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

IMPORTANT PERFORMANCE FACTORS IN GYMNASTICS FROM A BIOMECHANICAL PERSPECTIVE

Perhaps more than in any other sport, success in gymnastics depends on the ability of the athlete to blend a variety of physical, physiological, and psychological attributes in a routine that taxes the body and mind. Without denying the importance of physiological, psychological, and other variables, this paper (based on Prassas et al., 2006) will discuss performance variables important in putting together a winning gymnastics routine from a biomechanical perspectiv

TECHNIQUE ANALYSIS OF THE 1992 COMPULSORY DISMOUNT FROM THE PARALLET BARS

The purpose of this study was to identify the crucial mechanical factors that determine the successful performance of the 1992 compulsory dismount from the parallel bars. Mastering of the dismount, a backward somersault from a handstand position, is a must for most gymnasts since the great majority of them perform backward somersault(s) dismounts as part of their optional routines. Ten dismounts, recorded during the 1990 United States Gymnastics Federation Championships with a NAC 400 HSV camera operating at 200 Hz, were analyzed utilizing the Ariel Performance Analysis System (APAS). Two dimensional position data of 6 body points (ankles, knees, hips, shoulders, elbows and hands)were digitally smoothed before being submitted to further analysis. Product moment correlations between mechanical variables and the scores given to the dismounts by qualifying judges, indicate that the best predictors of a good score are the vertical velocity at take-off (

REVERSE HECHT (TKACHEV) ON THE HORIZONTAL BAR : A CASE STUDY

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COMPARATIVE STUDY OF GIANT SWINGS ON THE PARALLEL BARS

The purpose of this study was to provide descriptive and comparative data on kinematic data of giant swings on the parallel bars. Fourteen giants were studied. Results showed that, giants on the parallel bars exhibited larger range of motion in all joints as compared to giants in other apparatuses. No significant differences were found between (parallel bars) giants receiving larger or smaller deductions from qualified judges and this may be attributed to the (similar) skill level of the subjects

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 (

TECHNIQUE ANALYSIS OF THE BACK TOSS ON THE PARALLEL BARS PERFORMED BY ELITE GYMNASTS

The back toss (BT), a skill frequently performed by gymnasts on the parallel bars (PB), involves a release-regrasp swing type of motion from a handstand to a handstand position. Mastering the skill is beneficial not only for points awarded to gymnasts by the judges for the skill itself but also for its contribution towards the perfect execution of other PB skills including the most current1 PB dismounts. The purpose of this study was to: I) identify the skill variables best correlating with the scores given to the BTs by qualifying judges, and 2) to identify the differences in technique between the most and least skillful BTs. Seventeen BTs, recorded during the 1990 United States Gymnastics Federation Championships with a NAC 400 HSV camera operating at 200 Hz, were analyzed utilizing the Arid Performance Analysis System (APAS). Two dimensional position data of 4 (for BTs without knee or elbow joint flexion) to 6 (BTs with elbow and/or knee joint flexion) body points were digitally smoothed before being submitted to further analysis. Product moment correlations between mechanical variables and the scores given to the BTs by qualifying judges, indicate that the best predictors of a good score are the shoulder joint angle at regrasp (p = .001), the time the gymnasts were airborne (p = .021), the horizontal velocity of the center of gravity (COG) at release (p = .022), the hip joint angle at release (p = .025), the hip joint angle at release and the minimum hip joint angle (p = .025 and .048, respectively), the normalized maximum height of the COG above the bar (p =.028), the greatest total angular momentum (p = .035), and the shoulder joint angle at release (p = .054). Paired t tests between variables of the most (N=8) and least (N=9) skillful BTs indicate that the discriminating factors are the hip joint angle at release (p = .03), the shoulder joint angle at regrasp (p = .032), time from the smallest hip joint angle to zero degrees of anterior shoulder joint angle (p = .049), and the horizontal velocity of the COG at release (p = .058). Additional factors differentiating the best and worst BTs studied are the time from zero degrees of anterior shoulder joint angle to release (p = .06), and the shoulder joint angle at release (p = .066