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Musculoskeletal performance capacity envelope estimation.

Kondraske-GV; Vasta-PJ
Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R03-OH-003336, 2001 Apr; :1-16
The purpose of this study was to develop and evaluate an approach to modeling multidimensional (strength, joint angle, and speed) performance capacity envelopes (PCE) that more completely characterize specific human musculoskeletal subsystems (e.g., trunk extensor, wrist extensor). This is a logical extension to the typical twodimensional families of curves produced by isokinetic measures, which provide only limited utility. Isometric and new modified isokinetic protocols were used to obtain a parametric data set for each of 35 healthy volunteers, using the knee extensor as a representative subsystem for the approach. Using data for 21 subjects (Phase I of data collection), the functional form of a normalized three dimensional performance capacity envelope representing the general population was determined using statistical analysis of the subject data. A limited subset of each subject's data was then used in combination with the general population model to derive higher-fidelity subject-specific models (i.e., mathematical representations of the three-dimensional performance capacity envelopes. The estimated knee extensor torque capacity of each model was compared to the measured torque values. The approach provided torque capacity estimates that were comparable to test-retest accuracy. The analysis was repeated using data from an additional 14 subjects (Phase II of data collection). While the general model used to derive subject specific models was derived from the Phase I subjects, prediction accuracy was again generally comparable to test-retest accuracy. It is concluded that the PCE approach is a convenient and concise way to represent the performance capacity of the knee extensor system. More specifically, experimental results demonstrate that it is possible to obtain a fidelity for representation of the entire envelope for a particular individual that is essentially equivalent to that obtained by making a large number of measurements that sample the PCE surface by using a General Population Model that captures the shape of the envelope and a small set of direct measurements that scales or warps the shape model appropriately.
Musculoskeletal-system; Statistical-analysis; Mathematical-models; Models; Sampling
Human Performance Institute, University of Texas at Arlington, P.O. Box 19180, Arlington, TX 76019-0180
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Final Grant Report
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National Institute for Occupational Safety and Health
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University of Texas-Arlington, Arlington, TX