Alpha-keto acids are intermediate products formed during the process of cells converting amino acids into energy. If you give these intermediate products to athletes as a supplement they keep going better during training and their performance gets a boost too, discovered sports scientists at the University of Ulm in Germany. Alpha-ketoglutarate [structural formula shown here] in particular works well.
The more amino acids the body burns the more building blocks available for the muscles, but at the same time the amount of ammonia in the blood also increases. The latter causes fatigue. Athletes can help prevent this by increasing their carbohydrate intake, but carbs aren’t that healthy and often lead to obesity. Sports scientists are looking for alternatives, and alpha-keto acids might just be such an alternative.
Alpha-keto acids help lower the ammonia concentration in the blood. Enzymes attach the ammonia to the alpha-keto acids and in doing so convert them into amino acids. Alpha ketoglutarate for example is converted into glutamate. So you kill two birds with one stone: you provide your muscles with more amino acids and you reduce fatigue.
Sounds great in theory. But does it work in practice? That's what the Germans wanted to test.
They got a group of healthy but not athletic males in their twenties to train for four weeks. Five days a week they had to run for half an hour and then do three bursts of sprinting.
The researchers divided their subjects into three groups. One group were given a placebo, the second alpha-ketoglutarate and the third keto-BCAAs. The subjects took their supplements around the time they trained – within two hours before and two hours after their workout. The supplements were in granule form, packed in sachets, and the subjects had to dissolve them in water. The raw materials were provided by the French company Evonik Rexim. [rexim.fr]
The men in the alpha-ketoglutarate group took 0.2 g alpha-ketoglutarate [AKG] per kg bodyweight every day. To be precise: they took 127 mg alpha-ketoglutarate/kg/day in a sodium bound form and 73 mg/kg/day in calcium bound form. Including the calcium and sodium the men took a daily 0.24 g supplement/kg.
The men in the other experimental group took 0.2 g keto-BCAAs [BCKA] per kg bodyweight per day. This consisted for 47 percent of alpha-keto isocaproate [the keto analogue of leucine, which is converted in the body into HMB], 30 percent alpha-keto isovalerate [the keto analogue of valine] and 23 percent of alpha-keto methylvalerate [the keto analogue of isoleucine]. The first compound of the list above was sodium bound, the other two were calcium bound. Including the calcium and sodium, the men took a daily 0.23 g supplement/kg.
The men in the groups that took supplements missed fewer training sessions. In the fourth week of the experiment in particular the total training time of the people in the experimental groups was much higher, as the figures below show. The subjects in the groups that took supplements seemed to find the training less heavy going and less tiring, so were able to keep going for longer.
Before the training period, immediately after it and again a week later [after recovery] the researchers measured the amount of torque and power the subjects were capable of developing with their leg muscles. They used an Isokinetic Biodex Dynamometer - a sort of leg-extension machine - to do this. The groups that had taken supplements did better than the control group, as the graph above shows.
The p was smaller in the AKG group than in the BCKA group. That means that the AKG group reacted slightly more convincingly than the BCKA group.
The supplements had no effect on maximal oxygen uptake.
"Nutritional supplementation with alpha-keto acids in healthy, untrained subjects significantly improved exercise tolerance, training effects, and stress-recovery state", the researchers conclude. They hope that alpha-keto acid supplements can help starting athletes who often have trouble motivating themselves to keep going with sports, so that they don’t give up so easily.
J Int Soc Sports Nutr. 2012 Aug 2;9(1):37. [Epub ahead of print].