I got this term from listening to dev comment on HL2 where they talk about how lengty fight sections can become stressfull to there play testers and how they work about trying to avoid it.

Combat fatigue is that feeling of getting physically tired from being in constant heavy fighting in game, with little to no rest periods.

So my questions is, who gets this, when, and how do you deal with it?

I usualy get combat fatigue after playing 3 or 4 half hour matches in CoD4 against 5+ bots, where there allways another one around next corner. I hardly ever get a break other than those 30 seconds between rounds.

Only way I can deal with is to stop playing and eat something sweet.