[3] Athletes that are actively training lose water and electrolytes from their bodies by sweating, and expending energy.
"[5] Studies show that, contrary to popular belief, the consumption of an electrolyte-containing sports drink does not protect against hyponatremia (low sodium in the blood).
[6] A stated purpose of sports drinks, which provide many calories of energy from sugars, is to improve performance and endurance.
[8] A 2019 meta-review found that "dairy milk may provide either comparable or superior recovery nutrition qualities with regards to muscle protein synthesis, glycogen replenishment, rehydration, and subsequent endurance exercise performance, when compared to non-nutritive, carbohydrate replacement, and (or) carbohydrate-electrolyte alternatives.
[13] Generally, commercial sports drinks contain two-thirds the amount of sugar found in a normal soda.
[15] In the 19th and early 20th centuries, athletes occasionally drank beer of low alcohol content to replenish water, minerals and energy in the body.
[17] However, studies suggest that even a low dose of ethanol decreases endurance performance: it inhibits liver glucose output during exercise, and also impairs psychomotor skills such as reaction time, hand-eye coordination and balance.