Yesterday I was interested to read that Boris Gelfand moved his training camp to the Austrian Alps in order to ‘improve his concentration and stamina’. I’ve never heard of this before in relation to chess training, but the idea seems interesting. Being at altitude training is known to improve your red blood cell count, thus increasing the amount of oxygen that reaches the brain.
A simpler version of this approach is just to get some fresh air before a game, it’s known that air quality deteriorates when you are indoors. My 10 year old son became a firm convert to this approach during his last tournament; he felt it helped him so he dragged me outside even though it was raining, something that had dampened my enthusiasm.
Anyway, here’s an video with some discussion of altitude training. Of course they’re talking about football rather than chess but it still offers some interesting insights.