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 boost. Keep things simple. Pareto principle for the win.