Hi Koger,
Excellent question and one I deal with everyday. You're absolutely correct in regards to the "stimulus, followed by recovery for improvement" notion you lay out. The trick here is to know WHEN to purposely increase training load to result in "overreaching" and subsequently "improvements in fitness" and when to BACK OFF on training load to allow the body to rebuild stronger.
Both are correct, based on 1) the time of year of the training block 2) the current fitness and recovery level of the individual and 3) the demand for overreaching.
Typically, during the off-season and early season build blocks, like in my Cyclo-PLAN 4P, it is NOT advisable to continue to overreach your fitness as this period of time is FOUNDATIONAL in nature and moving into an intense workout when your body is commanding rest, will only lead to catabolism of the work previously done.
That being said, there are periods during our P2 Build Plans and definitely our P3 PEAKING PLANS where absolutely YES, you want to increase training load ON PURPOSE to result in overreaching. It is the individual that struggles to "know the difference" and to know when and how much to "execute" that problems set in. Usually, a result of the "if a little increase in training load is good, a lot, all the time--must be great!!" Yah, that will get you in some trouble.
Something to think about...
You always want to be pushing the body further through increases in stimulus, BUT that does not mean that every workout has to be gut-busting hard, like a Z4-5+ workout to achieve that. In fact, most of our toughest workouts in http://cyclo-club.com do not involve high HR's (cardio-respiratory stress) at all, but rather attack the body from weak areas such as the core, back, muscular endurance, flexibility, neuro-muscular performance, etc. THIS IS THE SECRET to be able to add more training days to your plan when you're fatigued in one way from a bike workout and can move to a Cyclo-CORE like training workout on the opposing day, allowing your body to recover. As training load increases from phase to phase, obviously you will see a marked improvement in recovery (you should, or something else is wrong) and the ability to add more intensity training load as you get closer to your goal.
Last thing...
Never, ever make the common everyday cyclist mistake in thinking that your "high end fitness" can always be improving month after month, etc. THIS is why so many of us cyclists continue to ride more and more (junk miles) and achieve MUCH LESS in tangible results because we're simply GETTING IN THE WAY. This is the discipline we discuss in our Everyday Cyclist Podcast that I think you'll enjoy regarding many of these issues.
I hope this has been helpful, my friend. You've got a good head on your shoulders. Listen to your body, and you are NEVER WRONG!
Best,
Graeme Street
Owner for Cyclo-CLUB and Creator for Cyclo-CORE Training