Multiple Transportable Carbohydrates (MTC) refer to a strategic combination of carbohydrates that enhances energy delivery to muscles during physical activity. In the context of sports nutrition, the absorption of carbohydrates in the small intestine plays a crucial role in determining how much ingested carbohydrate the muscles can effectively utilize. The small intestine has a limited absorption capacity, and the rate at which carbohydrates are absorbed can impact performance.

  • Multiple Transportable Carbohydrates (MTC):

    • Strategic combination of carbohydrates for enhanced energy delivery to muscles during physical activity.

    • Absorption limitations in the small intestine impact the effective utilization of ingested carbohydrates.

    • Sodium-dependent transporter (SGLT1) is crucial for glucose absorption but becomes saturated at around 60 grams per hour.

    • Concept involves combining carbohydrates that use different transporters, such as glucose (SGLT1) and fructose (GLUT5).

    • Allows for higher carbohydrate delivery to muscles by utilizing multiple transporters.

  • Absorption Process:

    • Movement of nutrients from the intestinal lumen into the body's circulation.

    • Two cell membranes act as barriers, requiring transporters (proteins) for nutrient passage.

    • Glucose uses SGLT1 for absorption, limited to approximately 60 grams per hour.

  • Metaphor of Opening Doors:

    • Opening additional doors (representing different transporters) allows for more efficient carbohydrate absorption.

    • Glucose saturation (people leaving a room) is compared to transporter saturation, and introducing fructose opens another "door."

  • Optimal Ratio and No "Magic" Ratio:

    • Recommended ratio often suggested as 2:1 glucose to fructose, with a total intake of around 90 grams per hour.

    • Emphasis on the type and absolute amount of carbohydrates ingested.

    • No universally applicable "magic" ratio; depends on individual factors.

  • Practical Recommendations:

    • Applicable for exercise durations of 2.5 hours or longer.

    • Carbohydrate intake may reach up to 90 grams per hour, with glucose/maltodextrin contributing around 60 grams per hour and fructose providing 30 grams per hour.

    • Multiple transportable carbohydrate strategies can be implemented through beverages, gels, or low-fat, low-protein, and low-fiber energy bars.

    • Expected benefits include improved performance, enhanced fluid delivery, and better gastrointestinal comfort during prolonged physical activity.

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