Before You Buy that $50 Tub of Electrolytes, READ THIS
The reality is a little more nuanced.
There are definitely situations where replacing sodium and fluid during or after exercise is useful, particularly during long, hot or high-sweat sessions.
But for most runners, electrolyte supplements aren't something you automatically need every day.
Before you spend $50 on another tub, let's look at what electrolytes actually do, when they matter, and what the research says.
What are electrolytes?
Electrolytes are minerals that carry an electrical charge when dissolved in bodily fluids.
The main electrolytes relevant to exercise include:
Sodium – the most important electrolyte to consider during prolonged exercise. It helps regulate fluid balance, blood volume, nerve signalling and muscle function.
Chloride – works closely with sodium to help regulate fluid and electrolyte balance.
Potassium – important for nerve signalling, muscle contraction and fluid balance.
Magnesium – involved in muscle and nerve function and energy metabolism.
Calcium – important for muscle contraction and nerve signalling.
When you sweat, you lose both water and electrolytes, particularly sodium. However, the amount of sodium lost in sweat varies considerably between individuals.
Does drinking plain water cause low sodium?
This is where things get interesting.
During prolonged exercise, drinking large amounts of fluid while replacing little or no sodium can contribute to exercise-associated hyponatraemia (EAH) — a potentially serious condition where blood sodium becomes dangerously diluted.
However, this is not simply because someone drank plain water.
The bigger issue is a mismatch between fluid intake and fluid losses. In particular, drinking beyond your body's needs can increase the risk.
So don't fall for the idea that:
“Water doesn't hydrate you unless it contains electrolytes.”
That's simply not true.
For everyday hydration and most shorter runs, water is perfectly capable of hydrating you.
Sodium can, however, increase thirst and help the body retain more of the fluid consumed, which can be useful in particular situations.
What about all the claims on electrolyte products?
This is where I'd encourage you to become a little more sceptical.
A 2024 analysis examined 114 health claims made on sports drink products and compared them with European Food Safety Authority (EFSA) evidence. None of the claims fully met the researchers' criteria. Only 14 claims (12.3%) from 13 products were considered to approximately conform with the relevant recommendations. The authors concluded that many of the marketing claims implied cause-and-effect relationships that were not adequately supported by evidence.
The study also reported that up to 70% of athletes may be highly influenced by information on sports supplement labels and advertising.
So what should make you raise an eyebrow?
“Prevents muscle cramps”
Electrolytes are commonly marketed as a cramp-prevention strategy.
But muscle cramps during endurance exercise are complex and aren't simply caused by “running out of electrolytes”. The evidence does not support electrolyte supplementation as a universal solution for preventing exercise-associated muscle cramps.
Your pacing, fatigue, training load, neuromuscular factors and individual physiology can all play a role.
“Prevents dehydration”
An electrolyte drink doesn't magically prevent dehydration.
Fluid intake is still the primary driver of hydration status.
Electrolytes can influence fluid retention and thirst, but you still need to consume an appropriate amount of fluid.
“You need electrolytes for every run”
Nope.
A 30–45 minute easy run in mild conditions is very different from a 3-hour run in 30°C heat.
The need for sodium and fluid increases with exercise duration, sweat losses, environmental conditions and individual sweat composition.
“More sodium = better performance”
Also not necessarily.
Current evidence suggests the relationship between sodium and fluid balance is more important than simply trying to replace every milligram of sodium lost in sweat.
In fact, the latest review by McCubbin highlights that most athletes do not require a higher sodium intake day-to-day simply because they exercise.
So when might electrolytes actually be useful?
This is where context matters.
Electrolyte or sodium supplementation can become more useful when you're:
Running for longer
For longer endurance sessions — particularly >90 minutes — there is more opportunity to accumulate substantial fluid and sodium losses.
Training in hot or humid conditions
Hot conditions generally increase sweat losses, meaning your fluid and sodium requirements may be considerably higher than they are on a cool day.
A high-volume or heavy sweater
If you have a high sweat rate and/or relatively salty sweat, sodium replacement may become more relevant during prolonged exercise. Importantly, being a “salty sweater” doesn't automatically mean you need to replace 100% of your sweat sodium losses.
Ultra-endurance events
For events lasting several hours, hydration and sodium strategies become much more important because the cumulative losses can be substantial.
This is where an individualised plan becomes particularly valuable.
How much sodium and fluid do you need?
There isn't one magic number that works for every runner.
You will often see recommendations such as 300–700 mg sodium per hour and 400–800 mL fluid per hour online.
These can be useful starting points, but they shouldn't be treated as universal prescriptions.
Your requirements depend on:
Sweat rate
Sweat sodium concentration
Exercise duration
Exercise intensity
Temperature and humidity
Access to fluid
Your tolerance for fluid during exercise
How much you're drinking in relation to your losses
Research modelling suggests that in many athletes, the amount of sodium required to maintain sodium balance during exercise is substantially lower than the amount lost in sweat — particularly when fluid replacement is not extremely high.
In other words: you don't necessarily need to replace every gram of sodium you sweat out.
What about potassium and magnesium?
Despite being included in many “electrolyte” products, potassium and magnesium generally aren't lost through sweat in quantities that require aggressive replacement during most runs. For most athletes, a varied diet provides plenty of these minerals.
Sodium is usually the electrolyte worth paying the most attention to during prolonged endurance exercise.
Do I need an electrolyte supplement after running?
Not necessarily.
If you've completed a shorter or moderate run, you can usually replace your fluid and electrolytes through your normal food and drinks.
For example:
Milk or a milk alternative with added electrolytes
A smoothie
A sandwich or wrap
Soup
Eggs on toast
A meal containing soy sauce or other salty ingredients
A normal meal with some added salt
Sodium-containing sports foods if you're also replacing carbohydrate
You don't need a fancy powder just because you exercised.
How do I work out my individual needs?
For runners doing longer endurance events, estimating sweat rate can be a useful starting point.
One simple method is to weigh yourself immediately before and after a training session while recording:
Fluid consumed
Urine losses, if relevant
Exercise duration
Environmental conditions
This gives you an estimate of your sweat losses.
For athletes with particularly high sweat losses, salty sweat, recurrent hydration issues or ultra-endurance goals, more detailed sweat testing can also be considered.
But remember: a sweat test is information, not a prescription to replace 100% of everything you lost. Around 50-70% during and 125-150% replacement after is gold standard.
The goal is to develop a hydration and sodium strategy that matches your individual needs.
So, should you buy the electrolyte tub?
Maybe. But you probably don't need it just because you're a runner.
For a short, easy run in mild conditions? Water + your normal diet is likely enough.
For a long run in the Queensland heat? Now we're having a different conversation.
For a 4–6 hour ultra? Absolutely worth having an individualised hydration and sodium strategy.
The key isn't finding the electrolyte product with the biggest sodium number, the most impressive ingredient list or the most expensive packaging.
It's understanding how much fluid and sodium YOU actually need.
The bottom line
Most runners don't need electrolyte supplements every day. Sodium is important for maintaining fluid balance and becomes increasingly relevant as exercise duration, sweat losses and environmental heat increase. For longer endurance sessions, hot conditions and athletes with high sweat losses, sodium and fluid replacement can be an important part of performance and safety. But don't let marketing convince you that every run requires a $50 tub of electrolytes.
Sometimes the best sports nutrition strategy is your simple basics, fuelling, water, sleep, training, recovery, and then supplement where necessary.
References
McCubbin, A. J. (2023). Modelling sodium requirements of athletes across a variety of exercise scenarios—Identifying when to test and target, or season to taste. European Journal of Sport Science, 23(6), 992–1000. https://doi.org/10.1080/17461391.2022.2083526
McCubbin, A. J. (2025). Sodium intake for athletes before, during and after exercise: Review and recommendations. Performance Nutrition, 1, Article 11. https://doi.org/10.1186/s44410-025-00011-9
Rodríguez-Hernández, M. D., Gil-Izquierdo, Á., García, C. J., Gabaldón, J. A., Ferreres, F., Giménez-Monzó, D., & Martínez-Sanz, J. M. (2024). Health claims for sports drinks—Analytical assessment according to European Food Safety Authority’s scientific opinion. Nutrients, 16(13), 1980. https://doi.org/10.3390/nu16131980
Veniamakis, E., Kaplanis, G., Voulgaris, P., & Nikolaidis, P. T. (2022). Effects of sodium intake on health and performance in endurance and ultra-endurance sports. International Journal of Environmental Research and Public Health, 19(6), 3651. https://doi.org/10.3390/ijerph19063651
