Carbohydrate concentration

Carbohydrate concentration refers to the amount of carbohydrate dissolved in a given volume of liquid, usually expressed as a percentage (% w/v) or grams per 100 millilitres. In sports drinks it is a key variable because it affects fluid absorption and energy delivery.

Explanation

During endurance exercise, muscles rely on both stored glycogen and external sources of carbohydrate. A beverage’s carbohydrate concentration determines how much sugar per sip reaches the bloodstream. Sports science recommends beverages containing about 4–8 % carbohydrate (4–8 g per 100 mL) for optimal gastric emptying and absorption. Drinks within this range provide a steady supply of glucose without drawing water into the gut or causing stomach upset. At lower concentrations the drink behaves more like water and may not deliver enough fuel, while concentrations above 8–10 % can slow stomach emptying, increase osmolality and lead to gastrointestinal discomfort. The type of carbohydrate also matters; glucose, sucrose and maltodextrin are absorbed rapidly, whereas fructose is taken up more slowly and is best paired with glucose to increase total absorption without oversaturating transporters.

Finding the right balance

To calculate carbohydrate concentration, divide the grams of carbohydrate by the volume in millilitres and multiply by 100. For example, a drink containing 60 g of carbohydrate in one litre (1 000 mL) has a 6 % concentration; 80 g per litre yields an 8 % solution. Many ready-to-drink sports beverages fall within this range. Powdered mixes can be tailored; adding too much powder produces a hypertonic drink that can cause cramping, while using too little results in a hypotonic solution that does not provide adequate energy. Energy gels and fruit juice are often 12–15 % carbohydrate and therefore should be consumed with water to prevent gastrointestinal issues. Adjusting the carbohydrate concentration based on exercise intensity, environmental conditions and personal tolerance helps athletes meet both hydration and fueling needs.

Maintaining an appropriate carbohydrate concentration in sports drinks ensures that fluid and energy are delivered efficiently, supporting performance without causing digestive distress.

Related Terms: Carbohydrate–electrolyte beverage, Multiple transportable carbohydrates, Osmotic gradient, Colligative properties, mg/L