By Matt Tanneberg STACK.com
Any time you round your lower back, you put strain on it—especially your lumbar discs. Sit-Ups are notorious for compromising the low back. Rounding your back during Sit-Ups puts excessive pressure on your lower back, which can cause or aggravate a lumbar disc herniation or protrusion.
Rotation during ab exercises is another risky move. Lumbar discs are most susceptible to harm with the combination of bending, twisting and rotation. There are much safer ways to work your obliques without putting your low back in danger.
Here are some alternatives to those traditional exercises.
Plank
The Plank is the safest and simplest way to work your entire core without putting a strain on your low back.
Forearms or palms should be flat on the floor. Your back should be in a neutral position. Your butt should be neither up in the air nor tucked under. Not only are you strengthening your abs, you are also strengthening your low-back stabilization muscles.
Starting out, hold for 30 seconds with 3 repetitions. Work your way up to holding for 2 minutes with 3 repetitions.
Side Plank
Right forearm is flat on the floor. The outside of your right foot is flat on the floor, and your left foot rests on top of it. Lift your hips off the floor so your body is neutral. Switch sides.
The Side Plank works the transverse abdominis muscle in your abs.
Starting out, hold for 15 seconds with 3 repetitions. Work your way up to holding for 1 minute with 3 repetitions.
Cross Crawls/Bird Dogs
These build strength and coordination within your core.
Get on your hands and knees with your hands directly under your shoulders and your knees directly under your hips. Point your right hand forward and simultaneously kick your left leg back. (Don’t kick your left leg up in the air; kick it directly back.) Hold for 3 seconds then relax.
Perform with your opposite leg and opposite arm, holding for 3 seconds. Do 10 repetitions on each side.
Once you have mastered this, get into a High Plank with only your hands and toes touching the floor. Go through the same motion, holding for 3 seconds.
Table Tops/Bridges
These stabilize the low-back muscles around your spine.
Lie on your back and place your feet flat on the floor so your knees are in the air. Lift your hips to the ceiling; hold the position for 15 seconds then relax.
Do 10 repetitions.
Stir the Pot
This one hits all of your core muscles by stabilizing them as you go through the range of motion.
Get in a plank position with your forearms on a physioball. Stabilize yourself then roll the ball in a circle in one direction. Once you get back to the starting point, roll in the other direction. Keep your back in a neutral position throughout.
Go through a full range of motion as smoothly as possible for 10 repetitions.
Dead Bug
This is a great core exercise but it’ tough to master.
Lie on your back with your arms extended above your head. Bring your knees up to your chest and keep your hips, knees and ankles at 90 degrees. Slowly lower one heel to the floor, then raise it back up to 90 degrees. Your knee and ankle must stay 90 degrees as you lower them to the floor. Engage your core and keep the motion as slow as possible.
Complete 20 repetitions.
Bridge with Alternating Arms & Legs
Lie on your back and place your feet flat on the floor and your knees are up in the air. Lift your hips to the ceiling, hold the position and extend your right arm over your head. Then extend your left leg straight up the air. Bring your limbs back to neutral and raise the opposite arm with the opposite leg. The entire motion happens with your hips lifted.
Complete 20 repetitions.
Source: http://www.stack.com/a/ab-exercises-for-toned-abs-without-straining-your-low-back?
