What's going to happen with front squats is that your upper back and quads will get stronger when compared to a back squat (high or low bar). That is due to the slightly different leverages involved with the lift. 225 lb front squats are really good.
As to spine compression, consider the following:
- The musculature you build up braces your spine in addition to lifting the weight. That means the weight is distributed so that the spine is not supporting all the weight.
- The spine is comprised of disks separating the vertebrae which are designed to handle a certain amount of compression.
- That said, there is some compression, but it should only be of concern if your spine is not healthy or your technique is wrong.
I'd like to clarify what I mean by incorrect technique:
- No two squats will be identical, as individual leverages affect how they look.
- Bad technique is where the load is transferred to the spine rather than being supported by the musculature.
- Bad technique is when due to how you muscle the bar you cause stretching or compression of the discs beyond normal operation.
The front squat has the following advantages:
- The back is in a more neutral position, which is advantageous for bearing load. The more the back is vertical, the lower the chance for injury.
- The bar will fall off your shoulders before you get in a position where the back would be in danger.
Basically, as long as you are maintaining good form (which is quite necessary for a 225 lb front squat), there really isn't much to worry about from a long term perspective. Elite level weightlifters are able to front squat over 500 lbs without ill effects. The number of spine related injuries vary based on strength sports. The greatest risk being sports that deadlift, both due to the weight lifted and what it does if the lifter's back buckles at all due to fatigue.
