SELECT * FROM `category`
JOIN `category_typed` ON `category`.`id` = `category_typed`.`category_id` WHERE `category_typed`.`user_id` = 1
JOIN `category_average_speed` ON `category`.`id` = `category_average_speed`.`category_id` WHERE `category_average_speed`.`user_id` = 1
Сабж. MySQL ругается:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'JOIN `category_average_speed` ON `category`.`id` = `category_average_speed`.`cat' at line 4