# Osmolality instead of gram counts: carbohydrates for very long sessions

> On multi-hour efforts it is not the carbohydrate amount that decides but gastric passage. Why high-molecular-weight starch has a physical advantage here - and how WOO® Fast Endurance Waldfrucht is set up.

On sessions of three, four hours or more, the problem shifts. What decides is not the carbohydrate amount on paper, but how fast it leaves the stomach and how well the gut still tolerates it in the fourth hour. That is not a question of willpower but of the physics of a solution.

## Osmolality: why particle count matters

How quickly a drink leaves the stomach depends substantially on its **osmolality** - the number of dissolved particles per kilogram of fluid. Vist and Maughan showed this clearly in 1995: the more osmotically active particles a solution contains, the slower the stomach empties and the sooner a feeling of fullness sets in.

The decisive point: it is the particle count, not the mass. 60 g of glucose consists of very many small molecules and produces a high osmolality. 60 g of a high-molecular-weight carbohydrate consists of few, very large molecules - the same energy content, considerably lower osmolality. That is precisely the lever for long sessions.

## High-molecular-weight corn starch in practice

Piehl Aulin and colleagues compared drinks with low and high molecular mass carbohydrates and found faster glycogen resynthesis with the high-molecular-weight variant. Leiper later summarised in a review which factors determine gastric emptying and intestinal absorption of beverages - osmolality ranks at the front, alongside volume and energy density.

For long efforts this means concretely: a solution with low osmolality can carry a high energy density without blocking gastric passage. Anyone who has struggled with a sloshing stomach in the third hour knows the opposite.

## The second component: rapidly available fractions

A purely slow formula would have a drawback: blood glucose would have to wait. That is why the combination makes sense. Short-chain carbohydrates such as maltodextrin, glucose and sucrose become available quickly and stabilise blood glucose, while the high-molecular fraction carries the supply across the hours. Jeukendrup has repeatedly described how exactly this continuous exogenous intake delays the late-phase drop in performance.

Electrolytes belong with it. Across several hours of sweat loss, sodium is quantitatively the most significant loss; magnesium contributes to normal muscle function.

## How WOO® Fast Endurance Waldfrucht puts this into practice

**[WOO® Fast Endurance Waldfrucht](/en/shop/woo-fast-endurance-mixed-berries-can)** is based on high-molecular-weight corn starch, supplemented with maltodextrin, glucose and sucrose - the slow carrier fraction plus the rapidly available components. Combined with water it forms a solution of low osmolality, which eases transport across the cell membrane.

Each 40 g serving delivers 56.1 g of carbohydrate, 300 mg sodium and 25 mg magnesium; 1000 g covers 25 servings. On long sessions the forest fruit flavour is no side issue: after two hours, flavour fatigue co-determines whether an athlete keeps drinking at all. The darker berry note is often tolerated over hours better than sharp citrus aromas. Vegan, gluten- and lactose-free.

## Frequently asked questions

**How do I dose for a very long session?**
The dosage can be adapted individually to your body. It has proven wise to increase intake gradually in training rather than testing it for the first time on race day.

**When is the best time to drink it?**
Before and during training. On multi-hour sessions, regular intake in small amounts is preferable to one large serving.

**Does it replace solid food?**
On very long efforts many athletes combine drink and solid food. Food supplements are not a substitute for a balanced and varied diet.

## Sources

Vist GE & Maughan RJ (1995), Journal of Physiology - The effect of osmolality and carbohydrate content on the rate of gastric emptying of liquids in man.
Piehl Aulin K et al. (2000), European Journal of Applied Physiology - Muscle glycogen resynthesis rate after supplementation of drinks containing carbohydrates with low and high molecular masses.
Leiper JB (2015), Nutrition Reviews - Fate of ingested fluids: factors affecting gastric emptying and intestinal absorption of beverages in humans.
Jeukendrup AE (2004), Nutrition - Carbohydrate intake during exercise and performance.

*WOO® Fast Endurance Waldfrucht in the NEMAPO shop.*