http://www.med.umich.edu/1libr/sma/sma_abdstrai_sma.htm
What is an abdominal muscle strain?
A strain is a stretch or tear of a muscle or tendon. People commonly call such an injury a "pulled" muscle. Your abdominal muscles may be strained during a forceful activity.
How does it occur?
During a vigorous activity, such as lifting or even hard coughing or sneezing, these muscles may become strained.
What are the symptoms?
You have pain over the abdominal muscles.
At times these muscles may be torn. A tear all the way through the muscles and the covering of the abdomen (called the fascia) may result in an abdominal wall hernia. In a hernia, some of the contents of the belly (intestines and connective tissue) protrude through the tear and cause a bulge in the abdominal wall.
How is it diagnosed?
Your health care provider will examine your abdomen. He or she will ask you to do an exercise such as a sit-up or abdominal "crunch" to check your symptoms. If you have a hernia, your provider will be able to feel and see a bulge in your abdomen.
How is it treated?
Right after you injure a muscle, you should put ice on the area for 20 to 30 minutes every 3 to 4 hours for 2 to 3 days or until the pain goes away. Your health care provider may prescribe an anti-inflammatory medicine. If you have an abdominal hernia you may need surgery to correct this problem.
How long will the effects last?
The effects of an abdominal strain will vary depending on whether it is a minor strain or a more significant strain. With a minor strain you will have symptoms for a few weeks while with a significant strain you may have symptoms for up to a few months.
When can I return to my normal activities?
Everyone recovers from an injury at a different rate. Return to your normal activities will be determined by how soon your muscle recovers, not by how many days or weeks it has been since your injury has occurred. In general, the longer you have symptoms before you start treatment, the longer it will take to get better. The goal of rehabilitation is to return you to your normal activities as soon as is safely possible. If you return too soon you may worsen your injury.
You may return to your normal activities when you can bend at the waist to touch your toes and straighten back up without pain. If you have a hernia, be cautious about doing strenuous abdominal activities and talk to your health care provider about having it repaired.
How can I prevent abdominal muscle strains?
Abdominal muscle strains are best prevented by having well toned abdominal muscles prior to vigorous activities. You can tone these muscles by doing sit-ups or abdominal crunches. You can also use an abdominal exercise machine. It is important not to overdo it when beginning your exercise program. When lifting heavy objects it is important to lift correctly, with knees bent and your back and abdomen straight.

....crap
CHARLOTTE, N.C., Dec. 28 (AP) -- Bobcats guard Brevin Knight is expected to be sidelined at least four weeks because of a torn abdominal muscle.
Knight flew to Philadelphia on Thursday to see a specialist and undergo an MRI, which revealed the tear. Knight will stay in Philadelphia to have surgery Friday.
Knight, averaging 11.9 points and a team-leading 7.3 assists, has been plagued by pain in his groin and abdomen for several weeks. He missed three straight games and five of six before the team decided to send him to a specialist.

...now i`m worried
Abdominal muscle strains are graded according to the severity of the injury:
Grade I (Mild): Mild discomfort, often no disability. Usually does not limit activity.
Grade II (Moderate): Moderate discomfort, can limit ability to perform activities such as crunches or twisting movements.
Grade III (Severe): Severe injury that can cause pain with normal activities. Often patients complain of muscle spasm and bruising.
Surgery awaits pair of Flyers Geoff Sanderson and Mike Richards will miss three to six weeks after suffering muscle tears.
COPYRIGHT 2006 The Philadelphia Inquirer
Byline: Tim Panaccio
Dec. 12--A clinical examination of Flyers winger Geoff Sanderson yesterday at Hahnemann University Hospital showed what his MRI exam did not -- a torn muscle in his abdomen. Sanderson and center Mike Richards will have abdominal surgery this morning and miss three to six weeks, Flyers trainer Jim McCrossin said.

...i pray he wont need surgery