Carbohydrate ingestion during exercise: liquid vs solid feedings

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Metabolic Responses

Background:

• Carbohydrate supplementation is crucial for maintaining performance during prolonged exercise.
• The physical form of carbohydrate (liquid vs. solid) may influence absorption and metabolic responses.
• Understanding these differences is important for optimizing sports nutrition strategies.

Purpose of the Study:

• To investigate the impact of liquid versus solid carbohydrate supplements on blood glucose and insulin levels during endurance exercise.
• To compare the metabolic effects of a rice-based liquid carbohydrate (L-CHO) versus a solid carbohydrate bar (S-CHO).

Main Methods:

• Six trained male subjects completed three randomized exercise trials at 65% VO2max.
• Participants ingested a placebo (CON), liquid carbohydrate (L-CHO), or solid carbohydrate (S-CHO) at set intervals during 2 hours of exercise.
• Blood glucose and plasma insulin levels were monitored throughout the exercise sessions.

Main Results:

• Carbohydrate ingestion significantly increased blood glucose levels compared to placebo.
• No significant differences in blood glucose response were found between liquid (L-CHO) and solid (S-CHO) forms.
• Plasma insulin levels were elevated after carbohydrate ingestion, with no difference between L-CHO and S-CHO.

Conclusions:

• The physical form of carbohydrate supplementation (liquid vs. solid) does not alter blood glucose or insulin responses during prolonged exercise.
• Both liquid and solid carbohydrate sources are equally effective in modulating key metabolic markers during exercise.
• These findings support the use of either liquid or solid carbohydrate forms for athletes based on preference and convenience.