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Estimations of relative effort during sit-to-stand increase when accounting for variations in maximum voluntary torque with joint angle and angular velocity.

Authors
Bieryla-KA; Anderson-DE; Madigan-ML
Source
J Electromyogr Kinesiol 2009 Feb; 19(1):139-144
NIOSHTIC No.
20039010
Abstract
The main purpose of this study was to compare three methods of determining relative effort during sit-to-stand (STS). Fourteen young (mean 19.6+/-SD 1.2 years old) and 17 older (61.7+/-5.5 years old) adults completed six STS trials at three speeds: slow, normal, and fast. Sagittal plane joint torques at the hip, knee, and ankle were calculated through inverse dynamics. Isometric and isokinetic maximum voluntary contractions (MVC) for the hip, knee, and ankle were collected and used for model parameters to predict the participant-specific maximum voluntary joint torque. Three different measures of relative effort were determined by normalizing STS joint torques to three different estimates of maximum voluntary torque. Relative effort at the hip, knee, and ankle were higher when accounting for variations in maximum voluntary torque with joint angle and angular velocity (hip=26.3+/-13.5%, knee=78.4+/-32.2%, ankle=27.9+/-14.1%) compared to methods which do not account for these variations (hip=23.5+/-11.7%, knee=51.7+/-15.0%, ankle=20.7+/-10.4%). At higher velocities, the difference in calculating relative effort with respect to isometric MVC or incorporating joint angle and angular velocity became more evident. Estimates of relative effort that account for the variations in maximum voluntary torque with joint angle and angular velocity may provide higher levels of accuracy compared to methods based on measurements of maximal isometric torques.
Keywords
Humans; Musculoskeletal-system; Muscle-function; Biomechanics; Age-factors; Sex-factors; Mathematical-models; Physiological-factors; Physiological-function; Physiological-response; Physiology; Author Keywords: Sit-to-stand; Relative effort; Joint torque; Strength
Contact
Michael L. Madigan, Department of Engineering Science and Mechanics (MC 0219), Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
CODEN
JEKIE3
Publication Date
20090201
Document Type
Journal Article
Email Address
mlm@vt.edu
Funding Type
Grant
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R03-OH-007821
Issue of Publication
1
ISSN
1050-6411
Source Name
Journal of Electromyography and Kinesiology
State
VA
Performing Organization
Virginia Polytechnic Institute and State University
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