The reason you experience those setbacks whenever you get back to submax is that insufficient input leads to insufficient output. Proper stimulation is required for all of the body’s systems and organs to work properly.
Training is simply a stimulus to the body. This stimulus causes adaptation in the body based on many different factors, with the amount of adaptation being directly related to the amount of stimulus. To maximize adaptation, we want to maximize the information that we put into the body through training.
There is no scientific definition for “CNS Stress”,“CNS Tolerance” as stated above yet (although this is a complex topic well worth separate discussion),and there is none for “relatively weak”,“relatively slow”,or “uniquely gifted”.
When I work with athletes and people I like to think of them as humans. And mammalians when it is horses.