a kinematic analysis 0 the front set and bac set in volleyball

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:::I140 _.-.- C-o_t--..-._.__ • -- 0-.--_.---·0120 >.......... _0................. _--0• .- ........ 0-....100 Cl-O-O-O-c-o~ +-.__Position (deg)._- Shoulder80 j -·_~o:::::o_o-oo.--D-0::r-0---0 -__- __·0- Hip60 0_ 0 _ 0 .•- Elbow·0- Kneeo2 3 4 567 8 9 10 11 12 13 14 15Time (1 unit .025)Figure 3.Position/time data for Ss 3's FS180 f 0_0 _ 00 ...............•160 0:::;:"'"o_o?140 [J-o 0 [J o_o-o-.~I - - - .-.120 _.-----.-.-.'0- ShoulderPosition (deg) lOO! .-.-. _._. .•- Hip80 0-0-0-0 .-.I -0_- .·0- Elbow60 .j. _._.-.-.-.-0.........::1.-.~~\~'o1 2 3 4 5 6 7 8 9 10 11 12 13 14Time (1 unit = .02s)Figure 4.Position/time data for Ss l's BSDISCUSSION ANDCONCLUSIONSWithin the limitations of this study, it was concluded that thesimilarities between setters when executing a FS or BS exceed any differencesobserved. While realizing there is rarely one form that is ideal forevery performer, many observations may be made regarding setting techniqueof the subjects analyzed in this study. From these results the criticalkinematic patterns that may dictate success in setting have begun to beidentified.245
In studying body segment movements during the two types of sets, thehead, trunk, and shoulder exhibited the greatest posit~onal variuncebetween the PS and BS. Greater angular displacement occurred during BSexecution. This was not unexpected when considering the task of projectinga ball overhead in a backward direction.The more vertical position of the head and tr~nk at the start of theback set may provide critical positionsl cues for the defense in anticipatingset destination. Also, the greater hyperextension movements Wllich wereexperienced by the head and trunk during the BS may be discernihle hydefensive players. Such information could result in allowing the defensetime to make defensive adjustments prior to the attack.From an offensive standpoint the setter should attempt to minimizebody position Jifferences in execut1ng tbe two types of sets, or at thevery least they should attempt to delay as long as possible, positioningthe body in an "obvious" back setting posture.The setters in this study varied to some extent in their settingtechnique in comparison to what has been reported in some of the volleyballliterature. An often reported statement (Scates 1985) regarding tileposition of the ball in relation to the head is to contact the ball sixinches in front of the face. The mean distances (hall-ta-forehead) wereapproximately 13.3 inches (FS) and 13.6 inches (8S). Even allowing forme8surRment to the edge of the ball instead of the geometric center doesnot account for such a discrepancy. Ridgway, Hay, & Gench (1985) reportedin a recent setting study a mean distance of 13 inches for the FS. Apossible explanation of the conflicting reports is that the setters analyzedin this investigation initiated movement toward the ball well before contact.Schaafsma, Heck, & Sarver (1985) state that little extension beginsprior to contact and only in the legs, with the elbows not beginningextension until contact with the ball. Such technique would result ina closer contact point relative to the forehead, and these authors recommenda contact point of approximately six inches from the forehead. Nore thanlikely some of these conflicting reports may be caused by the time gapbetween the time of new techniques or technique modifications being introducedin the sport and such technique changes being written up and published inthe volleyball literature.Movement of body segments prior to contact may be done to make settingmore of a striking skill instead of a catching-throwing skill, therebyreducing the potential of an illegal hit. Also such preliminary movementusually results in higher ball release velocities which can reduce thetiDe it takes the set to get to the attacker. Reducing time of deliveryalso decreases the time the defense has in defending against the attack.In contrast to statements reporting the relative lack of movement priorto initial ball contact, the majority of the trials analyzed in our studyinitiated elbow extension prior to the knees, and both elbows and kneesbegan movement almost from the start of both types of sets.Certain sources suggest that the knees and elbows are positioned at90 deg at the start of the set and both go to full extension. Our subjectsstarted at a mean knee angle of 114 deg and a mean angle of 101 deg forthe elbows. At time of release these joints were not at full extension.Furth£r study would be needed to substantiate if different skill levelsof setters selectively utilize body segments in a similar manner to whatthe subjects in this study exhibited.246
Page 1 and 2: A KINEMATIC ANALYSIS 0THE FRONT SET
Page 3 and 4: TABLE 1JOINT KINEMATICSJOINT SET !:
Page 5: Position (deg)160 1 .... •,·71
Page 9: 11iuewJY, H., Hay, 1

a kinematic analysis 0 the front set and bac set in volleyball

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