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Man drinking water trying to hydrate after exercise

How do Electrolytes fuel optimal human performance & maximise hydration?


By Awesome Supplements, Read time: 9 minutes

Who remembers Alistair Brownlee carrying his brother over the finish line in 2016? Moments away from winning the World Championship, Jonny Brownlee's legs just stopped working. If you've not seen it, go and watch the video on Youtube.

The race was in Mexico's sweltering 30+ degree heat, with 90% humidity. Jonny, the most successful Olympic Triathlete in history, lost control of his legs.

It's an extreme example, but it's a powerful display of dehydration affecting performance.

Electrolytes are essential, electrically-charged minerals (or salts). Their charge allows them to conduct signals along nerves, pull water into and out of cells and contract muscles . They play a vital role in hydration, muscular contraction and brain and nerve function.

The primary electrolytes involved in these processes include:

  • Sodium
  • Potassium
  • Calcium
  • Magnesium
  • Phosphorus


Our bodies are about 60% water. Two thirds of that is stored within our cells, the rest remains in the spaces between our cells or in our blood. Now, water flows passively. This means that, on its own, water will move freely until both sides of the cell membrane balance out. But to function optimally, we need twice as much inside our cells than outside.

This is where electrolytes come in. Their charge stops them from passing freely into or out of the cell. Transporter channels control the exchange of electrolytes through the cell membrane. This maintains a concentration of salts that affects the passing of water into the cell.

On average, we lose 2.3L of water per day. Most of this is through urination. But other processes like breathing and sweating also cause fluid loss. So it's important to replenish this water throughout the day.

But it's not only water that's important for hydration. Consuming too much fluid can flush out minerals by increasing urination. Fewer minerals means more water pulled out of cells to keep things balanced. This leads to cellular dehydration. When we sweat, we lose water and electrolytes (ever wonder why your sweat tastes salty?)

Cellular dehydration won't only make you feel thirsty. It can lead to insulin resistance, cognitive impairment and brain tissue shrinkage.


What about physical performance? We've already mentioned increased sweating causes water and electrolyte loss. But is this only important for endurance athletes or long bouts of exercise?

Remember Jonny? Heat exhaustion and dehydration reduced the ability of his nerves to communicate with his muscles. His legs went wobbly and couldn't carry him forward. Electrolytes are important for physical activity by maintaining proper nerve and muscle function. But this doesn't just apply to long duration activity. Calcium and magnesium are crucial for muscle contraction and relaxation. It's why muscle cramps are a common sign of an electrolyte imbalance. They're also involved in the electrical signal that causes your heart to beat.

If you're low on electrolytes, your nerves can't tell your muscles to work properly. And that's far from optimal. Calcium is also crucial for force generation by allowing interaction between muscle fibres. So if strength is important to you, electrolytes are important to you.

Equally as relevant, electrolytes play a role in energy production. We need an electrical gradient to allow protons to pass into the mitochondria. This is how we produce ATP for energy. Low electrolyte levels will lead to increased fatigue and lower performance.

Brain Function

We've all had a hangover before, right? Dry mouth, sore head, the shakes. All classic signs of dehydration and improper nerve and muscle function. How well can you think and focus during a hangover? We know that concentration and attention span drops, and short-term memory and recall ability decrease. What was the name of the pub you were in that night?

Remember that the electrical charge of electrolytes conduct a signal along nerves. If information can’t be passed through neurons to the hippocampus (memory storage area of the brain), then that information is lost. This results in gaps in memory.

Research has shown that a 2% reduction in body weight from fluid loss can result in significant cognitive impairment. That’s 1.6Kg for an 80kg person. For those of you who weigh yourselves first thing in the morning, you’re often significantly lighter than the night before, right? Most of that change will be water loss through breathing, any night time trip to the bathroom or your morning wee pre weighing, and 8-or-so hours of zero fluid intake. If you’re a couple of pounds down in the morning, even if fat loss is your goal, you may want to think about hydration ASAP. then weight yourself (or use that as a consistent benchmark), because most of that weight loss is water.


So staying hydrated is, clearly, very important. Drinking water throughout the day is crucial, but it's only part of the equation. Bottled spring water contains small amounts of minerals. Tap water has a little too, but both in tiny quantities compared with the levels within our bodies. Have a look below at the comparison of electrolyte levels. Tap water is also treated with chemicals such as chlorine to remove bacteria. If you're concerned about these chemicals, it may be that you filter your tap water. If so, it is likely that you are also removing any remaining minerals. In which case, it may be wise to replace the minerals in your filtered water with electrolytes.

You don’t need to consume electrolytes all day, every day. Too many electrolytes are as much of a problem as too little. The majority of your fluid intake should be from plain water. But if you follow the practical applications below, you’ll be better hydrated, and be optimising physical and mental potential.

Practical Applications

How much fluid should you consume per day?

Most of our daily fluid intake comes from drinks. A small percentage will also come from the foods we eat. Foods have locked-in water. Some, like fruits and vegetables, have higher amounts than others (think of a juicy pear or a cucumber). But for practical purposes, let’s focus on fluid intake here.

Most drinks we consume will contribute to hydration. Fruit juice, smoothies, tea, coffee (except espresso), even low percentage alcohol (eg. beers, wine). Hard spirits don't contribute because their dehydration effect outweighs their volume of liquid. More on alcohol shortly. For health, it would be sensible to try to get most of your daily hydration from water, as that is what our body needs.

We mentioned above that the average adult will lose 2.3L of fluids each day. This will vary based on factors such as body weight, lean mass, hydration status, and activity level. It's important to replace what we lose to keep functioning optimally.

Drink to thirst. This is advice we hear a lot and it is often, actually, pretty good advice. Our bodies are good at self-regulating and will send thirst signals when water is low. But it can be easy to ignore thirst signals, or confuse them with hunger. So a more accurate estimate of your daily fluid requirements is as follows:

Daily Fluid Intake (mls) = Body Weight (kg) x 28

Add 500ml per 30 minutes of moderate-intense exercise. If you're sweating, you're losing water AND electrolytes. So it's a good idea to add some in here too.

Caffeine and alcohol increase fluid loss. It's not necessary to get deep into the physiology here. Essentially, they affect the sympathetic nervous system through 2 different hormone pathways. This results in the kidneys reabsorbing less water, and passing more out as urine.

The diuretic (fluid loss) effect of most caffeinated drinks is neutralised by the volume of liquid. In other words, the amount of water or milk added to coffee drinks is usually enough to replace the extra fluid loss from the caffeine. This isn't the case for espresso as there is a very low volume of water.

Final point on caffeine and alcohol. It's sensible to avoid both close to bedtime. Caffeine and alcohol have a direct impact on sleep onset and sleep quality. But they will also increase the likelihood of waking for nocturnal urination. Avoid alcohol in the 2-3 hours before bed, and caffeine in the 8 hours leading up to sleep.

Electrolyte Supplementation

So when should we consider taking electrolytes? And how much?

A good rule of thumb is to add electrolytes to water after periods of dehydration:

  • Upon waking, after 7+ hours of zero hydration
  • After, or during, moderate-to-intense physical activity
  • On a hot day, if normal tasks are causing increased sweating
  • After alcohol
  • If your normal water intake causes excessive urination
Electrolyte Adequate Daily Intake Tap Water (UK) (per Litre) Awesome Hydrate (per serving)
Calcium 1000mg 30.5mg 340mg
Magnesium 320-420mg 3.6mg 100mg
Sodium 3000-5000mg 14.7mg 112mg
Pottasium 2600-3400mg 2.5mg 280mg
Phosphorus 700mg 1mg 285mg

Awesome Hydrate is a very cost-effective, great tasting supplement which can be added to water when you need it. It comes in 4 awesome flavours and is optimally dosed so that you get what you need, at the right time, in the right amounts.Try it for yourself here.

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