While water is the best option for rehydrating your body, drinking excessive amounts can cause an imbalance of electrolytes in the body. This condition is known as water intoxication and although it is very rare, it can be fatal. To reduce the risk of water intoxication, most sports drinks comprise ingredients that replenish fluids and electrolytes in a similar ratio to that usually found in the human body. For optimal performance, athletes should be hydrated and adequately fuelled during exercise. Although there is a wide range of beverages marketed with reference to sport or performance, sports drinks are specifically designed to provide the right balance of carbohydrates, electrolytes and fluid to adequately fuel exercise and provide fluid for hydration. When used appropriately they can result in performance benefits.
Let’s start with the basics-
What is a sports drink?
Sports drinks are functional drinks specifically designed to help athletes and other active people hydrate and refuel before, during and after exercise.
Why should I consume a sports drink?
Rehydration is the major requirement during exercise as performance deteriorates rapidly with dehydration. Minerals such as sodium and potassium are also frequently lost through sweat. Replacing the electrolytes, fluids and sugars lost during exercise promotes proper refuelling, which is important in delaying the onset of fatigue.
Hypotonic/ Isotonic/ Hypertonic- What are the key differences?
The term ‘isotonic’ describes a solution that is of a similar ‘thickness’ or concentration (tonicity) as another solution. In this case, it refers to a drink being of similar concentration to human blood. This matters in the world of sports drinks because whether a drink is hypotonic (lower concentration than blood), isotonic (about the same concentration) or hypertonic (higher concentration) affects how much energy (carbohydrate) it can deliver and how quickly you can absorb it into your bloodstream to replace the fluid you’re losing in your sweat.
Isotonic Sports Drinks-
Isotonic drinks contain similar concentrations of salt and sugar as in the human body and are formulated to quickly replace fluids lost during exercise but with an increase in carbohydrates. Most traditional sports drinks available in the market technically fall into this category.
They’re usually around 6-8% carbohydrate and so deliver 1.5 to 2x the number of carbs that most hypotonic drinks do (30g of carb per 500ml serving). This is generally most useful for a shorter duration, high-intensity exercise where getting carbs in quickly can be more important than warding off dehydration. One thing to be mindful of is that they can cause quite a lot of gastrointestinal distress – a sickly, bloated stomach, when consumed in large quantities, which is often the case in long endurance events. That’s especially the case in hotter and humid conditions, where high sweat rates drive a faster rate of drinking, or when combined with carb snacks like gels and energy bars.
Hypotonic Sports Drinks-
Designed to quickly replace fluids lost during exercise, hypotonic drinks have very low carbohydrate content and a lower concentration of salt and sugar than the human body.
Hypotonic drinks are usually of a low concentration because they are formulated using small amounts of carbohydrates (up to a 6% solution). Hypotonic drinks create something called a ‘favourable osmotic gradient’. In that, they are of a lower concentration than blood, so the water in them flows naturally across the gut wall into blood vessels, moving from an area of lower solute concentration (the gut) to an area of higher concentration (the blood) via osmosis. Hypotonic drinks should be your preferred option if the primary goal of your drink is hydration rather than delivery of large amounts of energy. Best suited for gymnasts and athletes who play indoor sports.
Hypertonic Sports Drinks-
Hypertonic drinks are more concentrated than your blood. That’s usually because they’re formulated with lots of carbohydrates in order to maximise energy delivery as a way to fuel high-intensity activities. The relatively new in the market- Hydrogels fall into this category along with most recovery drinks, with the addition of protein as another major ingredient.
Liquid calories tend to be more readily absorbed than solids, which need more work from the body to break them down first. And hypertonic drinks can be a very good thing when what you want is to deliver large amounts of calories or certain macronutrients quickly and efficiently into the bloodstream. They can cause issues though if you’re trying to use a hypertonic drink at times when fluid intake is the priority and dehydration is a concern, such as during long-duration activities where you’re sweating a lot. They are best consumed after exercise as it is important to replace glycogen levels quickly after exercise. These drinks can be taken during ultra-distance events to meet the high energy demands but must be used in conjunction with Isotonic drinks to replace lost fluids.
What to look for in a Sports Drink?
Carbohydrates- Sugars can have performance benefits in a range of sporting events by providing a fuel source for muscles and the brain. Carbohydrates also contribute to the palatability (taste) of sports drinks. Most sports drinks contain 6- 8% carbohydrates (6-8g/L Or Isotonic sports drinks). Carbohydrate concentrations above this can impair gastric emptying and lead to gut upset during exercise and impair performance.
Electrolytes- Sports drinks include the electrolytes sodium and potassium. The sodium content of sports drinks encourages fluid intake by driving the thirst mechanism, while also increasing absorption and fluid retention. Sports drinks may also help with salt replacement for athletes who are heavy or salty sweaters. Added sodium may reduce urine losses before exercise begins. Low-sodium drinks may not be suitable when speedy rehydration is necessary. The addition of potassium to sports drinks help maintain electrolyte balance and can assist with muscle contraction during exercise.
Flavour- Flavour is an important factor of sports drinks that helps to increase voluntary fluid intake (compared to water) during or after exercise.
Additional Ingredients- Some beverages marketed as sports drinks have other added ingredients like vitamins, minerals, protein and herbal ingredients. These extra ingredients are likely to offer very little or no additional benefit over standard sports drinks and may affect the palatability, and subsequently consumption of the fluid. Some sports drinks also contain caffeine which can have performance benefits.
The ideal sports drink depends on personal taste preferences and individual tolerance. While the exact nutrition composition of sports drinks varies, they generally contain similar amounts of carbohydrates and electrolytes unless otherwise mentioned on the nutrition label of the product. Sports drinks should be trialled during training rather than in competition.
