Hi there I am so sorry that you have been so badly advised, yoga is a wonderful complement to all physical activities as is pliates, and remember that all power training is actually excelent core training as well, as well as maximal strength work on Dead Lifts and Squats, if you want to use some great finishing core movements at the completion of any of your strength and power workouts, do some of the classical old time strong man exercises such as Turkish Get ups, Samson Sidebends, Zercher lift & squats, suit case dead lifts, full body twists and anything advocated by Pavel Tsatsouline or Bud Jeffries sucj as his side bend and pick up movement, also bent press and windmills, all these can be seen on You Tube or google them up or maybe Steve can do a video for us,
cheers, ashley