Science hasn't been able to prove the cause of DOMS, or why some people suffer from it more than other.

The general theory I tell my clients is that it is a result of micro tears in the muscle fibers that results in inflammation.

These micro tears are more likely to occur when trying new exercises. Or exercises that have not been done for a while.

Different exercises recruit different muscle fibers which might not be use to the strain, thus leading to tears/inflammation. It is completely normal and natural.

From my experience DOMS is affected by ones genes as well. Some clients will never get it, regardless of how intense and new an exercise or workout routine is. While others will get them all the time no matter what.

I have found that supplementing l-glutamine (an amino acid) before and after exercise helps minimize the negative effects.