Performance Lab Flex Vs. Relief Factor – Which Is Better?

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By Thomas Youngerman

Reviewed by Juliana Tamayo, MS, RDN - Last Updated

performance lab flex vs relief factor

According to the CDC (Center for Disease Control and Prevention), nearly one in four adults in the U.S. have arthritis. And it appears that, unlike fine wine, your joints don’t improve with age. A University of Michigan National Poll on Healthy Aging found that nearly 70% of people 50 and older experience joint pain. Almost half of those diagnosed with arthritis have pain daily, and some say it interferes with their day-to-day life. This article compares the approach to pain management and joint support by the products of two companies, Relief Factor from Promedev LLC and Flex from Performance Labs. 

Pain Relief vs. Joint Support

The difference between the two approaches is subtle. Relief Factor’s primary focus is pain relief from joints and general muscle aches and pain, while the Flex product promises to support joint health, including the ligaments, tendons, and cartilage, and provide soothing pain relief. We review how these approaches affect formulations, ingredients, and how the products are marketed to the consumer. But first, we offer a brief overview of the joints in your body, the causes of joint pain, diagnosis, and potential treatments. 

Joints of the Body

A joint is where two or more bones connect to move body parts. Think of your ankles and knees, hips, elbows, and shoulders. But these are just a few of the estimated 250 to 350 joints in the human body. Joints are categorized by the dominant type of connective tissue and by the movement they allow, immovable, slightly moveable, or freely moveable. 

Synarthroses (immovable). Fibrous tissue, primarily collagen, with two or more bones in close contact that allow no movement – skull bones.

Amphiarthroses (slightly movable). Cartilaginous joints. Two or more bones held tightly together, allowing only limited movement – spinal vertebrae.

Diarthroses (freely movable). Synovial (fluid) joints are the primary functional type of joints in the body, allowing the bones to move smoothly against each other for complete mobility, such as knees and shoulders. 

To further complicate matters, there are six primary types of synovial (freely movable) joints:

  • Ball and Socket Joints – shoulders/hips, allow backward, forward, sideways, and rotation
  • Hinge Joints – knees/elbow, allow only bending and straightening movements
  • Saddle Joint – thumbs, allows movement on two planes
  • Pivot Joint – forearms, permit axial rotation
  • Gliding Joint – wrists, produce very little rotation or angular movement of the bones
  • Condyloid Joint – jaw/fingers, allow for forward-backward and side-to-side movement and do not allow rotation

Causes of Joint Pain

As mentioned in our opening, the most common cause of joint pain for most people is arthritis. Osteoarthritis (OA), the more prevalent type, is sometimes referred to as “wear and tear” arthritis, with symptoms that worsen with age. Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease that attacks the joints. 

Other possible causes of joint pain include tendinitis ((inflammation of the joint), bursitis (inflammation of the cushioning pads around joints), cartilage breakdown, and injury. 

Joint Pain – Diagnosis and Treatment

Relief Factor gets it right that the symptoms of joint issues start with pain. Other symptoms include inflammation, redness, and limited mobility. In the case of an injury resulting in severe or persistent pain accompanied by more significant swelling and restricted mobility, see a medical professional as soon as possible. Diagnosis typically requires X-rays, ultrasound, or an MRI (magnetic resonance imaging). Depending on the severity of your diagnosis, your primary care physician may refer you to a sports medicine specialist or orthopedic doctor.

performance lab flex vs. relief factor. joint pain

Treatment for joint pain/injuries varies based on the severity of your diagnosis, from steroid injections or prescription drugs to surgical repair or joint replacement. Treatments for less severe injuries include pain management, RICE (rest, ice, compression, and elevate), or heat treatment. Additional considerations for dealing with consistent pain from joints include lifestyle measures such as maintaining a healthy weight, regular exercise, resistance training to strengthen the muscles surrounding your joints, and nutritional supplements for pain management/joint support.

What are Joint Supplements?

Joint supplements are vitamins and other compounds designed to help manage pain and inflammation, build, repair, and protect joint tissue, and improve mobility. These products focus on alleviating ongoing pain while improving the health of your ligaments, tendons, and cartilage and promoting synovial fluid production.

Spoiler Alert

So, which product do we prefer in this head-to-head comparison? Although both products address pain, we like the formulation and ingredients found in Flex from Performance Lab as being superior in supporting overall joint health. In addition, the science, patented and trademarked ingredients, testing, and third-party certifications of Performance Labs, are excellent for a natural products manufacturer. But please read on as we contrast the two companies and their approaches, including their go-to-market and pricing strategies.  

Performance Lab

Performance Lab supplements were introduced by UK-based Opti-Nutra Ltd. in 2018. Eleven items were included in the initial roll-out, including gender-specific Multivitamins, Energy, Mind, Sleep, Vision, and Prebiotic products. Their Performance Labs Sports line consists of a Pre-workout, Post-workout, BCAAs, and T-Booster. Flex, the subject of this article, was introduced a bit later but has become one of the brand’s best-selling items. 

The manufacturing practices of the parent company, Opti-Nutra, are state of the art in the industry:

  • Facilities are registered with the FDA
  • Facilities are Certified cGMP compliant by NSF International
  • Ingredients are USDA Organic Certified
  • Natural Products Association Certified
  • HACCP Certified
  • US Pharmacopeia Certified

Performance Lab products are encapsulated in Opti-Nutra’s 100% Vegan patented Capsugels or NutriCaps. Their products are suitable for vegans, non-GMO, and allergen-free, containing no eggs, soy, fish or shellfish, dairy, nuts, or wheat. Products are formulated with evidence-based compounds, many trademarked and clinically tested to support structure-function claims. After rigorous internal testing, finished products are sent for an Independent Assay at an external third-party laboratory to ensure nutritional purity, potency, and quality.

Performance Lab’s products are marketed worldwide, available exclusively on their website at

Promedev LLC.

The Relief Factor brand is owned by Promedev LLC, a private company based in Kirkland, Washington. The company, founded by the father and son team, Pete and Seth Talbott, has been in business since 2015. Promedev also operates under the name of its best-selling product, Relief Factor. Products are manufactured in the U.S. in a federally registered facility, following GMP (Good Manufacturing Practices). There was no further information relating to facility or product certifications, no seals of certification on the packaging, and no reference to third-party testing. 

In addition to the original Relief Factor, the company markets Calm, Energy, and Sleep varieties. Available as a “gift with purchase” when ordering the QuickStart Kit is either a 30-serving Vitamin C or D3 supplement; however, neither item is marketed separately on the site. 

Relief Factor products, like Flex, are not available in brick-and-mortar stores or on other eCommerce sites. The company aggressively markets its 3-Week QuickStart Kit with automatic renewal and monthly subscription service.

Performance Lab Flex vs. Relief Factor: The Products

Both products are capsule-based dietary supplements for easy consumption, designed to address pain and support your joints. Below are brief product overviews. We review each of the compounds in the products in more detail in the formulation segment.

Performance Lab Flex

As previously mentioned, Flex by Performance Lab is a supplement designed to soothe pain and stiffness and support joint health, including ligaments, tendons, and cartilage. The comprehensive formula protects against free radical damage, promotes synovial fluid, strengthens bones, and helps hydrate cartilage. 

performance lab flex supplement

Five of the six Flex ingredients are patented and trademarked compounds with clinical studies to support the above benefit claims. Performance Labs stops short of quoting specific structure-function claims with clinical data, most likely due to dosage issues. The company positions the product as a flexibility formula. It targets users involved in strength training, endurance events, activities with repetitive motions, and the active 55 and older crowd.

Flex is delivered in a 100% plant-based, prebiotic-infused capsule that is easy to swallow and digest and provides superior absorption. Vegan-friendly, Flex contains no soy, egg, fish, shellfish, dairy, peanut, tree nuts, wheat, or other allergens. In addition, it is non-GMO and free of synthetic additives, artificial colors, and preservatives.

The recommended dosage on the Supplement Facts panel is two NutriCaps daily. In the Q&A segment of the website, the company suggests an additional two capsules after exercise to further reduce pain and support joint health. Each bottle contains 60 capsules. 

Flex is supported by a thirty-day “Performance Promise” guarantee.

Relief Factor

Relief Factor is physician-formulated with four ingredients designed to alleviate joint pain from exercise, aging, and everyday living. The product is delivered in two capsules and two softgels in each serving packet. The capsules contain Icariin, Turmeric, and Resveratrol, and the softgels contain omega-3 fish oils. Relief Factor supports the body’s natural inflammatory response to relieve joint and muscle aches and pains. For transparency, each ingredient and dosage are listed on the Supplement Facts panel. We appreciate this practice versus the proprietary blend approach.

relief factor supplement

In a somewhat unique approach, the website states Relief Factor is non-addictive and drug-free, no doubt a reference to prescription pain relief drugs. The company is also on a slippery slope when it discusses “reducing inflammation throughout the body.” The FDA states that general inflammation claims from supplements and foods are illegal because chronic inflammation is a disease state. Relief Factor attempts to avoid legal issues by mentioning:

  • Healthy response to inflammation, or
  • Inflammatory response

Also unusual for a joint supplement, Relief Factor promotes its product to help reduce muscle pain. Other products/ingredients are better suited to address muscle soreness, although omega 3 (fish oil) should be beneficial.

Recommended dosage per the Supplement Panel is one packet consisting of two capsules and two softgels. The 3-Week QuickStart package contains 49 packets, equating to 2.33 per day. There needed to be more information on the website about how frequently to take the product. Further internet research uncovered a statement that, according to the manufacturer, the product should be taken three times daily until discomfort moderates. After that time, the packets should be taken twice daily. This would equate to three times per day for the first two weeks, two times per day for the next week, and then as needed in the future. The typical one-month supply after the QuickStart is 60 packets.

The company has a ninety-day money-back guarantee (less shipping and handling charges) for unopened packages.

Best-in-Class Practices to Seek in a Joint Health Product

When considering a joint health supplement, we recommend you consider the following:

  • Are the products made in a cGMP-certified (current Good Manufacturing Principles) facility?
  • Do the products contain patented, trademarked ingredients, with clinical studies to validate their structure/function claims – at the appropriate dosages?
  • Are Supplement Facts panels transparent? (No proprietary blends)
  • Are the finished products tested in an independent third-party lab for quality assurance?
  • Are the supplements certified by USP, NSF, or Safe for Sport? 
  • Do the manufacturers support the products with a Money-Back Guarantee? 

Performance Lab Flex vs. Relief Factor: Comparison Chart

So, which is better? First, let’s see how well Flex and Relief Factor perform against our best-in-class attributes.

FlexRelief Factor
    FDA Registered YesYes
    cGMP CertifiedYesGMP compliant – no certification
    NSF CertifiedYesNo
Label TransparencyYesYes
Quality Assurance/Third-party testedYesNo
Money Back Guarantee30 Day90 Day – Restrictive

The NSF certification of the Flex manufacturing facilities, the trademarked and patented compounds in Flex versus the generic ingredients in Relief Factor, and third-party testing are all advantages to Performance Labs and Flex. Due to restrictions and complexity, we were not impressed with the money-back guarantee of either product. 

Performance Lab Flex vs. Relief Factor: The Formulations

Flex from Performance Lab

There are six compounds in Flex, five of which are trademarked and clinically tested. Each ingredient is plant-based and Vegan friendly.

performance lab flex ingredients

Curcuwin (turmeric), 250 mg. Curcuwin is a registered trademark of Omniactive Health Technologies. The company’s clinical trials support its use for muscle recovery, to combat free radical damage, to promote a healthy inflammatory response, for anti-aging, and for cardiovascular health. Notably, Curcuwin’s patented process shows it is 46 times more bioavailable than other forms of turmeric. Omniactive’s clinical trials dosage was either 250 mg or 1000 mg. Results at the 1000 mg dosage were superior – other published clinical trials use a 1500 mg dosage. 

ApresFlex (Boswellia), 100 mg. ApresFlex, trademarked by PLT Health Solutions-Laila Nutraceuticals LLC, is from the Boswellia serrata tree, also known as Indian frankincense. Boswellia is an antioxidant with potent anti-inflammatory properties. Clinical tests at the 100 mg dose resulted in less knee pain in OA patients and improved flexion. In addition, ApresFlex Boswellia achieves 52% greater absorption than other forms of Boswellia.

Performance Labs stacks the Curcuwin and ApresFlex, providing two proven forms of joint support, both excellent compounds individually, even more effective when used in tandem. 

Phytodroitin, 100 mg. Phytodroitin is a registered trademark of ESB Developments Ltd.  This compound is a Vegan, plant-based alternative to chondroitin, structurally identically. Glucosamine and chondroitin are two of the most studied joint support compounds, often used in combination to hydrate and lubricate joints, support collagen production, and for shock absorption. Most competitive products contain a higher dosage (200 – 425 mg).

Glucosamine Sulfate, 500 mg. The glucosamine sulfate in Flex is sourced from corn versus most glucosamine from shellfish, maintaining the product’s plant-based approach. Endogenous glucosamine is naturally found in connective tissue such as ligaments, tendons, and cartilage. Glucosamine also supports the production of synovial fluids. Supplementing Phytodroitin with glucosamine aids in the prevention of age-related breakdown of cartilage. They are often used in sports performance products and for those with OA or RA. Web MD recommends a 500 mg dose three times a day for the treatment of OA. 

OptimMSM (MSM), 100 mg. Methylsulfonylmethane is another popular joint ingredient, frequently combined with glucosamine and chondroitin to aid in the formation of collagen in cartilage. Recommended dosage, again, is significantly higher than 100 mg. 

NutriGenesis Strontium, 300 mcg. Strontium is a calcium-like trace mineral used for bone health. Natural strontium is found primarily (99%) in your bones. In bone support products, the dosage is many times the micrograms in Flex. 

Flex is formulated with excellent ingredients, trademarked, patented, and clinically tested, in combinations such as turmeric and Boswellia or glucosamine, chondroitin, and MSM. Our primary concern is the dosing of these ingredients – in most instances, dosages are well below those used in clinical trials to prove efficacy.

Relief Factor from Promedev

There are four primary compounds in Relief Factor. Unlike Flex, there are no patented or trademarked ingredients in the blend. 

relief factor ingredients

Epimedium (Icariin), 200 mg. Epimedium, related to the Horny Goat Weed family, is an herb used in Chinese medicine to address fatigue, arthritic pain, and sexual dysfunction. Prevalent in dietary supplements to address libido, there is also some evidence that it may aid in preventing bone loss in postmenopausal women. 

Resveratrol, 70 mg. Resveratrol is part of a group of compounds called polyphenols. These compounds act as antioxidants and are also thought to have anti-inflammatory properties to protect against oxidation (free radical damage) and chronic inflammation. Dr. David Sinclair popularized resveratrol in the early 2000s as part of an anti-aging regimen. The doctor recommends 500 mg per day. 

Turmeric, 667 mg. Although not the patented turmeric found in Flex, the dosage in Relief Factor is significantly higher. However, research has shown that pain relief benefit for rheumatoid arthritis and osteoarthritis is achieved at doses of approximately 1,000 to 1,500 mg.

Omega 3, 900 mg. The EPA/DHA in fish oil (omega 3) has shown benefits for people with arthritis in reducing pain and stiffness. In addition, omega 3 is proven in clinical trials to reduce the chronic pain of OA in elderly trial participants. Omegas also boost the effectiveness of other anti-inflammatory ingredients; however, a standard dosage is 1,280 mg of EPA/DHA. Therefore, it may be necessary to take up 2.7 grams consistently for at least three months for optimum benefits. Note: Relief Factor does recommend three servings per day, equating to 2.7 grams, but only for the first two weeks. 

In researching the best joint supplements on the market, we reviewed clinical trial data and the required dosage to achieve the purported benefits of pain relief and increased mobility. Several notable compounds, such as collagen and hyaluronic acid, are missing from our subject products. In the table below, we highlight the dosages used in these products versus the dosages used in clinical trials.

IngredientProduct DosageDosage Used in Clinical Trials
Relief Factor:
Resveratrol70 mg500 mg
Turmeric667 mg1000 mg
Icariin (Epimedium)200 mg800 – 900 mg
Omega 3900 mg3000 – 4000 mg
Curcurwin (Turmeric)250 mg1000 mg
Boswellia100 mg500 – 1500 mg
Glucosamine500 mg1500 mg
Phytodroitin (Chondroitin)100 mg1200 mg
MSM100 mg2000 – 6000 mg
Strontium300 mcg2000 mg

The only caveats to our position on ingredient dosages are the trademarked compounds in Flex that suggest superior absorption and the potential synergistic of the various compounds in combination. Unfortunately, there was no clinical testing on either finished product, so benefits are difficult to quantity.  

Performance Lab Flex vs. Relief Factor: The Benefits of Each Brand

As established in our introduction, the benefits claimed differ only in that Relief Factor’s primary focus is the relief of joint and muscle pain. In contrast, Flex supports pain relief and soft tissue health. 

Flex from Performance Lab

  • Reduced joint pain
  • Joint flexibility, lubrication, and shock absorption
  • Supports ligaments, tendons, and cartilage
  • Reduced swelling
  • Greater flexibility
  • Bone Density

Relief Factor from Promedev

  • Joint and muscle pain relief 
  • Healthy inflammatory response
  • Supports the body’s natural healing process

Performance Lab Flex vs. Relief Factor: Price Comparison

Performance Lab Flex Flex

By comparison, the Flex pricing is far more straightforward than Relief Factor. Pricing is as follows on the Performance Lab website: 

performance lab flex website

Shipping is free. Flex is only available via the Performance Lab website.

Relief Factor 

Relief Factor employs one of the more unique pricing strategies we have encountered using a “Preferred Customer” feature – a subscription service by yet another name. Customers sign up for a three-week Relief Factor Quick Start membership and receive a three-week supply for $19.95 plus shipping and handling. 

relief factor website

After fifteen days from the date of purchase, the company processes your credit card for an additional $79.95 plus $6.95 shipping and handling and ships your next thirty-day supply. This practice continues until the customer cancels their membership. 

Your QuickStart and subsequent shipments qualify for a “free gift” of either Vitamin C or D3. An Anti-Inflammation Diet book also accompanies your QuickStart order.

Conversely, purchasing a single thirty-day supply without the trial or membership/subscription is $93.95 plus $6.95 shipping and handling. 

Relief Factor is only available online through the official website.

Performance Lab Flex vs. Relief Factor: Things To Consider 

We have paid great attention to the dosages of individual ingredients in this article. Another consideration is the dosage of the finished products. Two capsules per day, recommended by Flex, is a standard dose. Athletes are accustomed to taking a pre, or post-workout supplement, so the additional two capsules are manageable. Relief Factors’ recommended dosage for the QuickStart, four pills three times per day, is a regimen most people will find arduous. 

In today’s world of two-day shipping, we fail to see a need for subscription services. Simply order as needed, with no long-term commitment and no cancellation hassles. That said, the cost is prohibitive at over $100.00 for a single month’s supply of Relief Factor. 

It is possible to purchase the individual ingredients of our subject products, as stand-alone products, from established brands, typically in significantly larger dosages, at a saving.

Flex contains no soy, egg, fish, shellfish, dairy, peanut, tree nuts, wheat, or other allergens for those with allergies or restrictive diets.

Performance Lab Flex vs. Relief Factor: Which Supplement is Better?

Flex is the superior product in this comparison, from corporate policies and practices to superior formulation and ingredients and cost-value relationship. Of course, no joint supplement works for everyone, but the Flex approach is the better approach for most people.    

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Thomas Youngerman

Thomas Youngerman is an entrepreneur and author in the health and wellness space with extensive experience in the supplement industry. He has owned multiple sports nutrition stores and served as the Category Manager and Director of Business Development for a regional chain of nutrition stores. Thomas created a successful line of men’s healthy aging supplements that was distributed in GNC, The Vitamin Shoppe, and Kroger, and later sold to a West Coast corporation. Thomas was previously a certified nutrition coach. He has a strong understanding of nutrition, supplement formulations, DSHEA, cGMP, and FDA regulations.