Kinematical Analysis of Somersault with Twist in Men`s Vault: Focusing on the Lou Yun and Akopian Motions

Vaulting should be performed with all the technical motions required in gymnastics, such as board contact, horse contact, takeoff, somersault, twist, and landing. The degree of difficulty of a technique is determined based on the type of takeoff, the body position during somersault, and the number of turns (International Gymnastics Federation [FIG], 2013). The FIG has classified the types of vault into 5 groups according to the entry types established through the regulatory reform in 2013. The first group includes the forward handspring and Yamashita-style vault; the second group, the handspring with a one-fourth or half turn in the first flight phase (phase from the board takeoff to horse contact); the third group, the round-off entry vaults with a one-fourth turn in a backward direction in the second flight phase (phase from horse takeoff to mat landing); the fourth group, the round-off entry vaults with a half turn in the first flight phase; and the fifth group, the round-off entry vaults with three-fourth or full turn in the first flight phase (FIG, 2013). In the first group, forward somersault technique with a half turn and landing toward the vault is called Cuervo vault, where a technique score is given for every turn made. In other words, 1 turn in addition to the Cuervo vault is the Lou Yun vault, with 5.2 points, and 1 turn in addition to the Lou Yun vault becomes Yeo 2 vault, with 6.0 points (FIG, 2013). In addition, landing by backward somersaulting in group 2 is called the Tsukahara vault, and a half turn and forward somersaulting after the takeoff at this motion is the Kasamatsu vault. The technique score increases as the number of turns increases. Landing after 1 more turn with the body stretched as in the Kasamatsu vault is the Akopian motion, with 5.2 points. A half turn in addition to this technique is the Driggs vault, with 5.6 points, and a half turn in addition to this and landing to the vault is the Lopez vault, with 6.0 (FIG, 2013). As mentioned earlier, the techniques with a greater degree of difficulty in the first and second groups should be based on the accurate performance of the Lou Yun and Akopian motions. As discussed earlier, the scores in the two techniques are the same, and the motions in full and half turns with the body stretched during aerial movement are also identical. Contact with the vault is made after a side turn in the Akopian motion, causing a time difference between the vault landings with the two hands, with the load being inclined to one arm (Dilman, Cheetham, and Smith, 1985). Therefore, increasing momentary elasticity is challenging (Lee, Park, & Lee, 2006; Back et al., 2005). In addition, Lim (2005) argued that KJSB Korean Journal of Sport Biomechanics 2016; 26(3): 243-248 http://dx.doi.org/10.5103/KJSB.2016.26.3.243 http://e-kjsb.org eISSN 2093-9752 ORIGINAL