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One Week Pack

One Week Pack of Extreme Endurance

Helps to stop muscle burn and muscle trauma. Proven to substantially reduce Rhabdomyolysis (Rhabdo)*

During intense training, don't just "hit the wall" with muscle burn and pain - BLAST through it with Extreme Endurance, a revolutionary athletic performance formula. It's clinically proven to reduce lactic acid by 15-26% and increase aerobic threshold by double digits.*

All ingredients are in compliance for IOC, NCAA, NFL, NBA, NHL and MLB. Every single batch of Extreme Endurance is tested for banned substances by the world class sports doping control laboratory, LGC Group. In order to provide re-assurance that the product is suitable for use by elite athletes, the product is approved under the Informed-Sport and Informed-Choice programs.*

Extreme Endurance Advantages:

  • Clinically Proven to Reduce Lactic Acid by 15-26%*
  • 39% Reduction in Oxidative Stress*
  • 6X lowering of CK (Creatine Kinase) Levels*
  • Speeds Recovery*
  • Improve Aerobic Threshold by Double Digits*
  • Benefits Within 72 Hours*
  • Reduces Muscle Soreness*
  • Certified Drug-Free*

*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.

42-Tablet, Zip-Loc Pouch
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Product Information
Extreme Endurance is a revolutionary athletic performance formula created by athletes for athletes. This formula has a published, Gold-Standard, third party, double-blind, placebo-controlled, crossover study backing up claims of 15% reduction in lactic acid and a double digit increase in aerobic threshold. Many companies make claims on individual ingredients but Extreme Endurance has a published study on the formula itself. Each batch of Extreme Endurance is tested to ensure that it is not contaminated with banned substances to provide additional reassurance for elite athletes.*

11/02/2016 Second Double-Blind, Placebo-Controlled Study Just Released
Scroll down to Clinical Test 4 and read about Xendurance's newest study, completed at The University of Louisiana - Lafayette.
Results: 26% Reduction in Lactic Acid, 39% Reduction in Oxidative Stress and a 6X lowering of CK Levels.

Why is testing sports nutrition important?

Read Comparative incidence of the presence of banned substances in raw ingredients/materials sourced from global suppliers – summary of findings

P. Brown, C. Judkins, D. Hall, HFL Sport Science Ltd, Newmarket Road, Fordham, Cambridgeshire. CB7 5WW

As an athlete you already know the harder you exercise and compete, the more acid builds up in your muscles. Both your blood and muscle pH goes down into the dreaded acid zone. The increased use of muscle glycogen for energy produces lactic and pyruvic acid. Acidity reduces muscle power and reduces physical and mental endurance. You, your trainers and your coaches refer to this as lactic acid buildup or lactic acid fatigue. On the practice and playing field, it is also called "hitting the wall" or having the "bear jump on your back". It's simple. The harder you compete, the quicker you Go Acid! The Athlete who "Goes Acid" last, wins the competition.*

Intramuscular acidosis, is when your muscles have too much excess acid. This condition is caused by the production of H+ (Hydrogen ions) which is part of the energy released from the breakdown of glucose. As your muscles "go acid", this creates fatigue and muscle burn, which you feel during intense exercise. The Extreme Endurance formula and physical chemistry of its 9 ingredients not only assures you that it will buffer production of H+ (Hydrogen ions) and help prevent the acid buildup in your muscles, but it has also been clinically proven to increase aerobic threshold so you can work harder for a longer period of time.*

Every athlete should know about proper pH balance. PH balance is critical to top athletic performance. PH is measured on a 14 point scale. The lower pH value range, such as stomach acid could average between 1.0 to 3.0. A pH value of 7 is neutral. The arterial blood pH value of a healthy human ranges around 7.35 to 7.45, which is slightly alkaline. As our body uses fuel and metabolizes food, we produce acid waste which is part of the process of energy release from the breakdown of glucose. The body has numerous ways to remove this acid waste or try to neutralize this acid buildup. Our kidneys filter blood and excrete acids through urine. Our lungs release carbon dioxide and we sweat acids out of our skin. We also have built in acid buffers to help neutralize pH imbalances like calcium, hemoglobin and phosphorous to name a few.*

Your body's acid concentration increases as you produce lactic acid. Lactic acid is split into Lactate (Lactate ions) and Hydrogen ions. H+ (Hydrogen ions) is the acid in Lactic acid. Lactate is good and is an extremely fast fuel that is preferred by the heart and muscles during exercise. Lactate is vital for ensuring that your body gets a steady supply of carbohydrates. H+ (Hydrogen ions), the other half of Lactic Acid is not good, especially when the acid concentration exceeds the body's ability to no longer neutralize or flush the waste from your body.*

Clinical Test Number 1 - Clinical Study Proving Effectiveness of Extreme Endurance

A Gold-Standard, third party, double-blind, placebo controlled, cross over study, was conducted on Extreme Endurance whereby twenty-two (22) elite athletes were given baseline tests. Each athlete was given dosage protocol and either product A or product B. When the final test results were completed, the 22 athletes showed an average lactic acid reduction of 15% and an increase of aerobic threshold by double digits. All athletes reported less muscle burn and faster recovery with less muscle soreness.*

(Third party testing means that Lifespan International, the parent company of Xendurance, had no knowledge of what testing facility would be used and did not choose the testing facility)*

This clinical study was published in the Clinical Journal of the European Society for Clinical Nutrition and Metabolism, (vol 5, supplement 1, 2010) and presented at the March 13, 2010, 6th Annual Conference of the EU Nutraceutical Association. - And our testing continues on athletes at Corpus Diagnostik in Hilpoltstein, Germany.*

Jürgen Sessner, the lead researcher at Corpus Diagnostik has done over 9,000 Step Tests, (we call them VO2 Max tests in the US) in the last decade and has been testing athletes for 13 years including 3 Hawaii Ironman Champions. He has held over 70 training camps for triathletes and cyclists in the EU and Canary Islands.*

Clinical Test Number 2 - Open Label Trial for Cross Functional Athletes

Cross-Functional exercise, defined as "constantly varied, high intensity, functional movement," has revolutionized the sport of fitness in an attempt to seek out the world's fittest individuals. Within the generalized programming that Cross-Functional athletes use, there are a series of "Benchmark Workouts" designed to help measure the progress of a cross-functional athlete's development. Among these workouts is 'Fran,' quite possibly one of the most well-known and frequently tested benchmark workouts among cross functional athletes. Fran is a couplet that exercises a 21-15-9 repetition scheme of front squat thrusters (95lbs for men, 65lbs for women) and pull-ups. Due to the metabolic efficiencies needed to complete 'Fran,' and the physiological responses that it elicits, Xendurance chose to highlight this workout and put their showcase product, Extreme Endurance, to the test again.*

In September of 2013, Jürgen Sessner, lead researcher at Corpus Diagnostics in Hilpoltstein, Germany, flew out to conduct the test. Jürgen has conducted over 9000 stress tests in his 15-year career and was the lead researcher on the clinical study that was presented at the prestigious European Nutraceutical Association meeting in Vienna, Austria, March 13, 2010 and is published in the European Nutraceutical Journal.*

In the open label test conducted at East Valley Crossfit in Chandler, AZ, 11 cross-functional athletes, ages ranging from 22-66 were randomly selected. All athletes met the minimum criteria of at least 10 months of training leading up to the study and were required to complete 'Fran' twice over the course of a 7-day period. Upon being selected for the study, all of the athletes took part in a two-week washout period from all supplements. On day one of the study, a baseline 'Fran' test and blood samples were taken. Athletes were then provided with a 7-day trial of Extreme Endurance and were instructed to take 3 tablets in the morning and 3 tablets in the evening, with or without food. At both the baseline and post supplementation test, athletes had blood taken from the earlobe immediately before, after, and 10 minutes after completing 'Fran'. All 'Fran' times and movement standards were validated by a judge for each of the participating athletes.*

After further analysis, the single best and worst performances were omitted from the study to ensure more accurate results. Of the remaining 9 athletes, a 7-day supplementation of Extreme Endurance yielded an average of 6.2% or 22-second improvement on their respective 'Fran' times. All blood samples were analyzed by a Hitaldo Super, GL Biosensor System. Blood tests after a 1-week usage of Extreme Endurance reduced lactate levels by 8.9% immediately post workout and 7.1% 10 minutes post workout when compared to blood samples taken at baseline.*

Cinical Test Number 3 - Open Label Trial on Extreme Endurance and Creatine Kinase (CK) Levels in Cross Functional Athletes, Military Warfighters and Firefighters

As reported by the national media*, Rhabdomyolosis (Rhabdo) is an increasingly, alarming topic among the cross functional community, the military warfighters and firefighters. While this topic is not new to the military warfighters and firefighters, it is taking the cross functional community by surprise. Unlike the day-to-day occupational hazards the military warfighters and firefighters face, this unique style of training has many cross functional athletes discussing the possible repercussions that come with it, namely Rhabdo. Given the growth of the sport and the continued scrutiny that comes with the sport, this disease now has it's own mascot, Rhabdo the Clown.*

Rhabdo is a dangerous medical condition often associated with strenuous exercise and overuse, infections, crush injuries, elevated or reduced sodium levels, low potassium, unusually high or low body temperature, particular medications, and dehydration (or a combination of factors). And up until now, military warfighters and firefighters were the only groups worried about Rhabdo. We can now add the cross functional athletes to the list impacted by this medical condition.*

The breakdown of muscle tissue results in damaged cells entering the blood stream. Myoglobin, a toxic protein released by these cells, is harmful to the kidneys when released in large quantities and can lead to permanent kidney damage, or even kidney failure. Rhabdo is often diagnosed by measuring an enzyme released into the blood by damaged muscle tissue, creatine kinase (CK). It is not abnormal to see CK levels rise above 100,000 U/I in Rhabdo cases.*

With the growth of these communities, Xendurance set out to prove that Rhabomyolysis (muscle trauma) can be averted. Their scientific study, completed in January 2014 by Jürgen Sessner , showed astonishing results with usage of the sports supplement, Extreme Endurance and the reduction of CK levels, the precursor for Rhabdomyolysis.*

In this open label test, changes in CK levels were tested after a 7-day supplementation period on Extreme Endurance. A group of 31 cross functional athletes, both men and women, ranging in age (from 20 to 48) were chosen for the study. Prior to participating, all athletes who were using Extreme Endurance underwent a 2-week washout period. All the athletes were required to perform "Fran" twice over the course of an 8-day period.*

On the first test day, athletes completed "Fran". "Fran" is one of the best known workouts among cross functional athletes. Fran is a back-to-back exercise of a 21-15-9 repetition scheme of front squats thrusters and pull-ups. Due to the metabolic efficiencies needed to complete "Fran" and the physiological response that it elicits, Xendurance once again chose this epic workout for this CK study. After completing the first "Fran" workout, each athlete received their 7-day trial of Extreme Endurance. They were instructed to take a dosage of 3 tablets in the morning, and 3 in the evening, while keeping their current diet and training schedule unchanged. On day 8, the participants returned to complete the second test.*

On each testing day, CK levels were tested via blood taken from the index finger and analyzed by a Reflotron Plus System (37°C) immediately pre and post "Fran".

To place Fran in perspective, the increased CK levels associated with Fran could be equivalent to the CK levels a firefighter may experience on the front lines fighting a fire or a Military Warfighter on a 10 mile trek with full equipment. All three events have the ability to increase your CK level.*

Upon analysis of the data, the results showed that after a 7-day supplementation period on Extreme Endurance, a decrease by an average of 16.9% (33.1 U/I) in CK levels pre-workout and a 63.55% (32.6 U/I) decrease in CK levels after completing Fran were recorded. In addition, none of the athletes who participated recorded CK levels that would indicate the onset of Rhabdo. 29 of 31 athletes performed better in the second workout with an average of 8.55% or 32 seconds faster.*

A clearly recognizable lowering of beginning CK levels were evident before the second workout. As noted, the results showed a lower entry of 16.9% or 33.1 U/I.*

After completing the second workout, the data showed additional reduction of CK levels of 63.55% or 32.6 U/I (total 79.64%) While 29 of 31 athletes performed better in the second workout with an average of 8.55% or 32 seconds faster, all 31 athletes reported a quicker recovery.*


By looking at the results from this open label test, it can be concluded that Extreme Endurance is effective in decreasing muscle trauma and decreasing recovery time as indicated by lower CK levels. This means less cell damage, safer training, and a quicker recovery and allows more training load in both short and long term.*

CK analysis by Reflotron (Enzymatic testing system at 37*)

Clinical Test Number 4 - Conducted in 2016 at the University of Louisiana at Lafayette by Dr. David Bellar, Director of the School of Kinesiology, The Effects of 10 Days of Extreme Endurance on Performance, Buffering Capacity during Exercise and Post Exercise Muscle Damage, Oxidative Stress and Inflammation is a double-blind, placebo controlled, crossover study with 16 active males that assessed the total effects of Extreme Endurance during exercise. Results: 26% Reduction in Lactic Acid, 39% Reduction in Oxidative Stress and a 6X lowering of CK Levels.

Press Release below. Full Clinical Pdf to be online soon.
Xendurance Announces Extreme Endurance Clinical Study Results.pdf

Xendurance Studies:

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Extreme Endurance is tested by the largest sports lab in the world. LGC, (Formerly known as HFL) is located in the UK and its testing of Extreme Endurance is done using gaschromatography with mass spectrometric detection (GCMS) and liquid chromatography with mass spectrometric detection (LCMS). In layman's terms, - if you put one drop of a banned substance in an olympic size swimming pool, this testing would find it. It is costly, but we have many pros who can not afford to have their tests come up positive. LGC's testing programs for athletes are called Informed Choice and Informed Sports.*

To summarize, there is not another product in the world that has a Gold-Standard, third party, clinical study, that has been published, and has been tested drug-free.*

*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.


IF YOU TRAIN 5 to 6 TIMES PER WEEK, take 6 tablets daily; 3 in the morning and 3 in the evening, with or without food.

FIVE TO SEVEN DAYS BEFORE A RACE increase your dosage to 8 tablets a day; 4 in the morning and 4 in the evening and continue this 8 tablets for one day after the race and then drop back down to 6 tablets per day. We suggest this as it helps immensely with recovery.*


If you are a pro, amateur or weekend warrior who makes training a part of your health regimen, Extreme Endurance will keep your acid low and your pH more in balance. By adding lots of fruits and vegetables to your diet you can also help lower your body's acid and maintain a more healthy pH.*

Extreme Endurance is able to safely buffer the hydrogen ions (H+) acid in lactic acid with powerful buffers. In addition, Extreme Endurance adds second generation ingredients to its formula to address other biochemical changes that occur to an athlete's body during intense exercise, such as tissue damage, oxidative stress, suppression of the immune system and harmful inflammation.* These added ingredients are:
  • Papain, a protease enzyme derived from Papaya, which is a powerful anti-inflammatory that helps repair and rebuild muscle tissue and relieves muscle soreness.*
  • Catechins are added and are one of the most powerful antioxidants to help fight oxidative stress during exercise.*
  • Electrolytes complete this revolutionary formula to assist athletes with the ability to quickly recover and restore balance and maintain the competitive edge.*

*DO NOT CHEW. These tablets are meant to be swallowed.

*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.
Other Product Benefits
What Xendurance Products Should I Take? Do Xendurance Formulas Work Together?

Xendurance products are built to work together. Find the sport closest to yours and see what other athletes are taking.

Cross Functional Athletes
Are you sore everyday after your WOD? Want to reduce that muscle burn and make sure you spring out of bed the next morning? We recommend you try Extreme Endurance (reduce lactic acid buildup and soreness), Omega (to give you loads of EPAs and DHAs per serving) and then give Protein a shot - no pun intended.*

We call the first Protein drink in your morning an "energy starter shot". The 1500mg of lactate and 20g of protein is what Cross Functional Athletes are addicted to - really. And then if you have sore joints....put Joint-4 in your training bag.*

Also check out the 10% discount on the Bundles.

Triathletes, Duathletes and all Multi-Sport Athletes
We made our pouches of Extreme Endurance for you! Continuous travel make our zip-loc pouches the perfect packing buddy. (Keep the soreness down and the recovery up with Extreme Endurance.) And because you put so many hours into your training and don't want to get sick, build up your immune system with Immune Boost. (Power-packed multi-vitamin)*

Runners, Cyclists - those always on the go.....
Extreme Endurance, Immune Boost and Extreme HYDRO-X is in their training regimens. With the 1500mg of Lactate and a premium blend of Electrolytes, HYDRO-X has been discovered as a boost while training. It gets you hydrated fast with Sustamine™ and gives you energy throughout those miles of training.*

Weekend Warriors and all “wannabe" Olympians pushing hard!
Extreme Endurance will assist in reducing soreness in any sport whereby you produce lactic acid. If you find you trained a little too much or are nursing a nagging injury, try Joint-4. (4 powerful ingredients in one formula to help rebuild cartilage and decrease pain) Want to stay healthy during cold season, take our multi-vitamin, Immune Boost. Extreme HYDRO-X (electrolyte/lactate drink) and/or Protein (protein/lactate drink) may be the drinks you need for hydration and energy.*

Did we mention the golfers, paddle boarders, MMA Fighters, skiers, surfers....yes, you can mix and match any and all of our products for your specific sport or activity. Still not sure what to take?*

Send an email to and we will tell you what we hear other athletes are using to help them in their daily quest to be the best they can be.

*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.