HYDRATION & PERFORMANCE: WHY WATER ISN'T THE WHOLE STORY

How much should you drink, when do you need electrolytes, and how can you build your own hydration strategy?

We talk a lot about carbohydrate fuelling when it comes to endurance performance.

But there's another part of the equation that can have a huge impact on how you train and race:

Hydration. And hydration isn't simply about drinking more water.

Your fluid requirements are individual and can change dramatically depending on how long you're exercising, how hard you're working, the temperature, humidity, sun exposure, your clothing, your sweat rate and how much sodium and other minerals you lose in your sweat.

Get it right and you're giving your body the best chance of performing as intended.

Get it wrong and you may find yourself struggling with heat, fatigue, reduced exercise capacity or gastrointestinal discomfort.

So let's look at what actually matters.

WHY DOES HYDRATION MATTER FOR PERFORMANCE?

During exercise, your working muscles produce heat.

Sweating is one of your body's primary ways of getting rid of that heat. As you sweat, you lose fluid and minerals.

If those losses become substantial and aren't appropriately managed, cardiovascular and thermal strain can increase and exercise performance can be affected, particularly during prolonged exercise and in hot conditions.

But there's an important distinction:

Hydration isn't about replacing every drop of sweat.

It's about developing a strategy that appropriately manages your individual fluid losses without over-drinking.

And that strategy will look different for different athletes.

NOT EVERY TRAINING SESSION NEEDS THE SAME AMOUNT OF FLUID

Think about the difference between:

A 45-minute easy run on a cool morning

and a three-hour long run in 30°C heat and high humidity.

They're both running.

But your hydration requirements could be dramatically different.

The same applies to cycling, triathlon, HYROX and other endurance sports.

Your hydration strategy should reflect the demands of the session and the environment you're exercising in.

WHAT MAKES YOU NEED MORE FLUID?

Several factors can increase your fluid losses.

🌡️ TEMPERATURE

As the temperature rises, your body needs to work harder to dissipate heat.

That generally means increased sweating.

A session that feels perfectly manageable in cool conditions can become considerably more demanding when performed in hot weather.

💧 HUMIDITY

Humidity can make cooling more difficult because sweat doesn't evaporate as effectively when the surrounding air is already humid.

You may therefore sweat heavily without getting the same cooling benefit.

Hot and humid conditions can be particularly challenging for endurance athletes.

☀️ SUN EXPOSURE

Training in direct sunlight can increase your heat load compared with exercising in shade.

Two sessions performed at the same air temperature can therefore feel very different depending on whether you're running in direct sun, under cloud cover or indoors.

🏃 EXERCISE INTENSITY

The harder you work, the more heat your body produces.

A relaxed aerobic run and a hard interval session can therefore produce very different sweat rates, even when performed in the same environment.

HYROX is a great example.

You're combining running with repeated high-intensity functional movements, creating a significant cardiovascular and thermal demand.

⏱️ DURATION

The longer you exercise, the more opportunity there is to accumulate fluid losses.

A 45-minute session and a four-hour endurance event require very different planning.

For shorter sessions in comfortable environmental conditions, many athletes can rely largely on normal daily hydration and drink according to thirst.

As exercise duration increases, particularly during prolonged endurance exercise, paying closer attention to fluid and electrolyte losses becomes increasingly important.

YOUR SWEAT RATE IS UNIQUE TO YOU

This is one of the most important things to understand.

We don't all sweat the same amount.

Two athletes can run side by side for two hours in exactly the same conditions and lose very different amounts of fluid.

Some athletes are heavy sweaters.

Others sweat considerably less.

Some athletes lose more sodium in their sweat.

Others lose less.

This is why copying another athlete's hydration strategy isn't necessarily going to work for you.

Your hydration strategy should be yours.

HOW CAN YOU WORK OUT YOUR SWEAT RATE?

You can do a simple field test during training.

BEFORE YOUR SESSION

Weigh yourself with minimal clothing.

Record your weight.

DURING YOUR SESSION

Record:

· How much fluid you drink

· How long you exercise

· The environmental conditions

· Any urine produced during the session

AFTER YOUR SESSION

Weigh yourself again, ideally after drying off and changing out of wet clothing.

A simplified calculation is:

Sweat loss = pre-exercise weight − post-exercise weight + fluid consumed − urine produced

For example:

1. You start at 70.0 kg.

2. You finish at 69.0 kg.

3. You drink 1.0 litre during the session.

4. You don't urinate.

5. Your estimated sweat loss is approximately:

6. 2.0 litres

7. If the session lasted two hours:

8. Estimated sweat rate = approximately 1.0 litre/hour.

9. Repeat this test under different conditions and you'll start to build a much clearer picture of your individual requirements.

   
   

YOUR SWEAT RATE CAN CHANGE

Your sweat rate isn't fixed.

You might lose:

0.5 L/hour during a cool morning run.

But perhaps:

1.0 L/hour during a warm afternoon.

And potentially considerably more during a long session in hot, humid conditions.

Same athlete.

Different environment.

Different hydration strategy.

WHAT ABOUT ELECTROLYTES?

This is where things get a little more interesting.

Sweat doesn't contain only water.

You also lose electrolytes — including sodium, chloride, potassium, calcium and magnesium.

The amount you lose varies considerably between individuals.

Some athletes are naturally higher-salt sweaters.

Others lose considerably less.

This is one reason electrolyte requirements can't simply be reduced to:

"Everyone needs electrolytes."

For many athletes exercising for less than 60–90 minutes in normal conditions, a normal diet will generally provide sufficient electrolytes.

However, electrolyte replacement can become increasingly relevant when you have:

· High sweat rates

· Long-duration exercise

· Significant sweating

· Hot or humid conditions

· Multiple training sessions

· Evidence of high sweat sodium losses

· Limited opportunities to replace electrolytes through food during exercise

The AIS recognises electrolyte supplementation as particularly useful in situations involving substantial sweat losses and prolonged exercise. (ausport.gov.au)

ELECTROLYTES DON'T JUST MEAN SODIUM

Sodium is the major electrolyte lost in sweat and therefore receives much of the attention in endurance nutrition.

But electrolytes are a broader group of minerals.

Our BYF Electrolyte Mix contains a blend of mineral salts providing:

Magnesium Potassium Calcium

It has been designed to give athletes another flexible option when building their hydration strategy.

And this is where we think it becomes particularly useful.

TWO WAYS TO USE BYF ELECTROLYTES

1. MAKE YOUR OWN ELECTROLYTE DRINK

Simply mix the BYF Electrolyte Mix with water to create your own electrolyte drink.

This gives you a straightforward way to include electrolytes during training, racing or throughout the day when appropriate.

Your carbohydrate and hydration strategies don't always need to be combined.

Sometimes you simply want:

Water + electrolytes.

2. ADD IT TO YOUR BYF CARBOHYDRATE MIX

This is where the BYF system really comes together.

You can add your BYF Electrolyte Mix to your carbohydrate mix to create your own carbohydrate + electrolyte fuel.

That means one soft flask can contain both the carbohydrate you're using for fuelling and the electrolytes you're choosing to include as part of your hydration strategy.

Build your fuel. Build your hydration.

You control what goes into your flask and can adjust your strategy around the demands of your training or race.

WHY WE LIKE THE BYF SYSTEM

This is exactly how we use it ourselves.

We're endurance athletes training and racing across HYROX, running and triathlon, and our hydration needs aren't the same every day.

A short training session in cool conditions might require very little during the session.

A long run in the Australian summer is completely different.

An Ironman 70.3 is different again.

Instead of having one product that tries to do everything, we wanted a system that gives athletes flexibility.

BYF Carbohydrate Mix

Build your carbohydrate fuel.

BYF Electrolyte Mix

Build your electrolyte drink.

BYF Carbohydrate + Electrolyte

Combine the two when your training or race demands it.

One system. Your strategy.

HOW MUCH SHOULD YOU DRINK?

There isn't one magic number.

Your goal isn't necessarily to replace 100% of the fluid you lose during exercise.

In fact, drinking substantially more fluid than you're losing can be dangerous.

Exercise-associated hyponatremia can occur when excessive fluid intake dilutes the sodium concentration in your blood. Severe cases can be life-threatening. (ausport.gov.au)

Instead, develop a strategy based on:

Your sweat rate.

Your exercise duration.

Your intensity.

The environment.

Your access to fluid.

Your individual tolerance.

And, when appropriate, your electrolyte requirements.

DON'T WAIT UNTIL RACE DAY

Just like carbohydrate fuelling, hydration is something you can practise.

Your long training sessions are the perfect opportunity to experiment.

Try different fluid volumes.

Measure your sweat rate.

Pay attention to the conditions.

Work out what feels comfortable.

Practise carrying your bottles or soft flasks.

Test your carbohydrate and electrolyte combination.

Then refine it.

Your race-day strategy should not be a first experiment.

HYDRATION FOR MARATHON, TRIATHLON, HYROX & ULTRA

Different events create different hydration challenges.

MARATHON

Long duration, potentially high temperatures and limited opportunities to drink can make hydration planning important.

IRONMAN & 70.3

Several hours of continuous exercise combined with changing environmental conditions means hydration and electrolyte planning become an important part of race preparation.

HYROX

High-intensity running combined with functional stations creates significant cardiovascular and thermal demands, particularly during longer sessions and warmer conditions.

ULTRA RUNNING

Long duration means prolonged exposure to fluid losses, often combined with changing terrain, temperature and access to aid stations.

There is no universal strategy.

The event determines the demands.

Your body and your environment help determine the solution.

THE BIGGEST HYDRATION MISTAKES?

ONLY THINKING ABOUT WATER.

Hydration is more than just drinking water.

COPYING SOMEONE ELSE'S PLAN.

Your sweat rate isn't necessarily the same as theirs.

IGNORING THE ENVIRONMENT.

A strategy that works at 10°C may be completely inadequate at 30°C.

WAITING UNTIL RACE DAY.

Your hydration strategy should be pract

More fluid isn't automatically better.

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BUILD YOUR HYDRATION STRATEGY

Before a long training session or race, ask yourself:

• How long am I going to be exercising?

• How hard am I going to be working?

• What's the temperature?

• What's the humidity?

• Will I be in direct sun?

• How much do I normally sweat?

• How much fluid can I realistically carry?

• Will I need electrolytes?

• Am I also taking carbohydrate?

• Then build your strategy.

HYDRATION IS PART OF PERFORMANCE

When you're preparing for a marathon, Ironman, HYROX or ultra, hydration shouldn't be something you think about only when you're already thirsty.

It should be part of your preparation.

Your training plan tells you how far you're going.

Your fuelling plan tells you where your carbohydrate is coming from.

Your hydration plan tells you how you're going to manage the fluid and electrolyte losses along the way.

And when the environment changes, your strategy needs to change too.

Cool morning?

Your needs may be lower.

Hot afternoon?

Your fluid losses may increase.

Hot + humid + long duration + high sweat rate?

Now hydration and electrolyte planning become a much bigger part of your performance strategy.

BUILD YOUR HYDRATION. BUILD YOUR FUEL.

This is why we created BYF as more than just a carbohydrate mix.

We wanted athletes to have the flexibility to build their own fuelling and hydration strategy.

Use the carbohydrate mix when you need carbohydrate.

Use the electrolyte mix when you need electrolytes.

Or combine them to create your own carbohydrate + electrolyte fuel in a reusable soft flask.

Mix it. Fill it. Carry it. Fuel it.

Your training is individual.

Your sweat is individual.

Your environment is constantly changing.

So why shouldn't your hydration strategy be individual too?

BUILD YOUR FUEL.

BUILD YOUR HYDRATION.

TRAIN SMARTER. GO FURTHER.