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Effects of load carriage on the lower limbs
Abstracts
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A METHOD FOR COMPUTING THE THREE-DIMENSIONAL FORCES AND MOMENTS AT THE KNEE DURING GAIT Mary C. Verstraete Department of Biomechanics Michigan State University, fast hnsing, MI 48824 The Newton-Euler equations of motion were written for a rigid-body approximation of the shank segment of the lower limb. Three-dimensional position data and ground reaction forces and moments were recorded for five subjects during stance phase of walking gait. The ground reactions were resolved into an equivalent force vector and a moment vector parallel to it, and the center of pressure was computed as the point of force application to the foot. A local coordinate system was defined on the shank by the principal axes of the limb segment and the forces and moments at the center of the tibia1 plateau were solved for. The results of this model showed similar patterns as those reported in the literature. The variations in magnitudes were attributed to the local coordinate system in which the components of the force and moment were expressed.
EFFECTS OF LOAD CARRIAGE ON THE LOWER LIMBS Ang E.J. Goh J.C.H. Department of Orthopaedic Surgery, National University of Singapore Nicol A.C. and Paul J.P. Bioengineering Unit, University of Strathclyde The effects of frontal load carriage of 20% body weight were studied using a kistler force platform and a motion analysis camera system. Analysis of selected objective gait parameters during both gait initiation and the rhythmic stage were performed to compare the results obtained during weight carriage walking with that of normal walking. It was found that the 20% body weight frontal load produced significant changes in the range of motion of the knee and hip joints in both the sagittal and coronal planes. Similarly, in both stages of gait, there were also significant increases in the ground reaction forces. It IS obvious from this study that modification in the mechanics of the walking gait had to be effected to accommodate the extra demands on the musculo-skeletal system introduced by the 20% body weight frontal load.
ESTIMATION OF ISOMETRIC TENSIONS FROM MUSCLE HARDNESS J. Triano, R. Prastein*, M. Papakyriakou, B. Torres National College of Chiropractic, Lombard, IL 60148 *University of Illinois College of Medicine Methods used to estimate the tension of isometric contraction includes biomechanical models to calculate joint moments and myoelectric signal-force relationships. Intramuscular total pressure hasbeen suggested as a more reliable parameter of muscle force. Pressure load estimators have been shown to be linear with less susceptibility to fatigue and lower error (15%) than with myoelectric signals. The present study was carried out to evaluate durometer measures of surface hardnesses as a low technology means of determining muscle forces. Biceps and bilateral erector spinae muscles were quantified during systematic loading of the elbow and L3 spinal joints respectively. Joint moments caused by holding weights in quaslstatic postures were calculated and myoelectric signals monitored. Measures were then taken from the erector spinae while subjects performed symmetrical and asymmetrical tasks. Intrarater reliability for repeated measures over 9-51 days was high (r =.82). For both the biceps and paraspinal muscle models, highly significant correlations (p =.Ol, .66LrL.99) were found between joint moment, myoelectric action and muscle hardnesses. Symmetrical tasks demonstrated symmetrical response for all variables. Simple asymmetrical tasks produced predictable asymmetric changes. The greatest variation in measures was observed at positions and loads causing the lowest joint torques.
x75
A METHOD FOR COMPUTING THE THREE-DIMENSIONAL FORCES AND MOMENTS AT THE KNEE DURING GAIT Mary C. Verstraete Department of Biomechanics Michigan State University, fast hnsing, MI 48824 The Newton-Euler equations of motion were written for a rigid-body approximation of the shank segment of the lower limb. Three-dimensional position data and ground reaction forces and moments were recorded for five subjects during stance phase of walking gait. The ground reactions were resolved into an equivalent force vector and a moment vector parallel to it, and the center of pressure was computed as the point of force application to the foot. A local coordinate system was defined on the shank by the principal axes of the limb segment and the forces and moments at the center of the tibia1 plateau were solved for. The results of this model showed similar patterns as those reported in the literature. The variations in magnitudes were attributed to the local coordinate system in which the components of the force and moment were expressed.
EFFECTS OF LOAD CARRIAGE ON THE LOWER LIMBS Ang E.J. Goh J.C.H. Department of Orthopaedic Surgery, National University of Singapore Nicol A.C. and Paul J.P. Bioengineering Unit, University of Strathclyde The effects of frontal load carriage of 20% body weight were studied using a kistler force platform and a motion analysis camera system. Analysis of selected objective gait parameters during both gait initiation and the rhythmic stage were performed to compare the results obtained during weight carriage walking with that of normal walking. It was found that the 20% body weight frontal load produced significant changes in the range of motion of the knee and hip joints in both the sagittal and coronal planes. Similarly, in both stages of gait, there were also significant increases in the ground reaction forces. It IS obvious from this study that modification in the mechanics of the walking gait had to be effected to accommodate the extra demands on the musculo-skeletal system introduced by the 20% body weight frontal load.
ESTIMATION OF ISOMETRIC TENSIONS FROM MUSCLE HARDNESS J. Triano, R. Prastein*, M. Papakyriakou, B. Torres National College of Chiropractic, Lombard, IL 60148 *University of Illinois College of Medicine Methods used to estimate the tension of isometric contraction includes biomechanical models to calculate joint moments and myoelectric signal-force relationships. Intramuscular total pressure hasbeen suggested as a more reliable parameter of muscle force. Pressure load estimators have been shown to be linear with less susceptibility to fatigue and lower error (15%) than with myoelectric signals. The present study was carried out to evaluate durometer measures of surface hardnesses as a low technology means of determining muscle forces. Biceps and bilateral erector spinae muscles were quantified during systematic loading of the elbow and L3 spinal joints respectively. Joint moments caused by holding weights in quaslstatic postures were calculated and myoelectric signals monitored. Measures were then taken from the erector spinae while subjects performed symmetrical and asymmetrical tasks. Intrarater reliability for repeated measures over 9-51 days was high (r =.82). For both the biceps and paraspinal muscle models, highly significant correlations (p =.Ol, .66LrL.99) were found between joint moment, myoelectric action and muscle hardnesses. Symmetrical tasks demonstrated symmetrical response for all variables. Simple asymmetrical tasks produced predictable asymmetric changes. The greatest variation in measures was observed at positions and loads causing the lowest joint torques.