Backhandspring performance model by cluster analysis

The backward handspring(BH) is a basic skill action used in the back tumbling passes on the floor exercise. It's also performed as a great deal on the beam and it represents the fundamental action of the Yurchenko vault elements. It was hypothesized that some BH biomechanical variables were significantly correlated and that they could identify the movement model. The aim of this work is to highlight the most important temporal, spatial (linear and angular), and kinematics relationships for this movement. 5 Italian female gymnasts aged 10 to 14,competing for 2 local clubs, performed several repetition of round-off(RO) and BH. Statistic analysis has been done on data extracted by the 3d trajectories of 46 markers displaced on the gymnast's body recorded by an optoelectronics system(Vicon 3000pixel;100Hz). The center of mass(COM) location was identified according to the Davis-Kadaba proceeding. The variables were selected from the technical evaluation rules and in reference to the specific literature[1-4]. Starting from two correlation matrixes, for the first(1) and second(2) flights(FL) phases’ variables respectively, we have applied and then compared both the non-hierarchical and the hierarchical cluster analysis methods. The results show that the 1FL phase’s clusters are stronger than the 2FL ones and, that the clusters individualized with the two analysis methods are very similar. For the 1FL there are 2 enough complex clusters. In the first the hip(h), knee(k) and ankle(a) ROIMP angles(A) are tightly correlated among them and, with the delta gathering and pushing’s kA and, with the vertical velocity(Vz) at the ROIMP. The second cluster includes the aA takeoff(TKO) that is significant correlated to: - the maximum gathering Ha - the feet(F) SUPP time, the COM position versus the SUPP base both at the FIMP and TKO - the ROIMP horizontal velocity(Vx) - the gathering hA. The 2 clusters that grouped the next variables are: 1. The COM vertical lift, the 1FL time and, the F TKO kA. 2. The FTKO hA, the FTKO Vz, the vertical COM pushing during the FSUPP phase. The most important correlations for the 2FL are in the following clusters: 1. The 2FL time, the HTKO Vz; the 2FL space and the 2FL’s COM vertical lift. 2. The HIMP hA, the HTKO aA and, the COM’s vertical push space during HSUPP phase. The results show that is possible describe a technical model for the BH through clusters analysis and,how both the biomechanical and technical variables, evaluated by judges, are correlated among them. REFERENCES 1–DILLMAN C.J.et al“A kinematic analysis of men’s Olympic long horse vaulting”IntJouofSpBiomech,Vol 1,1985. 2– DAINIS A“Cinematographic analysis of the handspring vault”ResQuart,Vol50,n.3,1979. 3–TAKEI Y.“Comparison of on-horse mechanical variables between two handspring category vaults performed by elite gymnasts”Med&Sc inSports&Exercise Vol34(5) Suppl 1,2002 4–MERNI F.et al“3D biomechanical analysis & artistic gymnastics”XIVthIntConfonMechinMedandBiol. Bologna,Sept2004.