If an athlete does not lift with correct form then it will all come crashing down in due time. I myself have been able to work up to a 515 pound squat weighing 167 pounds, but have NEVER had a single injury. Let me reiterate that. I have been putting anywhere from 250-450 pounds on my back every single week for the past 4 years. Thousands of reps. No injuries. Not once. Now some people think that I am lucky or I must not be injury prone. I think the latter is true but luck has nothing to do with it.
If you lift weights with bad form, like for example you squat above parallel here are the negative consequences.
- You use more weight than your body can handle. Hurting recovery and over-straining your CNS. And most importantly, increasing the chance of a serious injury!
- The muscles used aren't even the same! In the squat you need to reach parallel to hit the glutes, hip flexors, and hamstrings. If you are quarter squatting, you are only hitting the front of your thighs!
- Progress is hard to measure. If you don't squat to parallel, then when do you stop? Wherever it feels comfortable? What will end up happening is you will adjust your depth to the weight you use, so you will never know when to stop increasing the weight since it gets easier actually because you are shortening the ROM.
- It won't be fun! If you are constantly struggling with weight that you can't handle, it flat out will not be fun. And if something is consistently stressful and not fun, you will not do it. That simple.
Here are some videos I made demonstrating proper form for both the squat and deadlift. Note how it is clear that I can handle the weight I am using. Even though I go till failure on the squat, I still am not shaking or having my back bend all over the place. With proper form, you can go as hard as possible, with little to no risk of injury.