Extreme Endurance is an intra-workout supplement manufactured by Xendurance. It ranks 258 out of 266 intra-workout supplements and earned an overall thumbs-down recommendation based on seven factors including nutrition label transparency, ingredients, dosing, claims, research rating, and ranking.


Extreme Endurance earned a thumbs-down recommendation. This recommendation is based on the criteria listed below. To earn an overall thumbs-up recommendation, a product must earn a thumbs-up in at least four of the seven areas below. Click on a graded area for an in-depth analysis.

Graded Area Thumb Up or Down
Effectiveness Rating
Ingredient Dosing
Research Rating
Nutrition Label Transparency
Ranking Within Category
Overall Recommendation

Vote Statistics

1 to 5 Star Rating Votes Votes for products are cast in two ways. First, visitors can rate each product with a 1 to 5 star rating. These votes are cast on a product's rating page (this page - below).

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Comparison Votes Visitors can also vote on which product works better on comparison pages. Comparison pages are a side-by-side analysis between two supplement products. The votes below illustrate whether visitors prefer Extreme Endurance, or the products listed in the table below. The number next to the thumb up is how many votes Extreme Endurance won; the number next to the thumb down is how many votes it lost to the other product.

There have been no comparison votes cast for Extreme Endurance.

Table of Contents

  1. Simple Report
  2. Detailed Report
  3. Ranking Within Category
  4. Summary

Extreme Endurance Simple Report

  • Product Name: Extreme Endurance
  • Manufacturer: Xendurance
  • Manufacturer Website: Xendurance's Homepage
  • Supplement Category: Intra-Workout Supplements
  • Serving Size: 6 tablets
  • Effectiveness Rating: 1.73 out of 3
  • Number of Ingredients: 8
  • Research Rating: 23 (above 60 indicates sufficient research)
  • Nutrition Label Transparency Score: 0%
  • Ranking within Intra-Workout Supplements: 258 out of 266 (bottom third within category)
  • Ranking within all Supplement Products: 3,535 out of 3,818 (bottom third of all products)

Extreme Endurance Detailed Report

The detailed report provides an in-depth analysis of the product's rating. In addition to showing ratings for each area, this report also provides the required criteria for a thumbs-up in each section.

Effectiveness Rating

Extreme Endurance earned a thumbs-up in this category because its effectiveness rating is 1.73. A product's effectiveness rating must be at least 1.5 to receive a thumbs-up in this area. This effectiveness rating means Extreme Endurance is made up of a mix of both high and low-quality ingredients and may lead to some positive results.

This category illustrates how well a product works based on what the research says about its ingredients. Researchers conduct studies on supplement ingredients to gauge effectiveness. The database grades products on how effective their ingredients are. The effectiveness rating of supplement products is evaluated on a 3 point scale: 3.0 is the most effective, 1.0 is the least effective.


Extreme Endurance earned a thumbs-down in this category because it contains 0% extremely and/or moderately effective ingredients. A product must contain at least 75% extremely and/or moderately effective ingredients to receive a thumbs-up in this area.

This category rates a product's ingredient makeup. A product should contain mostly extremely and/or moderately effective ingredients with little or no ineffective ones. The database categorizes ingredients as extremely, moderately, or ineffective based on conclusions from research articles.

Extreme Endurance contains:

  • total ingredients: 8

The following table lists all ingredients found in this product as well as their effectiveness ratings and amounts (if listed).

Ingredient Effectiveness Rating
Potassium Amount not listed. 2.7 out of 3
Selenium Amount not listed. 2 out of 3
Magnesium Amount not listed. 1.6 out of 3
Chromium Amount not listed. 1.4 out of 3
Black Pepper Fruit Extract (Piperine) Amount not listed. 1.4 out of 3
Calcium Amount not listed. 1.3 out of 3
Papain Enzyme Complex* not rated
Catechins* not rated
Product Effectiveness Rating 1.73

* These ingredients are not included in the Supplement Database.

Note: These ingredients are accurate as of July 10, 2020.

Ingredient Articles

Ingredient Dosing

Extreme Endurance earned a thumbs-down in this category because it does not disclose any ingredient amounts on its label making it impossible to gauge dosing effectiveness. Seventy-five (75)% of product's ingredients must be dosed within the effective range to receive a thumbs-up in this area.

This category compares a product's ingredient dosing to effective doses found in research articles and doses used in other products. When researchers study the efficacy of supplement ingredients, they use specific doses. Manufacturers should create products with ingredient doses that fall within established effective ranges.

Extreme Endurance does not list ingredient amounts on its label. This makes it impossible to analyze ingredient dosing.


Extreme Endurance earned a thumbs-down in this category because 46% of its claims are rated as either extremely or moderately effective. Seventy-five (75)% of a product's claims must be rated as extremely or moderately effective to receive a thumbs-up in this area.

The product’s effectiveness rating is an overall picture of how well a product does or doesn't work. Individual studies research an ingredient's effects on certain claims. For example: does creatine monohydrate increase strength, or does beta alanine improve running performance?

The Supplement Database compiles the conclusions of these studies, and based on a product's ingredient makeup, calculates how well a product does on various claims. The claims below are organized by effectiveness (extremely, moderately, ineffective).

Research Rating

Extreme Endurance earned a thumbs-down in this category because its research rating is 23. A product's research rating must be at least 60 to receive a thumbs-up in this area.

A research rating of 23 means there is an insufficient amount of research on the product's ingredients to ensure its effectiveness rating is valid.

The research rating is a measure of how much research has been conducted on a product's ingredient makeup. Manufacturers often rely on ingredients without adequate research backing. They may do this to compete with other products that are already using poorly researched ingredients. They may also only use a very small amount of cherry-picked research as a poor justification to use certain ingredients.

The amount of research contained in the database on a product's ingredients determines its research rating. Products with higher ratings are made up of thoroughly researched ingredients.

Nutrition Label and Ingredient Transparency

Extreme Endurance earned a thumbs-down in this category because it discloses 0% of its ingredient amounts. A product must disclose all ingredient amounts to receive a thumbs-up in this area.

Nutrition label transparency refers to how many ingredients are listed with amounts on the product label. Many supplement manufacturers hide ingredient amounts under the guise of great-sounding proprietary blends such as "Maximum Muscular Size Enhancer" or "Anabolic Cell Strength Matrix."

When manufacturers use proprietary blends, they can hide ingredient amounts making it difficult for consumers to know whether a product is effective.

Extreme Endurance contains:

  • total ingredients: 8
  • ingredients with amounts listed: 0
  • ingredients without amounts listed: 8
  • percent of ingredient amounts disclosed: 0%

Product Label

The label below was generated from the information contained in the database about the product's ingredients and amounts. Actual product labels may differ in appearance.

Extreme Endurance by Xendurance Product Label

Ranking Within Category

Extreme Endurance earned a thumbs-down in this category because it ranks 258 out of 266 in the category (bottom third). A product must be ranked in the top two-thirds of its category to receive a thumbs-up in this area.

Extreme Endurance ranks 258 out of 266 in the Intra-Workout Supplements category and 3,535 out of 3,818 in the entire database. The table below lists comparisons with similarly ranked . Click on a link for an in-depth comparison between the two.

Product Comparison
Extreme Endurance vs Peri-MD
Extreme Endurance vs PRO6 Plus
Extreme Endurance vs AminoFast Shred Series
Extreme Endurance vs EAA-XS Tablets
Extreme Endurance vs ISOTECH

See more comparisons: Is Extreme Endurance the best intra-workout supplement?


Graded Area Reason
Effectiveness Rating rating is greater or equal to the required 1.5
Ingredients less than 75% of ingredients are rated as effective
Ingredient Dosing dosing cannot be rated because all ingredient amounts are hidden
Claims less than 75% of claims are rated as effective
Research Rating research rating is lower than the required 60
Nutrition Label Transparency does not disclose all ingredient amounts on label
Ranking Within Category ranks in the bottom third of category
Overall Recommendation received a thumbs down in the majority of areas

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