Avoid: Tricep Dips on a Bench
You know this one. It's a hugely popular exercise that engages the triceps, but the problem with doing dips on a bench is the position they put your shoulders in, said Neff.
Why you shouldn't do it: At the top of your triceps dip, when the shoulders are locked out, a great deal of pressure is put on the AC joint, which is located just where the shoulder blade meets the collar bone. If your AC joint is already under stress or has previously been injured, this movement can cause damage or even separation. Then at the bottom of the dip, the unnatural position of the shoulder ligament and anterior deltoid (the front of your shoulder) will cause a great amount of pressure as well and can lead to a tear.