Oh, what a load of crap!
On workout days (3 days per week) I do in excess of 130 pushups. I'm 65 years old. I must have done over 150,000 pushups in my life.
Yesterday, I did 68 pushups in 90 seconds. I've never been stronger.
When I was a kid, I was big into pullups and held the Jr High and HS records. I can still do 20 pullups, because I do them often.
No sign of any breakage yet.
The people I see at the gym who have broken something are the ones who didn't get enough exercise, ate themselves into obesity and hurt themselves doing something simple.
Its one thing to do pushups or run for yourself... Try running 3 -5 miles everyday on the pavement, I dont mean slow jogging, I mean running.
Try 12, 15, 20 mile road marches with 35 - 60 lbs on your back not including full body armor and weapon, or jumping off the back of a 5 ton military vehicle with all the goodies.
How about push ups with someone elses feet on your shoulders.
My point isnt about complaining about what I swore to do and did do for my nation my point is all that fitness DOES have a price and it can be very high especially as you get older.
If its all so easy then why to only about 10% of military people actually make it to retirement?