Coughing Can Break Bones!

Whoa! I knew muscles were strong, but this is incredible. This 59 year old man, suffering from chronic bronchitis, coughed so much that he broke his own ribs! (He also had house-dust allergies and was an ex heavy smoker, which I believe had loads to do with his situation. * Smoking compromises the calcium in your bones and, obviously, the lungs.)
Coughing is the body's way of expelling something from the air cavity which doesn't belong ~ fast. How can that break ribs? The diaphram's action is to contract, thereby drawing air into the lungs.  On exhalation it normally relaxes... unless you are coughing.   The diaphragm contracts when you cough. (Okay Germs, everybody OUT!) So do your abdominal muscles, which could push the guts - stomach, intestines, etc. - up into the diaphragm.   These contractions, combined, causes the ribs to bend inward and down. If the cough is violent enough, all these sudden opposing actions will strain the ribs to the point of breaking. Yikes! The most common breaks happen on ribs 5 through 9.
Don't worry. The man is okay. Though he did have it pretty rough for a while. He had to be intubated for 6 days to prevent coughing, and have his torn muscles repaired... He is now home and healthy. Phew...  Really glad it turned out okay!