Amino acids, the building blocks of protein, are typically consumed for muscle growth and are often added to protein powders to create more robust formulas, but they’ve also begun to be included in several pre-workout energy supplements—the reason being that amino acids have some interesting effects on not just our muscles but our brains, too. The latest piece of research in this area centers on theanine—a nonessential amino acid that is found naturally in high concentrations in green tea—which scientists have discovered can significantly reduce stress and improve focus.

The study, published last year in the Journal Experimental Physiology, monitored the adrenal glands of male mice to gauge the physiological impact of stressful situations, such as sharing small living quarters with another male mouse (think of it like being forced to share a squat rack with your girlfriend’s ex). Once a baseline was established, the researchers performed the same method with mice who had been administered theanine. The result was a significant reduction in stress indicators. This is important since stress triggers the release of that dreaded catabolic agent cortisol.

It’s not the first study to find unique benefits in this amino acid. In 2008, a separate study looked at how theanine affected the body when paired with caffeine—which is useful since most pre-workout amino-acid supplements also contain caffeine. The researchers found that, in comparison with when caffeine or theanine was consumed alone, the combination of the two ingredients resulted in improved mental speed and accuracy and a reduced susceptibility to distraction (like the hot girl on the pec flye machine). These are just two studies atop a laundry list of similar research outlining the benefits of amino acids. The truth is that you can consume amino acids at any point throughout the day and you’d be doing yourself a favor—both physically and mentally.

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