I see people making a lot of mistakes in the gym, so I've compiled a list of the four most common lifting techniques. While it's a good idea to avoid bad technique, certain forms of cheating are okay if you are just trying to push that last rep out. Granted, I think it's better to just get assisted and use proper technique, since it reduces the risk of injury (at a slightly lower payout). Believe me, tearing your muscle or ligament will set you back a lot further than not doing cheat reps throughout your entire weight lifting career.

Anyway, here are the four most common lifting mistakes:

Leaning forward on the squat: This is one of the most dangerous lifting mistakes and something that you should avoid at all times. While you should lean forward a little bit when squatting, many people completely bend their back, curving it and making their spine susceptible to injury. When you lean forward to balance yourself, it should be at the hip, and you should only lean forward 20 degrees at most. This lifting mistake will cause serious injury if done incorrectly.

Barbell bouncing on the bench: This is another common mistake that, while relatively harmless, will greatly affect your gains. When you're doing the bench press, you are supposed the resist the weight on the way down, and then explode up without it touching your chest. The first portion of the push uses your chest, while the latter half uses your triceps. By bouncing the weight off your chest, you are harming your workout in three ways.

First, you are giving your muscles a period of rest by letting the weight rest on your chest for a moment.

Second, you are missing out on almost the entire chest part of the exercise, since the momentum will carry it past that threshold.

And third, you are losing control of the weight, which can increase your risk of injury. When you let the weight carry itself, you need to exert extra force to regain control of it. If the barbell bounces off at a weird angle, you might as well say goodbye to your shoulders.

Leaning back when curling: This is probably the most common mistake I see happen in the gym. People will grab a barbell and start curling while leaning back in order to help gain leverage. By doing this, they are hurting their gains and running the risk of injurying their back. While doing this on the last set is "acceptable," it is certainly not advisable under any circumstance.

Flaring the elbows out on the tricep cable pulldown: While you don't really open yourself up to injury on this one, you're just hurting your gains. Flaring your elbows out reduces the amount of resistance in the muscle, the range of motion, and just makes the exercise easier overall. I don't suggest doing this, as you're just cheating yourself. Keep your elbows at your sides when doing the tricep pull down.