fa International Journal of Kinesiology & Sports Science ISSN 2202-946X Vol. 3 No. 4; October 2015 Australian International Academic Centre, Australia Prediction of Kick Direction from Kinematics during the Soccer Penalty Kick Yumeng Li (Corresponding author) Department of Kinesiology, University of Georgia, Athens, Georgia, USA 330 River Rd, Athens, GA30605, USA E-mail: yumengli@uga.edu Marion J.L. Alexander Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Canada 306 Max Bell Center, Winnipeg, R3T 2N2, Canada E-mail: marion.alexander@umanitoba.ca Cheryl M. Glazebrook Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Canada 319 Max Bell Center, Winnipeg, R3T 2N2, Canada E-mail: cheryl.glazebrook@umanitoba.ca Jeff Leiter Pan Am Clinic, Winnipeg, Canada 75 Poseidon Bay, Winnipeg, R3M 3E4, Canada E-mail: jleiter@panamclinic.com Received: 01-08- 2015 Accepted: 18-09- 2015 Published: 31-10- 2015 doi:10.7575/aiac.ijkss.v.3n.4p.1 URL: http://dx.doi.org/10.7575/aiac.ijkss.v.3n.4p.1 Abstract Background: Speed and direction of the ball are key factors in successful soccer penalty kicks. The kinematics that contribute to the kick direction are unclear. Purpose: The purpose of the study was (1) to compare the differences in instep kick kinematics between left and right kick directions; (2) to determine the significant factors that predict kick direction. Method: Four digital video cameras (80 Hz) collected data from eleven experienced female soccer players during instep penalty kicks to the left and right. Video analysis software (Dartfish Team Pro 6.0) was used to process and analyze the video files. Results: Paired t-tests indicated that several variables before ball contact were different. The linear regression included three variables (support foot orientation, support foot position behind the ball and approach angle) to best predict kick directions (R 2 = 75.6%, p < .01). Conclusion: The results may be useful for goalkeepers to anticipate kick direction before ball contact to gain a better chance to save the penalty kick. Keywords: Instep kick, Anticipation, Goalkeeping 1. Introduction For a penalty kick in soccer the player kicks a stationary ball located 11 m away from the goal line. Two types of kicks are commonly used during penalty kicks: side-foot kick and instep kick (Nunome, Asai, Ikegami, & Sakurai, 2002). The side-foot kick is frequently used to gain accuracy, whereas instep kick is used to increase ball speed (Nunome et al., 2002). The ball speed can be up to 30 m/s (Andersen & Dörge, 2011), resulting in only 0.3 – 0.4 seconds from ball contact to when the ball passes the goal line. The level of difficulty in penalty defense was highlighted by Bar-eli, Azar, & Ritov, (2007) who analyzed 286 penalty kicks in top leagues and worldwide championships. They reported that 80% of the penalty kicks resulted in a goal being scored (Bar-eli, Azar, & Ritov, 2007). In order to increase the chance to save penalty kicks for goalkeepers, several strategies were proposed by previous authors. Kuhn (1987) described late strategy and early strategy. The late strategy indicated that goalkeepers move to one side or another at the moment of ball contact or immediately afterwards, whereas the early strategy involved moving before ball contact (Kuhn, 1987). The late strategy was suggested as a better strategy with a higher rate of successful saves (Kuhn, 1987; Morya, Bigatao, Lees, & Ranvaud, 2005). Another specific strategy was proposed by Bar-Eli et al. (2007). They suggested the optimal strategy for goalkeepers may be to stay in the center of the goal. The probability of saving the penalty kick is higher when the goalkeeper remains in the center (33.3%) compared to jumping to the left (14.2%) or right (12.6%) (Bar-eli et al., 2007). Goalkeepers should also strive to anticipate ball direction using visual cues before ball contact (Lees & Owens, 2011). Savelsbergh and colleagues (2002) investigated differences in anticipation and visual search behavior between expert Flourishing Creativity & Literacy