But before you head off to do sit-ups and crunch, true core stability comes from mixing in some unstable exercises to your training regime. This means squatting on a Bosu-ball, using a T-bar for single-leg Romanian deadlift or getting on a TRX for some plank jacks, all of which will test your core and improve your stability when jostling for the ball. Ignore strength training at your peril. Advances in sports science have awoken the soccer world to the positive effects of disciplines like Olympic lifting and general resistance training.