Kinematic and Temporal Evaluation of Swings, Stick Length and their Interaction in Field Hockey

Abstract

Introduction: Hit is one of the most fundamental skills in field hockey. The velocity of the ball is a crucial factor for a successful hit. After the change in the rule for hit, since 1982, many players have started hitting the ball with high swing taking the stick above the shoulder level with the belief that with the increase in the swing time, velocity of the ball increases. Many players have started taking circular swing more frequently which appears to be faster with naked eye observation. Theoretically longer is the back swing higher will be the velocity of the ball due to higher momentum in the stick. However in practice it may not hold true. This is well established in the case of jumps and throws (Hochmuth, 1984). There is no comparative study in the literature about short swing, high swing and circular swing in relation to swing time and velocity of the ball and the interaction of stick length with the type of swing. Methods: The study was undertaken on 20 hockey boys who were undergoing regular training for the last 3 years. To evaluate swing time, swing velocity and the velocity of the ball, the hit was filmed using high speed camera (Photosonics, USA) operating at 100 fps. The films were analyzed frame by frame by analyzing projector (NaC, Japan) to compute swing time and velocity of hit in different types of swings. To find the differences between various types of swings and their interaction, two way ANOVA was applied and post hoc analysis was performed using Schaffe's test. The stick lengths used were 34, 36 and 38 inches. Results and Discussion: The results of the present study reveal that short swing takes minimum time (0.13 s ± 0.05 s, 0.14 s ± 0.04 s, 0.16 s ± 0.05 s for 34, 36 and 38 inch stick respectively) and circular swing takes maximum time (0.27 s ± 0.14 s, 0.29 s ± 0.14 s, 0.27 s ± 0.07 s for 34, 36, and 38 inch sticks, respectively). The swing velocity is maximum (46.03 m/s ± 11.58 m/s) and the velocity of the ball is maximum (38.37 m/s ± 11.06 m/s) in high swing using 38-inch stick. The means and standard deviations of total time of contact, stick swing velocity and ball velocity is shown in following table.Table: No Caption AvailableThere are no statistically significant differences in the velocity of the ball in circular swing and short swing. There is no interaction between the stick length and swing time and also between the stick length and swing velocity. However, there is an interaction between the stick length and velocity of the ball. The circular swing has maximum disadvantage as it takes maximum time and the ball velocity is minimum in the hit. If we consider the velocity of the ball taking in to consideration the swing time, it may be concluded that fullbacks may use 38-inch stick with high swing to take 16 yards hit, free hit and penalty corner hit. When the opponent is too close, they may go for short swing. The forwards may use 34 inch or 36 inch with short swing which takes minimum time as their aim is to score goals, give passes and not leaving much chances for opponent to intercept the ball.