KINEMATIC ANALYSIS OF UNEVEN BAR DISMOUNTS IN THE 1994 WORLD GYMNASTICS CHAMPIONSHIP

INTRODUCTION - Research related to dismounts has been largely concentrated on the horizontal bar (Park et al., 1994; Kerwinet al., 1993; Takei et al,. 1992). Although similarities between horizontal bar and uneven bar dismounts may exist, differences should also be expected due to (among other things) differences in the physical characteristics and design of the apparatuses. The purpose of this study was to kinematically analyze dismounts from the uneven bars and, when appropriate, to compare the result with existing data from horizontal bar dismounts. METHODS - Eight dismounts (six double layout and two double piked somersaults),recorded during the 1994 World Gymnastics Championships with 2 Panasonic videocameras operating at 50 Hz, were analyzed utilizing the Ariel Performance Analysis System(APAS). Three dimensional position data of 8 (ankles, hips, shoulders and wrists)to 10 (the above, plus knees and/or elbows)body points were digitally smoothed before being submitted to further analysis. RESULTS - Results showed mean shoulder and hip joint release angles of 144 and148 degrees, respectively. All gymnasts released the bar with the center of mass below bar level (Mean = -12.43 degrees),which was similar to data reported by Kerwin et al. (1 993) for triple somersault dismounts and Park et al. (1 994) for triple and double layout somersault dismounts. Center of mass horizontal release velocities(Mean = 1.33 mlsec) were similar to those reported by Park et al., 1994, Kerwinet al., 1993, and Takei et al,. 1992 for male gymnasts. However, vertical release velocities(Mean = 3.53 mlsec) and consequently maximum height above the bar (Mean = 0.28m), were substantially smaller that those reportedby Takei et al. and Park et al. CONCLUSION - Results indicate that although the general pattern for uneven bar dismounts is similar to the one for horizontal bar dismounts differences exist warranting that specific instructions be given to athletes. REFERENCES Park, S.S., & Prassas, S. (1 994). A comparative analysis of the triple backward somersault and the double backward somersault on the high bar. In A. Barabas & Gy.Fabian (Eds.) Biomechanics in Sports XI1(pp. 252-254). Hungarian University of Physical Education.Kerwin, D., Yeadon, M., & Harwood, M.(1993). High bar release in triple somersault dismounts. International Journal of Sport Biomechanics, 9, 279-286.Takei, Y., Nohara, H. & Kamimura, M.(1 992). Techniques used by elite gymnastsin the 1992 Olympic compulsory dismount from the horizontal bar. International Journalof Sport Biomechanics, 8, 207-232

EFFECT OF EXTERNAL APPLICATION OF SEMICONDUCTORS ON MOTOR PERFORMANCE: CASE STUDIES

INTRODUCTION AND PURPOSE In order to enhance motor performance, humans have utilized a variety of agents and/or techniques. External application of semiconductors has been currently advertised as a stimulus and as an enhancer of muscle performance. If the claim is correct, one could hypothesize that external application of semiconductors, such as germanium, may positively enhance motor performance. Discovery of a non invasive, effective and safe performance enhancer will be of definite value. Thus, the purpose of this study was to investigate the effects of external application of germanium on motor performance. METHODS Two motor tasks, vertical jumping and kicking, were investigated. An experienced kicker and a student participant in a University activity class participated in the kicking and jumping tasks, respectively. A NAC 400 High Speed Video Recording System was utilized to record ten kicks performed by the subject. For the first 5 kicks (condition A), the subject was wearing germanium imbedded cloth knee wraps (Goode Wraps, Reno, Nevada, USA.). For the next 5 kicks (condition B), the subject was wearing cloth knee wraps without germanium imbedded in them. Prior to videotaping each group of kicks, the subject sat quietly for 20 minutes and then exercised at the same level of intensity on a stationary bicycle ergometer for a period of five minutes. The same protocol was utilized during vertical jump data collection with the addition of a Kistler force plate to simultaneously collect force data and with the subject wearing ankle wraps and (Stromgren) shorts imbedded with germanium in addition to knee joint wraps. Jumping heights were calculated utilizing force plate data. All kicks and the best trial from each group of jumps (based on jump height) were digitized utilizing an Ariel Performance Analysis System (APAS). RESULTS AND CONCLUSION Kicking results showed that maximum ball velocity, knee joint angular velocity, and thigh and shank angular velocities at contact were larger in condition A than in condition B (26.5 d s , 802 deg/s, 382 deg/s, and 11 83 deg/s vs. 25.6 d s , 785 deg/s, 344 deg/s, and 1130 deg/s for conditions A and B, respectively). Paired t-tests, however, showed that the differences between the two conditions were not statistically significant (

EFFECT OF FORCE CHARACWRISTICS AND REACTION ABILITY ON VERTICAL JUMPING IN YOUNG BASKETBALL PLAYERS

INTRODUCTION AND PURPOSE A vast quantity of scientific literature exists on the mechanisms and determinants of jumping ability. Yet, the influence of a) the maximum isometric push-off force, b) the speed by which maximum push-off force is developed, and c) the reaction ability to drop jump on the effective use of horizontal and drop vertical velocities in vertical jumping has not been thoroughly investigated. It was, thus, the purpose of this study to investigate the relationship and influence of these parameters on vertical jumping in young basketball players. Nine young male basketball players (age: 13.34 yrs; height: 1.71m; weight: 60.2 Kg) were tested on: a) maximum isometric push-off force (F-); b) vertical countermovement jumps with (CMJw) and without (CMJw,) the use of the arms; c) vertical jump from a flexed hip, knee, and ankle joint position (SJ); d) drop vertical jumps from heights of 18 (DJ18), 36 (DJ,,), and 42 cm (DJ,,); e) vertical jumps with one step (CMJ,), and horizontal velocities of 1.5 (CMJ,), and 2.2 mlsec (CMJ,); and, f) vertical jumps with self-paced horizontal velocity with (CMJ,) and without (CMJ,,) the use of the arms. Two pairs of photo cells, and two 1-D dynamometers were used for data collection. RESULTS AND CONCLUSION T-test results showed no significant differences (

EVALUATION OF AN EXERCISE PROGRAM BASED ON SELECTED SPEED AND STRENGTH CHARACTERISTICS IN ELITE FEMALE VOLLEYBALL ATHLETES

INTRODUCTION -The Purpose of this study was to: a) identify the strength and/or speed variables that determine jumping ability and b) evaluate the effectiveness of a training program attempting to modify these variables. METHODS-Sixteen highly ski lied female volleyball athletes, equally divided into control and experimental groups, were tested tor: a) maximum knee joint extension isometric strength (F.....' knee and hip joints at 90°), b) counter-movement vertical jump with (CMJ1) and without (CMJ2) the use of the arms, c) vertical jump from a flexed (hip, knee and ankle joint) position (SJ), without counter-movement, and d) drop vertical jump (OJ), dropping fram a height of 40cm. Regression analysis revealed that the best predictors (

KINEMATICS OF GIANT SWINGS ON THE PARALLEL BARS

The purpose of this study was to investigate the kinematics of giant swings on the parallel bars. A secondary purpose was to compare giants executed from a cast to the giants following, and to compare skilled vs. unskilled performances. A total of eight giants were studied. Results showed that, with few exceptions, giant swings performed on the parallel bars exhibit similar motion patterns to giants performed on other apparatuses. Between-apparatus differences in motion patterns at the knee (quantified), elbow and radioulnar (not quantified due to substantial out-at-plane components) joints were attributed to limitations mostly imposed by apparatus design. Skilled vs. unskilled differences-most pronounced at the shoulder joint-were related to both timing and ROM issues

TEMPORAL CHARACTERISTICS OF THOMAS FLAIRS ON THE POMMEL AND FLOOR

To perform successfully on any apparatus, gymnasts must execute skills with creativity and virtuosity. Whereas creativity is demonstrated by introducing new skills, combining existing ones, or adapting skills to different apparatuses, virtuosity is expressed by executing skills with exceptional technique (Prassas et al. 2006). The Thomas Flairs (Fig. 1), originally introduced and performed on the pommel horse, have been adapted on other apparatuses including the floor. Understanding the timing of the different phases of the skill and what effect the different physical characteristics of the two apparatuses may impose on that timing, would be valuable to coaches and gymnasts seeking to improve performance, judges evaluating gymnastic routines, and scientists studying motor skills

GIANT SWINGS ON THE PARALLEL BARS: A CASE STUDY

Giant swings, routinely performed by gymnasts on the high bar, rings and uneven bars, have been the subject of several investigations (Arampatzis & BrOggemann, 1998; Prassas, Papadopoulos & Krug, 1998; Yeadon & Brewin, 2003). They have not been studied, however, on the parallel bars, where they have been introduced only recently. The purpose of this study was to investigate the kinematics of giant swings on the parallel bars

ANALYSIS OF DROP JUMPS WITH AND WITHOUT CONTROL OF CONTACT TIME

The purpose of this study was to compare drop jumping from various heights with and without controlling for contact time. Twenty healthy individuals performed drop jumps from various. Preliminary EMG, power, and kinematic results showed some changes in motion patterns when controlling for contact time. Those patterns, however, did not significantly alter the height jumped

THOMAS FLAIRES ON THE POMMEL AND FLOOR: A CASE STUDY

To win bonus points, gymnasts must execute skills with creativity, virtuosity, and consistency. Creativity is demonstrated by introducing new skills, combining existing ones, or adapting skills that were initially performed in a particular apparatus to other ones. Virtuosity is expressed by executing skills with exceptional technique. The Thomas Flaires (circles performed with the legs split as shown in Figure 1) were originally introduced and performed on the pommel horse, but have since been adapted on other apparatuses including the floor exercises and parallel bars. Understanding the complexity by which consecutive Thomas Flaires are performed and what effect—if any—the different physical characteristics of the two apparatuses may impose on the execution of the skill would be valuable to coaches and gymnasts seeking to improve performance, judges evaluating gymnastics routines, and scientists studying motor skills

EFFECTS OF A 10 WEEK TRAINING PROGRAM ON PHYSICAL CONDITIONING AND INSTEP KICK KINEMATICS IN SOCCER

The instep kick is the kick of choice in soccer scoring and passing over medium to long distances. Its success depends on many factors including the strength of the muscles responsible for the actions of the (kicking lower) extremity, the rate of muscle force production, the synchronization and energy transfer between lower extremity segments (Plagenhoef, 1971), the linear approach velocity (Opavsky, 1988) and approach angle (Isokawa and Less, 1988), and the ability of muscle to utilize effectively the stretch/shorten cycle (BOhrle, 1985). Ultimately, on a given kick, the velocity of the kicking foot and the point of (foot) force application on the ball determine the trajectory characteristics of the ball. Other factors such as flexibility and aerobic/anaerobic capacities also determine the ability of players to successfully perform in a game. The purpose of this study was to study the effects of a 10 week training program on selected physical conditioning and instep kick kinematic parameters in soccer