This is a first-in-series feature on the reimagined EFS, focusing on a mind-over-matter compound that makes perfect sense for maximizing your brain’s control of your exercise performance: L-theanine, or more specifically, Suntheanine® L-theanine. Theanine calms anxiety and stress (both physical and mental), reinforcing mental toughness so you maintain perspective when an obstacle—your screaming legs, another gap to close, a looming wall—threatens to crush your motivation. It also provides immune system support, especially during intense exercise when your body may become vulnerable as it depletes its reserves.

In this installment, Dr. Luke R. Bucci explains how theanine produces calming effects and helps you maintain focus to improve endurance performance.

Winning the Mind Games

Short of outright bonking, what makes you give up during long, hard exercise? Is it your muscles? Not enough antioxidants? Too much lactate? Your joints, tendons, ligaments screaming? Your legs telling you to stop? Your brain saying ENOUGH!? Turns out it’s all of the above. But your brain makes the final decision that shuts down nerve impulses to muscles. Keeping your brain in the game keeps you running because it strengthens your resolve at those moments you need to tell your legs to shut-up and keep pedaling.

As long as you’re fueling properly and well rested, you should in theory be able to keep exercising until something mechanical breaks or wears out. But in practice—and even with the right nutrition during exercise—fatigue sets in sooner or later (Fitts 1994). Then your performance is more and more dependent on your brain, where a set of metabolic signals produced by exercise impact your brain’s excitatory and inhibitory (or “upper” and “downer,” respectively) neurotransmitters, which work in concert to fine-tune how your brain senses and handles everyday stress, exercise, and life in general. Extreme exercise causes stress and an imbalance by boosting the excitatory neurotransmitters, which in turn prompts your brain to throttle back on your efforts to avoid damaging your body. It makes your brain say “stop,” even when your body can keep going.

Fatigue “is a multifactorial phenomenon that includes physiological, neuromuscular, biomechanical and cognitive factors,” not just muscles
(Garbisu-Hualde 2020 Abstract)

This self-preservation response corresponds with a phenomenon called the Central Fatigue Hypothesis (Fitts 1994, Hureau 2018; Lepers 2002; Millet 2018; Temesi 2014; Weavil 2019) or, alternatively, the Central Governor Model (Noakes 2005, 2012; Shei 2013) and more recently the “Central Integrator.” The gist of this idea is that multiple interactive processes that include sleep quality, self-control, psychological, mental lapses, and decision-making (cognitive) brain activities are identified as important factors in causing performance-killing fatigue (Batson 2013; Garbisu-Hualde 2020; Inzlicht 2016; Knicker 2011; Millet 2011; Muraven 2006; Weir 2006).

As the name implies, Central Fatigue doesn’t accumulate in the muscles (that’s Peripheral Fatigue); rather, it affects the central nervous system, reducing your willingness to send neural drive commands—the brain’s signals that prompt physical movement—instead of your muscles’ ableness to carry out those commands (Lepers 2002 p.1487). Think of Central Fatigue as a check engine light for your body. It doesn’t cause the engine to stop on its own, but it does prompt the vehicle’s operator to stop the engine to diagnose and address the issue—in this case, duress caused by extreme effort and peripheral (or muscular) fatigue.

Given the documented effect of Central Fatigue, it follows that cognitive factors can predict performance in endurance exercise. To explore this connection, cognitive testing was conducted before and after an ultramarathon in 30 runners (Cona 2015). The faster runners outperformed slower runners in motor inhibition trials, doing two tasks simultaneously, and suppressing the activation of irrelevant information for decision-making. Faster runners had better inhibitory control and were less influenced by emotional stimuli. They were also more focused on external stimuli (such as ‘how do I conquer this hill’) and better at inhibiting internal interferences (such as negative thoughts associated with central fatigue—’my feet hurt’ or ‘I’m too tired to finish’). The research concludes that “cognitive and emotional factors can discriminate talented runners from less outstanding runners.” In other words, being cooler, calmer, and more collected means better performance in endurance athletics—conclusions that align with the demonstrated impact of Central Fatigue because that calm control over neural drive commands is exactly what Central Fatigue overrules.

This is where theanine comes into play by balancing your internal brain signaling to maintain your brain’s cognitive factors and alertness, which are governors of Central Fatigue. In other words, theanine activates your brain to maintain alertness and focus under stress, keeping your responses organized and productive so you can stay in control of your thoughts and actions like the higher performing athletes in the research detailed above. It helps you overcome a natural inclination to govern or dial back your efforts during the high-stress, high-output moments that define things like race finales, hill repeats, and intervals—the exact moments when you most need to be operating at full capacity but when peripheral and central fatigue are conspiring against you.

Ride the tightrope

Theanine achieves its effects by working with two of the psychoactive neurotransmitter systems in your brain that influence Central Fatigue—specifically the Glutamatergic System and the GABA System (Dietz 2017; Kakuda 2002, 2011; Lardner 2014; Nathan 2006; Rao 2015; Williams 2020). The Glutamatergic System relies on its namesake amino acid, glutamate, which is the brain’s primary excitatory or “upper” neurotransmitter; the GABA system relies on its own namesake, gamma aminobutyric acid (or simply GABA), which is the brain’s primary inhibitory or “downer” neurotransmitter. You need the Glutamatergic and GABA systems to work together with other neurotransmitter systems to balance stressors and inhibitors and enable clear thinking without confusion or consternation or trepidation or degenerating into TMI overload—the danger zone of reduced cognition giving way to Central Fatigue and threatening endurance performance.

We’ll get into finer details below, but here’s the long story short:

Theanine, delivered in EFS and EFS-PRO as Suntheanine L-theanine, is a back door glutamate inhibitor and a GABA enhancer, so it balances the interaction between your first-responder “uppers” (the Glutamatergic System) and “downers” (the GABA System), not letting too much excitement decrease mood and cognition, and not letting too much GABA make you too calm. A real tightrope balancing trick! This helps prevent the drive-killing lack of focus and eventual Central Fatigue documented in the research above by balancing out your brain’s inclination to go into self-preservation mode during extreme and ultraendurance exercise.

The Glutamatergic System

And now the long story long, starting with the “upper” side: The excitatory activity in the Glutamatergic System is what makes adrenalin (epinephrine) spike in your bloodstream under pressure. Simply put, glutamate in that system activates a set of brain neurons during stress to ramp up anxiety and fear (Bergink 2004). Those excitatory effects are necessary for extreme stress responses, but too much stimulation at the wrong time can be counterproductive, contributing to lack of focus, rise of internal interference, and—ultimately—the Central Fatigue that impedes endurance performance.

Theanine provides checks and balances for the excitatory influence of the Glutamatergic System. Your brain readily takes up theanine because it looks like glutamine, the most common amino acid and the precursor to the glutamate that the Glutamatergic System runs on. Normally, more glutamine becomes glutamate, but theanine inhibits that transformation, decreasing the effect of the major excitatory neurotransmitter pathway by decreasing the amount of glutamate it can use as fuel. Theanine is like Smokey the Bear—it prevents brain fires (overexcitement) before they happen by telling you to not make a fire. Basically, it’s one way to keep the brain sharp and calm, countering the fatigue-inducing effects of stress during extreme exercise.

The GABA System

The GABA System is the brain’s major inhibitory or “downer” neurotransmitter system, making it the brain committee member most often opposed to the Glutamatergic System. Although it might seem counterintuitive to use “downers” to give your brain more control, it makes perfect sense when you realize some of the triggers for Central Fatigue are the excitatory neurotransmitters, or “uppers,” and their sycophants. Central Fatigue is an imbalanced state, where an overload of “uppers” are causing a panic—we’re just nudging the brain to rebalance back to normal moods and mental functioning: cool, calm, collected, and in control. GABA makes your brain discriminatory, a gateway for balance, and theanine helps ensure you have the stockpile you need to balance the “uppers” that accumulate during exercise. Taking them during exercise is like priming a pump or being Smokey the Bear again, this time using his shovel to put out any brain fires.

While it’s preventing fires in the Glutamatergic System by pretending to be glutamine, theanine also shunts actual glutamine into the GABA System. Just like with the “upper,” glutamate, glutamine is the precursor to the “downer,” GABA, so introducing more into the GABA System gives you an overall boost of alert calmness if needed (Lardner 2014; Ota 2015). Theanine itself also becomes GABA when it is broken down by brain cells, further increasing the amounts of GABA available to counter stress and promote calm focus.

Take control

The end result is that, while EFS is providing fuel, electrolytes, and all the other benefits to your body, theanine is also providing support for your brain. The brain is, after all, the most important muscle at your disposal; however, it’s largely been ignored by endurance nutrition, which typically just focuses on fueling and maintaining your body. Staying calm and in control means you can dig deeper into your reserves and react better when the everyone is suffering, because you’ll be less influenced by that voice in your legs screaming at you to stop. When you’ve done everything you can to sharpen your body as a tool for a race or event, theanine helps ensure your brain can wield that tool to its greatest effect.

These statements have not been evaluated by the Food and Drug Administration.  This product is not intended to diagnose, treat, cure or prevent any disease.

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March 09, 2023 — Luke Bucci

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