ABSTRACT
BACKGROUND: The energy density of a nutrient drink is one of the main factors that affect the gastric emptying of the solution, while osmolality and viscosity are thought to have only a minimal influence. METHOD: The rate of gastric emptying of two isoenergetic carbohydrate solutions with different osmolality and viscosity was determined using a double sampling gastric aspiration technique. Six healthy male subjects were studied on two occasions using approximately 550 ml of a solution containing 13.5% of carbohydrate either in the form of a mixture of monomeric glucose and short chain glucose oligomers (G-drink) or of long chain glucose polymers composed of 78% amylopectin and 22% amylose (C-drink). RESULT: The half emptying time (t(1/2), median and range) for the viscous, markedly hypotonic (62 mosmol/kg) C-drink was faster (17.0 (6.2-31.4) min) than for the moderately hypertonic (336 mosmol/kg) G-drink (32.6 (25.2-40.7) min). The amount (median and range) of carbohydrate delivered to the small intestine was greater during the first 10 min after ingestion of C-drink (31.8 (15.8-55.9) g) than after ingestion of G-drink (14.3 (6.8-22.2) g). However, there was no difference in the blood glucose (P = 0.73) or serum insulin (P = 0.38) concentration at any time point after ingestion of the two test drinks. CONCLUSION: The results of this study show that the carbohydrate present in C-drink, although it has the propensity to form a gel, empties from the stomach faster than that of an isoenergetic carbohydrate solution (G-drink) without potentiating increased circulating blood glucose or insulin levels.
Subject(s)
Dietary Carbohydrates , Gastric Emptying , Glucans , Adult , Blood Glucose/analysis , Energy Intake , Gels , Glucose Solution, Hypertonic , Humans , Hypotonic Solutions , Insulin/blood , Male , Osmolar Concentration , Serum Albumin/analysis , ViscositySubject(s)
Energy Metabolism , Exercise/physiology , Appetite , Body Composition , Energy Intake , Female , Humans , Male , Oxygen Consumption , SportsABSTRACT
Gender-specific differences in body composition and body size are well documented and mainly due to hormonal differences. Women benefit from physical training in the same way as men do. Regarding substrate utilization during exercise, females seem to exhibit a greater ability to utilize fat as a substrate resulting in a glycogen sparing effect. This may indicate a greater ability for endurance exercise. High levels of aerobic activity coupled with an insufficient energy intake, will result in a rapid loss of body mass and amenorrhea, a loss of calcium from bone tissue and the development of early osteoporosis. Nutritional advice for athletes of both sexes is very much the same, except that females require more iron and calcium.
