Nutrition in Physical Endurance Training
I researched nutrition on physical endurance training. It turned out that human body needs a little bit carbonhydrates to improve water absorption. A good ratio is 6-8 % per litre which means, for example, one 375 ml Biokia bilberry juice bottle mixed with 3 litres of water.
Moreover because heavy sweating removes salts from the body, it's good to add 0,5-1,0 grams of table salt to every litre of the liquid.
Finally in case of more energy is needed, eat bananas. One banana, one extra boost. Keep it simple.