Researchers at the University of Sao Paulo and the Food Research Center in Brazil looked at the effects of supplementing resistance-trained rats with two amino acids—glutamine and alanine. They specifically looked at the effects supplementation may have on muscle fatigue parameters.
“We hypothesized that these amino acids could be used as energy substrates during exercise, avoiding glycogen depletion, and could also attenuate oxidative stress and muscle damage induced by resistance training,” they wrote in their report, currently in press for publication in the journal Nutrition.
Past research has shown that glycogen acts as fuel for muscles. When glycogen levels are depleted, then there’s less fuel for the muscles.
They also hypothesized that supplementation may increase physical performance because of delayed fatigue caused by supplementation.
At the end of the study, they found that glutamine and alanine did not affect exercise performance in the rats, but they did find improved muscle fatigue markers among rats that received supplementation.
Laboratory rats were divided into five groups: A sedentary group, an exercised group, an exercised groups supplemented with just alanine, an exercised group supplemented with glutamine and alanine in their free form, and an exercised group supplemented with L-alanyl-L-glutamine.
The inclusion of the dipeptide L-alanyl-L-glutamine was done because, in previous studies by the same group of researchers, they found that the dipeptide “was more effective in increasing glutamine in plasma and tissues compared with free glutamine administration.”
The study lasted eight weeks, in which the exercised group was trained to climb ladders with loads affixed to the base of their tails during the entire period. Rats received supplements chronically in the last three weeks of the experiment.
Researchers mixed the supplement ingredients with drinking water as an attempt to increase the frequency of amino acid intake throughout the day and to avoid the stress of manipulation in oral gavages. Sao Paulo-based Labsynth manufactured free L-glutamine and free L-alanine, and German company Fresenius Kabi S.A. manufactured the L-alanyl-L-glutamine.
Muscle fatigue parameters that the researchers observed included plasma lactate levels and amino acid levels in liver, heart, and skeletal muscle tissues.
The free glutamine and alanine group as well as the dipeptide group experienced increased muscle content of glutamine and glutamate. The dipeptide group experienced increased glycogen and lactate dehydrogenase concentrations.
Meanwhile, the alanine only and the free glutamine- plus alanine-supplemented rats exhibited decreased levels of plasma LDH and creatine kinase, typical markers for muscle damage and fatigue.
“It is worth highlighting that fatigue is a complex and multifaceted phenomenon, since several factors may limit exercise performance,” the researchers wrote. “Therefore, the improvement of single markers does not necessarily delay fatigue.”
In press, accepted manuscript, https://doi.org/10.1016/j.nut.2018.09.025
“Effects of glutamine and alanine supplementation on muscle fatigue parameters of rats submitted to resistance training”
Authors: Audrey Yule Coqueiro, et al.
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