Maximize your strength training routine by cutting out these time wasters.Read article
Crunches are not only safe and effective but also the best exercise for developing the abs.
Spinal flexion (bending the spine forward), as in crunches, has been shown to place a lot of stress on the disks and should be replaced with core exercises that do not flex the spine, such as the plank.
Some fitness “experts” try to make a mountain out of a molehill. The truth is that doing crunches or other exercises that involve spinal flexion is actually safe, healthy and effective.
So keep doing crunches. There are only two times of day when there’s a slight chance they could hurt your back. First, because your disks absorb fluid while you sleep, the pressure inside them when you wake is about 250% higher than before going to bed, thus increasing bending stresses at the disks by about 300%. As the day goes on, the disks become more elastic and flexible. So, if you train first thing in the morning, do your ab work at the end and at least one hour after waking up. Second, when you sit for a prolonged amount of time, disks gain height and decrease lumbar range of motion, which can increase the risk of injury. So if you sit at a desk all day and then drive to the gym, do not train abs as soon as you get there. Do a warm-up on a treadmill for 5 or 10 minutes or train abs last. – FLEX