The proper execution of the sprint start is crucial in determining the performance during a sprint race. In this respect, when moving from the crouch to the upright position, trunk kinematics is a key element. The purpose of this study was to validate the use of a trunk-mounted inertial measurement unit (IMU) in estimating the trunk inclination and angular velocity in the sagittal plane during the sprint start. In-laboratory sprint starts were performed by five sprinters. The local acceleration and angular velocity components provided by the IMU were processed using an adaptive Kalman filter. The accuracy of the IMU inclination estimate and its consistency with trunk inclination were assessed using reference stereophotogrammetric measurements. A Bland-Altman analysis, carried out using parameters (minimum, maximum, and mean values) extracted from the time histories of the estimated variables, and curve similarity analysis (correlation coefficient > 0.99, root mean square difference < 7 deg) indicated the agreement between reference and IMU estimates, opening a promising scenario for an accurate in-field use of IMUs for sprint start performance assessment.
Elena Bergamini, Pélagie Guillon, Valentina Camomilla, Hélène Pillet, Wafa Skalli and Aurelio Cappozzo
Jeffrey B. Driban, Nicole Cattano, Easwaran Balasubramanian, Michael R. Sitler, Mamta Amin, Joseph Glutting and Mary F. Barbe
Context: To better understand why a knee develops osteoarthritis after joint trauma we need to assess the local biochemical changes. Unfortunately, it is challenging to obtain synovial fluid from a knee with no effusion. Objective: To describe the authors' protocol for aspirating synovial fluid from noneffused knees. Second, they demonstrate the validity of this method by evaluating the relationships between normalized and raw biomarker concentrations among knees with effusion (undergoing a traditional aspiration) and without effusion (requiring a saline-assisted aspiration). Design: Validation study based on secondary analyses from 2 cohort studies. Setting: Outpatient orthopedic clinic and basic-science laboratory. Participants: Participants had moderate to severe radiographic knee osteoarthritis (n = 15 with and 11 without effusion) and no osteoarthritis or effusion (n = 4). Interventions: The same orthopedic surgeon performed all synovial-fluid joint aspirations, including saline-assisted aspirations. Main Outcome Measures: The authors used multiplex enzyme-linked immunosorbent assays to determine 7 synovial-fluid biomarker concentrations. They then calculated correlations between raw and normalized (to total synovial-fluid protein content) biomarker concentrations. Results: The authors excluded 1 sample collected with a saline-assisted aspiration because it contained blood. Normalized biomarker concentrations had positive associations with raw biomarker concentrations (r = .77-99), with the exception of interleukin-13 and interleukin-1Β among knees that underwent a saline-assisted aspiration. Excluding interleukin-1Β, associations between normalized and raw biomarker concentrations were consistent between knees that had a saline-assisted or traditional aspiration. Conclusions:Saline-assisted aspiration is a valid technique for assessing the local biochemical changes in knees without effusion.
Christina Evaggelinou, Nikolaos Tsigilis and Areti Papa
This study was designed to examine the underlying structure of the Test of Gross Motor Development (TGMD) in Ulrich (1985). The TGMD was administered to 644 children who were randomly divided into two groups (calibration group and validation group). The calibration group (n = 324) included 150 boys and 174 girls, and the validation group included 160 boys and 160 girls, ranging from 3 to 10 years. A two-factor model was postulated and supported. According to the model, seven variables measuring children’s ability for moving into space loaded on one factor (locomotor skills), while five variables measuring children’s ability for controlling objects loaded on the other factor (object control skills). In addition, the proposed model was found to be invariant across the two groups. Good cross-generalizability of the TGMD appears to support its validity. Physical educators working with young children may use it with confidence when assessing and planning physical education programs involving locomotor and object control skills.
Dany Lafontaine and Mario Lamontagne
Many human activities, particularly sporting skills, occur over large distances. But technical limitations have forced biomechanists to conduct studies only on portions of such skills. In this paper we present the design and validation of a mobile data collection system composed of a camera cart that allows the tracking of athletes along a larger portion of their movements. A key feature of this system is that it requires only a small field of view to record and analyze joint motions. The validation of this method was conducted with three approaches. For all approaches, intermarker distances obtained from real measures were compared to those obtained from digitized video data. In all three experiments, the results proved to be within the accepted error range of 5%. The net differences between measured values and digitized values ranged from 0.8 to 3 mm, while the relative errors ranged from 0.2 to 6%. This first experimentation using a mobile camera array to collect and reconstruct biomechanical data has proven to be valid and worth pursuing for recording and analyzing ice hockey skating.
Dusa Marn-Vukadinovic and Helena Jamnik
Valid patient-based outcome instruments are necessary for comprehensive patient care that focuses on all aspects of health, from impairments to participation restrictions.
To validate the Slovenian translation of Medical Outcome Survey (MOS) Short Form Health Survey (SF-36) and to assess relations among various knee measurements, activity tested with Oxford Knee Score (OKS) and health-related quality of life as estimated with SF-36 domains.
Descriptive validation study.
Isokinetic laboratory in outpatient rehabilitation unit.
101 subjects after unilateral sport knee injury.
All subjects completed the SF-36 and OKS, and isokinetic knee-muscle strength output at 60°/s was determined in 78 participants. Within a 3-d period, 43 subjects completed the SF-36 and OKS questionnaires again.
Main Outcome Measures:
Reliability testing included internal consistency and test–retest reliability. Correlations between SF-36 subscales and OKS were calculated to assess construct validity, and correlation between SF-36 subscales and muscle strength was calculated to assess concurrent validity.
Chronbach α was above .78 for all SF-36 subscales. ICCs ranged from .80 to .93. The correlation between OKS and the physical-functioning subscale, showing convergent construct validity, was higher (r = .83, P < .01) than between OKS and mental health (r = .50, P < .01), showing divergent construct validity. Knee-extensor weakness negatively correlated with physical-functioning (r = −.59, P < .01) and social-functioning (r = −.43, P < .01) subscales.
The Slovenian translation of the SF-36 is a reliable and valuable tool. The relationships between knee-muscle strength and activity and between knee-muscle strength and SF-36 subscales in patients after sport knee injury were established.
James L. Farnsworth II, Todd Evans, Helen Binkley and Minsoo Kang
sample used to validate the KOOS was limited to a specific demographic group (age, sex, etc), the validity of the instrument would only be supported for that particular group. Another major limitation of classical test theory models is that error is considered consistent across all ranges of scores. The
Phillip C. Usera, John T. Foley and Joonkoo Yun
The purpose of this study was to cross-validate skinfold and anthropometric measurements for individuals with Down syndrome (DS). Estimated body fat of 14 individuals with DS and 13 individuals without DS was compared between criterion measurement (BOP POD®) and three prediction equations. Correlations between criterion and field-based tests for non-DS group and DS groups ranged from .81 – .94 and .11 – .54, respectively. Root-Mean-Squared-Error was employed to examine the amount of error on the field-based measurements. A MANOVA indicated significant differences in accuracy between groups for Jackson’s equation and Lohman’s equation. Based on the results, efforts should now be directed toward developing new equations that can assess the body composition of individuals with DS in a clinically feasible way.
Martin E. Block, Yeshayahu Hutzler, Sharon Barak and Aija Klavina
The purpose was to validate a self-efficacy (SE) instrument toward including students with disability in physical education (PE). Three scales referring to intellectual disabilities (ID), physical disabilities (PD), or visual impairments (VI) were administered to 486 physical education teacher education (PETE) majors. The sample was randomly split, and exploratory and confirmatory factor analyses (EFA and CFA, respectively) were conducted. After deleting items that did not meet inclusion criteria, EFA item loadings ranged from 0.53 to 0.91, and Cronbach’s alpha reliability was high (for ID = .86, PD = .90, and VI = .92). CFA showed that the ID scale demonstrated good goodness-of-fit, whereas in the PD and in the VI scales demonstrated moderate fit. Thus, the content and construct validity of the instrument was supported.
Ricky Watari, Blayne Hettinga, Sean Osis and Reed Ferber
The purpose of this study was to validate measures of vertical oscillation (VO) and ground contact time (GCT) derived from a commercially-available, torso-mounted accelerometer compared with single marker kinematics and kinetic ground reaction force (GRF) data. Twenty-two semi-elite runners ran on an instrumented treadmill while GRF data (1000 Hz) and three-dimensional kinematics (200 Hz) were collected for 60 s across 5 different running speeds ranging from 2.7 to 3.9 m/s. Measurement agreement was assessed by Bland-Altman plots with 95% limits of agreement and by concordance correlation coefficient (CCC). The accelerometer had excellent CCC agreement (> 0.97) with marker kinematics, but only moderate agreement, and overestimated measures between 16.27 mm to 17.56 mm compared with GRF VO measures. The GCT measures from the accelerometer had very good CCC agreement with GRF data, with less than 6 ms of mean bias at higher speeds. These results indicate a torsomounted accelerometer provides valid and accurate measures of torso-segment VO, but both a marker placed on the torso and the accelerometer yield systematic overestimations of center of mass VO. Measures of GCT from the accelerometer are valid when compared with GRF data, particularly at faster running speeds.
Bo Fernhall, A. Lynn Millar, Kenneth H. Pitetti, Terri Hensen and Mathew D. Vukovsch
We cross validated the 20-m shuttle run test of aerobic capacity in children and adolescents with mild and moderate mental retardation (MR) using the population specific formula of Fernhall et al. (1998). Nine boys and 8 girls (age = 13.7 yr) completed a maximal treadmill protocol (measured V̇O2peak) and a 20-m shuttle run (predicted V̇O2peak). The measured peak oxygen consumption (V̇O2peak) was 39.4 ml kg-1 min-1. The relationship between measured and predicted V̇O2peak was r = .86 with an SEE of 6.2 ml kg-1 min-1. Multiple regression and Bland-Altman analyses showed that there was little bias, but the Bland-Altman analysis indicated highly variable limits of agreement (Bland & Altman 1986). Thus, the traditional approach (regression analysis) to concurrent validity revealed that the 20-m shuttle run is a valid indicator of V̇O2peak in these participants. The accuracy of prediction (Bland & Altman, 1986), however, was lower than expected in a population without MR.