Key takeaways
- A concentration in mg/L and an intake in mg/h describe different things.
- A product without sodium can suit your needs when sodium comes from other sources.
- Taking sodium does not protect you from drinking excessive amounts of fluid.
What does sodium do during exercise?
Sodium is an electrolyte: it carries an electrical charge when dissolved in body fluids. It contributes to fluid balance, nerve signalling and muscle function. You lose some sodium in sweat during exercise. Its contribution needs to be considered alongside water losses, rather than treating it as an ingredient whose quantity should always be maximised.
Table salt contains sodium and chloride, so salt and sodium are not interchangeable terms. Similarly, an ‘electrolytes’ claim may refer to sodium, potassium, magnesium or a mixture of minerals. To find out how much sodium a product supplies, look for its specific value rather than the total weight of an electrolyte blend.
A drink, gel and salty food can all contribute sodium while serving different purposes. One may supply fluid, another carbohydrate and another variety. Sodium content alone cannot determine which is most useful at a particular point in your activity. Consider what each product adds to everything else you are consuming.
Why do needs vary so much?
Two people running together do not necessarily lose the same amounts of water and sodium. Both sweat rate and sweat sodium concentration vary. Heat, exercise duration and race conditions also matter. The ACSM’s 2007 position stand therefore recommends individualising fluid replacement rather than assuming one approach will suit everyone.[1]
Start with simple observations: weather, duration, pace, the amount actually drunk and the food consumed. An approach that feels comfortable on a cool outing may suit a long, hot race less well. Salt marks on clothing can draw your attention to sweating, but they do not provide a precise measurement of hourly sodium losses.
Training trials help you learn what you can drink and eat in conditions similar to the event. Record what you actually consume rather than what you planned to consume. A bottle carried and brought home half full is different from a bottle finished. That difference matters as much as the concentration printed on its label.
How should you interpret drink guidance?
The reference range of 500–700 mg of sodium per litre appears in the ACSM’s 1996 position stand for drinks consumed during exercise lasting more than an hour. It is a concentration reference with a particular context and publication date. It is not a compulsory dose per gel or a universal hourly intake target.[2]
Concentration describes the contents of a volume of drink. Intake then depends on how much of it you actually drink. Half a bottle and a whole bottle of the same drink supply different amounts of sodium. Comparing mg/L with mg per sachet without accounting for volume therefore compares two different pieces of information.
For powders and tablets, also check the manufacturer’s preparation instructions. Sodium per serving may refer to a 500 mL bottle or another volume. Changing the amount of water changes the concentration, while the total sodium supplied by that dose of powder stays the same. Record both the dose and the amount of water used.
Add up sodium from everything you consume
Over an hour, sodium may come from your drink, several products and food at an aid station. One packet cannot describe your complete intake. Choose the same time period for every source and add the amounts actually consumed within that period. The aim is to understand the combined contribution, not to give every item an identical role.
A gel without sodium can be suitable when your drink or other foods provide it. Conversely, a gel containing sodium does not demonstrate that your whole approach is balanced. The useful question is what it contributes alongside your other products and the amount of fluid you consume during the same period.
An average over several hours can help you review an outing, but it hides the timing of intake. Eating something salty at the last aid station is different from consuming it regularly since the start. Keep a simple record that distinguishes the main periods without turning every session into an accounting exercise.
Understand imbalances between water and sodium
Hyponatraemia means a blood sodium concentration below the normal range. During exercise it is often associated with drinking more fluid than is lost, together with water retention. The 2015 international consensus emphasises that sodium intake does not reliably prevent it when an athlete drinks excessively.[3]
Hypernatraemia means an excessively high blood sodium concentration. It can accompany a water deficit. These terms describe concentration in the blood, not simply the number of milligrams swallowed. The word ‘sodium’ appears on packaging and in blood test results, but those numbers measure different things and cannot be substituted for one another.
Avoid the idea that taking more salt makes it safe to drink more water. Significant symptoms during an event do not let you diagnose an imbalance yourself or choose treatment from this guide. Confusion, impaired consciousness or serious illness require assessment by the event’s medical or emergency team.
Read the label and plan training trials
First check the unit and reference quantity: per 100 g, per serving, per litre or per prepared bottle. When only salt is declared, 1 g of salt corresponds to roughly 400 mg of sodium. For example, 0.25 g of salt represents about 100 mg of sodium. That conversion does not change a per-100-g value into a per-serving value.
Then record the serving consumed, drink volume and time period. Sodium per serving becomes an hourly intake only when you know how many servings were consumed in that hour. Keep missing information unknown: the absence of a sodium or salt entry does not establish that a product contains none.
Try the preparation you plan to use, including its dilution and taste, on a representative session. Check that you can keep drinking and eating comfortably. Numbers help you understand consumption and compare trials; they do not replace adapting to conditions or individual professional support when that is needed.
Worked example: a drink and a gel
Fictional teaching example: a drink contains 600 mg of sodium per litre. You drink 500 mL in one hour, or 0.5 L. The drink supplies 600 × 0.5 = 300 mg of sodium.
A gel consumed in that same hour supplies 100 mg. The total is 300 + 100 = 400 mg over the hour considered. This illustrates converting a concentration into an amount and adding two sources. It does not establish a target to copy.
Frequently asked questions
Does a gel need to contain sodium?
There is no scientific recommendation specifying a sodium dose per gel. Consider its contribution to your total intake. A product without sodium can be suitable when your drink or other food supplies sodium elsewhere during exercise.
Are salt and sodium equivalent?
No. Salt is approximately 40% sodium by mass. To convert grams of salt into milligrams of sodium, multiply by roughly 400. Then check whether the label value refers to 100 g, a serving or the whole prepared drink.
Does more sodium protect against overhydration?
No. Consuming more sodium does not make excessive fluid consumption safe. Balance depends on water intake and losses as well as sodium. A high sodium number on a product is therefore not protection against exercise-associated hyponatraemia.
How Glyk considers this topic
Glyk’s Sodium and hydration criterion helps interpret a product’s contribution during exercise. It does not measure your sweat losses or assess everything you eat and drink.
A declared value, a conversion from salt and the interpretation of a product are distinct pieces of information. This guide’s references provide scientific context; they do not validate the application’s scoring rubric.
Scientific sources
These references inform the guide. Published recommendations, study findings and their interpretation in Glyk remain distinct. They do not validate the application’s scoring rubric.
