Relationship between Ground Reaction Force and Attack Time According to the Position of Hand Segments during Counter Attack in Kendo

Abstract

The variability of sports performance is important not only in team matches (Gregson, Drust, Atkinson, & Salvo, 2010; James, Mellalieu, & Jones, 2005) but also in individual matches (Montelpare, McPherson, & Puumala, 2013; O'Donoghue, 2005). Sports performance factors are not as stable as physical measurements or physical examination results (Ogle & O'Donoghue, 2015). Although diverse factors can affect the variability, the biggest factor is the outstanding opponent (McGarry & Franks, 1994). Several sports such as Taekwondo, Judo, Hapkido, and Wushu require stable defenses and swift attacks under different conditions set by the opponent. Among these sports, it is difficult to predict the outcomes of a Kendo match because the outcomes are instantly decided by a valid hit with bamboo swords. Kendo literally means "the way of the sword" (Ogle & O'Donoghue, 2015). Kendo requires the alignment of the synchronization of the spirit, sword, and body. In a Kendo match, the fighter scores by striking or thrusting first (Min, Bae, & Lee, 2001). To win, the fighter needs to use diverse attack techniques and high precision (Min et al., 2001). Broadly, two types of attacks, namely attacking movements and counter-attacks, lead to scoring. Standard attacks refer to simultaneous charging towards the opponent and striking with the sword. The technical characteristics have been defined by Park (2005), who stated that the angle of the left elbow is maintained during the backswing motion in a head attack. Furthermore, the balance between the pushing strength of the right arm and the pulling strength of the left arm leads to a successful strike. Lim (2000) stated that the optimal distance between the striker and the opponent for men and kote attacks were 247 cm and 193 cm, respectively, while the strike times were 1.10 sec and 0.64 sec, respectively. To attack effectively, the tip of the sword should not waver and not deviate from the midline of the opponent's body (Min et al., 2001). During the attack motion, the strength is considered to originate from the left leg, although the right leg moves forward towards the opponent (Broderick, Chart, & Ko, 2004). The stride length of the attacker, distance between the attacker and the opponent, and attack time are known to be important factors that determine the results of the attack (Min et al., 2001). Another method of scoring, counter-attack, takes advantage of the instance when the opponent attacks to land a hit (Ogle & O'Donoghue, Korean Journal of Sport Biomechanics 2017; 27(1): 1-7 http://dx.doi.org/10.5103/KJSB.2017.27.1.1 http://e-kjsb.org eISSN 2093-9752 ORIGINAL