Most people’s core strength is compromised because we sit too much and we never developed proper posture. The core provides protection for your spinal cord, supports your skeletal system and supports your vital organs housed in your torso. When the body moves and is exercised correctly, the internal organs are mobilized. This natural mobilization helps keep your organs from adhering together, improves fluid flow through the organs and is very helpful in maintaining normal bowel habits. When key core muscles stop functioning correctly, support for your internal organs is diminished and their function is challenged.
Although the rectus abdominis (the six pack muscle) is part of the core it really is not the most important. The little tiny spinal stabilizer muscles which support your skeleton and insure you move properly are the most important. To improve these muscles you need to work on your posture and do exercises such as planks and Physio (or Swiss) Ball exercises.
Second most important core muscles are your pelvic floor muscles which can be improved by doing Kegel exercises.
Next important core muscles are your transverse abdominis, oblique abdominis and your diaphragm. These can best be improved by performing functional exercises. And lastly, the rectus abdominis is the last muscle (although it should not be forgotten) to focus on. When over worked, as it often is, it creates an imbalance between anterior and posterior muscles which can cause back pain, instability and general back problems.
Two great sources to improve your core are Paul Chek’s book, How to Eat, Move and Be Healthy and finding a good personal trainer who focuses on Functional Exercise.