scholarly journals The Accuracy and Reliability of a New Optical Player Tracking System for Measuring Displacement of Soccer Players

2017 ◽  
Vol 16 (3) ◽  
pp. 175-184 ◽  
Author(s):  
J. Mara ◽  
S. Morgan ◽  
K. Pumpa ◽  
K. Thompson
Keyword(s):  
Coefficient Of Variation ◽  
Tracking System ◽  
Intraclass Correlation ◽  
Positional Information ◽  
Absolute Difference ◽  
Camera System ◽  
Actual Distance ◽  
Non Invasive ◽  
Typical Error ◽  
Player Tracking

AbstractRecently, a novel optical player tracking system has been developed to determine positional information of athletes in a non-invasive manner. The aim of this study was to measure the accuracy and reliability of displacement estimates derived from the system. Participants completed five soccer-specific running courses at three different speeds three times each, while being filmed using the multi-camera system. The participant’sx,yfield positions were determined by the optical player tracking system and displacement was estimated using Euclidean distance, and compared with real distance. On average, the difference between actual distance and estimated displacement was 0.25% (mean absolute difference = 0.79 ± 0.56m) with a slightly larger coefficient of variation during 90° turns (4.89%) when compared with straight line running (4.09%). In addition, there were strong correlations between actual distance and measured displacement (r= 0.986 – 0.988). Collectively, the typical error (0.25 – 0.36 m), typical error as a coefficient of variation (1.06 – 1.75%) and intraclass correlation coefficient (0.88 – 0.93) showed high levels of intra-operator reliability. The optical player tracking system provides accurate and reliable estimates of displacement of players on a soccer field. This system provides non-invasive position detections for players and opposition players during soccer matches.

Reliability of a Clinical Test for Measuring Eccentric Knee Flexor Strength Using a Handheld Dynamometer

2021 ◽  
pp. 1-5
Author(s):  
Gabriel dos Santos Oliveira ◽  
João Breno de Araujo Ribeiro-Alvares ◽  
Felipe Xavier de Lima-e-Silva ◽  
Rodrigo Rodrigues ◽  
Marco Aurélio Vaz ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Load Cell ◽  
Effect Sizes ◽  
Clinical Test ◽  
Strength Assessment ◽  
Knee Flexor ◽  
Hamstring Strain ◽  
Typical Error ◽  
Flexor Strength

Context: Eccentric knee flexor strength assessments have a key role in both prevention and rehabilitation of hamstring strain injuries. Objective: To verify the reliability of a clinical test for measuring eccentric knee flexor strength during the Nordic hamstring exercise using a commercially available handheld dynamometer. Design: Reliability study. Setting: Physical Therapy Laboratory, Federal University of Health Sciences of Porto Alegre (Brazil). Participants: Fifty male amateur athletes (soccer or rugby players; 24 [3] y). Main Outcome Measures: Eccentric knee flexor strength. Results: When compared with a load cell–based device, the clinical test using a handheld dynamometer provided smaller force values (P < .05) with large effect sizes (.92–1.21), moderate intraclass correlation (.60–.62), typical error of 30 to 31 N, and coefficient of variation of 10% to 11%. Regarding the test–retest reproducibility (2 sessions separated by 1 week), the clinical test provided similar force values (P > .05) with only small effect sizes (.20–.27), moderate to good correlation (.67–.76), typical error of 23 to 24 N, and coefficient of variation of 9% to 10%. Conclusion: The clinical test with handheld dynamometer proposed by this study can be considered an affordable and relatively reliable tool for eccentric knee flexor strength assessment in the clinical setting, but results should not be directly compared with those provided by load cell–based devices.

scholarly journals Reliability and Usefulness of the 30-15 Intermittent Fitness Test in Male and Female Professional Futsal Players

2017 ◽  
Vol 60 (1) ◽  
pp. 191-198 ◽  
Author(s):  
Santiago Valladares-Rodríguez ◽  
Ezequiel Rey ◽  
Marcos Mecías-Calvo ◽  
Roberto Barcala-Furelos ◽  
Antonio J. Bores-Cerezal
Keyword(s):  
Heart Rate ◽  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Meaningful Change ◽  
Good Reliability ◽  
Male And Female ◽  
Fitness Test ◽  
Typical Error

Abstract The purpose of this study was to determine the reliability and usefulness of the 30-15 Intermittent Fitness Test (30-15IFT) in professional male and female futsal players. Thirteen male (24.4 ± 5.6 years; 174.5 ± 10.3 cm; 70.3 ± 9.9 kg) and fourteen female (23.3 ± 4.5 years; 165.8 ± 6.2 cm; 61.7 ± 5.5 kg) professional futsal players performed the 30-15IFT on two occasions, separated by 5 days. Maximal intermittent running velocity (VIFT) and heart rate at exhaustion (HRpeak) data were collected for both tests. Reliability was assessed by the intraclass correlation coefficient (ICC), typical error (TE) expressed as a coefficient of variation (CV), and smallest worthwhile change (SWC). VIFT demonstrated very good reliability between sessions, both for male (ICC = 0.92) and female (ICC = 0.96) players. As the TE for VIFT and HRpeak was similar to the calculated SWC for both male and female players, the usefulness of the test was rated as “medium”. A change in performance of at least 2 stages in male players, or a change of more than 1 stage in female players could be interpreted as a meaningful change in aerobic futsal fitness. The results of this study demonstrate that the 30-15IFT is both a reliable and useful test for male and female professional futsal players.

scholarly journals In Vitro and In Vivo Assessment of a New Workflow for the Acquisition of Mandibular Kinematics Based on Portable Tracking System with Passive Optical Reflective Markers

2021 ◽  
Vol 11 (9) ◽  
pp. 3947
Author(s):  
Marco Farronato ◽  
Gianluca M. Tartaglia ◽  
Cinzia Maspero ◽  
Luigi M. Gallo ◽  
Vera Colombo
Keyword(s):  
Measurement Error ◽  
Tracking System ◽  
Intraclass Correlation ◽  
Optical Tracking ◽  
Optical Tracking System ◽  
Rater Reliability ◽  
Tracking Device ◽  
Mandibular Kinematics

Clinical use of portable optical tracking system in dentistry could improve the analysis of mandibular movements for diagnostic and therapeutic purposes. A new workflow for the acquisition of mandibular kinematics was developed. Reproducibility of measurements was tested in vitro and intra- and inter-rater repeatability were assessed in vivo in healthy volunteers. Prescribed repeated movements (n = 10) in three perpendicular directions of the tracking-device coordinate system were performed. Measurement error and coefficient of variation (CV) among repetitions were determined. Mandibular kinematics of maximum opening, left and right laterality, protrusion and retrusion of five healthy subjects were recorded in separate sessions by three different operators. Obtained records were blindly examined by three observers. Intraclass correlation coefficient (ICC) was calculated to estimate inter-rater and intra-rater reliability. Maximum in vitro measurement error was 0.54 mm and CV = 0.02. Overall, excellent intra-rater reliability (ICC > 0.90) for each variable, general excellent intra-rater reliability (ICC = 1.00) for all variables, and good reliability (ICC > 0.75) for inter-rater tests were obtained. A lower score was obtained for retrusion with “moderate reliability” (ICC = 0.557) in the inter-rater tests. Excellent repeatability and reliability in optical tracking of primary movements were observed using the tested portable tracking device and the developed workflow.

MO794EVALUATION OF THE BONE ELASTIC STRUCTURE IN PERSONS WITH AND WITHOUT CHRONIC KIDNEY DISEASE ON DIALYSIS

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Pietro Manuel Ferraro ◽  
Alessandra Nicolosi ◽  
Alessandro Naticchia ◽  
Nicola Panocchia ◽  
Giuseppe Grandaliano ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Linear Regression ◽  
Bone Structure ◽  
Bone Fractures ◽  
Elastic Structure ◽  
Absolute Difference ◽  
P Value ◽  
Non Invasive ◽  
Age And Sex

Abstract Background and Aims Chronic kidney disease is a frequent condition, characterized, especially in its more advanced stages, by an array of derangements in bone structure and density, resulting in a higher rate of bone fractures. Current strategies to monitor the bone status and assess the risk of bone fractures in CKD patients are limited. The Bone Elastic Structure (BES) test is a recently-developed non-invasive tool that measures the elastic characteristics of the trabecular bone by simulating the application of loads on a virtual biopsy obtained from radiographic images of the proximal epiphyses in the patient’s hand fingers. The simulation results are combined to obtain a parameter defined Bone Structure Index (BSI). The aim of our study is to explore whether the BES test could be a useful monitoring tool of bone status in patients with CKD on dialysis by exploring whether such patients have different BSI values compared with persons without CKD. Method The BES test was performed on a sample of 41 patients undergoing chronic hemodialysis (HD) and the BSI compared with a group of 374 persons with normal renal function who had undergone the BES test in previous studies. Differences in BSI and 95% confidence intervals (CIs) between the two groups were obtained and tested for statistical significance with a linear regression model including BSI as the dependent variable and kidney status (HD vs no HD) as the independent variable, adjusted for age and sex. Subgroup effects were explored by including interaction terms (age x kidney status, age x sex, kidney status x sex) in the model. Finally, to further remove the potential confounding by age and sex, each HD patient was individually matched with up to 4 non-HD participants based on sex and age (with a 5-year caliper) and a matched analysis was conducted on BSI values. Results Average (SD) age was 64 (17) years in the HD group and 60 (12) years in the non-HD group, with a prevalence of males of 49% and 16%, respectively. The individual values of BSI divided by kidney status and sex in Figure. The multivariate linear regression model showed that, after adjustment for age and sex, the BSI in the HD group was significantly lower compared with the non-HD group (HD 145, 95% CI 140, 154; non-HD 179, 95% CI 177, 181; absolute difference −32, 95% CI −40, −25; p-value &lt; 0.001). There was no significant interaction between age, sex and kidney status on BSI values (all p-values &gt; 0.05). Individual matching was successful for 36 out of 41 HD patients, who were matched to 127 non-HD participants; matched analysis confirmed the results (absolute difference −31, 95% CI −40, −23; p-value &lt; 0.001). Conclusion The output of a non-invasive tool to determine the bone elastic structure appeared to be strongly associated with kidney function after control for differences in age and sex. Further studies are needed to determine the potential application of the BES test in patients with CKD.

Reliability and Construct Validity of Yo-Yo Tests in Untrained and Soccer-Trained Schoolgirls Aged 9–16

2016 ◽  
Vol 28 (2) ◽  
pp. 321-330 ◽  
Author(s):  
Susana C. A. Póvoas ◽  
Carlo Castagna ◽  
José Manuel da Costa Soares ◽  
Pedro Silva ◽  
Manuel Coelho-e-Silva ◽  
...  
Keyword(s):  
Heart Rate ◽  
Construct Validity ◽  
Coefficient Of Variation ◽  
Intermittent Exercise ◽  
Intraclass Correlation ◽  
Soccer Players ◽  
Confidence Limits ◽  
Peak Heart Rate ◽  
Level 1 ◽  
Level 2

Purpose:The reliability and construct validity of three age-adapted-intensity Yo-Yo tests were evaluated in untrained (n = 67) vs. soccer-trained (n = 65) 9- to 16-year-old schoolgirls.Methods:Tests were performed 7 days apart for reliability (9- to 11-year-old: Yo-Yo intermittent recovery level 1 children’s test; 12- to 13-yearold: Yo-Yo intermittent endurance level 1; and 14- to 16-year-old: Yo-Yo intermittent endurance level 2).Results:Yo-Yo distance covered was 40% (776 ± 324 vs. 556 ± 156 m), 85% (1252 ± 484 vs. 675 ± 252 m) and 138% (674 ± 336 vs. 283 ± 66 m) greater (p ≤ .010) for the soccer-trained than for the untrained girls aged 9–11, 12–13 and 14–16 years, respectively. Typical errors of measurement for Yo-Yo distance covered, expressed as a percentage of the coefficient of variation (confidence limits), were 10.1% (8.1–13.7%), 11.0% (8.6–15.4%) and 11.6% (9.2–16.1%) for soccer players, and 11.5% (9.1–15.8%), 14.1% (11.0–19.8%) and 10.6% (8.5–14.2%) for untrained girls, aged 9–11, 12–13 and 14–16, respectively. Intraclass correlation coefficient values for test-retest were excellent (0.795–0.973) in both groups. No significant differences were observed in relative exercise peak heart rate (%HRpeak) between groups during test and retest.Conclusion:The Yo-Yo tests are reliable for determining intermittent-exercise capacity and %HRpeak for soccer players and untrained 9- to 16-year-old girls. They also possess construct validity with better performances for soccer players compared with untrained age-matched girls, despite similar %HRpeak.

Should We Base Training Prescription on the Force–Velocity Profile? Exploratory Study of Its Between-Day Reliability and Differences Between Methods

2020 ◽  
pp. 1-7
Author(s):  
Pedro L. Valenzuela ◽  
Guillermo Sánchez-Martínez ◽  
Elaia Torrontegi ◽  
Javier Vázquez-Carrión ◽  
Zigor Montalvo ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Reliability Coefficient ◽  
Power Coefficient ◽  
Squat Jump ◽  
Jump Test ◽  
Force Velocity ◽  
Constrained Conditions ◽  
Vertical Jumps ◽  
Good Agreement

Purpose: To analyze the differences in the force–velocity (F–v) profile assessed under unconstrained (ie, using free weights) and constrained (ie, on a Smith machine) vertical jumps, as well as to determine the between-day reliability. Methods: A total of 23 trained participants (18 [1] y) performed an incremental load squat jump test (with ∼35%, 45%, 60%, and 70% of the subjects’ body mass) on 2 different days using free weights and a Smith machine. Nine of these participants repeated the tests on 2 other days for an exploratory analysis of between-day reliability. F–v variables (ie, maximum theoretical force [F0], velocity [v0], and power, and the imbalance between the actual and the theoretically optimal F–v profile) were computed from jump height. Results: A poor agreement was observed between the F–v variables assessed under constrained and unconstrained conditions (intraclass correlation coefficient [ICC] < .50 for all). The height attained during each single jump performed under both constrained and unconstrained conditions showed an acceptable reliability (coefficient of variation < 10%, ICC > .70). The F–v variables computed under constrained conditions showed an overall good agreement (ICC = .75–.95 for all variables) and no significant differences between days (P > .05), but a high variability for v0, the imbalance between the actual and the theoretically optimal F–v profile, and maximal theoretical power (coefficient of variation = 17.0%–27.4%). No between-day differences were observed for any F–v variable assessed under unconstrained conditions (P > .05), but all of the variables presented a low between-day reliability (coefficient of variation > 10% and ICC < .70 for all). Conclusions: F–v variables differed meaningfully when obtained from constrained and unconstrained loaded jumps, and most importantly seemed to present a low between-day reliability.

scholarly journals Hyperspectral imaging of retinal microvascular anatomy

2015 ◽  
Vol 2 (1) ◽  
pp. 139 ◽  
Author(s):  
Amir H. Kashani ◽  
Mark Wong ◽  
Nicole Koulisis ◽  
Chein-I Chang ◽  
Gabriel Martin ◽  
...  
Keyword(s):  
Hyperspectral Image ◽  
Model Organism ◽  
Science Research ◽  
Tomographic Imaging ◽  
Diagnostic Methods ◽  
Camera System ◽  
Computed Tomographic ◽  
Non Invasive ◽  
Computed Tomographic Imaging

Background: Hyperspectral image processing has been applied to many aspects of astronomical and earth science research. Furthermore, advances in computed tomographic imaging spectroscopy and diffraction grating design have allowed biological applications for non-invasive tissue analysis. Herein, we describe a hyperspectral computed tomographic imaging spectroscope (HCTIS) that provides high spatial, spectral and temporal resolution ideal for imaging biological tissue in vivo. Methods: We demonstrate proof-of-principle application of the HCTIS by imaging and mapping the microvascular anatomy of the retina of a model organism (rabbit) in vivo. The imaging procedure allows rapid and dense spectral sampling, is non-toxic, non-invasive, and easily adaptable to a commercially available fundus camera system. Results: HCTIS provides highly co-registered temporal, spatial and spectral data with resolution capable of reconstructing the fine vascular tree of the rabbit retina in vivo. Conclusions: We show that HCTIS allows for reliable and reproducible tissue classification and detection using signature discriminant analysis. Future applications of this system may provide promising diagnostic methods for diseases of many tissues. 

scholarly journals Intra-rater reliability of transversus abdominis measurement by a novice examiner: Comparison of “freehand” to “probe force device” method of real-time ultrasound imaging

Ultrasound ◽  
2019 ◽  
Vol 27 (3) ◽  
pp. 156-166 ◽  
Author(s):  
Vanessa L Kennedy ◽  
Carol A Flavell ◽  
Kenji Doma
Keyword(s):  
Measurement Error ◽  
Real Time ◽  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Coefficient Of Variation ◽  
Repeated Measures ◽  
Intraclass Correlation ◽  
Transversus Abdominis ◽  
Rater Reliability ◽  
Transverse Abdominis

A “free hand” real-time-ultrasound method is commonly applied to measure transversus abdominis. Potentially, this increases transversus abdominis measurement error due to uncontrolled variability in probe to skin force, inclination, and roll, particularly for novice examiners. This single-group repeated-measures reliability study compared the intra-rater reliability of transversus abdominis thickness and activation measurement by a novice examiner between free hand and a standardized probe force device method. The examiner captured ultrasound videos of transversus abdominis in a single session in healthy participants ( n =  33). Free hand ultrasound featured uncontrolled probe force, inclination, and roll, while probe force device method ultrasound standardized these parameters. Images of transversus abdominis at rest and contracted were measured and transversus abdominis activation calculated. Intraclass correlation coefficient, coefficient of variation, standard error of measurement, and worthwhile differences were calculated. The probe force device method resulted in greater reliability (intraclass correlation coefficient = 0.75–0.96) and lower measurement error (coefficient of variation = 8.89–28.7%) compared to free hand (intraclass correlation coefficient = 0.63–0.93; coefficient of variation = 6.52–29.4%). Reliability was good for all measurements except free hand TrA-C, which was moderate. TrA-C had the lowest reliability, followed by contracted thickness of the transverse abdominis, with resting thickness of the transverse abdominis being highest. Worthwhile differences were lower using a probe force device method versus free hand for resting thickness of the transverse abdominis and contracted thickness of the transverse abdominis and similar for TrA-C. Standardization using probe force device method ultrasound to measure transversus abdominis improved intra-rater reliability in a novice examiner. Use of a probe force device method is recommended to improve reliability through reduced sources of measurement error. Probe force device method intra- and inter-rater reliability in examiners of varying experience, in clinical populations, and to visualize other structures merits exploration.

Vinyasa Flow: Metabolic Cost and Validation of Hip- and Wrist-Worn Wearable Sensors

2018 ◽  
Vol 1 (4) ◽  
pp. 174-180
Author(s):  
Jennifer L. Huberty ◽  
Jeni L. Matthews ◽  
Meynard Toledo ◽  
Lindsay Smith ◽  
Catherine L. Jarrett ◽  
...  
Keyword(s):  
Wearable Sensors ◽  
Intraclass Correlation ◽  
Metabolic Cost ◽  
Moderate Intensity ◽  
Absolute Difference ◽  
Moderate Intensity Physical Activity ◽  
Time Stamps ◽  
Intensity Physical Activity ◽  
Resting Activity ◽  
Dependent Samples

Purpose: To estimate the energy expenditure (EE) of Vinyasa Flow and validate the Actigraph (AG) and GENEActiv (GA) for measuring EE in Vinyasa Flow. Methods: Participants (N = 22) were fitted to a mask attached to the Oxycon. An AG was placed on the left hip and a GA was placed on the non-dominant wrist. Participants were randomized to an initial resting activity before completing a 30-minute Vinyasa Flow video. AG data was scored using the Freedson VM3 (2011) and the Freedson Adult (1998) algorithms in the Actilife software platform. EE from GA were derived using cut points from a previous study. Date and time filters were added corresponding to the time stamps recorded by the tablet video files of each yoga session. Kcals and METs expended by participants were calculated using bodyweight measured during their visit. Data was analyzed using SPSS. A dependent samples t-test, an intraclass correlation coefficient (ICC), and mean absolute difference were used to determine agreement between variables. Results: According to the Oxycon, participation in Vinyasa Flow required an average EE of 3.2 ± 0.4 METs. The absolute agreement between the Oxycon, AG, or GA was poor (ICC < .20). The mean difference in METs for the AG was −2.1 ± 0.6 and GA was −1.4 ± 0.6 (all p < .01). Conclusion: According to the Oxycon, participation in Vinyasa Flow met the criteria for moderate-intensity physical activity. The AG and GA consistently underestimated EE. More research is needed to determine an accurate measurement for EE during yoga using a wearable device appropriate for free-living environments.

Rapid and non-invasive surface crack detection for pressed-panel products based on online image processing

2019 ◽  
Vol 18 (5-6) ◽  
pp. 1928-1942 ◽  
Author(s):  
Hwee Kwon Jung ◽  
Gyuhae Park
Keyword(s):  
Image Processing ◽  
Manufacturing Process ◽  
Crack Detection ◽  
Experimental Results ◽  
Inspection System ◽  
Camera System ◽  
Non Invasive ◽  
Panel Products ◽  
Traditional Approaches ◽  
Detection And Localization

Crack detection during the manufacturing process of pressed-panel products is an important aspect of quality management. Traditional approaches for crack detection of those products are subjective and expensive because they are usually performed by experienced human inspectors. Therefore, the development and implementation of an automated and accurate inspection system is required for the manufacturing process. In this article, a crack detection technique based on image processing is proposed that utilizes the images of panel products captured by a regular camera system. First, the binary panel object image is extracted from various backgrounds after considering the color factor. Edge lines are then generated from a binary image using a percolation process. Finally, crack detection and localization is performed with a unique edge-line evaluation. In order to demonstrate the capability of the proposed technique, lab-scale experiments were carried out with a thin aluminum plate. In addition, a test was performed with the panel images acquired at an actual press line. Experimental results show that the proposed technique could effectively detect panel cracks at an improved rate and speed. The experimental results also demonstrate that the proposed technique could be an extension of structural health monitoring frameworks into a new manufacturing application.

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