By eHow Sports & Fitness Editor
Rate: (2 Ratings)
If you feel like your regular crunch just isn't doing it anymore, you're probably right! Muscles get "bored" after doing the same exercise repeatedly. The double crunch works your upper and lower abdomen muscles because you are lifting both the upper and lower portion of your body. To "surprise" your muscles into working harder, try this twist on the classic crunch.
eHow Sports & Fitness Editor