>>8841843Ice cold showers are largely a meme, if anything they slightly reduce testosterone due to spiking cortisol. Actual benefits include toughening yourself up psychologically, and if you take them often enough your body's shock response to it probably attenuates a little, so you have a slightly higher chance of survival if you accidentally fall into an icy lake.
http://www.thebroscientist.com/bullshit-cold-showers-youve-told-far/ 