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Electromyography study of the patients with ankylosing spondylitis
Abstracts SONIC COORDINATE TRACKING SYSTEM FOR 3D DYNAMIC POSTURE! ACQUISITION U. Raschhe,J. Foullteand D.B. Chaffm
CenterforErgonomics,TheUniversityof Michigan,Ann Arbor.Ml 48109 Mosttypicalwork tasksrequirecomplexand dynamic3D movements. Recently,3D computerbiomechanical models have been introducedto estimatethe internalforceson individualsas they performthese typicalwork tasks. However,a majorobstacletoward the widespreaduse of these modelsis the accuraterepresentation of the postunm,both staticallyand dynamically. An enhancedsonic ccordinatetrackingsystemwas developedto providethese data. It uses a parallelhardwarearchitecturesupplyingredundantinformationfrommultiple body sites with minimalpenaltyto the samplingrate. Coupledwith errorreducingdataanalysistechniques, thii system is able to reducethe markerdetectiondropoutand noise interference problems common in complextasks. Staticlaboratoryaccuracytests showed the systemhad a meanerrorof 054cm (std. dev. of 0.27cm) over a 3m area. Fordynamicexperiments,in which a pendulumwas used to createa single frequencyreferencemotion,the peak velocitiesand accelerationsdeviatedon averageby 1.1% fromthe theoreticalvalues. The resultsprovideevidence that the sonic system represents a cost effective alternative tc video based systemsfor capturing3D dynamicposturesduringcomplexmotions.
THE EBPNCTS OF ACCELERATION AND CRBBT FACTOR ON BUNAN NECNANICAL IMPEDANCE RESPONSE DURING NNOLE-BODY VIBRATION S. D. Smith
Armstrong Laboratory Wright-Patterson Air Force Base, OH 45433-7901 Human subjects were exposed to sinusoidal and quasi-random whole-body vibration to evaluate the effects of the acceleration level and crest factor on the mechanical impedance frequency response. Two overall acceleration levels and three crest factors (for the quasi-random vibrations) were selected. Up to four regions of resonance were observed in the profiles. The highest incidence of resonance peaks were observed for the quasi-random vibrations. A significant lowering (l-2 Hz) of selected resonance frequencies occurred at the higher acceleration level. The appearance of the second and fourth resonance peaks was most obvious for the second crest factor. At the highest crest factor, identified by the subjects as producing the most discomfort, the second peak was eliminated and the fourth peak appeared more dampened, approaching the response of a dampened mass at the lower acceleration level. It appears that nonlinearities in the impedance response characteristics are not only affected by the acceleration level, but also by the crest factor or impulsiveness of the motion.
ELECTROMYOGRAPHY STUDY OF THE PATIENTS WITH ANKYLOSING SPONDYLITIS C.K. Cheng, S.W. Lin, Y.H. Tsuang and P.Q. Chen DepartmentofOrthopaedic SurgeryandCenterforBiomedicalEngineering, National TaiwanUniversity,Taipei, TaiwaqR.0.C. The trunkof the patients with ankylosing spondylitis (AS) has a tendency to lean forward owing to the structural change of the spine. As the center of gravity gradually shifts to the anterior, the back and hip muscle groups tend to keep sag&al balance. The objective of this study is to demonstrate this muscle abnormal activity which has been considered the secondary factor to cause the low back pain of the patients with ankylosing spondylitis. Ten normal subjects and ten patients with ankylosing spondylitis were studied. Six paired surface electrodes were put on the right and left Multifidus, Iliocostalis, and Hamstring muscles on each subject. Every subject were asked to perform three different postures, prone lying, sitting and standing. IEMG was calculated and used to represent the outcomes of the muscle activities from the electromyography (EMG). The results showed that in patients with ankylosing spondylitis, they need more back muscle activities to keep balance of the trunk. They have much higher EMG activities than normal subjects. They also showed in the standing position performed higher activities than the sitting position which is contrary to the normal subjects. After correction of the kyphotic deformity for the AS patients, their back pain decrease greatly. Thus the EMG activity of back muscle should be reduced due to the structural change. In conclusion of this study, the back pain of the AS patients can be reduced greatly after the surgical operation not only due to the primary correction of the spinal deformities but the muscle activity reduced.
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CenterforErgonomics,TheUniversityof Michigan,Ann Arbor.Ml 48109 Mosttypicalwork tasksrequirecomplexand dynamic3D movements. Recently,3D computerbiomechanical models have been introducedto estimatethe internalforceson individualsas they performthese typicalwork tasks. However,a majorobstacletoward the widespreaduse of these modelsis the accuraterepresentation of the postunm,both staticallyand dynamically. An enhancedsonic ccordinatetrackingsystemwas developedto providethese data. It uses a parallelhardwarearchitecturesupplyingredundantinformationfrommultiple body sites with minimalpenaltyto the samplingrate. Coupledwith errorreducingdataanalysistechniques, thii system is able to reducethe markerdetectiondropoutand noise interference problems common in complextasks. Staticlaboratoryaccuracytests showed the systemhad a meanerrorof 054cm (std. dev. of 0.27cm) over a 3m area. Fordynamicexperiments,in which a pendulumwas used to createa single frequencyreferencemotion,the peak velocitiesand accelerationsdeviatedon averageby 1.1% fromthe theoreticalvalues. The resultsprovideevidence that the sonic system represents a cost effective alternative tc video based systemsfor capturing3D dynamicposturesduringcomplexmotions.
THE EBPNCTS OF ACCELERATION AND CRBBT FACTOR ON BUNAN NECNANICAL IMPEDANCE RESPONSE DURING NNOLE-BODY VIBRATION S. D. Smith
Armstrong Laboratory Wright-Patterson Air Force Base, OH 45433-7901 Human subjects were exposed to sinusoidal and quasi-random whole-body vibration to evaluate the effects of the acceleration level and crest factor on the mechanical impedance frequency response. Two overall acceleration levels and three crest factors (for the quasi-random vibrations) were selected. Up to four regions of resonance were observed in the profiles. The highest incidence of resonance peaks were observed for the quasi-random vibrations. A significant lowering (l-2 Hz) of selected resonance frequencies occurred at the higher acceleration level. The appearance of the second and fourth resonance peaks was most obvious for the second crest factor. At the highest crest factor, identified by the subjects as producing the most discomfort, the second peak was eliminated and the fourth peak appeared more dampened, approaching the response of a dampened mass at the lower acceleration level. It appears that nonlinearities in the impedance response characteristics are not only affected by the acceleration level, but also by the crest factor or impulsiveness of the motion.
ELECTROMYOGRAPHY STUDY OF THE PATIENTS WITH ANKYLOSING SPONDYLITIS C.K. Cheng, S.W. Lin, Y.H. Tsuang and P.Q. Chen DepartmentofOrthopaedic SurgeryandCenterforBiomedicalEngineering, National TaiwanUniversity,Taipei, TaiwaqR.0.C. The trunkof the patients with ankylosing spondylitis (AS) has a tendency to lean forward owing to the structural change of the spine. As the center of gravity gradually shifts to the anterior, the back and hip muscle groups tend to keep sag&al balance. The objective of this study is to demonstrate this muscle abnormal activity which has been considered the secondary factor to cause the low back pain of the patients with ankylosing spondylitis. Ten normal subjects and ten patients with ankylosing spondylitis were studied. Six paired surface electrodes were put on the right and left Multifidus, Iliocostalis, and Hamstring muscles on each subject. Every subject were asked to perform three different postures, prone lying, sitting and standing. IEMG was calculated and used to represent the outcomes of the muscle activities from the electromyography (EMG). The results showed that in patients with ankylosing spondylitis, they need more back muscle activities to keep balance of the trunk. They have much higher EMG activities than normal subjects. They also showed in the standing position performed higher activities than the sitting position which is contrary to the normal subjects. After correction of the kyphotic deformity for the AS patients, their back pain decrease greatly. Thus the EMG activity of back muscle should be reduced due to the structural change. In conclusion of this study, the back pain of the AS patients can be reduced greatly after the surgical operation not only due to the primary correction of the spinal deformities but the muscle activity reduced.
629