If the basic crunches on the fitness ball in my all abs workout are starting to feel less than challenging, don’t ditch the exercise altogether – alter the move to make it harder. Here are some simple tweaks to tax your abs more while doing crunches on an exercise ball. Bring your legs together. The closer together your legs are, the harder

it is to keep balance on the ball, forcing your abs to work harder. Slow it down. Curl up and lower on a slow count of three. This takes momentum out of the picture , so the work is all in your belly. Learn three more variations.

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Increase the Challenge: Crunches on Exercise Ball