You don't give the brain as much blood as normal and the next thing you know, you are looking at the ceiling wondering if those people in white are angels and trying to figure out why clouds are so hard. Inc. Boston, MA Dehydration occurs when you lose more water than you take in. When related to karate this is mostly through sweat and open mouth breathing. Unfortunately, thirst itself may not be enough. When you sweat a lot you always want to make sure you drink a lot, even if you are not thirsty.
Stronger symptoms are headache, mind fogginess and weakness.
WI Several posters recently have commented on the effects of dehydration, noting quite rightly that it thickens your blood, and can result in weakness, decreased performance, and passing out. What I would like to add concerns the effects on the kidney. The more dehydrated you are, the higher in concentration these entities become. The enzymes which are released with the breakdown of the muscle cells is the most destructive part, and can cause damage to the kidney, even to the point of causing kidney failure. This is more likely to occur when the person is dehydrated.