I was thinking.....why is rounding the back slightly on squats a bad thing? Wouldn't that just strengthen the back even more by doing so? I normally don't round the back but every now and again I do..any thoughts?
"One of the most, if not the most critical factor in squatting is spinal position. It is incredibly important not to round the back. This can lead to problems with the lower back, and upper back as well. The back should be arched, and the scapulae retracted, to avoid injury. This position must be maintained throughout the entire lift, as rounding on the way up is even more common than rounding on the way down, and people who make this mistake are the ones who perpetuate the “squats are bad for your back” myth. Furthermore, spinal position is essential to maintaining a proper combined center of gravity (CCOG). The farther one leans forward or, even worse, rounds the back, the more strain the erectors are forced to bear, and the less the abdominals can contribute to the lift. To say nothing of the fact that the greater the lean, the greater the shearing force placed on the vertebrae. Proper spinal alignment will assist in ensuring that the majority of the force the spine must bear is compressive in nature, as it should be. Another reason for descending below parallel is that the sacrum undergoes a process known as nutation (it tilts forward, relative to the two ilia on either side of it). At only 90 degrees of knee flexion, the sacrum is still tilted backward, which inhibits proper firing of the erectors and gluteus maximus and minimus. Going through a full range of motion completes the rotation of the sacrum and allows maximal muscular recruitment."
Why retype it when someone else already said it best.