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.
Dany Lafontaine and Mario Lamontagne
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.
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.
Martin E. Block
This paper describes the development and validation of the Children’s Attitudes Toward Integrated Physical Education–Revised (CAIPE-R) inventory, an inventory designed to assess attitudes of children without disabilities toward including peers with disabilities in regular physical education. The CAIPE–R inventory includes a description of a student with disabilities, followed by seven statements regarding including a child with disabilities in regular physical education and five statements regarding specific adaptations to a team sport that would foster inclusion. Users respond to each statement on a 4-point Likert scale. Construct validity using factor analysis, internal consistency, and test-retest reliability was determined on a sample of 44 sixth graders. The CAIPE was revised (CAIPE-R) and given to a second set of subjects (n = 208). Results indicated that the CAIPE-R was a valid and reliable instrument for measuring attitudes of children without disabilities toward including children with disabilities in physical education. Preliminary data on children’s attitudes toward including a student with disabilities in regular physical education are also presented.
Brent L. Arnold
Norihisa Fujii and Mont Hubbard
A simulation and optimization procedure was constructed to investigate the relationships between optimal movement and muscular strength for baseball pitching. Four segments (torso, upper arms, lower arms, hands) and six torque generators (shoulders, elbows, wrists) are modeled. The torque generators have torque-angle and torque-angular velocity characteristics of Hill-type muscle function. The optimization objective function includes release velocity and negative terms penalizing joint loading and inaccuracy. The weighting coefficient for joint loads has a strong influence on the results. As this coefficient increases, the motion becomes more similar to actual measured pitches. Combining active state patterns optimized for different weighting coefficients gives larger joint loads in the simulated motion. This supports the hypothesis that well-coordinated active states are important for controlling the relationships of the different torque generators in order to create a reasonable and effective pitching motion. The model proposed here is superior to previous simulations for throwing, from the viewpoint of modeling with characteristics of Hill-type muscle function, and can be used to explore realistic baseball pitching.
Alexandra S. Voloshina and Daniel P. Ferris
Studying human and animal locomotion on an uneven terrain can be beneficial to basic science and applied studies for clinical and robotic applications. Traditional biomechanical analysis of human locomotion has often been limited to laboratory environments with flat, smooth runways and treadmills. The authors modified a regular exercise treadmill by attaching wooden blocks to the treadmill belt to yield an uneven locomotion surface. To ensure that these treadmill modifications facilitated biomechanical measurements, the authors compared ground reaction force data collected while a subject ran on the modified instrumented treadmill with a smooth surface with data collected using a conventional instrumented treadmill. Comparisons showed only minor differences. These results suggest that adding an uneven surface to a modified treadmill is a viable option for studying human or animal locomotion on an uneven terrain. Other types of surfaces (eg, compliant blocks) could be affixed in a similar manner for studies on other types of locomotion surfaces.