Sodium intake for athletes before, during and after exercise: review and recommendations

Sodium intake for athletes before, during and after exercise: review and recommendations.
A review article by Alan McCubbin in Performance Nutrition, 2025.

Sodium (or rather, ‘electrolytes’) is one of the hottest topics on the street at the moment. It seems like almost everyone is popping electrolyte tablets or powders in their water to ‘stay hydrated’. Is this necessary?

Thankfully, Alan McCubbin, an academic and practitioner (sports dietitian) has presented us with a long-awaited deep dive on this topic.

As always, I’d encourage you to read the full paper here (free to download). In which case, no need to read on!

If you don’t make it to the paper, here are the key takeaway quotes from the paper:
– In the absence of specific recommendations [from research], athletes have turned to other information sources for guidance on sodium replacement. These include fellow athletes, coaches, and marketing content from electrolyte supplement companies. The results of this is that athletes often have well-entrenched beliefs around sodium that are clearly not based on evidence.
– In recent years, these beliefs appear to have intensified and expanded, including an increasingly held view that daily sodium supplementation is necessary to maintain euhydration (normal hydration status), even in the absence of significant exercise.
– Athletes are likely already consuming considerably more sodium than required through their daily diet.
– For individuals not significantly hypohydrated (dehydrated), sodium supplementation is unnecessary to achieve a state of euhydration (adequate hydration).
– NaCl (sodium chloride) is the most comprehensively studied [type of sodium] and is well established for its ability to achieve hyperhydration.
– No studies have directly compared the efficacy of Sodium Citrate or Sodium Bicarb to Sodium Chloride.
– NaCl given in fluid is better retained after 3hr compared to when given as a tablets. Though both are efficacious.
– Beverage palatability (taste) is most often achieved when added sodium (consumed as NaCl) does not exceed 100mg/100mL.
– Exercise performance appears to be improved by sodium intake only in scenarios where fluid intake is greater in the sodium than placebo or control trial. No studies to date have shown a beneficial effect of sodium replacement on performance, independent of fluid replacement.
– In most scenarios outside of ultra-endurance sports, sweat composition testing is unnecessary, and will not add value or help inform the athletes sodium replacement strategy.

So where to from here with sodium supplementation?

It is very rare that athletes require active sodium replacement from supplementation.

Here are the scenarios where it is worthwhile:

1. Pre-exercise: If athletes struggle to achieve an adequate hydration status prior to exercise, sodium could be used to facilitate this. 275-420mg sodium per 100mL fluid will likely maximise fluid intake and/or retention. This should be done within 4 hours of initiation of exercise.
2. During-exercise: As sodium may influence thirst and therefore fluid intake, sodium could be used to drive fluid intake and therefore help maintain total body water. This is more important in prolonged exercise such as ultra events where plasma sodium is more likely to fall, therefore needing top ups. In shorter duration exercise, plasma sodium actually rises because water is lost through sweat at a quicker rate than sodium, making sodium replacement during the exercise bout unnecessary.
3. Post-exercise: if beverages are consumed in isolation from food, addition of sodium will help with retaining more fluid. If beverages are consumed together with food, sodium is unlikely to assist with restoring fluid balance. Trying to replace all the sodium lost from the body is unnecessary as the kidneys conserve sodium post-exercise (excrete less). However if there is good reason to rapidly restore sodium (within 24hr), then increased dietary sodium may assist (e.g daily prolonged ultra running – e.g running across Australia for charity).

As always, speak to your accredited sports dietitian for personalised advice.