Sit-ups and leg raises work the midsection in similar ways, but from opposite directions; in sit-ups, the abdomen contracts to lift the torso; in leg raises, the abdomen contracts to lift the lower limbs. Remember, you really don’t need to do both—as I said earlier, there are no “upper” or “lower” abs. Either the abdomen contracts or it doesn’t. So which of these two classics is best?
