The subscapularis tendon can tear in young or old individuals due to specific mechanisms, such as eccentric loading into external rotation or abnormal stretching.

“Now the one down below shows the subscapularis in the front and that is the one that can tear in young people or older people based on mechanism so if you have a linebacker who has he's going forward at full velocity to make and then somebody is knocked into him and shoots him across he's got his arms out there ready to go and he gets eccentrically loaded into external rotation like that that's how you can tear the subscapularis the other way is people falling down stairs and grabbing the banister and wrenching back that way that's the common it's commonly torn with easy stretch got it an abnormal weird stretch where they're Contracting and then it's just torqued on it”