In Exercise: What's your ab workout?: Stretching and Cross Training: Runner's

I work abs/core 4 x per week alternating 2 routines:Day 1/3-- 100 crunches on swiss ball 100 obliquie crunches on swiss ball 20 side crunches each side 100 bicycle crunches 20 reverse cruches 20 V-ups 25 situps on decline benchDay 2/4 100 crunches on swiss ball 50 oblique crunches on each side 20 weighted side crunches 1 minute plank, alternating legs every 15 sec 10 supermans 20 hanging leg raise ...Exercise