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Young-Hoo Kwon, Virginia L. Fortney and In-Sik Shin

Two of the most frequently performed vaults in the 1988 Olympic Games in Seoul were selected for 3-D cine-photogrammetry analysis: the Yurchenko layout with full twist and the Yurchenko layout. The performances included 20 vaults with the highest performance scores: 10 Yurchenko layout with Ml twist (YLF) and 10 Yurchenko layout (YL) vaults, which were performed in the women’s team optional competitions. The YLF group earned higher performance scores than the YL group. Average vaulting times were similar for the groups, but the YLF group showed shorter board and horse contact times and longer postflight times. The projectile motion variables were critical for better performance in the YLF group. Higher vertical velocity at horse takeoff was achieved mainly by minimizing its (Vv) loss during horse contact. The YL group showed the importance of angular momentum for better performance, with the normalized angular momentum during postflight being the critical variable for the YL vault.

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Jin-Young Park, Junhyun Kim, Beom Ho Seo, Ho Dong Yu, Ju Hyun Sim, Jae Hyung Lee, Kyung Soo Oh and Seok Won Chung

Background: The knowledge of 3-dimensional scapular kinematics is essential for understanding the pathological lesions of the shoulder and elbow in throwing athletes. Many studies about alterations of the resting scapular position, dynamic scapular motion, or scapular dyskinesis (SD) have been conducted, yet none of them have identified a consistent pattern of altered scapular kinematics in throwing athletes. Hypothesis/Purpose: To analyze the 3-dimensional scapular kinematics of dominant and nondominant arms in baseball players with a pathological condition of the shoulder or elbow. Study Design: Cross-sectional study. Methods: Bilateral scapular positions, consisting of upward rotation (UR), superior translation (ST), internal rotation (IR), protraction (PRO), and anterior tilting (AT) with an arm at rest and at 150° forward elevation, were measured among 319 baseball players with SD using 3-dimensional computed tomography. Angular values of scapula were compared between dominant and nondominant arms with statistical analysis. Level of Evidence: Level III, diagnostic study. Results: The scapular position of dominant arms showed significantly more AT, less ST at rest and more UR and IR and less ST, PRO, and AT at 150° full forward elevation compared with the nondominant arms. The magnitude of mean change of UR, IR, PRO, and AT during arm elevation increased significantly between the paired arms (P value: UR, ST, PRO, and AT: <.001 and IR: .001). Conclusion: When compared with the nondominant arms, UR, AT, and PRO with the arm at 150° forward elevation of dominant symptomatic arms in baseball players tilted toward positive compensation, whereas IR altered toward negative decompensation. In addition, the angular increment of the scapula increased significantly in dominant symptomatic arms compared with the nondominant arms.

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Kai-Yu Ho, Brenda Benson Deaver, Tyrel Nelson and Catherine Turner

controls ( r  = .46–.57; P  ≤ .003) (Figures  2A – 2C ) and individuals with ACLR ( r  = .52–.66; P  ≤ .004) (Figures  2D – 2F ). In addition, peak knee valgus obtained by the MAA was significantly greater than that obtained by 3D analysis across all tasks in both groups ( P  < .001; Table  1 ). No

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Víctor Torreblanca-Martinez, Fernando M. Otero-Saborido and José A. Gonzalez-Jurado

The purpose was to study the effects of muscle fatigue induced by countermovement jumps (CMJ) on instep kick foot velocity in young male soccer players. Fifteen under-18 soccer players from a professional club performed maximal velocity instep kicks before and after a fatigue protocol that consisted of continuous CMJ. Foot velocity at impact without fatigue, foot velocity at impact with fatigue, CMJ height without fatigue, maximum jump height in fatigue test, and CMJ height change in fatigue test on a dynamometric platform were measured. There was a significant difference between jump height with and without fatigue (P = .00; ES = 0.8), but there were no significant differences between kicking with fatigue and without fatigue (P = .580, ES = 0.10). In conclusion, although the protocol was intense enough to generate fatigue in the muscles involved in CMJ, there were no significant differences in kicking velocity under fatigue conditions with respect to kicking without fatigue in the soccer players studied.

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Anna Bjerkefors, Johanna S. Rosén, Olga Tarassova and Anton Arndt

Trunk, pelvis, and leg movements are important for performance in sprint kayaking. Para-kayaking is a new Paralympic sport in which athletes with trunk and/or leg impairment compete in 3 classification groups. The purpose of this study was to identify how physical impairments impact on performance by examining: differences in 3-dimensional joint range of motion (RM) between 10 (4 females and 6 males) elite able-bodied kayakers and 41 (13 females and 28 males) elite para-kayakers from the 3 classification groups, and which joint angles were correlated with power output during high-intensity kayak ergometer paddling. There were significant differences in RM between the able-bodied kayakers and the 3 para-kayak groups for the shoulders (flexion, rotation: able-bodied kayakers < para-kayakers); trunk and pelvis (rotation: able-bodied kayakers > para-kayakers); and legs (hip, knee, and ankle flexion: able-bodied kayakers > para-kayakers) during paddling. Furthermore, athletes with greater impairment exhibited lower trunk and leg RM compared with those with less impairment. Significant positive correlations were observed for both males and females between power output and peak shoulder and trunk flexion; trunk and pelvis rotation RM; and hip, knee, and ankle flexion RM. This information is important for understanding how key kinematic and kinetic variables for para-kayaking performance vary between athletes from different classification groups.

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Agnès Roby-Brami, Sylvie Fuchs, Mounir Mokhtari and Bernard Bussel

The present study quantified reaching movements in 17 patients with vascular hemiplegia at various stages of recovery and 6 control subjects. The task involved grasping a light cone placed at one of seven positions on a baseboard. 3D analysis of movement was performed. Quantification of the reaching movement in hemiparetic patients showed abnormal features that could be related either directly to the motor impairment or to two kinds of adaptation to the impairment: acquisition of a new motor coordination or acquisition of a new strategy. Two movement strategies were identified in hemiparetic patients. Patients with a predominantly proximal impairment slid their hands toward the target, thus making maximal use of the properties of the environment. Patients with a predominantly distal impairment made a downward grasping movement, which probably used the passive properties of the hand-object contact to ensure grasping. These features contribute to fulfillment of the goal and are thus consistent with the acquisition of adaptive behavior by the hemiparetic patients.

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Rosa M. Angulo-Kinzler, Stephen B. Kinzler, Xavier Balius, Carles Turro, Josep M. Caubet, Josep Escoda and J. Antoni Prat

This study explains the general aspects of the biomechanics of the pole vault and presents a 3D analysis of the best official performances of the top 8 pole vaulters at the 1992 summer Olympic Games in Barcelona. Two time code synchronized S-VHS video cameras operating at 50 Hz were used. All vaulters showed a reduced last stride and a low CM during the penultimate foot support. Great horizontal velocity at takeoff, high grip, and well timed angular momentum serve as good indicators of a jumper's performance. An early positioning of the hips parallel to the bar can be very beneficial, as can a close placement of the CM to the bar at the time of pole release. Finally, an advantageous bar clearance technique used by the winning Unified Team vaulters is noted.

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Mero Antti, Paavo V. Komi, Tapio Korjus, Enrique Navarro and Robert J. Gregor

This study investigated body segment contributions to javelin throwing during the last thrust phases. A 3-D analysis was performed on male and female javelin throwers during the finals of the 1992 Olympic Games in Barcelona. The subjects were videotaped from the right sight of the throwing area by two NAC high-speed cameras operating at 100 frames per second. Both men’s and women’s grip of javelin and body center of mass displayed a curved pathway to the right from the left (bracing) foot during the final foot contact. The position of the body center of mass decreased at the beginning of the final foot contact, but after the decrease period it began to increase. Simultaneously with the increase, the peak joint center speeds occurred in a proper sequence from proximal to distal segments and finally to the javelin at release. Release speed correlated significantly with throwing distance in both male and females.

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Anton Arndt, Gert-Peter Brüggemann, Mikko Virmavirta and Paavo Komi

This study was concerned with identifying important flight characteristics of the ski jump at the end of the early flight phase and describing how these characteristics developed from the run-in through the takeoff and during the early flight phase. The K90 individual competition of the 1994 Olympic Winter Games was analyzed. The 2-D data (takeoff) were collected by a high-speed video camera, and the 3-D analysis (early flight) used an algorithm whereby two cameras followed the jumpers through the early flight phase. Center of mass (CM) velocities at takeoff and after early flight and CM heights at these positions had no significant linear correlations with total distance. Only small differences in these parameters were distinguished between better and poorer performers. Significant differences between jumpers were identified in angular parameters at takeoff and in early flight. A combination of five defined flight angles yielded an R 2 value of .84. It was found that the complex movement sequences involved in ski jumping were therefore more important in their contributions to optimal flight position than the ballistic properties of the ski jumper reduced to a single point model.

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Aimée C. Smith, Jonathan R. Roberts, Eric S. Wallace, Pui Kong and Stephanie E. Forrester

Two-dimensional methods have been used to compute trunk kinematic variables (flexion/extension, lateral bend, axial rotation) and X-factor (difference in axial rotation between trunk and pelvis) during the golf swing. Recent X-factor studies advocated three-dimensional (3D) analysis due to the errors associated with two-dimensional (2D) methods, but this has not been investigated for all trunk kinematic variables. The purpose of this study was to compare trunk kinematic variables and X-factor calculated by 2D and 3D methods to examine how different approaches influenced their profiles during the swing. Trunk kinematic variables and X-factor were calculated for golfers from vectors projected onto the global laboratory planes and from 3D segment angles. Trunk kinematic variable profiles were similar in shape; however, there were statistically significant differences in trunk flexion (–6.5 ± 3.6°) at top of backswing and trunk right-side lateral bend (8.7 ± 2.9°) at impact. Differences between 2D and 3D X-factor (approximately 16°) could largely be explained by projection errors introduced to the 2D analysis through flexion and lateral bend of the trunk and pelvis segments. The results support the need to use a 3D method for kinematic data calculation to accurately analyze the golf swing.