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The normalization of electromyographic signal
Abstracts-International
Society
of Biomechanics
XII
Congress
1989
1043
THE LUMBARATOR - A REAL TIME SIMULATOR OF LUMBAR MUSCLES FORCE DISTRIBUTION Zvi Ladin and Sujoy Guha Biomedical Engineering Department and NeuroMuscular Research Center Boston University, Boston, MA 02215 This paper describes a system that can display in real-time the distribution of muscle Using a preforces in the lower-back in response to a generalized gravitational loading. calculated data-base of Muscle Activity Surfaces for twenty two muscles crossing the L3 level in the lumbar region, and a user interface that determines the loading condition, the system expresses the load distribution among all the different muscles using a color (or a The user is thus able to study immediately the effect of given loading gray-level) mapping. conditions (or quasi-static exercises) on the muscle force distribution in all the muscles of the cross-section of interest.
CONTRIBUTION OF ANGULAR MOTION AND GRAVITY TO TIBIAL ACCELERATION Mario A. Lafortune and Ewald M. Hennig Sportmed. Institute Essen e.V. Australian Institute of Sport P.O. Box 176, Belconnen Wittekindstrasse 54 A.C.T. 2616, Australia 4300 Essen 1, West Germany A bone mounted accelerometer was used in conjunction with high speed cinematography to determine the contribution of angular motion (AM) and gravity (GR) to the axial component of tibia1 acceleration (TAA). Measurements were taken during walking and running. The magnitude of TAA at ground contact depends upon the severity of the impact (IP), AM and GR. The magnitude of the contribution of AM to the acceleration measured by the accelerometer was estimated by the following equation: aR =&R where R is the distance from the accelerometer to the hinge point (constant with rigid body) andu;)isthe angular velocity of the tibia in the sagittal plane. The contribution of gravity depends upon the orientation of the tibia to the vertical. For running the acceleration (TAA) recorded by the bone mounted accelerometer underestimated the magnitude of the ground impact by approximately 45% (4.3 g instead of 7.9 g). Conversely, the accelerometer overestimated the walking ground impact by 16% (2.9 g instead of 2.5 g). These results indicated that angular motion and gravity contribute significantly to tibia1 axial acceleration.
THE NORMALIZATION OF ELECTROMYOGRAPHIC SIGNAL Yves Lajoie, Louis Laurencelle and Martin C. Normand Laboratoire de biomhcani’que, Universit6 du Qhbec B Trois-Rivikres, Trois-Rivihes, Qc, Canada, G9A 5H7 The measurement of the intensity of muscle activation is an essential prerequisite to determine the function of muscles during movement and the deficit of impaired muscles. But statistical mormalisation of the EMG signal is difficult to carry out when we consider the marked non-normality~,and asymmetry of the results. The purpose of this study was first to verify the symmetry and normality of some results through the g1 and g2 statistic, and second, to propose the utilization of an order statistic, the tolerance interval for norms construction. The statistics g1 and g2 indicated, indeed, the non normality and asymmetry of the EMG data. Futhermore, we found that 153 subjects need to be measured in order to establish a nonparametric interval with both a coverage and confidence of .95.
Society
of Biomechanics
XII
Congress
1989
1043
THE LUMBARATOR - A REAL TIME SIMULATOR OF LUMBAR MUSCLES FORCE DISTRIBUTION Zvi Ladin and Sujoy Guha Biomedical Engineering Department and NeuroMuscular Research Center Boston University, Boston, MA 02215 This paper describes a system that can display in real-time the distribution of muscle Using a preforces in the lower-back in response to a generalized gravitational loading. calculated data-base of Muscle Activity Surfaces for twenty two muscles crossing the L3 level in the lumbar region, and a user interface that determines the loading condition, the system expresses the load distribution among all the different muscles using a color (or a The user is thus able to study immediately the effect of given loading gray-level) mapping. conditions (or quasi-static exercises) on the muscle force distribution in all the muscles of the cross-section of interest.
CONTRIBUTION OF ANGULAR MOTION AND GRAVITY TO TIBIAL ACCELERATION Mario A. Lafortune and Ewald M. Hennig Sportmed. Institute Essen e.V. Australian Institute of Sport P.O. Box 176, Belconnen Wittekindstrasse 54 A.C.T. 2616, Australia 4300 Essen 1, West Germany A bone mounted accelerometer was used in conjunction with high speed cinematography to determine the contribution of angular motion (AM) and gravity (GR) to the axial component of tibia1 acceleration (TAA). Measurements were taken during walking and running. The magnitude of TAA at ground contact depends upon the severity of the impact (IP), AM and GR. The magnitude of the contribution of AM to the acceleration measured by the accelerometer was estimated by the following equation: aR =&R where R is the distance from the accelerometer to the hinge point (constant with rigid body) andu;)isthe angular velocity of the tibia in the sagittal plane. The contribution of gravity depends upon the orientation of the tibia to the vertical. For running the acceleration (TAA) recorded by the bone mounted accelerometer underestimated the magnitude of the ground impact by approximately 45% (4.3 g instead of 7.9 g). Conversely, the accelerometer overestimated the walking ground impact by 16% (2.9 g instead of 2.5 g). These results indicated that angular motion and gravity contribute significantly to tibia1 axial acceleration.
THE NORMALIZATION OF ELECTROMYOGRAPHIC SIGNAL Yves Lajoie, Louis Laurencelle and Martin C. Normand Laboratoire de biomhcani’que, Universit6 du Qhbec B Trois-Rivikres, Trois-Rivihes, Qc, Canada, G9A 5H7 The measurement of the intensity of muscle activation is an essential prerequisite to determine the function of muscles during movement and the deficit of impaired muscles. But statistical mormalisation of the EMG signal is difficult to carry out when we consider the marked non-normality~,and asymmetry of the results. The purpose of this study was first to verify the symmetry and normality of some results through the g1 and g2 statistic, and second, to propose the utilization of an order statistic, the tolerance interval for norms construction. The statistics g1 and g2 indicated, indeed, the non normality and asymmetry of the EMG data. Futhermore, we found that 153 subjects need to be measured in order to establish a nonparametric interval with both a coverage and confidence of .95.