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This project explored the use of large array surface electromyography (LASE ) as a technique for assessing the patterns of muscular activity under standardized loading conditions in patients with lumbar disc related pain and healthy subjects . Specifically , the project evaluated quantitative parameters of visually observed patterns of muscle action proposed to clinically discriminate between groups . If such correlates exist , then , this work may lead to technology assessment for sensitivity and specificity as a diagnostic procedure .
Solutions to the issues for determining the effects of low back pain (LBP ) on force and moment generation in the spine as well as its effect on the paraspinal muscle activity were sought in three stages . First , a biomechanical model was developed to calculate the passive forces and moments of the total subject population , which included 38 subjects (20 healthy and 18 LBP ) . The model also allowed for the assessment of the active forces and moments generated by the paraspinal muscles . Second , LASE recordings were collected from each subject using three standardized postures , upright , weighted (holding 5 lb weights in hand ) , and 20 degrees lumbar flexion at the hip . The LASE recordings were used to create a single muscle equivalent , root mean square myoelectric signal (RMS -MES ) model that evaluated muscle activation levels during the standardized tasks . Such a model must be able , to partition passive and active load components acting on the lumbar spine and to estimate equivalent muscle loads from activity observed during the given tasks . Finally , a novel RMS contour surface map was constructed as a means to quantify regional muscle behavior . A first parameter for testing differences between subject groups used symmetry /eccentricity .
Results confirmed that an increase in paraspinal muscle activity is directly related to the force generation of the muscles for both groups while performing the standardized tasks . However , the LBP group demonstrated a disproportionately greater increase in muscle force generation when subjected to the monotonically increasing loads than did the healthy subjects . Additionally , a stepwise logistic model was used to identify important parameter differences between the two groups . It may be fruitful for future work to examine other quantitative characteristics of RMS surface maps to differentiate the behavior of muscle activity . In contrast to small area surface electromyography , LASE may provide additional information for classifying type and severity of low back injury leading to the development of more successful treatment methods . |
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