Use heavy negatives on the dip machine for triceps. I absolutely love doing these. It's an effective, safe way to overload your triceps with heavy loads.
Have someone help you do the concentric portion of the lift. Then do the eccentric or negative portion by yourself. Take a few seconds to lower the weight.
Nobody cares about injuries (boring!) until they get one. That's too bad, because sooner or later your knee, shoulder, hip, or back is going to start barking like a coonhound on the hunt. Even babes aren't immune.