| Purposes: The vertical jump is a fundamental movement of human. In moderncompetitive sports events, the jumping category occupies an important part of the wholesports events. With the help of the motion analysis system, the experts who came fromthe overseas and inland discovered that arms swing improves the vertical jump heightsignificantly. However, the mechanism of the vertical jump height enhanced by armswing and how much the arm swing momentum occupies the whole vertical jump hasyet to be fully understood. Additionally, we are still confused about the change of thesurface Electromyography due to the arm swing.There are mainly four theories about arm swing increasing the vertical jump height.(1) Arm swing increases the peak ground reaction force.(2)During the take-off phase,arm swing increases the peak moment of lower extremities.(3) Pulled by arm swing,the whole body loses effective mass in the process of launch section.(4)As the reason ofaforenamed arms, the center of the body mass raised before the whole body takes off thefloor. Combined with kinematic and dynamic analysis as well as iEMG, this experimenttries to explore the influence of all kinds of vertical jumps (CMJ, SJ, DJ) caused by armswing. The study calculated the contribution rates of arm swing by human model andattempted to investigate the mechanism of how arm swing augmenting the vertical jumpheight. The results could improve the vertical jump theory and provide reference toexercise training.Methods: Randomly select forty healthy male volunteers without any injuredhistory form sport department of Soochow University to do three kinds of verticaljumps, counter movement jump (CMJ), squat jump (SJ) and drop jump (DJ). Thevertical jumps include three different arm movements-no arm swing, arm swing,arm-loaded (500g each arm) swing. The height for drop jump is30centimeters.Experimental instruments: The kinematic date were captured by VICON NEXSUSand the dynamic date were recorded by KISTLER force plate. The Electromyography signals were recorded by Daysilab8.0of Biovision in Swiss. The MVC motion wastested by CONTREX made in Swiss. The results exported in the form of number matrixof ASCII. The experimental calculations and pictures were operated by MATLAB7.0and SPSS17.0. A repeated measures ANOVA was used to assess the significance ofdifferent arm swing styles and variable vertical jumps.Results:(1)The arm swing could increase the vertical jump height and raise the peak speedof the center of mass. Besides, the magnitude of jump was also extended, so does thejumping magnitude.(2)The peak ground reaction force, the impulse of the launchsection and the work of the lower limbs were also increased as a result of the arm swing.(3)The Electromyography of shank was reduced by the arm swing. Therefore, thefunction of arm swing in the vertical jump is pulling the body and decreasing effectivemass during the vertical jump.(4)In different kinds of arm swinging vertical jumps, thepercent of arm swing momentum is between9%-12%.Conclusions: The mechanism of arm swing increasing the jump height are mainlydivided into points as following:(1) Due to arm swing, the vertical jump height isincreased by reducing the effective mass and elevates the center of mass height oftaking-off and augments the jumping impulse.(2)The increased lower limbs momentleads to the growth of peak ground reaction force and increased impulse raises the peakspeed of the center of body mass. Therefore, the growth peak ground force and theincreased speed of the center of body mass cannot be treated as the mechanism that armswing augments the vertical jump height. |
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