3. Balance-ball Crunches

Balance balls are becoming much more popular, primarily because they can make a lot of exercises -- like crunches -- even more successful.

To do this crunch, lie with a balance ball in the small of your back, with your feet apart, placed firmly on the ground.

Do three sets of 12 crunches, and you'll feel your core struggling to keep you on balance.

Fantastic!

Incline Crunches
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