Obesity comes with its fair share of problems, a major one being back pain. While much of this can be due to the spine carrying excessive weight, some of the pain may be due to weakness of muscles around the area. The major muscles around the area that support the lower back are the abdominals, buttocks and erector spinae muscles. As a general rule, people who are obese should avoid high-impact exercises to protect the spine and joints, but there are several exercises that can be done to strengthen these muscles while also minimizing stress to the spine and joints.
A pelvic tilt works the abdominal muscles which play a large role in lower back stability. To do a pelvic tilt, first lie down on your back. Keep both knees bent up so that you are in a comfortable position. Try to flatten out the curve of your lower back by tightening your abdominal and buttock muscles. Your pelvis should "tilt" backward. To make sure you are doing this correctly, place your own hand behind your back. You should feel your back pressing into your hand. Start out with three sets of 15.
A "bridge" exercises will work your abdominals, lower back, buttocks and thigh muscles. To begin, lie again on your back with your knees bent up so that you are comfortable. Slowly and segmentally "bridge up" by raising your hips from the surface starting with your tailbone. Only raise to your level of comfort, and avoid arching the lower back. Breathe throughout the exercise -- as with all exercises -- and avoid pain. Start with three sets of 10 bridges.
The mini crunch is another exercise that focuses on the abdominals. Again, lie on your back with your knees bent up. Your arms can be behind your head, crossed over your chest or at your sides. Arm position will determine how difficult the exercise is. Arms behind head is the hardest, while arms at sides is the easiest. Once you are in position, curl your upper body up and off the surface you are lying on, arms sliding forward if they are at your sides. Curl up enough so that your shoulder blades come off the surface. Continue breathing throughout the exercise and minimize neck motion. Start with three sets of 10.
This exercises works it all -- erector spinae, abdominals, buttocks, thighs, and even arms. To do this one, you will need to be in the quadruped, or "all-fours" position. Be sure your lower back is neither too arched or too rounded. The goal being to keep the core stable, try and lift one leg from the surface and straighten it out. Then try the other leg. If this is too easy, you can also do the alternating arm and leg lift: raise one arm out straight while at the same time raising the opposite side's leg out straight. Then bring those down and try the other two. Alternate either the leg lifts or the arm and leg lifts, all the while trying to keep your core from "wobbling." Start with two sets of 10 and build your way up as you're able.