After two years of layoff I recently started powerlifting again. Although I restrained myself to ridiculously low weights, the first sessions gave me significant soreness.
I've heard that athletes who come back from a long layoff run the risk of starting with to much greed, and the resulting soreness could cause serious muscle damages.
What are the risks of such extreme soreness?
Intense pain is an indication of injury. The biggest risks for people who come back after an extended layoff is usually (in order of decreasing likelihood):
After a long layoff your recovery and strength has gone down. In many ways you are back to a beginner again--although due to your muscle memory you can get to where you left off much sooner than the first time it took you to get there.
Assuming you haven't injured yourself, I would repeat the initial workout sessions until the soreness between sessions subsides. Once the soreness gets to manageable levels, you can start increasing again.
Soreness is a symptom, rather than the risk itself. One possible consequence of going too hard before your body is prepared is Rhabdomyolysis, where damaged muscle enters the blood stream. Although it is rare, it can be life threatening.
Preventing it includes lowering weight, as you have done, lowering volume, and reducing intensity to start. You probably aren't experiencing rhabdo, but you should probably slow down and reduce volume until you understand the current condition of your body better.
