Prostaglandins is one of the chemicals released in response to microtrauma. If the body isn't used to it, you experience pain. Once you follow a regular and productive routine, you don't experience this pain since you're now accustomed to the prostaglandins - but the microtrauma STILL HAPPENS. If you want to explain the lack of hypertrophy with the lack of DOMS - what about the thousands of athletes worldwide who experience excellent hypertrophy with no DOMS?
To keep the DOMS up, you either need to drop frequency (which we know isn't too productive), go on a strict diet (which also isn't too productive), or increase the tension and/or duration of loading from workout to workout dramatically - which we know is productive, but it's beyond me why you think it's easier on the connective tissue to do this in a way that induces DOMS every workout.
- The degree of tension and duration of load necessary to induce DOMS after several weeks of frequent training would most likely induce damage that is counterproductive to the hypertrophic process. Demonstrated numerous times in research.
- The MAPks associated with loaded or passive stretching (erk1/2) have lesser importance for hypertrophy compared to the p38 associated with eccentrics (2-3 secs).
- Do not assume that the swelling and inflammation associated with potential disruptive overload of tissues is productive (rather the contrary). DOMS or no DOMS.
- Train through the DOMS (I agree with that) since it is just a temporary pain signal from the prostaglandins released after non-fatal damage to cells associated with mechanical overload of non-conditioned tissues.
We're not after remodeling of tissues, you can't achieve that with regular weight training anyway. We want:
- frequency, which elevates the MAPks, ribosome and mRNA activity, and protein synthesis associated with hypertrophy on a regular basis.
- progressive increase in loading, necessary to induce the tearing of sarcolemma (leaking out growth factors into interstitial space, stimulating cells in paracrine and autocrine fashion). This progressive increase is necessary due to the buildup of connective tissue which protects (conditions) the muscle to the load you used previously.