Re: Sarge hits the 5x5 for Ginormous Soleus Muscles!! - Log
Um, there seem to be a lot of uncertainties in and in your knowledge of his reasoning (or lack thereof). Dumping the bar is a decent reason to prefer SLDLs over GMs, but it's beside the point because you shouldn't be getting heavy or close enough to failure that it would be an issue, given that you already know that your back is aggravated by lifts that place high demands on it.
Chances are that you could get away with whatever you do if you go light enough, and at some point strengthening your back, and particularly whatever muscle groups are causing an imbalance if that's the cause of the problem, will be a part of your plan. But the chiro's logic and services have produced nothing but the most ephemeral and mediocre results so far, so I'm not sure why you're trusting him now.
T-Nation has an excellent series of articles entitled "Neanderthal No More" about posture, and one of the main things they discuss is lordosis, the extreme spinal arch you just described. It might be worth a look.