Can You Drink Too Much Water During Exercise? Hyponatremia Explained

Written by Tomasz Antczak · Published March 21, 2026 · Updated September 24, 2026

Exercise-associated hyponatremia can occur when fluid intake exceeds losses and blood sodium becomes diluted. Learn the causes, warning signs, role of electrolytes and practical ways to avoid overdrinking.

Most hydration advice focuses on one problem:

not drinking enough.

That makes sense.

Exercise increases fluid loss, especially when you:

• train for a long time
• sweat heavily
• exercise in heat
• wear protective equipment
• train several times in one day

But there is another side to hydration that gets much less attention.

You can also drink too much.

During prolonged exercise, consuming fluid faster than your body is losing and excreting it can contribute to a potentially dangerous condition called:

exercise-associated hyponatremia — EAH

This does not mean you should become afraid of water.

It does not mean drinking during exercise is dangerous.

And it does not mean everyone needs to carefully ration every sip.

The practical lesson is much simpler:

replace fluid sensibly without deliberately forcing yourself to drink more than you are losing.

If you want the general hydration framework first, read Hydration Basics: What Actually Matters.

What is exercise-associated hyponatremia?

Exercise-associated hyponatremia is generally defined as a blood sodium concentration below:

135 mmol/L

that develops during exercise or within approximately 24 hours after physical activity.

It has been reported most often during prolonged endurance activities such as:

• marathons
• ultramarathons
• triathlons
• long-distance hiking
• military activity
• long cycling events

But it is not limited exclusively to traditional endurance sport.

Cases have also been reported in other forms of prolonged physical activity.

The important factor is not the name of the sport.

It is the combination of:

fluid intake, fluid loss, sodium balance and the body’s ability to excrete water.

What does sodium have to do with it?

Sodium is one of the main electrolytes in the fluid outside your cells.

Your body regulates the concentration of sodium in the blood within a relatively narrow range.

Hyponatremia means that the blood sodium concentration has fallen too low.

In exercise-associated hyponatremia, the main problem is frequently not that the athlete suddenly lost all their sodium.

It is often that there is too much water relative to the amount of sodium and body water present.

In simple terms:

too much retained water can dilute blood sodium.

That distinction matters.

EAH is not simply “sodium deficiency”

It is tempting to think:

low blood sodium = not enough salt

but that is incomplete.

Exercise-associated hyponatremia is often primarily a disorder of:

water balance

rather than simply a lack of dietary sodium.

The major mechanism identified in the sports-medicine literature is excessive fluid consumption relative to losses.

Another important contributor can be continued secretion of:

arginine vasopressin — AVP

also known as antidiuretic hormone.

AVP tells the kidneys to conserve water.

During prolonged exercise, several non-osmotic factors may stimulate AVP release.

These can include:

• physical stress
• nausea
• pain
• low blood glucose
• heat
• other physiological stressors

So an athlete may be:

drinking large amounts

while also:

retaining more water than expected.

That combination can reduce sodium concentration.

The biggest preventable risk: overdrinking

The strongest practical message from international EAH consensus guidance is remarkably simple:

do not drink more fluid than you are losing.

Historically, athletes were sometimes told to:

• drink before they became thirsty
• drink at every aid station
• drink the maximum amount they could tolerate

That advice can lead some people to drink far more than they need.

Modern sports-hydration guidance recognises that:

both dehydration and overhydration can create problems.

The goal is not maximum fluid intake.

The goal is:

appropriate fluid intake.

Drinking more is not always safer

Imagine two runners.

Runner A

Sweat loss:

0.8 L/hour

Fluid intake:

0.5 L/hour

They gradually develop a modest fluid deficit.

Runner B

Sweat loss:

0.5 L/hour

Fluid intake:

1.0 L/hour

Runner B is consuming:

0.5 L more fluid every hour than they are losing.

During four hours of exercise, that could create a substantial positive fluid balance.

That is the pattern you want to avoid.

Body-weight gain during exercise is a warning sign

One of the clearest practical clues of overdrinking during prolonged exercise is:

finishing heavier than you started.

Suppose you start an event at:

70.0 kg

and finish at:

71.0 kg

because you drank large quantities of fluid.

Your body has gained roughly:

1 kg of mass

during a period when you were exercising and sweating.

That strongly suggests you consumed fluid in excess of your losses.

For hydration planning, this is generally the opposite of what you want.

But weight gain is not required for EAH

This distinction is important.

Body-weight gain can be a strong warning sign of excessive fluid intake.

But you cannot diagnose or exclude hyponatremia based on body weight alone.

Some people with EAH may not finish heavier than they started because other mass changes occur during prolonged exercise.

Blood sodium must be measured to confirm hyponatremia.

Body weight is therefore:

a useful practical clue

not:

a diagnostic test.

What activities carry the greatest risk?

EAH is most strongly associated with prolonged exercise where there is enough time to accumulate excess fluid.

Examples include:

• marathons
• ultramarathons
• Ironman-distance triathlon
• long-distance hiking
• military endurance events
• prolonged cycling
• long adventure races

Risk tends to increase when exercise lasts several hours.

That makes sense.

Even a modest excess of fluid per hour can accumulate into a large surplus over a long event.

Can EAH happen during a normal gym workout?

It would be unusual.

A healthy person doing:

• 45 minutes of weights
• drinking normally
• sweating moderately

is very unlikely to develop exercise-associated hyponatremia.

There is normally neither enough time nor enough fluid intake to create the same problem seen during long endurance events.

That does not mean you should deliberately consume several litres during a short workout.

It simply means the context is very different.

What about Muay Thai?

A normal:

• 60-minute
• 75-minute
• 90-minute

Muay Thai session is generally a very different scenario from an eight-hour endurance event.

The larger practical hydration issue during a hard Muay Thai session is often:

high sweat loss

rather than overhydration.

But the same basic safety rule applies:

do not force huge amounts of fluid simply because you are sweating.

If you lose approximately:

0.8 L/hour

you do not improve your hydration by forcing:

1.5 or 2 L/hour

into yourself.

Match your strategy to your actual loss.

How can you estimate your fluid loss?

One useful method is a sweat-rate test.

Measure:

• body weight before training
• body weight after training
• fluid consumed
• urine produced
• session duration

A simplified calculation is:

body-weight loss + fluid consumed − urine = estimated sweat loss

Then:

estimated sweat loss ÷ session duration = sweat rate

For the complete method, use Sweat Rate Calculator: Your Workout Hydration Plan.

Example

Before training:

80.0 kg

After training:

79.4 kg

Fluid consumed:

0.6 L

No urine.

Estimated sweat loss:

0.6 kg + 0.6 L = approximately 1.2 L

If the session lasted:

90 minutes

then your estimated sweat rate was:

1.2 ÷ 1.5 = 0.8 L/hour

This does not mean you must drink exactly 0.8 L every hour.

But it tells you that routinely consuming:

1.5 L/hour

would clearly be more fluid than this session appears to require.

Thirst can be useful

For many recreational athletes, drinking according to thirst is a reasonable safeguard against both:

• excessive dehydration
• forced overdrinking

The major international EAH consensus statement specifically emphasised avoiding drinking beyond thirst as a prevention strategy.

This does not mean thirst is the only hydration tool.

People with:

• very high sweat rates
• prolonged competition
• repeated same-day sessions
• hot-weather events

may benefit from a more structured strategy based on measured losses.

A sensible combination is:

thirst + knowledge of your own sweat rate.

Does thirst mean you are already dehydrated?

Not necessarily.

Thirst is a normal regulatory mechanism.

The idea that:

“If you’re thirsty, it’s already too late”

encouraged some athletes to drink pre-emptively and excessively.

For most healthy people, thirst provides useful information.

You do not need to treat the first sensation of thirst as a medical emergency.

Electrolyte drinks do not make unlimited drinking safe

This is one of the most important myths to remove.

You may think:

“If my drink contains sodium, I can’t get hyponatremia.”

That is not correct.

Most commercial sports drinks still contain a much lower sodium concentration than blood.

If you consume them in very large amounts, you can still take in excessive fluid.

Adding sodium may help replace some sweat sodium losses.

But it does not give you permission to drink without limit.

The main protection against dilutional EAH remains:

avoiding excessive fluid intake relative to losses.

What about salt tablets?

Salt tablets are not a licence to overdrink either.

Taking more sodium while simultaneously forcing excessive volumes of fluid does not transform an inappropriate hydration plan into a safe one.

Sodium replacement can be useful during:

• long exercise
• heavy sweating
• substantial sodium loss

but hydration strategy still has to respect overall fluid balance.

For a broader explanation, read Electrolytes for Workouts: When You Need Them.

Sweat sodium loss still matters

None of this means sodium losses are irrelevant.

Sweat contains sodium.

Some athletes lose substantially more sodium than others because of differences in:

• sweat rate
• sweat sodium concentration
• exercise duration

In certain circumstances, significant sodium loss can contribute to the overall problem.

But research consistently identifies excessive fluid intake as the central modifiable factor in most cases of exercise-associated hyponatremia.

For more on sodium loss, read How Much Sodium Do You Lose in Sweat?.

Also see Sweat Rate vs Sodium Loss: What to Measure After Hard Training.

What are the symptoms of exercise-associated hyponatremia?

Symptoms vary widely.

Mild cases may cause few or no obvious symptoms.

Possible symptoms can include:

• headache
• nausea
• vomiting
• bloating
• dizziness
• unusual fatigue
• weakness

More severe cases can involve the brain as water moves into cells and causes swelling.

Serious warning signs can include:

• confusion
• unusual behaviour
• severe or worsening headache
• repeated vomiting
• disorientation
• seizures
• reduced consciousness
• coma
• respiratory distress

Severe symptomatic EAH is a medical emergency.

The dangerous part: symptoms overlap with other problems

This is why self-diagnosis is risky.

A runner who develops:

• headache
• nausea
• weakness
• dizziness

could be experiencing:

• dehydration
• heat illness
• hypoglycaemia
• exhaustion
• hyponatremia
• another medical problem

These conditions do not all require the same treatment.

Giving large amounts of plain water to somebody with hyponatremia can make the problem worse.

That is one reason severe symptoms during or after prolonged exercise require proper medical assessment rather than assuming:

“They must be dehydrated.”

Hyponatremia vs dehydration

These two conditions can sometimes produce overlapping symptoms, but the fluid-balance problem is very different.

Feature	Dehydration	EAH / overhydration pattern
Main fluid problem	Too little body water	Too much retained water relative to sodium
Body weight	Usually decreases	May remain stable or increase
Thirst	Often present	May be absent or variable
Drinking history	Often inadequate	Often excessive
Sodium concentration	May be normal or high	Below 135 mmol/L
More water automatically helps?	Often helpful when appropriate	Can worsen the condition

This table is only a guide.

You cannot diagnose EAH from symptoms or body weight alone.

Do not automatically give water to every collapsed athlete

This is particularly important during endurance events.

If somebody collapses after prolonged exercise, do not automatically assume:

dehydration = needs lots of water

especially if the person:

• has been drinking heavily
• appears bloated
• has gained weight
• is confused
• is vomiting repeatedly
• has neurological symptoms

Severe EAH requires medical treatment.

It is not something to correct by experimenting with drinks at the side of the road.

What should you do if severe EAH is suspected?

If someone develops:

• confusion
• seizures
• markedly altered behaviour
• reduced consciousness
• serious breathing problems

during or following prolonged exercise:

seek emergency medical assistance immediately.

Do not continue forcing fluids.

Do not give drinks to somebody who is not fully alert or cannot swallow safely.

Hospital or event medical teams can assess blood sodium and provide appropriate treatment.

Severe symptomatic EAH may require hypertonic saline, which is medical treatment and should not be improvised.

Why simply drinking more water can make it worse

Imagine blood sodium has already become diluted.

If the person continues to consume large amounts of low-sodium fluid while the kidneys are retaining water:

the sodium concentration can fall further.

That can increase movement of water into cells.

In severe cases, swelling of brain cells can lead to:

hyponatremic encephalopathy.

This is why confusing EAH with dehydration can be dangerous.

Mild EAH can be difficult to recognise

Some athletes with low blood sodium may have:

• no symptoms
• mild symptoms
• vague symptoms

The condition may only be identified through blood testing.

That is another reason not to attempt to diagnose yourself based on:

• thirst
• headache
• urine colour
• cramps

None of those tells you your blood sodium concentration.

Who is at greater risk?

Risk factors described in the EAH literature include:

• drinking beyond fluid losses
• prolonged exercise duration
• slower event times, creating more opportunities to drink
• very frequent drinking
• low body mass combined with high intake
• weight gain during exercise
• persistent AVP secretion

Some research has also discussed medications such as non-steroidal anti-inflammatory drugs — NSAIDs — as a possible contributing factor.

The most consistently preventable behavioural factor remains:

excessive fluid intake.

Long duration matters

Imagine an athlete drinks just:

300 mL/hour more than they lose.

Over one hour:

+0.3 L

Over three hours:

+0.9 L

Over six hours:

+1.8 L

Over ten hours:

+3.0 L

A relatively small hourly mismatch becomes a large total excess during an ultramarathon or long hiking event.

That helps explain why EAH is much more closely associated with prolonged activity.

Hot weather does not mean unlimited drinking

Heat increases sweat loss.

So yes, you may need substantially more fluid in hot weather.

But the rule is still:

replace according to loss.

Someone sweating:

1.2 L/hour

may genuinely need much more fluid than someone sweating:

0.4 L/hour.

That does not mean either person should consume:

2 L/hour

simply because it is hot.

For heat-specific guidance, read Hydration in Hot Weather: How to Train in Heat Without Crashing.

EAH can happen in cold weather too

This is sometimes surprising.

Hyponatremia is not exclusively a hot-weather problem.

People can still:

• exercise for many hours
• drink excessively
• retain water

in cool or cold environments.

Some prolonged events in cold conditions may even reduce perceived sweat loss, making athletes more likely to overestimate how much replacement they need.

Think about fluid balance.

Not just temperature.

Running example

A marathon runner plans to:

drink at every aid station whether thirsty or not.

They finish in five hours.

Because the pace is moderate and conditions are cool, their sweat rate is:

0.5 L/hour

But they drink:

1.0 L/hour

Fluid consumed:

5 L

Estimated sweat loss:

2.5 L

Potential excess before accounting for urine and other losses:

approximately 2.5 L

That is exactly the type of mismatch you want to avoid.

A better running strategy

Use:

• thirst
• previous sweat-rate measurements
• environmental conditions
• duration

to estimate what you actually need.

Do not turn:

“There is water available”

into:

“I must drink all of it.”

Aid stations provide an option.

They do not create a hydration requirement.

Muay Thai example

You train for:

75 minutes

in a hot gym.

Your measured sweat rate is approximately:

1.0 L/hour

You finish soaked.

In this scenario, underdrinking may be a more realistic concern than EAH.

But suppose you become anxious about dehydration and drink:

3 litres

during the 75-minute class.

That is unlikely to match your actual losses and may make you:

• bloated
• nauseous
• uncomfortable

There is no performance advantage in forcing fluid far beyond need.

Gym example

You perform:

45 minutes of strength training

in an air-conditioned gym.

You barely sweat.

Drinking:

3 litres

during that workout is unnecessary.

Your body’s water requirement does not suddenly multiply because you entered a gym.

Drink according to the session.

Hiking example

Long hikes deserve more attention.

A person may:

• walk slowly
• exercise for eight hours
• pass many water stations
• repeatedly drink “just in case”

The intensity may not feel extreme.

But the duration creates enough time for fluid excess to accumulate.

EAH has been reported in hikers as well as traditional endurance athletes.

Does drinking lots of water before exercise help?

Not if you are already hydrated.

Deliberately “water loading” before a normal workout can result in:

• stomach discomfort
• frequent urination
• unnecessary fluid excess

The goal before exercise is:

start reasonably hydrated.

Not:

start as full of water as physically possible.

If you are wondering whether drinking extra water simply makes you sweat more, read Can Drinking Too Much Water Make You Sweat More?.

Read How Much Water to Drink Before, During and After a Workout for the broader timing guide.

What about after exercise?

Overdrinking can also occur during recovery.

Suppose you finish training:

0.5 kg lighter

and then immediately drink:

3 litres of plain water

because you want to “hydrate properly.”

That is far more fluid than the measured deficit suggests.

For ordinary recovery:

• drink
• eat
• respond to thirst

After a large measured deficit with a short recovery window, more structured rehydration can make sense.

For the full method, read How Much Water Should You Drink After Exercise?.

Do not chase perfectly clear urine

Another way people end up overdrinking is trying to keep their urine:

completely transparent all day.

Urine colour is only one hydration clue.

Clear urine can simply reflect recent fluid intake.

You do not need to continuously force water until every sample looks like tap water.

A pale-yellow general pattern is usually perfectly compatible with normal hydration.

Is there a maximum amount of water per hour?

You will sometimes see one universal kidney-limit number quoted online.

Real physiology is more complicated.

The amount of water a person can safely process depends on factors including:

• body size
• kidney function
• hormone activity
• food intake
• sodium balance
• exercise stress
• time

During exercise, AVP secretion can also limit the body’s ability to excrete free water.

That is why simply saying:

“The kidneys can process X litres per hour, therefore X is safe”

is not a reliable exercise-hydration strategy.

Use actual fluid loss instead.

A better question than “How much can I drink?”

Ask:

How much am I actually losing?

That is far more useful.

If your sweat rate is approximately:

0.7 L/hour

there is little reason to design a routine around drinking:

1.5 L/hour

just because somebody says the kidneys can theoretically process it.

What about drinking exactly your sweat rate?

Even that is not always necessary.

If your sweat rate is:

0.8 L/hour

and you train for:

45 minutes

you might comfortably allow a modest deficit and replace it afterwards.

The goal is not necessarily to finish every workout at exactly the same body weight.

The goal is to avoid:

• excessive dehydration
• excessive fluid intake

For sweat-rate calculations, see Sweat Rate Calculator: Your Workout Hydration Plan.

Practical rule for short workouts

For most healthy adults doing:

• gym training
• short runs
• normal combat-sport classes
• recreational workouts under roughly an hour

hydration usually does not require complex calculation.

Start normally hydrated.

Have fluid available.

Drink when needed.

Continue drinking afterwards.

Practical rule for long workouts

As duration increases, planning becomes more useful.

For sessions lasting several hours:

• estimate your sweat rate
• understand how it changes with weather
• drink according to thirst and expected losses
• consider sodium replacement
• avoid cumulative overdrinking
• monitor body-weight trends if practical

Practical rule for endurance events

Do not create a plan whose goal is:

drink as much as possible.

Create a plan whose goal is:

maintain an appropriate fluid balance.

That may include:

• drinking to thirst
• using your tested sweat-rate range
• adjusting for weather
• including sodium where appropriate
• avoiding weight gain from excessive drinking

What if I am very thirsty?

Drink.

The purpose of this article is not to make you suppress normal thirst.

It is to stop the opposite behaviour:

forcing large amounts of fluid despite having no physiological need for them.

Thirst is useful information.

What if I sweat extremely heavily?

Then your legitimate fluid requirement may be high.

Someone with a sweat rate of:

1.5 L/hour

has a different problem from someone losing:

0.4 L/hour.

That is why sweat-rate measurement matters.

Heavy sweaters should not intentionally underdrink because they are afraid of hyponatremia.

The goal is balance.

What if I am a salty sweater?

Then sodium replacement may deserve more attention, especially during:

• prolonged exercise
• heat
• repeated sessions

But salty sweat still does not justify consuming unlimited water.

Total sodium loss depends on:

sweat volume × sweat sodium concentration

For more detail, read How Much Sodium Do You Lose in Sweat?.

Common mistake: drinking at every opportunity

Having a water station does not mean you need to empty a cup every time you pass it.

Use:

• thirst
• conditions
• duration
• your own fluid-loss data

Common mistake: believing dehydration is always more dangerous

Both ends of the spectrum can create health problems.

Dehydration can impair performance and increase physiological strain.

Severe symptomatic hyponatremia can be life-threatening.

Good hydration is not about choosing one fear.

It is about avoiding both extremes.

Common mistake: thinking sports drinks solve everything

Sports drinks can provide:

• fluid
• carbohydrate
• sodium

They can be useful.

But they do not prevent hyponatremia if you consume them in volumes greatly exceeding your losses.

Common mistake: diagnosing yourself from a headache

A headache during exercise could have many explanations.

It does not tell you whether your sodium is:

• low
• normal
• high

Do not respond automatically by either:

• drinking litres of water
• taking large amounts of salt

Use context and seek medical help when symptoms are severe.

Common mistake: treating cramps as proof of low sodium

Exercise-associated cramps are multifactorial.

A cramp does not diagnose hyponatremia.

It does not automatically diagnose dehydration either.

Common mistake: ignoring unexplained weight gain

During prolonged exercise, gaining meaningful body weight from drinking is a useful warning that intake may be exceeding losses.

That is a signal to reassess your strategy.

A simple hydration safety checklist

For prolonged exercise, ask:

Am I drinking because I am thirsty, because my tested plan calls for it, or simply because water is available?

Do I know approximately how much I sweat in these conditions?

Am I repeatedly forcing fluid despite feeling full or bloated?

Am I gaining weight across a long event?

Am I assuming electrolytes make unlimited drinking safe?

Do I have a different plan for hot and cool conditions?

These questions prevent many of the mistakes that create excessive fluid intake.

FAQ

Can you really drink too much water during exercise?

Yes.

During prolonged exercise, consuming fluid substantially faster than you lose and excrete it can contribute to exercise-associated hyponatremia.

What is exercise-associated hyponatremia?

It is a blood sodium concentration below 135 mmol/L developing during or within about 24 hours of physical activity.

What is the main cause?

The major preventable factor is excessive fluid intake relative to losses, often combined with continued water retention caused by vasopressin.

Is hyponatremia just a lack of salt?

No.

It is a low sodium concentration in the blood.

In EAH, excessive body water is commonly a major part of the problem.

Can drinking plain water cause it?

Yes, if sufficiently excessive relative to losses.

Can sports drinks cause hyponatremia too?

Yes.

A sodium-containing drink does not make excessive fluid consumption safe.

Do electrolyte tablets prevent it?

Not reliably if you continue to overdrink.

Is hyponatremia only an endurance-sport problem?

It is most strongly associated with prolonged exercise, but it has been reported across a wider range of activities.

Can it happen in cold weather?

Yes.

It is a fluid-balance problem, not exclusively a heat problem.

Can it happen during a one-hour gym workout?

That would be unusual in a healthy person drinking normally.

Risk becomes much more relevant during prolonged exercise with excessive fluid intake.

Does gaining weight during a race mean I have hyponatremia?

No.

But weight gain during prolonged exercise can indicate fluid intake exceeding losses and is an important warning sign.

Does losing weight mean I definitely cannot have hyponatremia?

No.

Blood testing is required for diagnosis.

What are the symptoms?

They can include headache, nausea, vomiting and fatigue.

Severe cases may involve confusion, seizures, altered consciousness, respiratory distress or coma.

Should I give lots of water to someone who collapses after a marathon?

Not automatically.

Collapse can have many causes, and giving more fluid to someone with EAH can worsen the problem.

Seek appropriate medical assessment.

Should I stop drinking during exercise to avoid hyponatremia?

No.

The goal is appropriate hydration, not intentional dehydration.

Is thirst a useful guide?

Yes.

For many athletes, drinking according to thirst is a practical strategy that helps reduce unnecessary overdrinking.

Should I measure my sweat rate?

It can be very useful if you do prolonged, hot or very sweaty training.

Can severe hyponatremia be fatal?

Yes.

Severe symptomatic EAH can cause cerebral oedema, seizures, coma and death.

It requires urgent medical treatment.

Sources and further reading

The recommendations and explanations in this guide are informed by international consensus guidance and sports-medicine reviews on exercise-associated hyponatremia and fluid replacement.

• Hew-Butler T et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference. Clinical Journal of Sport Medicine. 2015;25(4):303–320. PMID: 26102445.
  https://pubmed.ncbi.nlm.nih.gov/26102445/

• Hew-Butler T et al. Exercise-Associated Hyponatremia: 2017 Update. Frontiers in Medicine. 2017;4:21. PMID: 28316971.
  https://pmc.ncbi.nlm.nih.gov/articles/PMC5334560/

• Rosner MH. Exercise-Associated Hyponatremia. Transactions of the American Clinical and Climatological Association. 2019;130:76–87. PMID: 31516170.
  https://pmc.ncbi.nlm.nih.gov/articles/PMC6735969/

• McDermott BP et al. National Athletic Trainers’ Association Position Statement: Fluid Replacement for the Physically Active. Journal of Athletic Training. 2017;52(9):877–895. PMID: 28985128.
  https://pubmed.ncbi.nlm.nih.gov/28985128/

• Seal AD, Kavouras SA. A Review of Risk Factors and Prevention Strategies for Exercise-Associated Hyponatremia. Autonomic Neuroscience. 2022;238:102930. DOI: 10.1016/j.autneu.2021.102930.

• Klingert M et al. Exercise-Associated Hyponatremia in Marathon Runners. Journal of Clinical Medicine. 2022;11(22):6775. PMID: 36431252.
  https://pmc.ncbi.nlm.nih.gov/articles/PMC9699060/

The risk of EAH depends heavily on exercise duration, fluid intake, fluid loss and individual physiology.

Do not use one universal drinking volume for everyone.

Final takeaway

Yes, you can drink too much water during exercise.

The biggest practical risk arises when:

fluid intake repeatedly exceeds fluid loss during prolonged exercise.

You do not prevent dehydration by drinking the maximum amount possible.

You prevent both extremes by drinking an amount that makes sense for:

• your sweat rate
• the weather
• exercise duration
• your thirst
• your recovery needs

Electrolytes can help replace sodium losses.

They do not make unlimited drinking safe.

And if a person develops:

confusion, seizures, reduced consciousness or other severe neurological symptoms during or after prolonged exercise, treat it as a medical emergency rather than simply giving them more water.