Scientific Basis
& References

The Fuel Calculator in SUPLiR is based on current, evidence-based guidelines in sports nutrition. The calculations follow the recommendations of leading institutions (ACSM, ISSN) and strictly adhere to physiological oxidation rates.

1. Carbohydrate Intake During Exercise

Recommendations are derived from the duration and intensity of the session:

• < 60 Min: Body glycogen stores are usually sufficient; external fueling is generally not necessary, though carbohydrate mouth rinses can be effective for high-intensity efforts.
• 60–150 Min: An intake of 30–60 g of carbohydrates per hour is recommended to maintain performance and delay glycogen depletion.
• > 2.5 Hours: For prolonged endurance efforts, requirements can rise to up to 90 g per hour to support metabolic demands.

2. The "Dual-Source" Principle

The human intestine can absorb glucose at a maximum rate of approx. 60 g/h (via the SGLT1 transporter).

For higher intake rates (>60 g/h), scientific research recommends combining glucose (maltodextrin) and fructose. This utilizes the GLUT5 transporter as well, maximizing absorption rates and minimizing gastrointestinal distress. Our calculator advises users to ensure this ratio for targets exceeding 60 g/h.

3. Recovery

To rapidly replenish glycogen stores after training ("resynthesis"), the calculator follows the recommendation of approx. 1.0 g to 1.2 g of carbohydrates per kg of body weight, combined with proteins (20–30 g) to support muscle repair immediately post-exercise.

4. Gut Tolerance ("Gut Training")

Since gastrointestinal tolerance is individual and must be trained, the algorithm caps recommendations for untrained athletes at physiologically conservative levels to prevent gastrointestinal issues during activity.