2. BICEP TENDON RUPTURE. This tendon attaches the bicep muscle of the arm to a bone in the forearm, and if you attempt to curl a too-heavy weight or suddenly drop the barbell or dumbbell, you’re risking a tear. "The arm turns black and blue, and the biceps muscle actually appears larger," says Geier.
Prevent it: As with the chest muscle tear, work with a weight you know you can handle and always engage the help of a spotter.
3. LABRAL TEAR. Ever hear a catching or clicking sound deep in your shoulder while on the chest press or military press? This could spell trouble brewing. More specifically, the cartilage bumper that surrounds your glenoid—the shoulder’s ball-and-socket joint—could be giving way. (Say it with us now: ouch.)
Prevent it: Labral tears typically don't happen overnight, so if you hear that dreaded click—or feel any uncomfortable popping or pain deep in your shoulder—don’t be a dummy. Get that shoulder get checked ASAP, says Geier. (Relax. You'll likely just need to make some simple modifications to your workout until you're healed, such as reducing your range of motion.)