A strongercorewill maximize your extremity (limbs) strength,speedandpower.Ball crunches, reverse crunches and trunk rotations are great but maybe you need to "kick up your core exercise" to another level.Challenge yourself in the gym with this core exercise: Hanging Hip Raise.
1) Grab the bar a little wider than shoulder width. Hang from the bar with your arms straight.
2) Keep your head/back neutral (straight) and core tight (navel drawn in towards spine) throughout the entire movement. Lift your knees up with hips flexed at approximately 90°.DO NOT USE MOMENTUM TO SWING YOUR LEGS, LIFT YOUR LEGS!
3) Slowly lower legs. That's one repetition.
To further challenge yourself, place a medicine ball between your feet or try the Hanging Straight Leg Raise!