Ad description

A website for Under Armour,, seen on 13 October 2018, featured a banner ad for Under Armour’s ‘Athlete Recovery Sleepwear’ range that stated “RECOVER FASTER…RETURN BETTER…ALL DAY, ALL NIGHT RECOVERY…Sleep eight hours, feels like ten. Athlete Recovery Sleepwear helps you recover faster, get more zzz’s [sic] and wake up ready to do it all again”.


The complainant challenged whether the claim that “Athlete Recovery Sleepwear helps you recover faster” was misleading and could be substantiated.


Under Armour UK Ltd said that the Athlete Recovery Sleepwear range contained a material called Celliant that had been developed and manufactured by a third-party company called Hologenix. Celliant was made of a number of different minerals that, when woven into clothing, were supposed to reflect body heat in the form of infrared (IR) light which in turn penetrated muscle and increased blood flow. They said that increased blood flow following exercise was important for the uptake of lactate and the facilitation of protein synthesis through amino acid transportation to muscle, which helped repair and grow muscle.

Under Armour also provided a response from Hologenix addressing the complaint. First Hologenix gave background to the principles underpinning IR. They said that the composition of Celliant had been developed to maximise the amount of IR reflected back into the body when used in clothing and provided a study they said showed IR could penetrate up to 4 cm into deep tissue and muscle. They also set out the minimum amount of Celliant per weight of clothing that needed to be used in order for the effective operation of Celliant-containing clothing. Additionally, they said that the emission of IR by Celliant-containing products had been established in their patent filings in the United States, as well as amply in other studies, and provided copies of those filings and studies. They said that it was well accepted that IR emissions caused capillaries to dilate, resulting in greater blood flow and increased oxygenation to the relevant area. It therefore stood to reason that Celliant-containing products, through the emission of IR, could produce that physiological effect.. They said tissue oxygenation was measured with reference to the transcutaneous partial pressure of oxygen (tcPO2) and that an increase in tcPO2 of 7% was necessary for garments to be cleared for production by Hologenix.

They provided four studies that they said were “ample evidence” of Celliant’s ability to increase oxygenation. They also set out the health benefits of IR-related increased blood flow and oxygenation. They said that there was a substantial body of general scientific evidence supporting the principle that blood flow increased with IR-stimulation and that oxygenation had positive health effects, including lactate removal, post-exercise muscle repair, increased muscle strength, and cell growth and repair.

They also said that Celliant-specific evidence showed the potential for Celliant’s application in performance-enhancing athletic apparel and post-exercise recovery. By way of substantiation for their arguments, Under Armour and Hologenix provided 44 different documents, including published and unpublished studies, patent filings and a letter from an academic.



The ASA considered that the headline claim “RECOVER FASTER…RETURN BETTER…ALL DAY, ALL NIGHT RECOVERY…” would be understood by consumers to mean that wearing Under Armour’s Athlete Recovery Sleepwear would aid sleep and help their muscles recover from exercise. We considered that the additional claim “Sleep eight hours, feels like ten. Athlete Recovery Sleepwear helps you recover faster, get more zzz’s [sic]” would add to that impression. We considered the advertiser should hold robust scientific evidence in support of those claims. However, when we reviewed the evidence provided by both Under Armour and Hologenix, we considered that the documentation provided did not meet the standard of evidence we required for the types of claims being made, both in terms of adequacy and relevance to the ad’s claims that the clothing would aid sleep and muscle recovery.

We reviewed the documentation provided confirming that Celliant could absorb IR emissions and reflect them into the body as IR light. We noted that Hologenix considered the mechanism of Celliant to be “essential, fundamental, and foundational”. We also noted the comments made by a medical academic in a letter provided, that “Hologenix … have clearly demonstrated that [Celliant] does indeed emit [Far Infrared (FIR)] radiation upon absorbing heat … This power density is much lower than values that might be expected from electrically powered sources of FIR radiation … Nevertheless, Celliant [is] designed to cover large areas of the body … moreover, [it] can be worn for several hours and even over the entire night of sleeping time. Thus, the total dose of FIR can be calculated to be roughly equal to the dose delivered in a 10-15 minute session under a heat lamp or infrared sauna”. The letter cited a peer-reviewed and published journal article that supported the claim that materials similar to Celliant – containing ceramic microfibers – could emit FIR. We noted that the academic in question sat as an advisor on Hologenix’s Scientific Advisory Board and so was not independent of the organisation. Moreover, we noted that the letter did not relate specifically to the product advertised.

We also considered the US patent filings for Celliant provided by Hologenix. We noted that the filings, in and of themselves, did not provide any information showing that Celliant could absorb and re-emit IR radiation. Under Armour believed the IR, that they maintained was emitted by Celliant, could increase oxygenation and blood flow. Hologenix said that the main test for this was the transcutaneous partial pressure of oxygen (tcPO2), a measure of tissue oxygenation, and that products must increase tcPO2 by 7% in order for them to be cleared for production. Under Armour and Hologenix provided six papers in support of that hypothesis. Two papers were unpublished, internal test reports. Two of the studies related to the use of Celliant on the bicep and upper torso. Both studies used methodologies that took measurements pertaining to tcPO2 while the subjects were at rest and then compared tcPO2 levels in a garment made with Celliant and a garment with no Celliant present. Neither of the studies had been peer-reviewed.

The third study related to the application of Celliant to the foot. We noted that Under Armour’s clothing range did not include footwear. The fourth was a published version of one of the other studies. In the published version, Celliant clothing was used in a single-blind controlled study of 153 subjects. The study found an increase in tcPO2 levels of between 8.2 and 8.8% when measured at various intervals and in comparison with clothing that did not contain Celliant. We noted that the study methodology involved participants who were at rest while wearing the clothing. We also noted that Under Armour’s clothing was clearly intended to be worn post-exercise rather than at rest. The paper explicitly stated that subjects were only allowed to “read or play video games but not sleep or converse” during the study.

We reviewed the studies provided that related to the proposition that IR-stimulated increase in blood flow and oxygenation can have positive health effects, in support of the claim made in the ad. Five of the studies provided related to clinical trials involving animals. One related to muscle strength in dogs, the others to in vivo and in vitro studies in rats and amphibians. In the absence of supporting evidence showing their relevance, we did not think studies involving animals rather than people were sufficient to support the ad’s claims. A further study on protein synthesis and muscle repair used a sample of five men with a median age of 24 years. The study concluded that, as long as muscle synthesis after exercise outweighed muscle breakdown, this would result in net muscle growth. The study said this was due to an increase in blood flow, transporting more amino acids to muscle, rather than because of an increase in amino acid in the blood. Under Armour said this study was merely illustrative and showed that an increase in tcPO2 would lead to post-exercise muscle growth and repair. Hologenix also cited it in their evidence as substantiation for the ability of increased tcPO2 to aid muscle repair. We considered that a sample size of five male participants was unlikely to be representative of Under Armours target market.

Hologenix provided a further six studies that specifically related to the physiological benefits the IR radiation emitted by Celliant-containing items. One study related to the use of Celliant in socks to relieve diabetes-related chronic foot pain. We noted that it did not relate to the use of Celliant in muscle repair. Another, unpublished, study related to the use of Celliant in mattresses to help with back pain. We noted that this study also did not relate to clothing or muscle repair. We found this also to be the case with the third study, since its primary focus was bedsheets. The fourth study involved the use of Celliant-containing clothing by 12 male cyclists whose oxygen uptake was measured at different intensities of exercise. We noted that the subject of the ad was sleepwear, and that the subjects in the study were all male, which was not representative of Under Armour’s consumer base. The final two studies provided by Hologenix related to FIR emitting clothing but not specifically to Celliant-containing clothing.

As well as the studies provided by Under Armour and Hologenix we noted that the  aforementioned academic letter stated there was no generally accepted explanation as to why IR produced effects such as better recovery post-exercise and that those effects had only been observed as ‘measurable changes’. The letter concluded that “[f]urther study is needed to better define the precise physiological changes occurring after FIR therapy”. Under Armour provided a literature review suggesting an increase in blood flow promoted lactate uptake in skeletal muscle, thus preventing lactic acidosis. We understood that ‘lactic acidosis’ referred to a build-up of lactic acid in the blood and that this could lead to nausea and vomiting. The study took a comprehensive and detailed look at the literature on the subject. We acknowledged Under Armour’s comments that the contents of the review was considered to be established by the scientific community and understood that this was generally accepted.

A study provided by Under Armour related to the concentration of lactate in the blood after exercise and the synthesis of protein after exercise. Under Armour felt that the study was significant since it showed that an increase in tcPO2 could help decrease post-exercise lactic acid levels in muscles, and aid muscle repair through protein synthesis. We noted that the study looked at blood lactate concentration following activity during passive rest – sitting – and active rest – cycling at low velocity. The study concluded that the impact of heat on blood lactate concentration was significantly more noticeable during active rather than passive rest. However, we noted that Under Armour’s clothing range was intended to be used as sleepwear rather than active wear and that the study did not relate specifically to Celliant-containing clothing.

We concluded that the body of evidence presented by Under Armour and Hologenix had a number of deficiencies. While some of the arguments put forward involved uncontroversial statements about settled areas of science – for example, that increased blood flow helps in the removal of lactic acid from the blood – the level of uncertainty about both the mechanism of IR in post-exercise recovery, and the clear need for further study on the health benefits of IR on the body meant that the role of IR in this area was some way from settled scientific fact. Additionally, while some of the studies related to Celliant-containing clothing, the majority did not, and the majority of those that did relate to Celliant did not accurately mirror the conditions under which the clothing would generally be used by consumers, or the type of consumers at whom the garments were targeted.

We therefore concluded that because the body of evidence provided had not sufficiently evidenced the claim that the clothing could aid in muscle repair after exercise, the claims were unsubstantiated and misleading.

The ad breached the CAP Code (Edition 12) rules 3.1 (Misleading advertising), 3.7 (substantiation), and 12.1 (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 to ensure, in the absence of sufficiently robust supporting documentation, that future ads did not claim that their Athlete Recovery Sleepwear containing Celliant could speed up muscle recovery after exercise.

CAP Code (Edition 12)

3.1     3.7     12.1    

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