Well. I used to get them in the 60s when I did The Twist.
I sometimes got them doing sit ups.
They are muscle spasms along your rib cage from excercise.

@flo ”...pain after exercise is pain after exercise, sn’t it?”

Not quite. A stitch is painful but goes away after a few minutes. Compare that to exercise induced pain resulting in a hamstring tear, a stretched Achilles tendon, or an anterior cruciate ligament (ACL) tear. Those pains are long lasting and require checking with a medical professional to insure no further damage occurs.

@zenvelo Re. **A stitch is painful but goes away after a few minutes.’’*
But pain that goes away in a few minutes, can occur anywhere in the body whether it’s after exercise or not, correct or not?

https://medical-dictionary.thefreedictionary.com/stitch
-a sudden transient cutting pain, generally in the flank.
-A sharp, sticking pain of momentary duration.
-a sudden, transient cutting pain.
-A sudden sharp pain, especially in the side.

Whether it’s whenever you wake up, or whatever else… what is the difference?