome Measures: Data on demographics; functional, cognitive, and affective status; and falls efficacy using a 10-item version of the Falls Efficacy Scale (FES; range, 0-100) were collected upon admission. Data about gait speed and functional status (Barthel Index and Basic Activities of Daily Living [BADL]) were measured at admission and discharge. In addition, BADL performance was self-reported 1 month after discharge.

Results: Compared with admission, all rehabilitation outcomes improved at discharge: gait speed (0.41±0.15 m/s vs 0.50±0.16 m/s; P<.001), Barthel Index score (68.4±16.3 vs 82.5±13.6; P<.001), and BADL (3.5±1.6 vs 4.7±1.3; P<.001). Adjusting for baseline status and other potential confounders, baseline FES independently predicted gait speed (adjusted coefficient: 0.002; 95% confidence interval [CI], 0.000-0.004; P=.025) and Barthel index (adjusted coefficient: 0.225; 95% CI, 0.014-0.435; P=.037) at discharge, with higher confidence at baseline predicting greater improvement. Baseline FES was also independently associated with self-reported BADL performance at the 1-month follow-up (adjusted coefficient: 0.020; 95% CI, 0.010-0.031; P<.001).

Conclusions: In older patients, higher falls efficacy predicted better gait and functional rehabilitation outcomes, independently of baseline performance. These results suggest that interventions aiming at falls efficacy improvement during rehabilitation might also contribute to enhancing gait speed and functional status in patients admitted to this setting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.apmr.2020.12.017DOI Listing
January 2021

Real-world speed estimation using single trunk IMU: methodological challenges for impaired gait patterns

Annu Int Conf IEEE Eng Med Biol Soc 2020 07;2020:4596-4599

Walking speed (WS) is recognized as an important dimension of functional health and a candidate endpoint for clinical trials. To be adopted as a powerful outcome measure in clinical assessment, WS should be estimated pervasively and accurately in the real-life context. Although current state of the art points to possible solutions, e.g., by using pairing of wearable sensors with dedicated algorithms, the accuracy and robustness of existing algorithms in challenging situations should be carefully considered. This study highlights the main methodological issues for WS estimation using single inertial sensor fixed on trunk (chest/low back) and data recorded in a sample of stroke patients with impaired mobility.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/EMBC44109.2020.9176281DOI Listing
July 2020

A Sensor Fusion Approach to the Estimation of Instantaneous Velocity Using Single Wearable Sensor During Sprint.

Front Bioeng Biotechnol 2020 18;8:838. Epub 2020 Aug 18.

Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

Power-Force-Velocity profile obtained during a sprint test is crucial for designing personalized training and evaluating injury risks. Estimation of instantaneous velocity is requisite for developing these profiles and the predominant method for this estimation assumes it to have a first order exponential behavior. While this method remains appropriate for maximal sprints, the sprint velocity profile may not always show a first-order exponential behavior. Alternately, velocity profile has been estimated using inertial sensors, with a speed radar, or a smartphone application. Existing methods either relied on the exponential behavior or timing gates for drift removal, or estimated only the mean velocity. Thus, there is a need for a more flexible and appropriate approach, allowing for instantaneous velocity estimation during sprint tests. The proposed method aims to solve this problem using a sensor fusion approach, by combining the signals from wearable Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) sensors. We collected data from nine elite sprinters, equipped with a wearable GNSS-IMU sensor, who ran two trials each of 60 and 30/40 m sprints. We developed an algorithm using a gradient descent-based orientation filter, which simplified our model to a linear one-dimensional model, thus allowing us to use a simple Kalman filter (KF) for velocity estimation. We used two cascaded KFs, to segment the sprint data precisely, and to estimate the velocity and the sprint duration, respectively. We validated the estimated velocity and duration with speed radar and photocell data as reference. The median RMS error for the estimated velocity ranged from 6 to 8%, while that for the estimated sprint duration lied between 0.1 and -6.0%. The Bland-Altman plot showed close agreement between the estimated and the reference values of maximum velocity. Examination of fitting errors indicated a second order exponential behavior for the sprint velocity profile, unlike the first order behavior previously suggested in literature. The proposed sensor-fusion algorithm is valid to compute an accurate velocity profile with respect to the radar; it can compensate for and improve upon the accuracy of the individual IMU and GNSS velocities. This method thus enables the use of wearable sensors in the analysis of sprint test.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fbioe.2020.00838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7461787PMC
August 2020

Walking Speed of Children and Adolescents With Cerebral Palsy: Laboratory Versus Daily Life.

Front Bioeng Biotechnol 2020 14;8:812. Epub 2020 Jul 14.

Laboratory of Kinesiology Willy Taillard, Geneva University Hospitals, University of Geneva, Geneva, Switzerland.

The purpose of this pilot study was to compare walking speed, an important component of gait, in the laboratory and daily life, in young individuals with cerebral palsy (CP) and with typical development (TD), and to quantify to what extent gait observed in clinical settings compares to gait in real life. Fifteen children, adolescents and young adults with CP (6 GMFCS I, 2 GMFCS II, and 7 GMFCS III) and 14 with TD were included. They wore 4 synchronized inertial sensors on their shanks and thighs while walking at their spontaneous self-selected speed in the laboratory, and then during 2 week-days and 1 weekend day in their daily environment. Walking speed was computed from shank angular velocity signals using a validated algorithm. The median of the speed distributions in the laboratory and daily life were compared at the group and individual levels using Wilcoxon tests and Spearman's correlation coefficients. The corresponding percentile of daily life speed equivalent to the speed in the laboratory was computed and observed at the group level. Daily-life walking speed was significantly lower compared to the laboratory for the CP group (0.91 [0.58-1.23] m/s vs 1.07 [0.73-1.28] m/s, = 0.015), but not for TD (1.29 [1.24-1.40] m/s vs 1.29 [1.20-1.40] m/s, = 0.715). Median speeds correlated highly in CP ( < 0.001, rho = 0.89), but not in TD. In children with CP, 60% of the daily life walking activity was at a slower speed than in-laboratory (corresponding percentile = 60). On the contrary, almost 60% of the daily life activity of TD was at a faster speed than in-laboratory (corresponding percentile = 42.5). Nevertheless, highly heterogeneous behaviors were observed within both populations and within subgroups of GMFCS level. At the group level, children with CP tend to under-perform during natural walking as compared to walking in a clinical environment. The heterogeneous behaviors at the individual level indicate that real-life gait performance cannot be directly inferred from in-laboratory capacity. This emphasizes the importance of completing clinical gait analysis with data from daily life, to better understand the overall function of children with CP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fbioe.2020.00812DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7381141PMC
July 2020

The association of basic and challenging motor capacity with mobility performance and falls in young seniors.

Arch Gerontol Geriatr 2020 Sep - Oct;90:104134. Epub 2020 Jun 6.

Network Aging Research, Heidelberg University, Bergheimer Str. 20, 69115, Heidelberg, Germany; Department of Clinical Gerontology and Rehabilitation, Robert Bosch Hospital Stuttgart, Auerbachstr. 110, 70376, Stuttgart, Germany; Institute of Sports and Sports Sciences, Heidelberg University, Im Neuenheimer Feld 700, 69120, Heidelberg, Germany. Electronic address:

Background: Understanding the association between motor capacity (MC) (what people can do in a standardized environment), mobility performance (MP) (what people actually do in real-life) and falls is important for early detection of and counteracting on functional decline, particularly in the rapidly growing population of young seniors. Therefore, this study aims to 1) explore the association between MC and MP, and between MC and falls, and 2) investigate whether challenging MC measures are better associated with MP and falls than basic MC measures.

Methods: Basic (habitual gait speed, Timed Up-and-Go) and challenging (fast gait speed, Community Balance & Mobility Scale) MC measures were performed in 169 young seniors (61-70 years). MP was assessed using one-week sensor-monitoring including time being sedentary, light active, and at least moderately active. Falls in the previous six months were reported. Associations and discriminative ability were calculated using correlation, regression and receiver operating curve analysis.

Results: Mean age was 66.4 (SD 2.4) years (50.6 % women). Small to moderate associations (r = 0.06-0.31; p < .001-.461) were found between MC, MP and falls. Challenging MC measures showed closer associations with MP and falls (r = 0.10-0.31; p < .001-.461) compared to basic (r = 0.06-0.22; p = .012-.181), remained significant in three out of four regression models explaining 2.5-8.6 % of the variance, and showed highest discriminative ability (area under the curve = 0.59-0.70) in all analyses.

Conclusions: Challenging MC measures are closer associated with mobility performance and falls as compared to basic MC measures in young seniors. This indicates the importance of applying challenging motor capacity assessments in young seniors. On the same note, small to moderate associations imply a need for an assessment of both MC and MP in order to capture the best possible MC and the actual daily-life MP in young seniors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.archger.2020.104134DOI Listing
December 2020

Postural transitions detection and characterization in healthy and patient populations using a single waist sensor.

J Neuroeng Rehabil 2020 06 3;17(1):70. Epub 2020 Jun 3.

Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne (EPFL), Station 9, Lausanne, 1015, Switzerland.

Background: Sit-to-stand and stand-to-sit transitions are frequent daily functional tasks indicative of muscle power and balance performance. Monitoring these postural transitions with inertial sensors provides an objective tool to assess mobility in both the laboratory and home environment. While the measurement depends on the sensor location, the clinical and everyday use requires high compliance and subject adherence. The objective of this study was to propose a sit-to-stand and stand-to-sit transition detection algorithm that works independently of the sensor location.

Methods: For a location-independent algorithm, the vertical acceleration of the lower back in the global frame was used to detect the postural transitions in daily activities. The detection performance of the algorithm was validated against video observations. To investigate the effect of the location on the kinematic parameters, these parameters were extracted during a five-time sit-to-stand test and were compared for different locations of the sensor on the trunk and lower back.

Results: The proposed detection method demonstrates high accuracy in different populations with a mean positive predictive value (and mean sensitivity) of 98% (95%) for healthy individuals and 89% (89%) for participants with diseases.

Conclusions: The sensor location around the waist did not affect the performance of the algorithm in detecting the sit-to-stand and stand-to-sit transitions. However, regarding the accuracy of the kinematic parameters, the sensors located on the sternum and L5 vertebrae demonstrated the highest reliability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12984-020-00692-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7271521PMC
June 2020

Reply to Comments: Hurdle Clearance Detection and Spatiotemporal Analysis in 400 Meters Hurdles Races Using Shoe-Mounted Magnetic and Inertial Sensor.

Sensors (Basel) 2020 May 25;20(10). Epub 2020 May 25.

Laboratory of Movement Analysis and Measurement, EPFL, 1015 Lausanne, Switzerland.

The current document answers the comment addressed by Schmidt, M [...].
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s20102993DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7287772PMC
May 2020

Drift-Free Foot Orientation Estimation in Running Using Wearable IMU.

Front Bioeng Biotechnol 2020 13;8:65. Epub 2020 Feb 13.

Laboratory of Movement Analysis and Measurement, EPFL, Lausanne, Switzerland.

This study aimed to introduce and validate a new method to estimate and correct the orientation drift measured from foot-worn inertial sensors. A modified strap-down integration (MSDI) was proposed to decrease the orientation drift, which, in turn, was further compensated by estimation of the joint center acceleration (JCA) of a two-segment model of the foot. This method was designed to fit the different foot strike patterns observed in running and was validated against an optical motion-tracking system during level treadmill running at 8, 12, and 16 km/h. The sagittal and frontal plane angles obtained from the inertial sensors and the motion tracking system were compared at different moments of the ground contact phase. The results obtained from 26 runners showed that the foot orientation at mean stance was estimated with an accuracy (inter-trial median ± IQR) of 0.4 ± 3.8° and a precision (inter-trial precision median ± IQR) of 3.0 ± 1.8°. The orientation of the foot shortly before initial contact (IC) was estimated with an accuracy of 2.0 ± 5.9° and a precision of 1.6 ± 1.1°; which is more accurate than commonly used zero-velocity update methods derived from gait analysis and not explicitly designed for running. Finally, the study presented the effect initial and terminal contact (TC) detection errors have on the orientation parameters reported.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fbioe.2020.00065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7031162PMC
February 2020

A Vibrational Technique for In Vitro Intraoperative Prosthesis Fixation Monitoring.

IEEE Trans Biomed Eng 2020 10 20;67(10):2953-2964. Epub 2020 Feb 20.

Objective: In this paper, a new vibrational modal analysis technique was developed for intraoperative cementless prosthesis fixation evaluation upon hammering.

Methods: An artificial bone (Sawbones)-prosthesis system was excited by sweeping of a sine signal over a wide frequency range. The exponential sine sweep technique was implemented to the response signal in order to determine the linear impulse response. Recursive Fourier transform enhancement (RFTE) technique was applied to the linear impulse response signal in order to enhance the frequency spectrum with sharp and distinguishable peak values indicating distinct high natural frequencies of the system (ranging from 15 kHz to 90 kHz). The experiment was repeated with 5 Sawbones-prosthesis samples. Upon successive hammering during the prosthesis insertion, variation of each natural frequency was traced.

Results: Compared to classical Fast Fourier Transform, RFTE provided a better tracing and enhancement of frequency components during insertion. Three different types of frequency evolving trends (monotonically increasing, insensitive, and plateau-like) were observed for all samples, as confirmed by a new finite element simulation of the prosthesis dynamic insertion. Two main mechanical phenomena (i.e., geometrical compaction and compressive stress) were shown to govern these trends in opposite ways. Follow-up of the plateau-like trend upon hammering showed that the frequency shift is a good indicator of fixation.

Conclusion: Alongside the individual follow-up of frequency shifts, combinatorial frequency analysis provides new objective information on the mechanical stability of Sawbone-prosthesis fixation.

Significance: The proposed vibrational technique based on RTFE can provide the surgeon with a new assistive diagnostic technique during the surgery by indicating when the bone-prosthesis fixation is acceptable, and beyond of which further hammering should be done cautiously to avoid bone fracture.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/TBME.2020.2974380DOI Listing
October 2020

Long-term unsupervised mobility assessment in movement disorders.

Lancet Neurol 2020 05 11;19(5):462-470. Epub 2020 Feb 11.

Department of Neurology, Kiel University, Kiel, Germany.

Mobile health technologies (wearable, portable, body-fixed sensors, or domestic-integrated devices) that quantify mobility in unsupervised, daily living environments are emerging as complementary clinical assessments. Data collected in these ecologically valid, patient-relevant settings can overcome limitations of conventional clinical assessments, as they capture fluctuating and rare events. These data could support clinical decision making and could also serve as outcomes in clinical trials. However, studies that directly compared assessments made in unsupervised and supervised (eg, in the laboratory or hospital) settings point to large disparities, even in the same parameters of mobility. These differences appear to be affected by psychological, physiological, cognitive, environmental, and technical factors, and by the types of mobilities and diagnoses assessed. To facilitate the successful adaptation of the unsupervised assessment of mobility into clinical practice and clinical trials, clinicians and researchers should consider these disparities and the multiple factors that contribute to them.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S1474-4422(19)30397-7DOI Listing
May 2020

Comparison of gait characteristics between clinical and daily life settings in children with cerebral palsy.

Sci Rep 2020 02 7;10(1):2091. Epub 2020 Feb 7.

Laboratory of Kinesiology Willy Taillard, Geneva University Hospitals and University of Geneva, 1205, Geneva, Switzerland.

Gait assessments in standardized settings, as part of the clinical follow-up of children with cerebral palsy (CP), may not represent gait in daily life. This study aimed at comparing gait characteristics in laboratory and real life settings on the basis of multiple parameters in children with CP and with typical development (TD). Fifteen children with CP and 14 with TD wore 5 inertial sensors (chest, thighs and shanks) during in-laboratory gait assessments and during 3 days of daily life. Sixteen parameters belonging to 8 distinct domains were computed from the angular velocities and/or accelerations. Each parameter measured in the laboratory was compared to the same parameter measured in daily life for walking bouts defined by a travelled distance similar to the laboratory, using Wilcoxon paired tests and Spearman's correlations. Most gait characteristics differed between both environments in both groups. Numerous high correlations were found between laboratory and daily life gait parameters for the CP group, whereas fewer correlations were found in the TD group. These results demonstrated that children with CP perform better in clinical settings. Such quantitative evidence may enhance clinicians' understanding of the gap between capacity and performance in children with CP and improve their decision-making.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-020-59002-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7005861PMC
February 2020

Hurdle Clearance Detection and Spatiotemporal Analysis in 400 Meters Hurdles Races Using Shoe-Mounted Magnetic and Inertial Sensors.

Sensors (Basel) 2020 Jan 8;20(2). Epub 2020 Jan 8.

Institute of Sport Science, University of Innsbruck, 6020 Innsbruck, Austria.

This research aimed to determine whether: (1) shoe-worn magnetic and inertial sensors can be used to detect hurdle clearance and identify the leading leg in 400-m hurdles, and (2) to provide an analysis of the hurdlers' spatiotemporal parameters in the intervals defined by the hurdles' position. The data set is composed of MIMU recordings of 15 athletes in a competitive environment. The results show that the method based on the duration of the flight phase was able to detect hurdle clearance and identify the leading leg with 100% accuracy. Moreover, by combining the swing phase duration with the orientation of the foot, we achieved, in unipedal configuration, 100% accuracy in hurdle clearance detection, and 99.7% accuracy in the identification of the leading leg. Finally, this study provides statistical evidence that contact time significantly increases, while speed and step frequency significantly decrease with time during 400 m hurdle races.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s20020354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013538PMC
January 2020

Changes in spatio-temporal gait parameters and vertical speed during an extreme mountain ultra-marathon.

Eur J Sport Sci 2020 Nov 25;20(10):1339-1345. Epub 2020 Jan 25.

Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.

The aim of the present study was to investigate the effects of altitude and distance on uphill vertical speed (VS) and the main spatio-temporal gait parameters during an extreme mountain ultra-marathon. The VS, stride height (SH) and stride frequency (SF) of 27 runners were measured with an inertial sensor at the shank for two different altitude ranges (low 1300-2000 m vs high 2400-3200 m) of 10 mountains passes distributed over a 220 km course. There was a significant interaction ((4,52) = 4.04,  < 0.01) for the effect of altitude and distance on VS. During the first passes, the mean VS was faster at lower altitudes, but this difference disappeared at a quarter of the race length, suggesting that neuromuscular fatigue influenced the uphill velocity to a larger extent than the oxygen delivery. The average VS, SH and SF were 547 ± 135 m/h, 0.23 ± 0.05 m and 0.66 ± 0.09 Hz. The individual VS change for each uphill portions was more strongly correlated with the changes in SH ( = 0.80,  < 0.001, = 321) than SF ( = 0.43,  < 0.001,  = 321). This suggests a large effect of the knee extensors strength loss on the diminution of VS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/17461391.2020.1712480DOI Listing
November 2020

A Personalized Approach to Improve Walking Detection in Real-Life Settings: Application to Children with Cerebral Palsy.

Sensors (Basel) 2019 Dec 3;19(23). Epub 2019 Dec 3.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.

Although many methods have been developed to detect walking by using body-worn inertial sensors, their performances decline when gait patterns become abnormal, as seen in children with cerebral palsy (CP). The aim of this study was to evaluate if fine-tuning an existing walking bouts (WB) detection algorithm by various thresholds, customized at the individual or group level, could improve WB detection in children with CP and typical development (TD). Twenty children (10 CP, 10 TD) wore 4 inertial sensors on their lower limbs during laboratory and out-laboratory assessments. Features extracted from the gyroscope signals recorded in the laboratory were used to tune thresholds of an existing walking detection algorithm for each participant (individual-based personalization: Indiv) or for each group (population-based customization: Pop). Out-of-laboratory recordings were analyzed for WB detection with three versions of the algorithm (i.e., original fixed thresholds and adapted thresholds based on the Indiv and Pop methods), and the results were compared against video reference data. The clinical impact was assessed by quantifying the effect of WB detection error on the estimated walking speed distribution. The two customized Indiv and Pop methods both improved WB detection (higher, sensitivity, accuracy and precision), with the individual-based personalization showing the best results. Comparison of walking speed distribution obtained with the best of the two methods showed a significant difference for 8 out of 20 participants. The personalized Indiv method excluded non-walking activities that were initially wrongly interpreted as extremely slow walking with the initial method using fixed thresholds. Customized methods, particularly individual-based personalization, appear more efficient to detect WB in daily-life settings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s19235316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6928702PMC
December 2019

Behavioural compass: animal behaviour recognition using magnetometers.

Mov Ecol 2019 27;7:28. Epub 2019 Aug 27.

1School of Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

Background: Animal-borne data loggers today often house several sensors recording simultaneously at high frequency. This offers opportunities to gain fine-scale insights into behaviour from individual-sensor as well as integrated multi-sensor data. In the context of behaviour recognition, even though accelerometers have been used extensively, magnetometers have recently been shown to detect specific behaviours that accelerometers miss. The prevalent constraint of limited training data necessitates the importance of identifying behaviours with high robustness to data from new individuals, and may require fusing data from both these sensors. However, no study yet has developed an end-to-end approach to recognise common animal behaviours such as foraging, locomotion, and resting from magnetometer data in a common classification framework capable of accommodating and comparing data from both sensors.

Methods: We address this by first leveraging magnetometers' similarity to accelerometers to develop biomechanical descriptors of movement: we use the static component given by sensor tilt with respect to Earth's local magnetic field to estimate posture, and the dynamic component given by change in sensor tilt with time to characterise movement intensity and periodicity. We use these descriptors within an existing hybrid scheme that combines biomechanics and machine learning to recognise behaviour. We showcase the utility of our method on triaxial magnetometer data collected on ten wild Kalahari meerkats (), with annotated video recordings of each individual serving as groundtruth. Finally, we compare our results with accelerometer-based behaviour recognition.

Results: The overall recognition accuracy of > 94% obtained with magnetometer data was found to be comparable to that achieved using accelerometer data. Interestingly, higher robustness to inter-individual variability in dynamic behaviour was achieved with the magnetometer, while the accelerometer was better at estimating posture.

Conclusions: Magnetometers were found to accurately identify common behaviours, and were particularly robust to dynamic behaviour recognition. The use of biomechanical considerations to summarise magnetometer data makes the hybrid scheme capable of accommodating data from either or both sensors within the same framework according to each sensor's strengths. This provides future studies with a method to assess the added benefit of using magnetometers for behaviour recognition.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s40462-019-0172-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6712732PMC
August 2019

A Robotic Glenohumeral Simulator for Investigating Prosthetic Implant Subluxation.

J Biomech Eng 2019 Aug 1. Epub 2019 Aug 1.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 9, 1015 Lausanne, Switzerland.

Total shoulder arthroplasty is an effective treatment for glenohumeral osteoarthritis. However, it still suffers from a substantial rate of mechanical failure, which may be related to cyclic off-center loading of the humeral head on the glenoid. In this work, we present the design and evaluation of a glenohumeral joint robotic simulator developed to study glenohumeral translations. This five-degree-of-freedom robot was designed to replicate the rotations (±40deg, accuracy 0.5deg) and 3D forces (up to 2kN, with a 1% error settling time of 0.6sec) that the humeral implant exerts on the glenoid implant. We tested the performances of the simulator using force patterns measured in real patients. Moreover, we evaluated the effect of different orientations of the glenoid implant on joint stability. When simulating realistic dynamic forces and implant orientations, the simulator was able to reproduce stable behavior by measuring the translations less than 24 mm of the humeral head with respect to the glenoid implant. Simulation with quasi-static forces showed dislocation in extreme ranges of implant orientation. The robotic glenohumeral simulator presented here was able to reproduce physiological glenohumeral forces, and may therefore be used to further evaluate the effects of glenoid implant design and orientation on joint stability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1115/1.4044388DOI Listing
August 2019

Real-World Gait Speed Estimation Using Wrist Sensor: A Personalized Approach.

IEEE J Biomed Health Inform 2020 03 6;24(3):658-668. Epub 2019 May 6.

Gait speed is an important parameter to characterize people's daily mobility. For real-world speed measurement, inertial sensors or global navigation satellite system (GNSS) can be used on wrist, possibly integrated in a wristwatch. However, power consumption of GNSS is high and data are only available outdoor. Gait speed estimation using wrist-mounted inertial sensors is generally based on machine learning and suffers from low accuracy because of the inadequacy of using limited training data to build a general speed model that would be accurate for the whole population. To overcome this issue, a personalized model was proposed, which took unique gait style of each subject into account. Cadence and other biomechanically derived gait features were extracted from a wrist-mounted accelerometer and barometer. Gait features were fused with few GNSS data (sporadically sampled during gait) to calibrate the step length model of each subject through online learning. The proposed method was validated on 30 healthy subjects where it has achieved a median [Interquartile Range] of root mean square error of 0.05 [0.04-0.06] (m/s) and 0.14 [0.11-0.17] (m/s) for walking and running, respectively. Results demonstrated that the personalized model provided similar performance as GNSS. It used 50 times less training GNSS data than nonpersonalized method and achieved even better results. This parsimonious GNSS usage allowed extending battery life. The proposed algorithm met requirements for applications which need accurate, long, real-time, low-power, and indoor/outdoor speed estimation in daily life.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/JBHI.2019.2914940DOI Listing
March 2020

Protocol for the PreventIT feasibility randomised controlled trial of a lifestyle-integrated exercise intervention in young older adults.

BMJ Open 2019 03 20;9(3):e023526. Epub 2019 Mar 20.

Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.

Introduction: The European population is rapidly ageing. In order to handle substantial future challenges in the healthcare system, we need to shift focus from treatment towards health promotion. The PreventIT project has adapted the Lifestyle-integrated Exercise (LiFE) programme and developed an intervention for healthy young older adults at risk of accelerated functional decline. The intervention targets balance, muscle strength and physical activity, and is delivered either via a smartphone application (enhanced LiFE, eLiFE) or by use of paper manuals (adapted LiFE, aLiFE).

Methods And Analysis: The PreventIT study is a multicentre, three-armed feasibility randomised controlled trial, comparing eLiFE and aLiFE against a control group that receives international guidelines of physical activity. It is performed in three European cities in Norway, Germany, and The Netherlands. The primary objective is to assess the feasibility and usability of the interventions, and to assess changes in daily life function as measured by the Late-Life Function and Disability Instrument scale and a physical behaviour complexity metric. Participants are assessed at baseline, after the 6 months intervention period and at 1 year after randomisation. Men and women between 61 and 70 years of age are randomly drawn from regional registries and respondents screened for risk of functional decline to recruit and randomise 180 participants (60 participants per study arm).

Ethics And Dissemination: Ethical approval was received at all three trial sites. Baseline results are intended to be published by late 2018, with final study findings expected in early 2019. Subgroup and further in-depth analyses will subsequently be published.

Trial Registration Number: NCT03065088; Pre-results.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmjopen-2018-023526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527989PMC
March 2019

The effects of dual tasks on gait in children with cerebral palsy.

Gait Posture 2019 05 21;70:148-155. Epub 2019 Feb 21.

Willy Taillard Laboratory of Kinesiology, Geneva University Hospitals and University of Geneva, Geneva 1211, Switzerland. Electronic address:

Aim: To assess the gait and cognitive performances of children with cerebral palsy (CP) during dual tasks (DT) in comparison to typically developing (TD) children.

Method: This prospective, observational, case-control study included 18 children with CP (7 girls, 11 boys; median age 12 [10:13] years and 19 controls (9 girls, 10 boys; median age 12 [10:13y6mo] years). Performances were recorded during a simple walking task, 5 DT (walking + cognitive tasks with increasing cognitive load), and 5 simple cognitive tasks (while sitting). Gait parameters were computed using an optoelectronic system during walking tasks. Six parameters were selected for analysis by a principal component analysis. Cognitive performance was measured for each cognitive task. The dual-task cost (DTC) was calculated for each DT.

Results: Gait performance decreased in both groups as DT cognitive load increased (e.g., walking speed normalized by leg length, in simple task: 1.25 [1.15:1.46] s for CP, 1.53 [1.38:1.62] s for TD; DT with highest load: 0.64 [0.53:0.80] s for CP, 0.95 [0.75:1.08] s for TD). The CP group performed significantly worse than TD group in every task (including the simple task), but DTC were similar in both groups. A task effect was found for the majority of the gait parameters.

Interpretation: The reduced gait performance induced by DT may generate underestimated difficulties for children with CP in daily-life situations, where DT are common. This should be considered in clinical assessments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.gaitpost.2019.02.014DOI Listing
May 2019

A Magnet-Based Timing Tystem to Detect Gate Crossings in Alpine Ski Racing.

Sensors (Basel) 2019 Feb 22;19(4). Epub 2019 Feb 22.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.

In alpine skiing, intermediate times are usually measured with photocells. However, for practical reasons, the number of intermediate cells is limited to three⁻four, making a detailed timing analysis difficult. In this paper, we propose and validate a magnet-based timing system allowing for the measurement of intermediate times at each gate. Specially designed magnets were placed at each gate and the athletes wore small magnetometers on their lower back to measure the instantaneous magnetic field. The athlete's gate crossings caused peaks in the measured signal which could then be related to the precise instants of gate crossings. The system was validated against photocells placed at four gates of a slalom skiing course. Eight athletes skied the course twice and one run per athlete was included in the validation study. The 95% error intervals for gate-to-gate timing and section times were below 0.025 s. Each athlete's gate-to-gate times were compared to the group's average gate-to-gate times, revealing small performance differences that would otherwise be difficult to measure with a traditional photocell-based system. The system could be used to identify the effect of tactical choices and athlete specific skiing skills on performance and could allow a more efficient and athlete-specific performance analysis and feedback.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s19040940DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412682PMC
February 2019

Correction to: Locomotion and cadence detection using a single trunk-fixed accelerometer: validity for children with cerebral palsy in daily life-like conditions.

J Neuroeng Rehabil 2019 Feb 12;16(1):27. Epub 2019 Feb 12.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 9, CH-1015, Lausanne, Switzerland.

The original article [1] contained a minor error whereby the middle initial of Christopher J. Newman's name was mistakenly omitted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12984-019-0498-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6373023PMC
February 2019

Locomotion and cadence detection using a single trunk-fixed accelerometer: validity for children with cerebral palsy in daily life-like conditions.

J Neuroeng Rehabil 2019 02 4;16(1):24. Epub 2019 Feb 4.

Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 9, CH-1015, Lausanne, Switzerland.

Background: Physical therapy interventions for ambulatory youth with cerebral palsy (CP) often focus on activity-based strategies to promote functional mobility and participation in physical activity. The use of activity monitors validated for this population could help to design effective personalized interventions by providing reliable outcome measures. The objective of this study was to devise a single-sensor based algorithm for locomotion and cadence detection, robust to atypical gait patterns of children with CP in the real-life like monitoring conditions.

Methods: Study included 15 children with CP, classified according to Gross Motor Function Classification System (GMFCS) between levels I and III, and 11 age-matched typically developing (TD). Six IMU devices were fixed on participant's trunk (chest and low back/L5), thighs, and shanks. IMUs on trunk were independently used for development of algorithm, whereas the ensemble of devices on lower limbs were used as reference system. Data was collected according to a semi-structured protocol, and included typical daily-life activities performed indoor and outdoor. The algorithm was based on detection of peaks associated to heel-strike events, identified from the norm of trunk acceleration signals, and included several processing stages such as peak enhancement and selection of the steps-related peaks using heuristic decision rules. Cadence was estimated using time- and frequency-domain approaches. Performance metrics were sensitivity, specificity, precision, error, intra-class correlation coefficient, and Bland-Altman analysis.

Results: According to GMFCS, CP children were classified as GMFCS I (n = 7), GMFCS II (n = 3) and GMFCS III (n = 5). Mean values of sensitivity, specificity and precision for locomotion detection ranged between 0.93-0.98, 0.92-0.97 and 0.86-0.98 for TD, CP-GMFCS I and CP-GMFCS II-III groups, respectively. Mean values of absolute error for cadence estimation (steps/min) were similar for both methods, and ranged between 0.51-0.88, 1.18-1.33 and 1.94-2.3 for TD, CP-GMFCS I and CP-GMFCS II-III groups, respectively. The standard deviation was higher in CP-GMFCS II-III group, the lower performances being explained by the high variability of atypical gait patterns.

Conclusions: The algorithm demonstrated good performance when applied to a wide range of gait patterns, from normal to the pathological gait of highly affected children with CP using walking aids.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12984-019-0494-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6360691PMC
February 2019

Abnormal postural behavior in patients with functional movement disorders during exposure to stress.

Psychoneuroendocrinology 2019 03 14;101:232-239. Epub 2018 Nov 14.

Department of Neurology, Inselspital, Bern University Hospital, Freiburgstrasse, CH-3010 Bern, Switzerland; Department of Neuroscience, Faculty of Medicine, University of Geneva, 24 rue du Général-Dufour, 1211 Geneva, Switzerland. Electronic address:

Background: Patients affected by functional (psychogenic) movement disorders (FMD) have abnormal processing of stress responses. However, little is known about the influence of this abnormal stress processing on automatic motor defense behavior, such as freeze response. Our aim was thus to investigate stress-induced postural motor responses in FMD.

Methods: Nine FMD patients and thirteen healthy controls were engaged in the Trier Social Stress Test, while we measured the movement of their body by means of accelerometers and gyroscopes attached to the thorax. Standard deviation of thorax acceleration, reflecting the variability of movement amplitude (body sway), was compared across groups over time in a 2 × 2 ANOVA design. Higuchi's fractal dimension (HFD), reflecting the complexity of movement pattern over time, was also analyzed. Salivary cortisol and α-amylase samples were collected before and after the experiment, as stress biomarkers. Pearson's correlation coefficients were calculated between these biomarkers and movement parameters.

Results: A significant interaction effect was found, showing that healthy controls reduced their thorax sway over time during exposure to stress (from 0.027 ± 0.010 m/s to 0.023 ± 0.008 m/s, effect size of Cohen's d = 0.95), whereas patients with FMD did not. This change in body sway in controls over time negatively correlated with salivary cortisol values (ρ = -0.67, p = 0.012). A significant group effect revealed that FMD patients had an overall larger body sway (0.038 ± 0.013 m/s) compared to controls (0.025 ± 0.009 m/s - effect size of Cohen's d = 1.29) and a lower HFD (1.602 ± 0.071) than controls (1.710 ± 0.078 - Cohen's d = 1.43).

Conclusions: Patients with FMD failed to show a reduction of body sway over time, i.e., freeze response observed in the controls, thus suggesting an impairment in the automatic defense behavior. Moreover, our analysis found a lower complexity of movement (HFD) in FMD, which deserves future research in order to verify whether this could represent a characteristic trait of the disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.psyneuen.2018.11.020DOI Listing
March 2019

Simple Gait Symmetry Measures Based on Foot Angular Velocity: Analysis in Post Stroke Patients.

Annu Int Conf IEEE Eng Med Biol Soc 2018 Jul;2018:5442-5445

In this paper, we propose symmetry measures for post stroke assessment based on gait signal profiles from inertial sensors. Ten healthy controls and eight post stroke patients performed 6-Minute Walk Tests while wearing an inertial sensor on top of each shoe. Symmetry measures based on the linear correlation and the normalized sample distance between left and right foot pitch angular velocity showed high discriminating power to differentiate post stroke gait from healthy controls (Cliff's D = 0.95, Wilcoxon test p<0.001). The proposed symmetry measures are simple to estimate and do not require spatiotemporal gait parameters while they provide comparable discriminating power than symmetry measures based on spatiotemporal gait characteristics such as maximum angular velocity and stance ratio of each cycle. The proposed symmetry measures have the potential for generalization in wearable sensor based gait symmetry assessment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/EMBC.2018.8513585DOI Listing
July 2018