The consumption of electrolytes before, during and after exercise is recommended to athletes for a number of reasons, particularly for the purpose of immediate recovery when engaging in back-to-back or extended activities, when water alone will not suffice.
The basis of these recommendations is to sustain total body water (euhydration), as hypohydration increases cardiovascular and thermal strain, and impedes aerobic performance. Vigorous exercise and hot weather induce an excess of sweat production that causes both water and electrolytes to be excreted from the body. These need to be replaced in order to achieve euhydration to sustain athletic output.
The importance of electrolytes before and during exercise is highlighted by the impact of hypohydration on cognitive performance. This has been extensively reviewed with findings elucidating that this might be related to changes in permeability of the blood-brain barrier induced by hyperthermia, thermal discomfort and an increase in the subjective sensation of effort and perceived exertion if hypohydration during exercise is allowed to develop. 
Thus, electrolytes to restore euhydration and sustain thermoregulation during exercise is important in order to avoid a reduction in cognitive, and subsequently athletic, performance.
One study, concentrating on the importance of nutrition in elite soccer players who have limited time between matches, outlined practical nutritional recovery strategies for post-match refuelling. The study noted that rehydration is important for immediate recovery and should occur as soon as exercise finishes, with key electrolytes (particularly sodium) being replaced through electrolyte-containing drinks.
The choice of which electrolytes to use in recovery, however, can greatly impact the outcome of recovery and performance.
A study comparing a variety of non-caffeinated sports beverages on short-term performance following moderate dehydration found that drinks containing carbohydrates, sodium, potassium, magnesium and calcium provided greater rehydrating benefits and enhanced athletic output in comparison to sports drinks that didn’t include these elements.
One popular beverage in particular, coconut water, which is high in potassium and contains sodium, chloride and carbohydrates, has also been scientifically verified, with results showing it is just as effective at promoting rehydration as conventional sports drinks.
To ensure the greatest athletic support, scientific literature outlines the following protocol for the use of electrolytes before, during and after exercise:
- before exercise : electrolyte-containing fluids to help retain any water that has been consumed to establish euhydration prior to starting exercise.
- during exercise : electrolyte consumption along with water is recommended when exercise duration extends beyond two hours, when significant losses of water/electrolytes are likely to occur or when consuming too much water alone to achieve a state of euhydration is likely to cause an inverse reduction in plasma sodium concentration.
- after exercise : the replacement of electrolytes is a prerequisite for the effective replacement of nutrients and restoration of euhydration.
- Shirreffs SM, Sawka MN. Fluid and electrolyte needs for training, competition, and recovery. J Sport Sci 2011;29(S1):S39-S46. [Abstract]
- Ranchordas MK, Dawson JT, Russell M. Practical nutritional recovery strategies for elite soccer players when limited time separates repeated matches. J Int Soc Sport Nutr 2017;14:35. [Abstract]
- Snell PG, Ward R, Kandaswami C, et al. Comparative effects of selected non-caffeinated rehydrations sports drinks on short-term performance following moderate dehydration. J Int Soc Sports Nutr 2010;7:28. [Abstract]
- Kalman DS, Feldman S, Krieger DR, et al. Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. J Int Soc Sports Nutr 2012;9(1):1. [Full Text]