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First Endurance

First Endurance EFS Hydration Drink

First Endurance EFS Hydration Drink

Regular price $34.99 USD
Regular price Sale price $34.99 USD
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An isotonic formula that supports physical and mental performance, efficient energy production, industry-leading cramp-prevention, and reduced GI distress.


  • Improves mental toughness
  • Prevents cramping & helps you hydrate fast
  • Provides immediate & sustained fuel

First Endurance spared no expense upgrading the EFS drink mix, investing in the latest research-driven innovation and technology. The new isotonic formula delivers complete nutrition that supports physical and mental performance, redefining the limits of endurance nutrition so you can redefine your limits of endurance.

We know how frustrating it is to have your day wrecked because you’re seized up with debilitating muscle cramps. It’s the number one issue most athletes face. That’s why we engineered EFS.

Unlike most hydration mixes, EFS delivers a clinically effective dose of all 5 electrolytes (sodium, potassium, chloride, calcium, magnesium) in the levels shown to prevent cramping.

The brain plays an essential role in endurance and performance. Mental toughness and presence of mind are equally as important as fitness. You have to be able to suffer and handle stress when your body is begging you to stop.

That’s why the reimagined EFS includes Suntheanine ®, a patented innovation that gives you the mental toughness you need to push further and find a gear you didn’t know you had.

Suntheanine® is protected by over 40 U.S. and international patents for its various physiological efficacies and L-isomer specific production processes.

Suntheanine® boosts mental toughness to help you push through suffering

Prevents cramping and dehydration—delivers 1160mg of electrolytes

Carbs from multiple sources provide immediate and sustained fuel

7% osmolality ensures bioavailability and reduces GI distress

Citric and malic acids promote oxygen uptake and energy production

New taste profile eliminates the flavor vs function compromise

EFS provides everything you need to maximize endurance and performance. Our industry-leading electrolyte levels help you stay hydrated and avoid cramping.

With the latest amino acid technology and ideal carbohydrate sources, EFS refuels working muscles faster than ever. Plus, the new flavor technology eliminates the formula over flavor compromise.

With EFS, you can train and race with confidence knowing you don’t have to worry about gaps in your nutrition.

EFS is for use during exercise to prevent cramps, maintain fuel levels, and support mental toughness when it’s needed most. It can be supplemented with Liquid Shots before and during an event, and Ultragen helps consolidate gains during recovery between sessions. 

Regardless of your training load, a daily dose of our MultiV and Optygen lines help you lay a foundation to achieve your goals.

From the carbohydrates (osmotically balanced with your body in a 7% solution) to the electrolytes (20-100% better absorption rates), every ingredient in EFS is selected and portioned for faster and easier absorption without GI distress.

The inclusion of citric and malic acids also encourages oxygen uptake and production of ATP (the body’s energy source), helping your cells use the fuel once it’s delivered.


We prioritize purity by using only Suntheanine, the original and cleanest L-theanine, and free-form amino acids, which have a purity level of 99-100%.


We also omit ingredients with no value—even the ubiquitous vitamin C, which features in virtually every other mix despite research that shows it reduces endurance when taken during exercise. EFS still provides immune system support courtesy of theanine, just without impacting performance.


Our approach to product design eschews unexamined ingredients, traditional processes, and trendy minimalism in favor of research-based innovation, premium ingredient sourcing, and the uncompromising expectations of elite athletes. We’re always ready to show our work and support our products with the scientific literature that informs our design choices, but we also know what virtually every athlete and publication using or reviewing our products learns firsthand: First Endurance products speak for themselves, and you can feel the difference right away.


Supplement Facts

Serving Size: 1 scoop (32 g)
Servings per Container: 30

    Amount Per Serving     %DV
Calories-110 Calories from fat-0
Total Carbohydrate     26 g     9%
Sugars     16 g     **
Calcium (as DiCalcium Malate)     100 mg     8%
Magnesium (DiMagnesium Malate)     150 mg     36%
Chloride (as sodium chloride)     450 mg     20%
Sodium (as sodium chloride)     300 mg     13%
Potassium (as di-potassium phosphate)     160 mg     3%
L-Glutamine     1750 mg     *
Branched Chain Amino Acids (L-Leucine, L-Isoleucine, L-Valine)     250 mg     *
L-Theanine     50 mg     *
*Daily Value Not Established
**Percent Daily Values are based on a 2,000 calorie diet.
Other ingredients: Sucrose, Maltodextrin, Glucose, Citric Acid, Natural Flavor, Stevia Extract.

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