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(gspartan @ Nov. 24 2009,3:10)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Hey Omega,
The gains i do/did get from HST came the first couple of weeks after taking 8-9 days off. Then i realized that i could go on any program after 8 days away from the gym and make good gains the first couple of weeks. Most programs (unfortunately HST as well) work well for 2 weeks then you hit a wall. 1 program has worked for me for more than 2 weeks. I went on it in 1995 which i used with great results for about a year. And the program i'm on right now (after almost one and a half weeks), seems even better than the first one.</div>
There is no way you should hit a wall when following any sensible program of progressive loading after only two weeks so perhaps something is amiss. It takes at least that long to induce any long-term effects from weight training. Like Omega said, what you are interpreting as gains in such a short time are likely just intracellular increases in glycogen and water storage. Real gains in fibre CSA come after a longer period of progressive and frequent loading.
What sort of program have you been following? ie. exercises, sets, reps etc. How's your diet? Have you been getting a decent calorie excess to accommodate any potential gains? Perhaps if you wouldn't mind posting your most recent program, it would enable us to give you some more constructive help.
As far as working out an effective long-term strategy for gains is concerned, you could do a lot worse than to read everything you can find by guys like Bryan Haycock, Børge Fagerli, Dan Moore, Lyle McDonald, Mike Tuchscherer, to name a few. These guys seem to be at the cutting edge of training methodology right now. If you want to try something a bit different to HST, Børge's Myoreps and Dan's Maxstim methods are definitely worth a shot assuming hypertrophy is your goal. Similar to what Mikeynov said, all these guys are giving out very valuable info for free. Don't fall into the trap of thinking that this freely available info is of lesser value than what you will find on some pay-to-play site (eg Build Your Bod 101).
The effects you have seen following a 9 day SD are interesting and no doubt significant. Børge recently posted the following on his MyoRevolution forum:
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">... presentations at the ECSS also showed that two weeks of rest (after a period of heavy loading) gave an unexpected boost in satellite cell proliferation which was somewhat surprising to the researchers. There was no time-course data, so we do not know whether one week is sufficient, but striking a balance between neural and tissue deconditioning would theoretically make one week a viable compromise (9 days to be more exact, last workout friday, first workout monday the week after the rest week).</div>
Incorporating some kind of SD into your training regimen seems like a smart move.