Here's the rundown on obliques from Will Carroll at Baseball Prospectus writing for Rotowire:
More than any other injury, the oblique strain seems to have come out of nowhere to place more players on the DL than any other. Was the injury unheard of a decade ago or has something else changed? There are a number of theories. Players, especially those who use creatine, tend to be dehydrated during the season, putting muscles at risk. Players also focus on their abs more. All the abdominal exercise equipment you see on late-night TV strengthens the upper and lower abdominals, without balancing the obliques. Muscle strength imbalances are often the precursor to injury. The regular, unconscious use of the muscle group makes it difficult to heal. Core training, a new conditioning technique, is being rapidly adopted throughout sports and could help correct the ab/oblique imbalance. Until then, watch out for this painful and slow healing injury.
I've seen some other articles that say that these injuries can feel
better in 2-3 weeks. The problem is that even though there is no pain they're not always completely healed and given the unconscious use of the muscles while twisting, sitting up, etc (not even necessarily during game play) they've very easy to reaggravate. It's the type of injury that the guy starts coming back from right at the end of the the 15 day DL stint and then has a minor setback that pushes them into the 4-6 week range.[/i]