A COMPARISON OF UNSKILLED AND SKILLED STANDING BACK HANDSPRING PERFORMANCES IN YOUNG FEMALE GYMNASTS
AbstractINTRODUCTION Gymnasts are beginning competition at an earlier age than ever before. Complex maneuvers and routines are a regular part of the training regimen. Most gymnastic skills involve the upper extremity in a weight bearing situation. It has been estimated that over 80% males and 50% females experience wrist pain at some point in their careers. Little attention has been given to this aspect of gymnastics in research studies. P PURPOSES AND METHODS Nine USGF (United States Gymnastics Federation) Level 5 (unskilled) and ten USGF Level 8 (skilled) competitive female gymnasts served as subjects in a study to kinetically and kinematically compare unskilled and skilled standing back handspring performances. Kinetic variables were vertical ground reaction force (GRF), time to peak (TP), a time of hand contact (THC). Kinematic variables were velocities of the shoulder, elbow, wrist, hip, knee, ankle and vertical displacement of the shoulder during hand contact. A secondary purpose was to determine which kinematic factor or factors correlated with GRF, TP, and THC. Data collection instrumentation included the Kistler force plate, operating at 540 Hz, and Peak 2D Video, operating at 120 Hz. Each subject was asked to perform three trials of the standing back handspring over the force plate while at the same time being filmed. Independent groups t-tests with alpha level set at p < 0.05 were used to determine the differences in the kinetic and kinematic variables between the unskilled and skilled groups. RESULTS Results indicated significant differences in the GRF (3.34 BW +0.47; 2.78 BW +0.51) and time to peak GRF (0.025s + 0.006; 0.034s + 0.004) between the unskilled (Group A) and the skilled (Group B) group, respectively. Significant differences were also noted in the linear velocities of the elbow (5.809 m*s +0.519; 6.239 m*s + 0.234), wrist (9.187 m*s + 0.769; 9.737 m*s + 0.521), hip (2.649 m*s + 0.203; 3.199 m*s + 0.281), and ankle (7.452 m*s + 0.641; 8.276 m*s + 0.382) between Group A and Group B, respectively. Thepearson productmoment correlation was used to determine which kinematic variables correlated with the magnitude of the peak GRF, TP and THC. The hip velocity was the only variable found to have a significant relationship to the GRF (r = -.4792), and vertical shoulder displacement (r = .7742) hada significant relationship to THC. CONCLUSIONS It was concluded that skilled gymnasts were able to produce lower GRF and attenuate them over a period of time. The less skilled gymnast is not able to achieve this to the same degree. Skilled gymnasts also were able to utilize the greater amount of shoulder vertical downward displacement to assist them in the catapulting action needed to execute the skill properly. Likewise, skilled individuals were able to produce greater linear velocities in the hip, elbow, wrist, and ankle prior to takeoff which contributed to greater rotary motions. Additionally, the greater hip velocity accounted for 55% of the GEW production. Coaches.should take into consideration the impleme&tion of upper body strength training in their gymnastic programs. Decreases in GEW over a career in gymnastics competition may possible relate to fewer and less frequent injuries of the wrist.
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