After a tough workout, many people reach for a sports drink or electrolyte powder. The packaging promises better fluid balance, faster recovery and more energy. But is all that really necessary after a 45-minute workout, or would water and regular food be enough?
What are electrolytes?
Electrolytes are minerals found in body fluids as electrically charged particles known as ions. They help regulate fluid balance and support nerve signalling and muscle function.
The main electrolytes are sodium, chloride, potassium, calcium and magnesium. Electrolytes themselves do not provide energy or act like caffeine or carbohydrates. They simply help the body function normally.
What happens during exercise?
When you sweat, you lose both water and electrolytes, particularly sodium and chloride. The amount lost depends on the duration and intensity of the workout, the air temperature and how much you sweat.
For example, someone exercising for an hour in a cool gym may lose relatively little fluid and minerals. During a two-hour run in hot weather, however, the loss can be considerably greater.
Electrolyte deficiency is often considered a cause of muscle cramps, but cramps can also result from muscle fatigue, unfamiliar exertion and heat. A cramp therefore does not automatically mean that someone needs an electrolyte drink.
How can you assess your fluid loss and electrolyte needs?
Workout duration alone does not tell the whole story, as two people may sweat very different amounts during the same activity. You can roughly estimate your fluid loss by weighing yourself before and after exercise. If your body weight is one kilogram lower after your workout, your body has lost approximately one litre of fluid. You should also take into account how much water you drank during the workout.
The change in body weight indicates approximate fluid loss, but it does not reveal how many electrolytes were lost through sweat. White salt stains on dark workout clothes, sweat that stings your eyes or a salty film left on your skin after exercise may indicate greater sodium loss. These signs do not reveal the exact amount of sodium lost, but they may suggest that during prolonged, sweaty exercise, it is worth considering replenishing sodium as well as water.
Can you get electrolytes from water and food?
Regular tap water and mineral water may contain calcium, magnesium, sodium and other minerals, but the amounts depend on the source of the water.
In reality, however, we get most of our electrolytes from food rather than water. Sodium and chloride come mainly from table salt and salty foods; potassium from potatoes, fruit, vegetables, dairy products and meat; calcium from dairy products; and magnesium from nuts, seeds, whole grains and legumes. After a typical workout, water and a meal will usually provide the body with both the fluid and minerals it needs.
Is more water always better?
Drinking water is essential, but during prolonged endurance exercise, more is not always better. If someone drinks a very large amount of plain water over several hours without replacing the sodium lost through sweat, their blood sodium level may fall too low. This is known as hyponatraemia.
This situation is rare during a typical gym workout. The risk is greater during long runs, hikes and other endurance activities where someone drinks more water than they lose through sweat for several hours at a time. During prolonged exercise, both water and sodium should therefore be considered, while also avoiding forcing yourself to drink more than your body needs.
Do you need an electrolyte supplement?
Most people who exercise for less than 90 minutes under normal conditions are unlikely to lose enough fluid and electrolytes to make a special sports drink essential. An electrolyte drink may be useful during prolonged endurance exercise, in hot weather or when sweating very heavily.
It is important to check what is actually being sold as a sports drink. One good example is ICONFIT Isotonic, which is sold in Estonia. It is an isotonic sports drink powder designed primarily to provide fluid, electrolytes and energy during prolonged exercise.
One 40-gram serving is mixed with 500 millilitres of water. A serving provides 147 kilocalories and contains 35 grams of carbohydrates, of which 19.1 grams are sugars. This is equivalent to approximately five teaspoons of sugar. Carbohydrates therefore make up almost 88% of the entire serving.
At first glance, this may seem like a very large amount, but this is an isotonic sports drink, not a pure electrolyte supplement. The prepared drink contains about seven grams of carbohydrates per 100 millilitres. This falls within the typical carbohydrate concentration of 6–8% found in sports drinks and is intended to provide energy during prolonged exercise. The question is therefore not whether the sugar is in the product by accident, but whether the person drinking it needs that energy.
In terms of electrolytes, a serving provides 60 milligrams of calcium, 28.1 milligrams of magnesium and 149.5 milligrams of potassium. Each amount corresponds to 7.5% of an adult’s daily reference intake. You can get approximately the same amount of potassium from less than half a banana and a similar amount of magnesium from a small handful of seeds.
The drink contains 0.25 grams of salt, equivalent to approximately 100 milligrams of sodium. Sodium is one of the most important electrolytes to replenish during prolonged, sweaty exercise. For comparison, an athlete who sweats heavily may lose about 500–700 milligrams of sodium during one hour of intense exercise, although the actual amount varies greatly from person to person.
The product also contains vitamin C and B vitamins, but these are not electrolytes and are not the main factors in restoring fluid balance. More importantly, the consumer gets 35 grams of carbohydrates along with a relatively small amount of electrolytes.
During a long run, bike ride or other endurance workout, these carbohydrates may be useful because they provide energy to keep going. After a typical 45–60-minute workout, however, there is usually no need to consume almost 150 extra kilocalories and nearly five teaspoons of sugar just to get a small amount of electrolytes. In that case, water and a regular meal serve the same purpose more simply.
What should you look for on the packaging?
When choosing an electrolyte product, the words “hydration” or “recovery” on the front of the packaging are not enough. First, check the serving size and how much water should be added. Then check the amounts of sodium or salt, carbohydrates and sugars.
The amount of sodium is not always listed separately on the packaging. Instead, the nutrition table may show the amount of salt. These figures are not the same: 0.25 grams of salt contains approximately 0.1 grams, or 100 milligrams, of sodium.
If a drink contains a lot of carbohydrates, it is designed to provide energy as well as restore fluids. This may be useful during prolonged exercise, but the extra energy may not be needed after a short workout. It is also worth remembering that the percentage of the daily reference intake shown on the packaging does not indicate how much of a particular person’s electrolytes lost through sweat the drink will replace.
Match your electrolytes to your workout
Imagine two people exercising. One finishes a 45-minute strength workout, while the other completes a two-hour run in hot weather. Water and a proper meal will usually be enough for the first person. For the second, the carbohydrates, fluid and sodium in a sports drink may be a practical aid.
An electrolyte drink is therefore neither inherently necessary nor pointless. Its value depends on the situation. Before buying one, consider the duration of your workout and how much you sweat, and check the back of the packaging. If your workout does not require extra carbohydrates and the minerals you have lost can be replenished with your next meal, a glass of water may still be the most sensible alternative to a colourful powder.
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