The Research On The Mechanics Characteristic Of Flexor-extensor During Trunk Isokinetic Exercise

Object: To research the mechanics characteristic of flexor-extensor and their cooperative function, the author chose 14 healthy male as testing objects from soochow university, and measured a series parameters undergoing lumbar flex-extend exercise , to analyze the mechanics characteristic and the correlation between the changes of rectus abdominis peak torque and sEMG during the flexion and extension of trunk.Method: Using CON-TREX isokinetic testing system and German Biovision bioelectricity record analyze system, a series parameters are recorded such as peak torque,angle at peak torques total work,average power,iEMG., undergoing lumbar flex-extend exercise in the way of Isokinetic centripetal/ centrifugal exercise.Results:(1) Isokinetic centripetal exercise,peak torque of extensor decreased as the geniovelocity reduced, but no inerratic change in flexor peak torque; when undergoing isokinetic centrifugal exercise, peak torque of flexor-extensor had decreased trend while geniovelocity reduced.(2) During isokinetic centripetal exercise, F/E increased with the geniovelocity expedited. it`s range is 0.776-0.865 from 30°/s to 90°/s. and a little big at 0.887-0.926 from 120°/s to 180°/s; when undergoing isokinetic centrifugal exercise, F/E of flexor-extensor decreased slightly as geniovelocity expedited. the range of F/E is 1.29-1.27.(3)During slow isokinetic centripetal/centrifugal exercise with different geniovelocity, the angle at peak torque of flexor and extensor distributed discretely, 30°/s is -48.56°,-52.73°; 90°/s is -46.18°,-60.45°; when undergoing fast isokinetic exercise, the angle at peak torque of flexor was very close to that of extensor, each was -48.71°,-51.61°at 120°/s and -54.86,-53.11 at 180°/s.(4)During isokinetic centripetal/centrifugal exercise with different geniovelocity, total work of flexor and extensor was reduced with geniovelocity expedited, extensor total work is more than that of flexor. (5) During isokinetic centripetal and centrifugal exercise with different geniovelocity, average power of flexor and extensor was increased linearly with geniovelocity expedited, flexor. Average power is less than that of extensor all along.(6) During flexion and extension of trunk, IEMG was less in thoracic erector spinae than in lumbar erector spinae,and upper rectus abdominis`s IEMG was less than that of lower rectus abdominis. The change of upper rectus abdominis`s IEMG was significant correlated with flexor peak torque at 30°/s velocity. The change of erector spinae IEMG was not correlated with extensor peak torque.Conclusion:(1) During isokinetic centripetal and centrifugal exercise,trunk muscle strength descended with the geniovelocity expedited. Slow isokinetic test was more precise, more reliable than fast isokinetic test to assess trunk muscle function.(2)During isokinetic centripetal and centrifugal exercise,the stability of trunk is preferable in slow exercise than in fast exercise(3)Total work of flexor and extensor descended with the geniovelocity expediting during isokinetic exercise, but the intramuscular eruption increased.(4)During fast isokinetic centripetal and centrifugal exercise, the angles at flexor and extensor peak torque were more discrete than that during slow fast isokinetic centripetal and centrifugal exercise, flexor and extensor were at maximal tension synchronously, at this moment muscles would be damaged and spine would be unstable suffered from outside force suddenly.(5)when trunk completed flexion and extension, upper rectus abdominis collected more fibre than lower rectus abdominis. thoracic erector spinae collected less fibre than lumbar erector spinae. And there is an obvious correlation between the changes of upper rectus abdominis peak torque and sEMG during the flexion and extension of trunk.