Ad description

A website for Under Armour,, seen on 15 February 2020, included a page which featured their long sleeve T-shirt baselayer “Men's UA RUSH Compression Long Sleeve”. Under the heading “Product DNA”, text stated “This groundbreaking baselayer has been tested and proven to improve strength and endurance. Seriously. The way it works is that the mineral-infused fabric absorbs the energy your body emits and reflects it back into your tissues and muscles. That means your muscles can work harder. And you get better”. In bullet points underneath text stated “Compression: Ultra-tight, second skin fit”, “As your body emits energy, the mineral-infused fabric absorbs & reflects it back into tissues & muscles, improving endurance & strength”, “Mesh panels for strategic ventilation”, “Modified raglan sleeve & low profile collar construction”, “Powered by Celliant” and “Imported”.


The complainant challenged whether the claim “tested and proven to improve strength and endurance” was misleading and could be substantiated.


Under Armour UK Ltd said that the target audience for the product was healthy young adult athletes. They said the product contained a material called Celliant, manufactured by Hologenix. The substance was a blend of thermo-reactive minerals, including titanium dioxide, silicon dioxide and aluminium dioxide, which could be embedded into fabrics used for clothing. Under Armour said Celliant was what allowed the product to enhance athlete performance. They said that products with Celliant improved performance, and specifically strength and endurance, by recycling an athlete’s own energy. Celliant clothing captured, converted and reflected heat generated by exercising back to the athlete’s body in the form of infrared (IR) energy. That IR energy, or heat, penetrated into the body’s tissues and the warming of the tissues temporarily increased blood flow to those areas. This increased blood flow, in turn, helped muscles perform better, which led to improved strength and endurance. They said the RUSH product contained 35-45% Celliant yarn. Under Armour also provided three studies to support the claim, one related to how the product improved strength and two related to how it improved endurance.



The ad included references to the long-sleeve T-shirt baselayer product featured, for example “This groundbreaking baselayer” and “Ultra-tight, second skin fit”, alongside the way in which the fabric worked, for example “Powered by Celliant” and “The way it works is that the mineral-infused fabric absorbs the energy your body emits and reflects it back into your tissues and muscles”. The ASA therefore considered that the claim “tested and proven to improve strength and endurance” would be understood as an indication that during exercise the product featured would noticeably improve strength and endurance for the wearer, over the area of the upper-body that it covered.

The advertiser had provided one study in support of the “improve strength” claim. The study involved 24 participants wearing a placebo shirt for 90 minutes before then wearing a shirt made of 42% Celliant fibre. The study found that after wearing the Celliant shirt, there was, on average, an increase in grip strength of 12.44%. We noted the Celliant shirt in the study was not the same as the advertised product, nor was it clear whether the product advertised was comparable to the shirt in the study in terms of its Celliant content.

We considered the study’s testing of ‘strength’ related to participants’ grip strength in their dominant hand only, and did not show that it improved strength for other areas of the body which would be covered by the product. Although the study had been peer reviewed, three out of the four academics behind it were not independent of the organisation. We considered the study was not an adequate body of evidence to show that the product was capable of improving strength.

We assessed the two peer-reviewed studies provided by Under Armour which related to how Celliant within the product improved endurance. The first involved the use of Celliant-containing clothing by 12 male cyclists whose oxygen uptake was measured at different intensities of cycling. The study found that at low exercise intensities the mean amount of oxygen consumed was lower when participants were wearing Celliant-containing clothing. At higher intensity levels, however, no difference was found in oxygen consumption between wearing and not wearing Celliant-containing clothing. It was therefore unclear whether the clothing would provide an advantage when cycling at an endurance race pace.

We again noted the Celliant shirt in the study was not the same as that featured in the ad, nor was it clear how the Celliant fibre content in the tested shirt differed from the advertised product. We considered the study’s sample size was small and did not indicate how oxygen consumption varied by participant across cycling intensities. We considered the study was undertaken on a narrow type of exercise and that its results were only conclusive when exercising at low intensity. The final study included a treadmill running test where five participants, aged between 18 and 22 years, wore a control or bioceramic shirt while running for 30 minutes. The study found that compared to the control group there was a tendency towards decreased tiredness and skin temperature in the bioceramic group, and that the respiration and heart rates in that group were relatively more stable. We considered the sample size of the study was very low and we noted its results did not state whether the relationships were statistically significant. It was not clear whether the bioceramic shirt was of the same type or manufacture as the product featured in the ad. For the above reasons we did not consider the two studies were an adequate body of evidence to show the product advertised was capable of improving endurance.

Because we considered the evidence was not adequate to substantiate the claim “tested and proven to improve strength and endurance”, we concluded that the ad was misleading. The ad breached CAP Code (Edition 12) rules  3.1 3.1 Marketing communications must not materially mislead or be likely to do so.  (Misleading advertising),  3.7 3.7 Before distributing or submitting a marketing communication for publication, marketers must hold documentary evidence to prove claims that consumers are likely to regard as objective and that are capable of objective substantiation. The ASA may regard claims as misleading in the absence of adequate substantiation.  (Substantiation),  3.11 3.11 Marketing communications must not mislead consumers by exaggerating the capability or performance of a product.  (Exaggeration) and  12.1 12.1 Objective claims must be backed by evidence, if relevant consisting of trials conducted on people. Substantiation will be assessed on the basis of the available scientific knowledge.
Medicinal or medical claims and indications may be made for a medicinal product that is licensed by the MHRA, VMD or under the auspices of the EMA, or for a CE-marked medical device. A medicinal claim is a claim that a product or its constituent(s) can be used with a view to making a medical diagnosis or can treat or prevent disease, including an injury, ailment or adverse condition, whether of body or mind, in human beings.
Secondary medicinal claims made for cosmetic products as defined in the appropriate European legislation must be backed by evidence. These are limited to any preventative action of the product and may not include claims to treat disease.
 (Medicines, medical devices, health-related products and beauty products).


The ad must not appear again in its current form. We told Under Armour UK Ltd not to state or imply that the advertised product would improve strength and endurance unless they held adequate new evidence to support the claim.

CAP Code (Edition 12)

3.1     3.7     12.1     3.11    

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