Science Backed Supplements

“In science…what is relevant is reproducible results.”—Michael Crichton

Xendurance has a rigorous history of scientific testing, demonstrating the clear advantage of our product line. Studies date back over a decade and have been expanded upon with repeatable, favorable performance.


Our flagship product, Extreme Endurance, is the only supplement in the world that has a gold-standard, third party, double-blind, placebo-controlled, crossover study – that has been published.  While other companies pay a third party to conduct studies with skewed results, we hired one to conduct their research without any knowledge of our company brand or identity. The results?  An off the charts 15% reduction in lactic acid and a double digit increase in aerobic threshold.


Jürgen Sessner, lead researcher and owner of Corpus Diagnostik, was so fascinated by these results that he requested a 30 Day Trial be conducted with 6 pro-triathletes. The 10 year veteran strength and conditioning coach from the German Bundesliga found that with longer use of Extreme Endurance, there was continued improvement and an increase in VO2 Max and power output.

The clinical results of our double-blind study were presented at the 6th Annual European Nutraceutical Convention in Vienna, Austria, March 13, 2010 and are published in the Clinical Journal of the European Society for Clinical Nutrition and Metabolism, (Vol. 5, Supplement 1, 2010).


In 2013, Jürgen would put Extreme Endurance to the test again, but this time on functional fitness athletes in the U.S.  Eleven experienced athletes, ages ranging from 22-26, underwent the “Fran” stress test at East Valley CrossFit in Chandler, AZ, a controlled environment under observation with movement standards.  Blood samples were taken from each athlete immediately before, after, and 10 minutes following a baseline test.  Each athlete was then prescribed a 7-Day Trial of Extreme Endurance.

After a weeks supplementation, the stress test was repeated and athletes demonstrated an average improvement of 6.2%, or 22 seconds in their “Fran” time.  Blood tests conducted immediately after revealed 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.


Dr. David Bellar, Director of the School of Kinesiology, and Jason Soileau M.S., CSCS, from the University of Louisiana at Lafayette, conducted a double-blind, placebo controlled, crossover study with 16 active males that assessed the total effects of Extreme Endurance during exercise. Their findings? An astounding 26% Reduction in Lactic Acid, 39% Reduction in Oxidative Stress and a 6x lowering of Creatine Kinase Levels.

More details can be found by reading their study published in the Journal of Athletic Enhancement listed below. Here is a summary of their findings:  The Effects of 10 Days of Extreme Endurance on Performance, Buffering Capacity during Exercise and Post Exercise Muscle Damage, Oxidative Stress and Inflammation.

Clinical Resources

Tested and Certified For Banned Substances

Lifespan International US. was the first US Sports Nutrition company to use LGC Sport Science's certification programs: INFORMED CHOICE & INFORMED SPORT.

Extreme Endurance is “Tested For Banned Substances" by LGC, and has received certification by both INFORMED CHOICE INFORMED-SPORT. LGC Sport Science is one of the world's premier independent drug surveillance laboratories, providing unrivaled and internationally trusted expertise in doping control for sports. LGC has been testing supplements/ingredients for banned substances since 2002 and has a institutional history dating back to 1842.

The LGC laboratory is ISO Certified and accredited for forensic testing and meets or exceeds World Anti-Doping Agency standards and requirements. Tests performed on our products use state-of-the-art gas chromatography, liquid chromatography, and mass spectrometric detection. These test results can detect substances down to ten parts per billion for steroids and 100 parts per billion for stimulants. Testing is very expensive, but the world's best athletes and professional sports teams demand the safest, drug-free nutritional products.

Tested endurance supplements, and batch samples are catalogued and retained for the product shelf life. If an athlete who has been using Xendurance products tests positive for banned substances, these sealed batch samples will be made available for a third party, independent test, to prove the positive test was NOT due to our products.

LGC Sport Science


INFORMED-CHOICE & INFORMED-SPORT (EU Certification) is a supplement testing and certification program assuring athletes that products carrying these marks have been regularly tested for prohibited substances. Responsible supplement companies have made INFORMED-CHOICE & INFORMED SPORT part of their existing quality assurance systems to ensure their products are safe for athletes to use.

Some supplement products from less meticulous manufacturers have tested positive with low levels of steroids and stimulants prohibited by WADA and other sporting bodies. The INFORMED-CHOICE & INFORMED SPORT program aims to work closely with supplement manufacturers and suppliers by providing high quality, analytical testing to minimize the incidence of banned contaminants finding their way into sport.

INFORMED-CHOICE & INFORMED-SPORT were established in 2007 by LGC Sport Science when it became clear that there was a need for a comprehensive certification program which not only tested products for banned substances, but were manufactured in qualified facilities meeting FDA GMP standards.

Athletes who see the INFORMED-CHOICE & INFORMED-SPORT logo on a product can be confident it has undergone a rigorous screening program for banned substances and are safe to use.

Collegiate and Professional Team Information

Can Extreme Endurance be used by collegiate athletes? – YES.

Extreme Endurance can be and is being used by professional and collegiate athletes in numerous sports across the globe.

NCAA Bylaw 16.5.2(g) states, “only non-muscle building nutritional supplements may be given to student athletes for the purpose of providing additional calories and electrolytes as long as the sports supplements do not contain NCAA-banned substances."

Extreme Endurance's formula is classified as an electrolyte, mineral supplement and is permissible for use by collegiate athletes.

In addition, Extreme Endurance is certified ISO/17025 Tested For Banned Substances by the largest sports drug laboratory in the world, LGC and certified by INFORMED-CHOICE INFORMED-SPORT

Manufacturing Facilities

Our supplement manufacturing facility is certified in compliance with GMP requirements set forth in NSF/ANSI Standard 173, Section 8, Athletic Dietary Supplements. According to NSF International, “GMP Registration" reflects continued commitment to ensuring the highest quality.

NSF International is an independent, non-profit organization which certifies our manufacturing facility and operating procedures to ensure we conform to the highest industry standards. A manufacturer can earn certification and receive a Good Manufacturing Practice (GMP) registration, a designation signifying our commitment to the safety and efficacy of our products.

ISO-17025 Certification for dietary supplements requires each product to undergo analytical testing to ensure the absence of any banned substance that is banned by sports organizations such as:

  1. World Anti-Doping Agency (WADA)

  2. International Olympic Committee (IOC)

  3. National Collegiate Athletic Association (NCAA)

  4. National Football League (NFL)

  5. Major League Baseball (MLB)

  6. National Basketball Association (NBA)

  7. National Hockey League (NHL)

With Global and U.S. Anti-Doping testing and certification, Xendurance is taking all precautions and steps to ensure you a drug-free supplement.