user12876: It used to be a common problem for me to have very high calculating ability for the first few matches, and then I would make tons a blunders when I play the 10th or more. While for the most part memorizing lines, and having tactics become more inherent is allowing me to play more games, but I still can’t command the high level of analysis I would of at the beginning of the day.
So how do I keep from my brain exhausting?

“Do you drink water during that time? Do you snack or drink soda?”
For the most part, no. I’m in the zone

user7657: Following the general rules for staying physically fit are probably a good idea.  Also getting enough sleep before a match. These things always helped me.  Fischer was noted for staying physically fit.  Also he drank apple juice during play.  Getting up and moving around also would seem desirable, since that keeps your blood pumping as well as providing a temporary distraction from your game, which should refresh your thinking.  There are human limits to endurance though no matter what you do.  I've noticed that as I age (I'm 80), I tend to fatigue sooner than I used too.  There's probably no cure for that. 

12876: <p>It used to be a common problem for me to have very high calculating ability for the first few matches, and then I would make tons a blunders when I play the 10th or more. While for the most part memorizing lines, and having tactics become more inherent is allowing me to play more games, but I still can’t command the high level of analysis I would of at the beginning of the day.</p>

<p>So how do I keep from my brain exhausting?</p>

<hr>

<p>“Do you drink water during that time? Do you snack or drink soda?”</p>

<p>For the most part, no. I’m in the zone</p>
 7657: <p>Following the general rules for staying physically fit are probably a good idea.  Also getting enough sleep before a match. These things always helped me.  Fischer was noted for staying physically fit.  Also he drank apple juice during play.  Getting up and moving around also would seem desirable, since that keeps your blood pumping as well as providing a temporary distraction from your game, which should refresh your thinking.  There are human limits to endurance though no matter what you do.  I've noticed that as I age (I'm 80), I tend to fatigue sooner than I used too.  There's probably no cure for that. </p>
