Having a strong core is paramount in having good posture, ensuring you don't injure your back and having all over strength. When people think of core we often think of crunches, which actually aren't the best exercise because of the amount of flexion it puts on the spine! Here are 6 exercises that are way better and more beneficial then the typical crunch to add into any exercise regime. 

1. Pikes *can be performed with shins on stability ball
Place feet in TRX start in plank position, push hips and bum up into the air and then slowly lower back into plank position. Do not let hips drop down from plank position! 10x 3 sets. 
Difficult

2. Ab Roller
Start from knees (cushion underneath them), start with roller under shoulders and press out away from body. Lower slowly so you are in a hovered position, then bring roller back under body so you're in starting position. This is a difficult move! Requires shoulder stability 10x 3 sets
Difficult

3. Supported Rotation
Back and neck are supported on the ball, hips are high in line with the ball. Have the weight extended directly over you keep core tight, arms straight, lower weight to one side without dropping or moving hips. Bring back to middle position and out to the side. This is a great oblique and transverse abdominal move 10x per side 3 sets
Intermediate

4. Deadbug with Stability ball
Arms are extended ball supported between arm and legs, knees are bent as picture. Lower right arm, and left leg so they are both straight and in line with your body. Keep core super tight, repeat and do other side. 10x per side 3sets
Intermediate

5. Ball v-sits
Start with ball in between hands and then bring upper body towards lower body keeping a straight tight core. Pass ball to feet and lower down slowly. 10x 3 sets
Intermediate 

6. Plank on ball Circles
Plank on ball with forearms, make little circles with forearms in one direction and then change directions. 10x per side 3 sets
Intermediate (put knees on ground to make it beginner)