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141124s2013 miu sm 000 0 eng d |
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|a9781303159459
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|a(MiAaPQ)AAI3565735
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|aMiAaPQ|beng|cMiAaPQ|dTMUE|eaacr
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|aCrotin, Ryan Lewis.
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|aA kinematic and kinetic comparison of baseball pitching mechanics influenced by stride length|h[electronic resource].
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|aAnn Arbor, Mich :|bUMI,|c2013.
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|a293 p.
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|aSource: Dissertation Abstracts International, Volume: 74-10(E), Section: B.
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|aAdviser: Dan K. Ramsey.
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|aThesis (Ph.D.)--State University of New York at Buffalo, 2013.
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|aThe dissertation investigated the effect of stride length through seven studies. To determine an overall representation of stride length impacts on the kinetic chain and temporal events, linear and angular momentum analyses were performed for the total body and throwing arm. Trunk-throwing arm momentum exchanges were represented by momentum compensation ratios to identify the proportion of the throwing arm to the total body momentum (contributed mostly by the trunk). In the results, stride length affected the instant of SFC, as longer strides increased single support generation and abbreviated the duration of the brace-transfer phase.
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|aThe second study differentiated propulsion and bracing ground reaction force profiles, as vertical weighting, anterior-shear forces and their normalized impulses were greater for longer strides prior to SFC, while thereafter, the drive foot applied braking forces in tandem with the stride leg. Shorter strides minimized drive foot posterior-shear force, maintained propulsion after SFC in double support, and applied peak vertical weighting of the stride leg near ball release.
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|aAffected ankle dynamics were featured in the third study, which related to the aforementioned differences in ground reaction force profiles. Longer stride's drive ankle applied greater propulsion dynamics prior to SFC with closed-chain dorsiflexor moments thereafter to assist braking and landed the stride foot with greater heel-strike. Shorter strides maintained drive ankle propulsion dynamics after SFC, minimized hind ankle braking, landed more in toe-strike, and required greater stride ankle braking dynamics during acceleration.
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|aBilateral knee flexion-extension dynamics were investigated in succession where greater propulsive dynamics during generation and greater hind leg extension kinetics were found with longer strides, believed to increase inertial and frictional effects in braking effects. Maintained propulsion after SFC, greater stride knee flexion and extension power occurred with shorter strides.
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|aIn the fifth study, femoral-acetabular hip dynamics revealed greater internal rotation and abduction, which facilitated greater maximum drive hip kinetics in extension prior to SFC with longer strides. Following SFC, longer strides generated greater stride hip extension power in braking and eccentrically slowed internal rotation in greater stride hip flexion. Longer strides improved stride hip biomechanics to better moderate internal pelvic rotation toward home plate and added stability, throwing from a lowered position within a wider base of support. Shorter strides revealed greater stride hip extension, believed to elevate the center of mass within a narrower base of support, reducing stability to most likely minimized braking to maintain drive hip propulsion kinetics and expedite internal pelvic rotation in double support after SFC.
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|aThe sixth study, proximal segment kinematics were examined as longer strides anterior pelvic rotation, forward trunk flexion, upward pelvic rotation, non-dominant trunk bending, as well as internal rotation kinematics of the trunk and pelvis were greater prior to SFC. Thereafter, the kinematics mentioned above were greater for shorter strides.
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|aLastly, pelvic-trunk separation angles and proximal plyometric effects denoted stride length influences upon the transverse pelvic-trunk rotational couple. Greater separation occurred prior to SFC with longer strides with peak separation found shortly thereafter. Shorter strides further counter-rotated the pelvis away from home plate at the onset of the pitching delivery and also coordinated peak separation later in the delivery near the acceleration phase, producing greater proximal plyometric effects at BR, evidenced by a 3.3-fold faster internal rotation velocity of the trunk than that of the pelvis. (Abstract shortened by UMI.).
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|aBiophysics, Biomechanics.
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|aHealth Sciences, Recreation.
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|aState University of New York at Buffalo.|bExercise and Nutrition Sciences.
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|tDissertation Abstracts International|g74-10B(E).
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|uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3565735|z連結全文
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