Most trainers still believe the way for cyclists, runners and other athletes to improve their times and extend the boundaries of their endurance capacity is supplementation with fast carbohydrates. As far as the researchers at the Japanese company Ajinomoto are concerned though, the end of the ‘hegemony of carbs’ is in sight. Their animal study, published in the Journal of Nutritional Science and Vitaminology, shows that a mixture of carbohydrates and the amino acids alanine and proline works better than carbs alone.
Alanine and proline [the first and second structural formulas shown below, respectively] are simple amino acids. They are created from other amino acids in the body, and can in turn can be converted in glucose. Hence their description: gluconeogenic precursors of gluconeogenic amino acids. We, the ignoramus compilers of this free webzine, have occasionally wondered to ourselves if this kind of amino acid isn’t a much more interesting anticatabolic than BCAAs.
The interest of the researchers at Ajinomoto took a different direction. They wondered whether these amino acids might be of interest to endurance athletes. A supplement based on these, taken during long periods of intensive exertion, might maintain the body’s glucose levels for longer than carbohydrates can. And that would benefit athletes’ performance.
Ajinomoto manufactures amino acids, so commercial motives no doubt also played a role in this study.
The researchers gave a group of mice 2 g maltodextrin per kg bodyweight. Another group of mice were given 1 g carbohydrates, 0.9 g alanine and 0.1 g proline per kg bodyweight.
After 15 minutes the researchers got the mice to run on a treadmill. The machine turned at a speed of 14 metres per minute for one hour, after which the researchers increased the speed by 2 metres per minute every five minutes.
The figure below shows that the mice that had been given the mixture of maltodextrin, alanine and proline performed better than the mice that had only been given maltodextrin.
The researchers divided the mice into three groups.
The first group was given 1 g maltodextrin per kg bodyweight. The second group was given 1.25 g maltodextrin per kg bodyweight. The third group of mice were given 1 g maltodextrin, 0.225 g alanine and 0.025 g proline per kg bodyweight.
After 15 minutes the researchers got the mice to run on a treadmill for 170 minutes. They measured the mice’s glucose levels in their blood throughout the session. The figure below shows that the blood glucose level went down more slowly in the mice that had been given the maltodextrin and amino acid mix.
The mixture stimulated the synthesis of glycogen in the liver, which functions as an energy buffer during extended periods of exertion.
“We demonstrated that combined supplementation of alanine, proline, and carbohydrates maintained blood glucose levels during the later stages of exercise and improved endurance performance compared to supplementation of isocaloric carbohydrates alone”, the researchers wrote. “These results suggest that carbohydrates supplementation with alanine and proline may be a more effective strategy for energy intake during long-term exercise than carbohydrates alone.”
Combined Supplementation of Carbohydrate, Alanine, and Proline Is Effective in Maintaining Blood Glucose and Increasing Endurance Performance during Long-Term Exercise in Mice
Carbohydrate supplementation is extremely important during prolonged exercise because it maintains blood glucose levels during later stages of exercise. In this study, we examined whether maintaining blood glucose levels by carbohydrate supplementation could be enhanced during long-term exercise by combining this supplementation with alanine and proline, which are gluconeogenic amino acids, and whether such a combination would affect exercise endurance performance. Male C57BL/6J mice were orally administered either maltodextrin (1.25 g/kg) or maltodextrin (1.0 g/kg) with alanine (0.225 g/kg) and proline (0.025 g/kg) 15 min before running for 170 min. Combined supplementation of maltodextrin, alanine, and proline induced higher blood glucose levels than isocaloric maltodextrin alone during the late exercise phase (100-170 min). The hepatic glycogen content of mice administered maltodextrin, alanine, and proline was higher than that of mice ingesting maltodextrin alone 60 min after beginning exercise, but the glycogen content of the gastrocnemius muscle showed no difference. We conducted a treadmill running test to determine the effect of alanine and proline on endurance performance. The test showed that running time to exhaustion of mice that were supplemented with maltodextrin (2.0 g/kg) was longer than that of mice that were supplemented with water alone. Maltodextrin supplementation (1.0 g/kg) with alanine (0.9 g/kg) and proline (0.1 g/kg) further increased running time to exhaustion compared to maltodextrin alone (2.0 g/kg). These results indicate that combined supplementation of carbohydrate, alanine, and proline is effective for maintaining blood glucose and hepatic glycogen levels and increasing endurance performance during long-term exercise in mice.