What do sports drinks actually do? Unpacking the science of athletic hydration

October 23, 2025 •

4 min read

According to Sports Dietitians Australia, sports drinks are specifically formulated to provide the right balance of carbohydrates, electrolytes, and fluid to adequately fuel exercise and provide hydration. This differs significantly from plain water, as what do sports drinks actually do depends on their unique composition designed for athletes undergoing prolonged or intense physical activity. For casual workouts, however, their high sugar content might be unnecessary and potentially detrimental to health.

Quick Summary

Sports drinks aid athletic performance by providing carbohydrates for energy, and electrolytes like sodium and potassium to balance fluids lost in sweat. They are most beneficial during high-intensity or prolonged exercise, and less necessary for casual physical activity.

Key Points

Replenish Electrolytes: Sports drinks replace essential minerals like sodium and potassium lost through sweat, which are vital for maintaining fluid balance and muscle function during intense exercise.
Provide Carbohydrates for Energy: The sugars in sports drinks offer a quick fuel source to replenish muscle glycogen stores, delaying fatigue and improving endurance during prolonged or high-intensity activity.
Enhance Fluid Absorption: The presence of electrolytes, particularly sodium, helps to stimulate thirst and accelerate fluid absorption, leading to more effective hydration than plain water alone in demanding conditions.
Benefit for Endurance Athletes: These drinks are primarily designed for endurance athletes or those exercising for over an hour, especially in hot conditions, where both electrolytes and energy need rapid replenishment.
Unnecessary for Casual Exercise: For low-to-moderate intensity workouts lasting less than an hour, plain water is sufficient. The added calories and sugar from sports drinks are not needed and can be detrimental for health.
Can be High in Sugar: Many commercial sports drinks contain as much sugar as soda, increasing the risk of weight gain, diabetes, and dental erosion if consumed without vigorous exercise.
Potential for Over-Hydration Issues: While rare, consuming excessive amounts of sports drinks can lead to electrolyte imbalances, which can cause symptoms like nausea, weakness, and irregular heartbeat.
Zero-Sugar Options Exist: For those needing electrolyte replacement without the extra calories, low-sugar or zero-calorie sports drinks, or DIY versions, are viable alternatives.

The core components: Electrolytes and carbohydrates

To understand what do sports drinks actually do, you must look at their core ingredients: water, carbohydrates, and electrolytes. While water is the fundamental base, the other components are what provide the performance-enhancing benefits during specific types of exercise.

The function of carbohydrates

Carbohydrates in sports drinks serve as a readily available fuel source for the muscles and brain, which is crucial during prolonged or high-intensity exercise. The body’s natural glycogen stores are depleted during strenuous activity, and consuming carbohydrates helps to maintain blood sugar levels, delay fatigue, and improve endurance.

Sports drinks typically contain a 6–8% carbohydrate solution, which is considered optimal for rapid absorption without causing gastric distress. A blend of sugars, such as glucose, sucrose, and fructose, is often used to maximize carbohydrate absorption. For instance, a 2:1 ratio of glucose to fructose can enhance absorption rates compared to using only one type of sugar.

The role of electrolytes

Sweating causes the body to lose electrolytes, primarily sodium and potassium. These minerals are vital for nerve and muscle function, fluid balance, and blood pressure regulation. Sports drinks are formulated with these electrolytes to help replenish what is lost, preventing issues like muscle cramps and hyponatremia (low blood sodium).

Sodium: The sodium in sports drinks serves two key purposes: it helps stimulate the thirst mechanism, encouraging the athlete to drink more, and aids in the absorption and retention of fluids.
Potassium: This electrolyte helps maintain fluid balance and proper muscle function, assisting with muscle contraction during exercise.

Comparing sports drinks and water

It's important to distinguish when a sports drink is necessary and when plain water will suffice. The choice depends on the duration, intensity, and environmental conditions of the exercise.


Feature	Water	Sports Drinks	When to use
Composition	Pure H₂O, no calories, carbs, or electrolytes	Water, carbohydrates, electrolytes, and flavorings	Varies based on activity intensity and duration
Hydration	Excellent for general hydration and short, light exercise.	Enhanced fluid absorption due to the presence of sodium, especially during intense sweating.	Long-duration, high-intensity exercise, or in hot conditions.
Energy	Provides no energy.	Offers a quick source of energy from carbohydrates to fuel working muscles and delay fatigue.	Exercise lasting over 60-90 minutes.
Replenishment	Replaces lost fluid but not electrolytes or glycogen stores.	Replaces fluids, electrolytes, and glycogen lost through sweat.	During and after intense, prolonged activity.
For casual exercise	Best choice, as it's calorie-free and effective for rehydration.	Often unnecessary calories and sugar for low-intensity activities.	Best avoided for most daily activities and workouts under an hour.

The potential downsides of overconsumption

While sports drinks offer benefits for athletes, they are not without risks, particularly when consumed excessively by non-athletes. Their high sugar content can contribute to weight gain, type 2 diabetes, and dental issues. Excessive intake of electrolytes can also lead to imbalances, with symptoms ranging from muscle cramps to an irregular heartbeat.

Other ingredients to consider

Some sports beverages contain additional ingredients, though many do not have proven performance benefits.

Caffeine: Added for a potential performance boost or improved alertness, but can cause jitteriness and, in excess, can be dehydrating.
Vitamins and minerals: While some are added, it's generally more effective to obtain these from a balanced diet.
Flavoring and colorants: These are added primarily for taste and palatability, which can encourage people to drink more.

How to decide what's right for you

The best hydration strategy is personal and depends on your activity level. For the average person engaging in moderate exercise for less than an hour, water is the best choice. For endurance athletes or individuals exercising intensely for over an hour, especially in hot conditions, a sports drink can offer significant benefits by providing the necessary fuel and electrolytes to sustain performance and recovery. Many zero-sugar alternatives also exist for those seeking electrolyte replenishment without the extra calories.

Ultimately, understanding what do sports drinks actually do empowers you to make an informed decision based on your specific needs, ensuring you fuel your body effectively for any activity.

Conclusion

Sports drinks are engineered for a specific purpose: to optimize athletic performance by efficiently replacing fluids, electrolytes, and carbohydrates lost during intense or prolonged physical activity. They differ fundamentally from plain water, which is suitable for shorter, lower-intensity workouts. While they offer distinct advantages for endurance athletes and those exercising in extreme heat, their high sugar and calorie content make them unnecessary and potentially unhealthy for casual exercisers or as a daily beverage. By understanding the composition and purpose of sports drinks, you can align your hydration strategy with your training goals, using them judiciously when their benefits are most needed.

Homemade sports drink recipe

For those who want to avoid artificial ingredients, a simple homemade sports drink is easy to make.

Ingredients:

2 cups of water
1/4 teaspoon of sea salt
2 tablespoons of fresh lemon or lime juice
1-2 tablespoons of honey or a natural sweetener of your choice

Instructions: Mix all ingredients together until the salt and honey are dissolved. You can adjust the sweetness and flavor to your liking. The lemon or lime juice provides flavor, while the honey and salt replace carbohydrates and electrolytes.

Frequently Asked Questions

Water is the best choice for general hydration and for most workouts that are less than 60 minutes long and not extremely intense. For short, moderate-intensity exercise, your body doesn't require the extra carbohydrates and electrolytes found in sports drinks.

Sports drinks focus on hydration, electrolyte replacement, and providing a small amount of carbohydrate fuel. Energy drinks, by contrast, typically contain stimulants like high levels of caffeine and guarana to boost mental alertness, and are not designed primarily for hydration during exercise.

For most children, plain water is sufficient for hydration during physical activity. The American Academy of Pediatrics advises against sports drinks for casual exercise due to their high sugar content, which can contribute to weight gain and dental problems.

Yes, excessive consumption, especially without intense exercise, can lead to health issues. The high sugar content can cause weight gain and dental erosion, while an overdose of electrolytes can lead to imbalances with side effects like nausea and heart rhythm problems.

Electrolytes are essential minerals, such as sodium, potassium, and magnesium, that carry an electric charge. They help regulate nerve and muscle function, maintain fluid balance, and keep blood pressure stable. They are lost through sweat during exercise.

Yes, you can easily make a homemade version using water, a pinch of salt, a natural sweetener like honey, and a squeeze of fruit juice. This gives you full control over the ingredients and avoids the artificial additives found in many commercial products.

Athletes should consider using a sports drink during exercise lasting more than 60–90 minutes, or in hot and humid conditions where sweat loss is high. It can also be used for recovery to replenish fluids and glycogen stores.