The Effect Of Different Intensity Muscle Mobilization For Depth Jumping

Background: Explosive force is a main factor that affect the results of many sports. Asa means to estimate the explosive force of lower limbs, depth-long-jump practice iswidely accepted. Traditionally, when adapt depth-long-jump practice to do a test forexplosive force, unarmed preparatory activities was mostly to be used. This kind ofslight load stimulus is very limited to neuromuscular, so it could not get an accurateresult for the muscle’s mobilization status, therefore, the depth-long-jump practice canonly get a result in condition of limited motor unit. However, explosive force isactually a reflection of the ability to limit human muscle contraction, it should beexpressed by motor units as much as possible, and explosive performance by a verysmall number of muscle fibers can not accurately and completely expressed human’slower limb explosive. To measured human’s lower limb explosive force accurately,take a larger load stimulation before testing to mobilize the working condition of theneuromuscular is needed. At present, there are no research in this area, so evaluationmethods for the explosive of lower extremity need further research.Objective: According to the principles of mechanics, in the case of constant weight,the greater the leg strength is, the higher the height of the depth jump. The individualleg strength has a lot to do with the functional status of neuromuscular at that moment.Stimulation of different load intensity can mobilize the functional status ofneuromuscular and have influence on depth-long-jump practice in some degree. Thispaper is to verify the influence of the neuromuscular’s different working status on thelower limb explosive force, and to show that testing methods with heavy loadstimulation are more reasonable assessment for lower limb explosive.Method: Testing11normal male college students with self-contrast method afterusing different intensity of load stimulation. The contents of experiment is that the testgroup using strength exercises to mobilize the muscles at high proportion, then doingdepth-long-jump practice. Contrast group also doing the same test after generalpreparatory activities. In the process of test, each points such as the grades ofdepth-long-jump, the corresponding muscle electromyographic signal, threedimension test force platform force value changes and the condition changes of theAngle of the lower extremities’ three joint. With respectively kinematics characteristicobservation, it will prove that result of depth-long-jump testing with high proportionof mobilization for large load motor unit would be better than the traditional test withsmall load. It is proved that different degree of muscle mobilizations are of greatsignificance to the evaluation of explosive force, and big stimulus intensity loadmethod can evaluate explosive force more accurately. Results and Analysis:1.Compared to the general preparation activities, with weight preparatory activities,the same subjects have improved on the score of depth-long-jump test to some extent,in the meantime, each of the subjects has also been increased in the other aspects ofdepth-long-jumping. It shows that different working status of neuromuscular have animportant influence on depth-long-jump practice.On EMG aspects, in the landing and buffering stage, the higher jump deep heightis,the higher the same subjects extremity muscle surface electromyography is withina certain range. On the contrary, when the height of the depth-long-jump gets to theoptimum height, the IEMG will be decrease. At the same time,the IEMG values ofsubjects group who taking the force preparation activities appears to be slightly largerthan those who taking the general preparatory activities; while in the pedaling andstretching stage, the score for testers who adopt the forceful preparation activities aremuch higher than those who adopt general preparation activities,which indicates thatstimulation with a large of load can raise more motor units involved; In the aspect ofEMG spectrum, the same subjects do the same height depth-long-jump practice, theforceful preparatory activities turns to be much higher than the general preparationactivities, which express that big load stimulation would be better to mobilizefast-twitch muscles.2. The take-off time for who taking forceful preparatory activities is much shorterthan those who taking general preparatory activities, and the take-off time is in directproportion to the score of depth-long-jump.3. In terms of joint Angle change, the take-off angle of knee after forceful preparatoryactivities is much closer to the best take-off angle than the general one.Conclusion: Different levels of load stimulus have the different effect on mobilizingthe working state of neuromuscular. Heavy load stimulus can be much better tomobilize the number of muscle fibers, particularly white muscle fibers. It also canimprove the resistance ability of muscle, and accelerate the muscle contraction speedso that we can achieve the ideal drop-jump grade and express the explosive force ofhuman legs better. Therefore, it is a much more reasonable method to evaluate theexplosive force of human lower limbs.