Electrolytes for HYROX

HYROX combines repeated running with functional workout stations, creating different hydration considerations from a continuous run or a traditional gym session.

Water and electrolytes can be lost through sweat throughout the event, but this does not mean every HYROX athlete needs an electrolyte product for every session.

The relevance of electrolytes depends on factors including session duration, intensity, environmental conditions, individual sweat losses and how quickly the athlete needs to recover.

Why does HYROX create different hydration demands?

A HYROX race alternates eight 1 km runs with eight functional workout stations.

Rather than exercising at one steady intensity, athletes repeatedly transition between running and exercises such as sled work, rowing, carries, lunges and wall balls.

Early research into HYROX describes the sport as a high-intensity functional fitness format with a substantial endurance component. [1]

From a hydration perspective, this means athletes should consider the demands of the complete race rather than treating the running and workout stations as separate events.

Relevant factors include:

• Total race duration
• Exercise intensity
• Individual sweat rate
• Venue temperature and humidity
• Clothing
• Opportunities to drink
• Starting hydration status
• Fluid and sodium lost during previous training

Two athletes completing the same HYROX race may experience very different fluid and sodium losses. [2][3]

Do HYROX athletes need electrolytes for every training session?

Not necessarily.

HYROX training can include very different types of sessions, such as:

• Easy running
• Strength training
• Threshold or interval running
• Erg work
• Functional stations
• Compromised running
• Longer mixed HYROX sessions
• Double training days

A shorter strength session or easy run may create very different hydration demands from a long mixed session performed in warm conditions.

For many shorter or lower-sweat sessions, normal meals, water and everyday fluid intake may be sufficient.

Electrolytes may become more relevant when:

• Sessions are prolonged
• Sweat losses are high
• Conditions are warm or humid
• Running and functional work are combined for an extended period
• Several sessions are completed on the same day
• Recovery time before the next demanding session is limited

The decision should therefore reflect the session and the athlete rather than the fact that the training is labelled “HYROX”. [2][3]

Why do sweat rate and sodium loss matter for HYROX?

Sweat rate describes how much sweat an athlete produces over a period of time.

Sweat sodium concentration describes how much sodium is present within that sweat.

They are not the same measurement.

An athlete can have:

• A high sweat rate with a lower sweat sodium concentration
• A lower sweat rate with a higher sweat sodium concentration
• High values for both
• Relatively low values for both

Total sodium loss depends on the total volume of sweat lost and the sodium concentration of that sweat. Exercise duration influences how much sweat can accumulate over the session.

Research across athletic populations shows considerable variation in both sweat rate and sweat sodium concentration. [3]

This means one fluid or sodium target should not automatically be applied to every HYROX athlete.

Changes in body mass before and after representative training sessions, considered alongside fluid consumed and urine produced, can help estimate sweat rate.

However, one measurement should not be treated as a permanent prescription. Sweat losses can change with training intensity, session duration, environmental conditions and heat acclimatisation. [2][3]

How should HYROX athletes approach hydration before a race?

Race-day hydration should begin before the athlete reaches the start line.

The aim is to begin the event normally hydrated rather than trying to compensate by drinking a large amount immediately before racing.

Normal meals and fluids may be sufficient for many athletes.

Additional attention to fluid and sodium before the race may be more relevant when:

• Training or travel has contributed to previous fluid losses
• Conditions are warm
• The athlete tends to sweat heavily
• There has been limited opportunity to eat and drink normally
• The athlete is competing more than once across a weekend
• The expected race duration is relatively long

Drinking excessively before the race is not a better strategy. Fluid intake should be appropriate rather than forced. [2][4]

The pre-race approach should also be practised before important training sessions rather than introduced for the first time on competition day.

When should HYROX athletes take electrolytes?

There is no single electrolyte timing strategy that suits every HYROX athlete.

Electrolytes may be considered:

• Before the session or race
• During longer training sessions
• During the race where practical
• After training or competition
• Between sessions on double-training days
• Between races where an athlete competes more than once within a short period

The most relevant timing depends on what the athlete is trying to achieve.

Before exercise, the focus may be on beginning normally hydrated and addressing previous fluid and sodium losses.

During exercise, the focus may be on managing ongoing fluid and electrolyte losses.

After exercise, the focus may shift towards replacing losses and preparing for the next session or competition.

Timing should therefore be considered alongside fluid intake, sweat losses, race duration, food intake and recovery time rather than treating electrolytes as something that must be consumed at one specific point. [2][4]

What should HYROX athletes consider during a race?

HYROX creates practical limitations because athletes alternate between running and functional workout stations rather than continuously carrying a bottle.

This means a race-day hydration strategy should be simple and realistic.

Athletes should consider:

• Expected race duration
• Venue conditions
• Individual sweat rate
• Opportunities to drink
• How much fluid can comfortably be consumed while racing
• Sodium supplied by any drink used
• Carbohydrate coming from drinks, gels or other sources
• Gastrointestinal comfort

Trying to replace every estimated fluid or sodium loss during the race is not necessarily required or practical.

The objective is to have a strategy that supports the athlete without disrupting running, stations or gastrointestinal comfort.

Athletes should also avoid assuming that because fluid is available they need to consume as much as possible. Excessive fluid intake is not desirable, and the presence of electrolytes does not make overdrinking safe. [2][4]

Should HYROX athletes drink at every opportunity?

Not necessarily.

The usefulness of a drink opportunity depends on the athlete, race duration, conditions and what has already been consumed.

A planned strategy can be useful, but it should not become a rule that forces an athlete to drink regardless of thirst, comfort or changing race conditions.

Faster athletes and athletes taking considerably longer to finish may also have different opportunities and requirements.

This is another reason why a hydration plan should be tested in HYROX-specific training rather than copied directly from another athlete. [2][3][4]

Should hydration differ between HYROX training and race day?

Yes.

HYROX training can vary considerably from one day to another, so the same hydration strategy does not need to be used for every session.

An easy run, strength session or short station workout may create relatively modest sweat losses.

A longer compromised-running session, full HYROX simulation or demanding mixed session can create greater fluid and electrolyte losses, particularly in warm conditions.

Athletes should consider:

• Session duration
• Exercise intensity
• Amount of running involved
• Time spent on ergs and functional stations
• Temperature and humidity
• Individual sweat losses
• Fluid available during the session
• Whether another session is planned later

Race day also creates practical differences.

An athlete may have fewer opportunities to drink, greater competitive intensity and less flexibility than during normal training.

Race-day hydration should therefore be developed through representative training sessions rather than simply copying the athlete’s normal daily drinking habits. [2][4]

What about double training days?

HYROX athletes may combine running, strength, cycling, ergs or functional training within the same day.

When two demanding sessions are completed close together, hydration after the first session becomes part of preparation for the second.

The athlete should consider:

• Fluid lost during the first session
• Sweat and sodium losses
• Time available before the next session
• Access to normal meals and drinks
• Carbohydrate required for recovery
• Environmental conditions
• Expected demands of the second session

When losses are relatively small and several hours are available for normal eating and drinking, a dedicated electrolyte product may not be necessary.

A more deliberate rehydration strategy may become useful when sweat losses are substantial or the recovery window is short.

Sodium can be replaced through normal food as well as electrolyte-containing drinks.

Following meaningful exercise-induced dehydration, sodium-containing fluid can support greater fluid retention than plain water under some conditions, but the result also depends on the volume consumed and the wider recovery strategy. [2][5]

The aim between sessions is not to consume the largest possible amount of fluid or sodium. It is to restore an appropriate hydration state while also addressing the athlete’s wider nutrition and recovery needs.

What should HYROX athletes compare in an electrolyte product?

Electrolyte products can provide very different formulas even when they are marketed for similar purposes.

HYROX athletes should compare the declared amounts and serving instructions rather than relying only on the word “electrolytes” on the front of a product.

Useful comparison points include:

• Sodium per serving
• Other declared electrolytes
• Carbohydrate content
• Additional ingredients
• Serving size
• Mixing instructions
• Practicality around training and race day

Sodium per serving

Sodium is generally the main electrolyte lost through sweat, making the amount provided per serving an important comparison point.

A higher sodium amount is not automatically better for every HYROX athlete.

The declared amount should be considered alongside:

• Expected sweat losses
• Session or race duration
• Environmental conditions
• Fluid intake
• Sodium obtained from food or other drinks
• Recovery requirements

Two electrolyte products may provide very different amounts of sodium per serving, so athletes should compare the actual declared quantity rather than assuming similar products provide similar amounts. [2][3][4]

Carbohydrate content

Some electrolyte products also provide carbohydrate, while others provide little or none.

A carbohydrate-containing sports drink can contribute fluid, electrolytes and carbohydrate at the same time.

A low-carbohydrate or carbohydrate-free electrolyte product allows hydration and carbohydrate intake to be managed separately through options such as meals, gels or other sports nutrition products.

Neither approach is automatically better.

The athlete should consider where carbohydrate is coming from across the full training or race-day strategy rather than assessing the electrolyte drink in isolation. [4][6]

Other electrolytes and additional ingredients

Products may also contain potassium, magnesium, calcium and other ingredients alongside sodium.

The presence of more ingredients does not automatically make a product more suitable for HYROX.

Athletes should distinguish between:

• Electrolytes
• Carbohydrates
• Amino acids or other additional ingredients
• Flavourings and sweeteners

The usefulness of a product should be judged from its declared formula and how that formula fits the athlete’s needs.

Practicality

Race-day hydration needs to be simple.

A product may look suitable on paper but still be inconvenient if:

• The serving is difficult to prepare
• The taste becomes unpleasant around intense exercise
• It does not fit alongside the athlete’s carbohydrate strategy
• The timing is unrealistic around warm-up, racing and recovery

HYROX athletes should therefore test both the formula and the practical routine during representative training sessions.

How can a HYROX athlete build a race-day hydration strategy?

A useful HYROX hydration strategy should be simple enough to follow under race conditions.

Rather than trying to calculate one perfect fluid or sodium intake for every athlete, the plan should consider expected race duration, individual sweat losses, venue conditions, available drinking opportunities and what the athlete has successfully practised in training.

Before the race

Before racing, the priorities are to begin normally hydrated and avoid starting with meaningful fluid losses from travel, previous training or inadequate drinking.

Athletes should consider:

• Normal fluid intake across the day
• Food and sodium consumed with pre-race meals
• Previous sweat losses
• Venue temperature
• Expected race duration
• How close fluid is consumed to the start
• Gastrointestinal comfort

There is no benefit in forcing excessive amounts of fluid immediately before the start.

If an electrolyte drink forms part of the pre-race strategy, the athlete should already know how it feels to consume before intense exercise. [2][4]

During the race

The race strategy should reflect the opportunities that are realistically available.

Athletes should consider the event setup and determine beforehand where they are likely to have access to fluid.

During the race, the aim is not necessarily to replace every estimated fluid or sodium loss.

The athlete should balance:

• Fluid availability
• Individual thirst and comfort
• Expected remaining race duration
• Venue conditions
• Sodium supplied by the chosen drink
• Any carbohydrate being consumed
• Gastrointestinal tolerance

A simple strategy that has been practised is generally more useful than introducing multiple unfamiliar products or complicated timing rules on race day. [2][4][6]

After the race

After finishing, hydration needs depend on the losses accumulated during the race and what the athlete is doing next.

Normal food and fluid may be sufficient when losses are modest and there is plenty of time to recover.

More deliberate rehydration may become relevant when:

• Sweat losses were substantial
• The venue was warm
• The athlete has another race or demanding session soon
• Normal meals or drinks will be delayed
• The athlete began the race with previous fluid losses

Fluid, sodium, carbohydrate and normal food intake should be considered together as part of the recovery strategy.

Sodium-containing drinks can support fluid retention after meaningful exercise-induced dehydration under some conditions, but sodium is only one part of the recovery process. [2][5]

The key principle: practise the plan

Race day should not be the first time an athlete tests a hydration strategy.

Representative HYROX sessions can be used to practise:

• Pre-session drinking
• Electrolyte timing
• Fluid volume
• Carbohydrate intake
• Drinking around high-intensity running and stations
• Post-session rehydration

The objective is not to create a rigid routine that can never change.

It is to develop a familiar strategy that can be adjusted for race duration, venue conditions and individual needs.

Where does Hydration+ fit?

Assured Sports Hydration+ is a powdered electrolyte supplement designed to be mixed with water.

Each 9 g serving provides:

• 600 mg sodium
• 300 mg potassium
• 100 mg magnesium
• 120 mg calcium
• 2,000 mg taurine

Taurine is included as an additional ingredient and is not itself an electrolyte.

For HYROX athletes, the 600 mg sodium per serving provides a clearly declared amount that can be considered alongside expected sweat losses, session or race duration, venue conditions and sodium obtained from food or other drinks.

Hydration+ may be particularly relevant around longer mixed sessions, high-sweat training, double training days and HYROX competition, where fluid and electrolyte replacement can require greater consideration.

It also allows hydration to be managed separately from carbohydrate fuelling. Hydration+ is not a carbohydrate fuelling product, so athletes completing demanding sessions or races should still consider where their carbohydrate intake is coming from.

Hydration+ should not be treated as an exact replacement target for every athlete or session, and it is not necessary for every HYROX workout. The amount required will depend on the athlete, the session and the conditions.

View Assured Sports Hydration+

Key takeaways

• Not every HYROX session requires an electrolyte product.
• Hydration needs differ between easy training, hard mixed sessions, double days and race day.
• Sweat rate and sweat sodium concentration vary between athletes.
• Sodium per serving should be considered alongside sweat losses, session demands and the wider hydration strategy.
• A higher-sodium product is not automatically better for every athlete.
• Electrolyte timing can be considered before, during and after training or competition depending on the situation.
• Race-day hydration should be simple, practical and tested during training.
• Hydration and carbohydrate fuelling should be considered together but are not the same thing.
• Normal food and fluids may be sufficient when sweat losses are modest and recovery time is not restricted.
• Electrolytes do not make excessive fluid intake safe.

Related guides

For a basic explanation of the main electrolytes, read: What Are Electrolytes?

For more detail on fluid balance and rehydration, read: How Do Electrolytes Help With Hydration?

For a closer look at sweat sodium losses and sodium replacement, read: Sodium and Exercise Hydration

Sources

[1] Brandt T, Ebel C, Lebahn C, Schmidt A. Acute physiological responses and performance determinants in Hyrox© – a new running-focused high intensity functional fitness trend. Frontiers in Physiology. 2025;16:1519240.

[2] McDermott BP, Anderson SA, Armstrong LE, et al. National Athletic Trainers’ Association Position Statement: Fluid Replacement for the Physically Active. Journal of Athletic Training. 2017;52(9):877–895.

[3] Baker LB. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Medicine. 2017;47(Suppl 1):111–128.

[4] Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ and Stachenfeld NS. American College of Sports Medicine Position Stand: Exercise and Fluid Replacement. Medicine & Science in Sports & Exercise. 2007;39(2):377–390.

[5] Shirreffs SM, Taylor AJ, Leiper JB and Maughan RJ. Post-Exercise Rehydration in Man: Effects of Volume Consumed and Drink Sodium Content. Medicine & Science in Sports & Exercise. 1996;28(10):1260–1271.

[6] Thomas DT, Erdman KA and Burke LM. Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise. 2016;48(3):543–568.