Extreme Endurance Review – Is This Workout Supplement Legit?

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By Jack Cincotta, MS

Reviewed by Juliana Tamayo, MS, RDN - Last Updated

extreme endurance

If you’re an athlete or intense exerciser of any kind, you likely have at least thought of using supplements to improve performance and have more than likely tried out a few to see if they help.

Well, if you haven’t gotten the results you’ve wanted or are simply interested in learning about more supplements, you’ll want to pay attention to this article as we go over a performance supplement called Extreme Endurance.

We’ll get right into this Extreme Endurance review to see what’s in the formula, the possible benefits, side effects, and who could benefit from taking it.

Extreme Endurance Review Highlights

  • Extreme Endurance is clinically-researched, which sets it apart from many others
  • You need to take six pills per day, which can be a lot for some people
  • It is Informed Sport Certified and thus safe for competitive and recreational athletes alike
  • All of the ingredients are in proprietary blends so we don’t know the doses of each compound
  • Extreme Endurance is generally highly rated and even used by many pro athletes

About Extreme Endurance

Extreme Endurance is boldly advertised as the #1 endurance supplement for stamina, recovery, and soreness. 

The Extreme Endurance formula contains electrolyte minerals magnesium and calcium, herbal compounds such as papain, and other key minerals like chromium, all of which are designed to work synergistically to enhance workout performance and recovery.

extreme endurance tablets
Source: Extreme Endurance Instagram Page

Plus, Extreme Endurance says it stands apart from other formulas because this formula has specific clinical research behind it and is third-party tested by Informed Sport.

Extreme Endurance Benefits

Extreme Endurance has several key benefits advertised for athletes, including:

  • Enhanced Endurance
  • Reduced Soreness
  • Faster Recovery 

Enhanced Endurance

One of the main advertised benefits of Extreme Endurance is, unsurprisingly, enhanced endurance!

Specifically, they say this formula is clinically proven to reduce lactic acid by 26% and to improve your overall aerobic capacity. In turn, this means that you can go harder, for longer, and improve your endurance performance like never before.

Reduced Soreness

Extreme Endurance is also promoted to reduce soreness. In particular, they claim that Extreme Endurance can reduce lactic acid, as mentioned above, and lead to a 39% reduction in oxidative stress, all of which can decrease muscle soreness and inflammation.

This can be especially important for athletes going through intense training sessions or competitions. 

Faster Recovery

Lastly, Extreme Endurance is advertised to help you recover faster, including a 6x reduction in creatine kinase (a marker of muscle damage), and decreased oxidative stress.

In turn, you may be able to recover more effectively from your workouts and keep making progress without hitting any plateaus.

Overall, these are some great potential benefits. 

But does Extreme Endurance really work this well?

Keep reading to find out!

Extreme Endurance Ingredients

Extreme Endurance is a combination of nine ingredients, all of which are contained in the Extreme Endurance Proprietary Complex®. These are:

  • Calcium Carbonate
  • Papain
  • Magnesium Oxide
  • Potassium
  • Magnesium Hydroxide
  • Catechins
  • Selenium
  • Chromium
  • Black Pepper Fruit

The only other ingredients in the formula are stearic acid and magnesium stearate.

extreme endurance supplement facts

Calcium, Potassium, and Magnesium

Extreme Endurance has calcium carbonate, magnesium oxide, potassium, and magnesium hydroxide. So, this provides calcium, potassium, magnesium, which are three essential minerals and electrolytes.

They are necessary for proper muscle contractions, fluid balance, nervous system function, and energy metabolism, among other things.

Athletes going through intense training typically need more calcium, potassium, and magnesium (as well as other nutrients) than non-exercisers because of the nutrient demands from training stress.

Magnesium oxide isn’t the greatest form due to poorer bioavailability, although the other ingredients here are pretty bioavailable. 


Papain is an enzyme found naturally in papaya fruit. It helps break down proteins into amino acids. Additionally, there is some evidence that papain can reduce muscle pain and soreness from intense exercise.

It’s also found in many gut health formulas and even certain protein powders like Swolverine Whey Protein Isolate to help with protein digestion. 


Catechins are a group of polyphenols that have strong antioxidant and anti-inflammatory properties. Plus, they can improve energy metabolism. 

This is why they may be useful for exercise recovery and performance. 

Selenium & Chromium

Selenium and chromium are both trace minerals with a variety of similar roles, such as in blood sugar regulation and energy metabolism.

Additionally, selenium has some antioxidant and anti-inflammatory effects. 

Black Pepper Fruit

Black pepper fruit contains a compound called piperine, which can enhance the bioavailability of certain vitamins, minerals, herbs, and other compounds.

Additionally, black pepper has anti-inflammatory effects. 

Clinical Research

Interestingly, there has also been clinical research done on the same Extreme Endurance formula, including this placebo-controlled, double-blind study

The researchers found that Extreme Endurance led to significant reductions in creatine kinase, lactic acid accumulation, and oxidative stress. They said this suggests that Extreme Endurance is potentially beneficial for improving athletic performance and recovery. 

Does Extreme Endurance Work?

It seems likely that Extreme Endurance will work. This is mainly because it has clinical research behind it showing that it can improve athletic performance and recovery. 

The benefits seem to be stronger for recovery, but it can likely enhance endurance and overall performance too.

Of course, not everyone will experience the same results. And it likely depends on the type of exercise you’re doing too, in which longer, more aerobic-based exercisers are more likely to benefit. 

How Does Extreme Endurance Compare?

Extreme Endurance, first and foremost, is a unique workout supplement because it has direct clinical research behind it. This sets it apart from other formulas that, although they may have well-researched individual ingredients, the whole formula itself hasn’t been researched.

Not to mention the Informed Sport certification makes it safe for even competitive athletes to take, which is critical, especially in the supplement world filled with scams and shady ingredients at times.

With that said, Extreme Endurance could be better if it didn’t have a proprietary blend. Some people may want all the ingredients listed out, in which case better choices for endurance performance and recovery would be Ignite Pre-Workout or something like Key Nutrients Electrolyte Recovery Powder

You’ll also pay slightly more for Extreme Endurance compared to most products in this category, but then again, they also have very good subscription and member savings. And you also have to consider that this formula is more evidence-based compared to a lot of other supplements.

Who is Extreme Endurance Best For?

Extreme Endurance is best for endurance-based athletes who want to improve athletic performance and recovery. Given the safety profile and third-party testing, it can be used safely whether you’re a recreational or competitive athlete.


  • Backed by clinical research
  • Informed Sport Certified
  • Free from major allergens
  • Nothing artificial
  • Good subscription savings available


  • Uses a proprietary blend
  • Need to take six pills per day
  • Somewhat high-priced 

How to Take Extreme Endurance

The total dose is important when taking Extreme Endurance to experience the best results. The serving size is six capsules. They say to take three capsules in the morning and another three capsules in the evening.

Whenever you take it, make sure to be consistent. 

extreme endurance supplement

Also, they say some athletes benefit from a “Loading Dose” which is a total daily dose of eight capsules for 7-10 days leading up to a competition, as well as one day after the event. Then, you drop back down to the normal dose.

Lastly, they recommend not consuming coffee or acidic beverages within an hour of taking Extreme Endurance as they say this impedes absorbability. 

Is Extreme Endurance Safe?

Extreme Endurance is generally safe to take and poses little to no risk of side effects. Still, there is a chance of experiencing:

  • Upset stomach
  • Heartburn
  • Headache
  • Loose stools/diarrhea

Extreme Endurance is made in a cGMP, FDA-registered facility. It is also Informed Sport Certified, which means it’s safe for athletes to take and proven to be free of any banned substances.

Additionally, Extreme Endurance is non-GMO, gluten-free, free of major allergens, and free from artificial colors, preservatives, and flavors. 

Where to Buy Extreme Endurance

You can buy Extreme Endurance from the Xendurance website

There are 30 servings (180 tablets) per container. The regular price is $59.95, but you can also get 10% off through their Subscribe & Save option ($53.96) or 25% through their Member option ($44.96). 

So, the price per serving ranges from $1.50 to $2, which is pretty normal for this type of supplement, albeit slightly higher than average. But it’s also one of the higher-quality supplements you can get, so it seems to be priced fairly.

Final Verdict: Extreme Endurance Review

Overall, Extreme Endurance is a solid workout performance and recovery supplement. While the use of a proprietary blend isn’t ideal, this is made up for given the clinical research behind it, since this essentially shows that it works regardless of any hesitation or doubt there may have been. 

Additionally, Extreme Endurance is Informed Sport Certified, so it can be used by competitive athletes too, not just recreational gym-goers. 

It probably won’t lead to any crazy improvements in endurance or recovery, but it certainly has the potential to give you that extra boost you need as an athlete to be a little bit better than before.


  • Ingredient Quality: 4.2
  • Ingredient Dosage: 4.0
  • Effectiveness: 4.0
  • Safety: 4.2
  • Value: 4.0
  • Comparison to Alternatives: 4.0
  • Company Trustworthiness: 4.4

Overall Rating:
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Jack Cincotta, MS

Jack Cincotta is a certified holistic health coach through AFPA and a board-certified holistic health practitioner through AADP. He has written hundreds of articles on nutrition and supplementation. Jack has a M.S. degree in Psychology and is passionate about researching the science behind nutrition. He often uses research-backed supplementation protocols for many of his clients to optimize results.

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