Exogenous carbohydrate oxidation from maltose and glucose ingested during prolonged exercise.

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Gastroenterology

Background:

• Intestinal perfusion studies suggest faster glucose absorption from maltose compared to isocaloric glucose.
• Carbohydrate (CHO) intake is crucial for endurance athletes.
• Investigating optimal carbohydrate sources for athletic performance is ongoing.

Purpose of the Study:

• To compare gastric emptying, absorption, and oxidation rates of maltose and glucose in endurance athletes.
• To determine if maltose is a superior carbohydrate source for endurance exercise.
• To assess the utilization of ingested carbohydrates during prolonged exercise.

Main Methods:

• Six endurance-trained cyclists participated in the study.
• Participants consumed 1200 ml of either U-14C maltose or U-14C glucose solutions.
• Measurements included gastric emptying, plasma 14C appearance, and exogenous CHO oxidation during a 90-minute cycling test.

Main Results:

• No significant differences were observed in gastric emptying rates between maltose and glucose.
• Peak exogenous carbohydrate oxidation rates were similar for both maltose (1.0 g/min) and glucose (0.9 g/min).
• Approximately 49-50% of ingested carbohydrate was oxidized during the 90-minute exercise period, with no significant difference between maltose and glucose.

Conclusions:

• Neither gastric emptying nor intestinal digestion appears to limit ingested carbohydrate utilization in the early stages of endurance exercise.
• Maltose and glucose demonstrate similar rates of absorption and oxidation in endurance athletes under these conditions.
• These findings suggest that both maltose and glucose can serve as effective carbohydrate sources for endurance athletes.