upper abdominal or under the rib cage?
Could be oblique or serratus strain.
Probably AIDS with a side of cancer...
I can feel my core when I'm holding a dumbbell with my legs or have my legs out in front of me while doing pull-ups, but otherwise, as I'm not a doctor, I have no idea what to tell you besides you might have hurt yourself, and if it concerns you, go see a doctor.
your stomache muscles could be holding up your legs and balanceing the body while the biceps provide the strength ive had this pain before when i first started doing pull ups i think its just the abs being overwoked from balanceing the body it eventually goes away.i sometimes have mine in a knee raise position while im doing pull-ups . do you think that could contribute to it?
when i do my chin-ups i tend to get a very painful strain in my upper abs. anyone know what the reason is?