[Traps]

Get more details about single factor theory and dual factor theory here

(i.e. overtraining doesn't happen in a day, it is mulative fatigue so doing a program for 4 weeks might be quite stimulative yet 10 weeks would kill someone). Also, overtraining is systemic - symptoms include increased reaction time, sustained decrease in performance by 10-15% or greater, sleep disruption, depression, and a bunch of other stuff. You don't get that from a few too many sets one day, that's the body's nervous system breaking down due to high levels of aculated fatigue.

So now you know that fatigue can be aculated as a result of training. Obviously the other result of training is what you are driving for strength, speed, hypertrophy - whatever. This is basically refered to as fitness. Interestingly fitness and fatigue accrue and disipate at very different rates....what is the implication? Well obviously fatigue limits your ability to accrue fitness so maybe it's worth looking at their respective rates of accrual and disipation to see if we can plan a workout program around it. This is not a new or novel concept - this is basically the way training is done for elite athletes all over the world in every sport except BBing which although massively affected by it due to the application of weight training stimulus has managed to keep itself ignorant.

Anyway, this is called fitness fatigue theory or dual factor theory. The overwhelming majority of BBing still look at the world in a single factor framework where you train and recover workout to workout making the timing critical, this model as been shot to living dog by science and has been totally supplanted by the dual factor model as single factor falls appart reliably and repeatedly under different cirstances while the dual can account for and explain the whole lot. This is what is done with theories - get a better one and junk the old one, although in the case of beginners, novices, and lower intermediate lifters the single factor style programming is considered most appropriate.