Oldertimer1: One man's brutal is another man's normal. It's becoming accustomed and adapting to do what is required when smart and logical training is taught. Never underestimate the ability of the human body to adjust to extreme conditions, as far as strength and physical condition is concerned. It can become quite manageable after awhile. Second nature, really.
A loose example might be to take an average 30 year old man, without any athletic background, and train him for a short one mile run. He probably couldn't run a true mile, if a gun was held against his head, at first. If he sticks with it, with proper workouts & recovery periods between, and most important.....a good mental attitude...3 to 4 weeks should show a somewhat easy one mile run. And perhaps, if he stays with the program, he could be running 3 miles without and problem. That original one miles would seem like only a light warm-up for him after a while. Depending on his level of ambition, perhaps half marathons after awhile.
I'm familiar with TRI athletes around Sd county. Some on those men, and women, started in their 40's and a few in their 50's, setting PB all the time.
Montague: Don't know of any special products (suggestion that Clear, and other like coverups, had been a major "helper" in the past ...not so much present day.) Most athletes, power sports included, are directed to complex carb/protein based diet. N.O. may also be added to a supplement program, along with creatine & a whey protein mix.
Just to note: N.O., combined with select amino acids, have been know as a great male sex booster, for some who compare it with sildenafil (viagra), etc.. In any event N.O. & creatine research suggest their aid with memory and general brain health/repair. Just drink lots of water during the day. Good Luck.