Abstract
The purpose of this study was to investigate double blocking techniques against side attacks with combination attacks in volleyball. 36 occurrences of blocking motions in 3 games（Poland vs Iran, Poland vs Japan, Iran vs Argentina）from the 2011 Men's World Cup Volleyball were analyzed by the Direct Linear Transformation Method. The results were as follows：
（1）When the ball was released from the setter, a middle blocker rotated one foot, put his weight on his directional foot on the spot（this motion saved time）, and then, he took off with two steps（crossover step）.
（2）After the ball was set, the middle blocker moved approximately 2m to the side attacker and jumped diagonally upwards after takeoff because he couldn't arrive at hitting point of the side attacker. When he touched the ball with his finger − tips, he touched the ball in the air as he was jumping upward.
（3）If the middle blocker wasn't very tall, he wasn't able to use read blocking techniques because he wasn't able to arrive at the path of the ball and touch the ball which had been hit by the side attacker. The authors concluded that shorter middle blocker’s only option was to move quickly to block against side attacks.
（4）The side blocker moved approximately 1m in the direction of the attacker after setting and he jumped vertically. The timing of side blocker’s takeoff was faster than that of the middle blocker’s（an average of 0.209 seconds before the left side attacker hit the ball and an average of 0.215 seconds before the right side attacker hit the ball）.
（5）The side blocker was positioned approximately 0.5m at the inner hitting point against left side attacks and approximately 0.6m against right side attacks. The side blocker also blocked diagonal spikes（not in front of the hitting point）.
