Once the leg press machine is set up correctly, leg presses are a safe exercise to do. But like most equipment, the setup is key. You will need to adjust the seat to make sure it is in the right position. Also, the foot plate if you can.   You should be comfortable in your seat and not over stretching or feeling cramped. Try to keep your hands on or close to the safety spotters just in case you need to pull them.   Make sure you go through some warmup sets to ensure the seat and footplate are correctly positioned.   The leg press is an exercise that you can lift a lot of weight, especially if you are cheating. By cheating I mean using poor form where you are not focussing your effort on your quads. Not only is the dangerous and can lead to injuries. It is counterproductive. You leg press to work your quads.  A true Iron Warrior will not boast about their leg press. Their legs do all the talking. So focus on form and be safe.