Electrolyte drinks are useful in specific situations and unnecessary in most others. Here is how to tell the difference, using public health guidance rather than shelf hype.
Quick points
- For workouts of an hour or less at moderate effort in normal weather, plain water plus your usual food covers fluid and electrolyte needs.
- Sodium is the electrolyte lost in the largest amounts in sweat, so it is the one worth replacing after long, hard or hot sessions.
- Australian dietary guidelines group sports drinks with other sugary drinks that are recommended to be limited.
- A fluid loss of two per cent of body weight is enough to measurably reduce exercise performance.
- Check with a doctor, nurse or pharmacist if you take diuretic medication, have a health condition, or have been unwell with vomiting or diarrhoea.
Walk down the drinks aisle after a hard session and you will find bottles promising rapid rehydration, faster recovery and better performance. Most of the time, what your body actually needs after exercise is far simpler, and public health guidance is refreshingly blunt about it. Here are the questions we hear most often about electrolyte drinks, answered with general information rather than marketing.
What are electrolytes and what do they do?
Electrolytes are minerals that carry an electric charge once they dissolve in liquid, including the liquid in your blood. The main players in exercise are sodium, potassium, calcium, magnesium and chloride. Between them, they help your heart beat, your blood circulate and your nerves and muscles fire, and they help your body absorb and hold on to the right amount of water.
Sodium is the mineral your body loses in the largest quantity through sweat, followed by chloride, while potassium, magnesium and calcium leave in smaller amounts. Water matters just as much. Depending on how much lean mass you carry, your body is between 50 and 80 per cent water, and because it has no way to store water, it needs fresh supplies every day.
Why does exercise drain them?
When your internal temperature climbs during a workout, sweating is how your body cools you back down, and sweat carries water out along with those minerals. Sweat is mostly water, but the sodium and other minerals leave with it.
How much you lose depends on the weather, your clothing, how hard and how long you are working, and your own physiology. Two people in the same class can lose very different amounts. Fitness plays a counterintuitive part: the more trained you are, the earlier in a session you start sweating, and the more of it you do. Over an ordinary day, an adult body typically turns over somewhere in the range of two and a half to three litres of water, and hot weather or a long session pushes that figure higher.
When is plain water enough?
For most everyday workouts, water is all you need. If you are exercising for an hour or less at moderate intensity in normal weather, tap water will rehydrate you and your usual meals will replace the minerals. Tap water carries a small extra advantage too: in many areas it has fluoride added, which helps protect your teeth.
It also helps to start each session already well hydrated, because that delays the point where fatigue sets in. Thirst is a late warning rather than an early one. By the time you notice it, your fluid levels have usually already dipped. Urine colour gives a rough guide instead: the darker it is, the more fluid you need. Some supplements change urine colour, so do not rely on that sign by itself. As a general guide, somewhere between 500 and 900 ml per hour of exercise should be enough in normal situations, adjusted for your size, the conditions and how much you sweat.
When does replacing electrolytes genuinely matter?
The picture changes when sessions get long, hard or hot. For rigorous exercise, water on its own is not enough, especially in hot or humid conditions. Sodium is the mineral to focus on, because it is what you lose most of in sweat.
Signs that your losses may be on the salty side include dried white salt crystals on your skin, clothes or hat once sweat dries. Long sessions count as well. People who train strenuously for more than 60 to 90 minutes every day generally need to increase their energy intake, particularly from carbohydrate, and sessions beyond an hour are where fluid and sodium planning starts to matter.
One honest caveat: for endurance exercise beyond an hour, and ultra-endurance events beyond four hours, public guidance on exactly how much sodium to take is still unclear. Electrolyte replacement products come as powders, tablets and ready-to-drink options, and tablets dissolve straight into your bottle. Taste matters more than marketing, because the drink you enjoy is the one you will actually keep drinking.
| Your session | What usually does the job |
|---|---|
| Under an hour, moderate effort, mild weather | Plain tap water |
| An hour or more, hard effort, or hot and humid conditions | Water plus a source of sodium, such as a sports drink or a salty snack |
| Fluid losses from vomiting, diarrhoea or fever | Ask a doctor, nurse or pharmacist about the right rehydration approach |
| Everyday activity like a walk or a short gym class | Water with your normal meals and snacks |
Can everyday foods and drinks replace electrolytes too?
For most people, yes. Eating a variety of foods and drinking plenty of water should keep your electrolytes topped up unless you are an athlete or exercising intensely for long stretches. Food quietly does some of the work too: roughly a fifth of the fluid your body needs each day comes from the food you eat, and digestion generates a small extra amount on top of that.
Salty foods replace sodium, while fruit, vegetables, dairy and other whole foods supply potassium, magnesium and calcium. For an energy boost during or after exercise, public health advice points to simple fruit such as mandarins, melon wedges or cut orange segments, alongside water, rather than a sweet drink.
How do you read a drink label without falling for the hype?
Start by knowing what the drink actually is. In Australia and New Zealand, a drink must contain between 5 and 10 per cent carbohydrate when made up as directed to be legally called an electrolyte drink, which is one reason sports drinks double as a source of sugar. Many sports drinks contain 250 milligrams or more of sodium per serve, more than 10 per cent of what is typically recommended for daily sodium intake. That is a genuine dose of sodium, useful in the situations above and unnecessary otherwise.
The Australian dietary guidelines place sports drinks in the same group as soft drinks, cordials, energy drinks and vitamin-style waters: sugary drinks that all Australians are advised to limit, because they add kilojoules without other nutrients and are linked with excess weight gain and tooth decay. If you do compare products, check the sodium amount, the carbohydrate content and the serve size before you buy.
Can you have too much of a good thing?
You can, on both counts. Too many electrolytes can produce symptoms similar to having too few, although falling short is the more common problem for people exercising intensely. Drinking far more fluid than you need carries its own risk: in rare cases it can lead to hyponatraemia, sometimes called water intoxication. There is no benefit to forcing down bottles on a timer, and you cannot train your body to cope with dehydration either. The goal is steady replacement, not extremes at either end.
Do electrolyte drinks prevent muscle cramps?
Marketing often says yes, but the evidence is messier. Exercise-associated muscle cramps can have several causes, and the main risk factors are fatigue from doing more exercise than you are used to, and having a history of cramps. There is some evidence, which researchers describe as controversial, that whole-body sodium depletion may cause certain cramps in some individuals. So a sodium-containing drink might help some people in some situations, but it is not a guaranteed shield. Building up your training loads gradually matters more, which is also the thinking behind our advice on rest, stretching and avoiding common injuries.
Which situations call for professional advice?
Some situations are worth a conversation with a doctor, nurse, pharmacist or sports dietitian before you stock up on electrolyte products. You may need more fluid than average if you have cystic fibrosis, which means a higher concentration of sodium in your sweat, or if you take a medication that acts as a diuretic. Illness changes the picture too: fever, vomiting and diarrhoea drain both fluid and electrolytes, and replacing those losses is a different job from recovering after a workout. If you are an athlete, the advice from public health bodies is to seek guidance about fluid replacement from a health professional rather than self-prescribing. And if you feel dizzy, nauseated or unwell during or after exercise, treat that as a signal to stop and check in with a professional, not a prompt to buy a stronger drink.
Training tip
One practical approach used in sport is to weigh yourself before and after a long session and aim to keep the loss under two per cent of your body weight. Losing more than that, for example 1.4 kg for a 70 kg person, is enough to cause a detectable drop in performance.
When should you worry about not drinking enough?
Usually only after the session has gone wrong. Signs of too little fluid include feeling more fatigued than usual, a body temperature and heart rate that climb more than they should, and performance that falls short of what you would expect. The effect is worse when you are active and dehydrated in hot conditions. One less obvious warning sign is a lack of sweat during vigorous activity, when you would normally expect to be drenched. If you notice any of these, stop, get out of the heat, rehydrate and take the rest of the day gently.
For more on putting this into practice, our fuel and hydration guide looks at what to eat and drink around exercise, and our walking and running guide covers how to add kilometres safely while keeping your fluid intake in step with your training.
You may also want to read Read a Sports Drink Label Before You Buy and Should I Eat Before an Early Morning Workout?.
Questions we get
Do I need an electrolyte drink after every workout?
No. For sessions of an hour or less at moderate intensity in normal conditions, water and a normal meal will replace everything you have lost. Electrolyte drinks earn their place after long, hard or hot-weather sessions, or for people who sweat heavily.
How can I tell if I am a salty sweater?
One common sign is dried white salt crystals on your skin, clothes or hat once sweat has dried. If you notice this, you may benefit from more sodium in your recovery fluids, and a sports dietitian can help you work out how much.
Are sports drinks and electrolyte drinks the same thing?
In Australia and New Zealand, a drink must contain between 5 and 10 per cent carbohydrate when made up as directed to be legally called an electrolyte drink, so most sports drinks qualify. Powders, tablets and ready-to-drink electrolyte products sit in a similar category.
Can I get enough electrolytes from food alone?
For most people, yes. A varied diet with plenty of water covers electrolyte needs unless you are training intensely or for long periods. Food tops up your fluids as well, supplying a decent share of the water you need each day.
This article is general information, not personalised medical or fitness advice. Talk to your GP, a physiotherapist or an accredited exercise physiologist before starting a new exercise program if you have a health condition or injury, are pregnant or haven’t been active for a while. In an emergency, call 000.