Here comes the science bit, Mr Djokovic
Does germanium and charcoal in your knee sleeve help healing?
This is a departure from the usual topics of this blog—it’s only incidentally about people getting worked up on social media (though there’s a bit of that)—but I found the topic irresistible.
Exciting tennis star/product news! On Thursday August 21, PRNewswire had an announcement:
24-time Grand Slam champion and Olympic gold medalist Novak Djokovic has acquired a significant stake in Incrediwear, the leader in bioactive infrared fabric technology, together marking a powerful new chapter in the future of athletic recovery and performance.
Djokovic discovered Incrediwear following his 2024 knee surgery and believes the company's wearable technology played a role in his recovery. "I'm always looking for ways to support my performance and shorten recovery time," said Djokovic.
The surgery was for a torn meniscus in his right knee, which Djokovic suffered when playing in the French Open in Paris. It prevented him continuing in the event, and he had to withdraw in the quarterfinals. Lots of people thought he wouldn’t be back on the circuit for ages; Djokovic, as he so often does, proved them wrong. He was back playing at Wimbledon within a few weeks, and reached the final, only losing to Carlos Alcaraz.
While playing there, and in quite a few tournaments since, Djokovic wore a distinctive grey-and-white elasticated sleeve on his knee. It was obviously meant to stabilise his knee against the incredible sideways forces that tennis imposes on the limbs during side-to-side rallies, particularly when pushing out of corners after hitting a shot.
Not surprising: lots of pro players wear stabilising sleeves on various parts of their body while they’re coping with injuries. They act as shock absorbers and can control inflammation (aka “effusion”, fluid collecting around injuries).
Anyway! Here we are just over a year later and Djokovic is taking a “significant” stake in the company. So what is Incrediwear’s USP? What is this “bioactive infrared fabric technology”? From the press release:
Incrediwear's clinically proven, element-infused fabric is activated by body heat to deliver infrared and negative ion therapy, accelerating recovery without drugs, compression, or side effects.
Not surprised about the drugs bit. Though it’s interesting to see a sleeve saying it doesn’t compress. Side effects, well, did we expect any?
That phrase “clinically proven” jumped out at me, though. Incrediwear says that its sleeves contain germanium—famously used in transistors because it’s a semiconductor—and charcoal. “WEARABLE ANTI-INFLAMMATORY THERAPY”, says the website. “PATENTED TECHNOLOGY”.
The company does indeed have patents. Here’s what one claims in part to do:
[consists of] a combination of at least three components including:
a first material comprising a plurality of fibers;
a plurality of semiconductor nanoparticles compounded with the fibers and a plurality of charcoal nanoparticles compounded with the fibers;
the semiconductor nanoparticles configured to release negative ions and the charcoal nanoparticles configured to release infrared rays;
the expanse configured to initiate a transdermal effect from body heat in the region having the wound causing the semiconductor nanoparticles to release the negative ions and the charcoal nanoparticles to release the infrared rays onto the wound.
I think by “wound” they are including “region which hurts”. There’s a lot more in the patent, which would be too long to excerpt here, but is very entertaining if you like phrases such as “Upon contact with that, the apparel causes the cellular movement to occur at a second rate that is greater than the first rate.” Cellular movement, eh.
I then wondered what the “clinically proven” bit would look like. If you dig around the Incrediwear site for a bit, you find the Research page. This, mirabile dictu, has links to three studies. Real studies! Maybe this is where the clinical proof will emerge. Let’s look at them.
Study 1
The first study is titled Effect Of Germanium-Embedded Knee Sleeve On Osteoarthritis Of The Knee. It used Incrediwear sleeves in the treatment of knee osteoarthritis in 46 outpatients at a London hospital. To qualify, they had to have had knee pain for six months.
If you’re familiar with scientific experiments, you’ll already know how you’d design this. Split the patients into three groups. One group gets no knee sleeve. One group gets an ordinary knee sleeve. One group gets an Incrediwear knee sleeve. Obviously the people without a knee sleeve know they don’t have one, but in the other two groups you try to disguise the sleeve (or tell the patients it’s not important). You randomly pick which patient gets a sleeve, and ideally you don’t let those handing out the sleeves know, nor do you let those assessing them know. The latter comprises a double-blind (neither patient nor doctor knows which they have) randomised (you handed them out randomly) trial with a control group. DB-RCT, double blind randomised controlled trial. (You may know them from hits such as Covid vaccines.)
Then you assess the outcome: how much have those without sleeves improved, if at all, compared to the ordinary sleeves and the germanium-infused ones? If the improvement is significantly larger for one group than another (“statistically significant”), you’ve found an effect.
So what did this trial do?
All participants were given the same model of knee sleeve, varying in sizes (M to XXL) as required.
That’s… not how you design a study that will tell you if your technology works. It might tell you if knee sleeves work—except there’s no control group without sleeves. So it’s not blinded (to patients or doctors), not random, and doesn’t have a control group. Still, it’s a trial.
Even so, the paper brightly concludes:
This is the first study to assess the outcomes of GE knee sleeves in patients with knee OA. Our results confirm that GE knee sleeves could play an important role in managing patients with knee OA, as demonstrated by the clinically significant improvements in OKS, VAS, and Lysholm scores.
Well, they could. But we don’t know if some of the improvement was just patients getting better; nor whether it was just that wearing any knee sleeve, rather than a germanium/charcoal infused one, reduces the pain of knee OA. I wonder if “clinically tested” might be a better phrase than “clinically proven” here?
Study 2
On to the second study: Non-Compressive Sleeves Versus Compression Stockings After Total Knee Arthroplasty: A Prospective Pilot Study. This compared non-compressive sleeves v compressive stockings for 55 people who have just had total knee replacements. (Yikes.) Once again, there’s no “nothing at all” group; one group wore compressive stockings on both legs (primary aim being to protect against deep vein thrombosis), the other group had Incrediwear on the leg/knee that had been operated on, and a compressive stocking on the other (untroubled) leg.
There was one definite clinical outcome:
At week 3, when compared to pre-op, Incrediwear subjects experienced a 19% decrease in effusion [fluid retention around the operation site] while controls experienced a 35% increase in effusion. This change was statistically significant (p = .003).
That change is indeed very significant—about 10 times greater than you’d need for it to count. The Incrediwear patients also had greater range of motion in the operated knee—which would make sense, as they had less effusion. The paper says hopefully
This change approached statistical significance (p = .07)
Which means: this change wasn’t statistically significant. (p=0.05 is the standard requirement for significance, ie the level at which you say you’ve found something that is out of the ordinary.) The conclusions note that “This study has several limitations” and that a followup could do some things better, such as
To assess the impact of Incrediwear's therapeutic semiconductor technology, sham sleeves without semiconductor elements could serve as a control.
Radical idea! So once again we don’t know whether it’s the chemicals in the Incrediwear sleeve, or just the fact of it being a sleeve that has made the difference.
Study 3
The third study is Combined Rehabilitation Protocol In The Treatment Of Osteoarthritis Of The Knee: Comparative Study Of Extremely Low-Frequency Magnetic Fields And Soft Elastic Knee Brace Effect. This one is a bit weird. There are lots of medics who are prepared to try any sort of treatment to see if it might, by some unknown mechanism, turn out to have a positive effect. Thus it turns out to be with the nine Italian and one Swiss researchers on this one, who are using low-frequency magnetic fields to treat knee OA. Wacky idea, but who knows? If it works, it works.
This study had, surprise!, a control group: one with the Incrediwear knee brace/sleeve, one without, and both getting low-intensity, low-frequency magnetic fields zapped into their OA-affected knee. According to the paper, “Magnetotherapy provides a non-invasive, safe, and easy method to directly treat the site of injury, the source of pain and inflammation, and it is widely used in rehabilitation in OA”. This is news to me, so TIL.
My reading of the results is that those with the knee sleeve (who also wore it during the magnetotherapy) had less pain when at rest, at a statistically significant rate. For other measures—pain when in motion, and other self-reported scores—there wasn’t a statistically significant difference. The study authors offered a hypothesis for how the observed benefit might happen:
The use of the Incred knee brace was based on the assumption that embedding germanium into cotton garments could improve the transdermal effect to create a microelectromagnetic field, leading to increased circulation and affecting the inflammatory process.
Well, maybe. The study authors also let slip a rather significant fact:
Lee et al. [44] showed that knee braces positively affect the patient’s quality of life and, as per NICE guidelines for the conservative management of KOA [knee osteoarthritis], should be used in combination with other standard treatments.
That Lee et al study is from 2017, and found that in the short term, a knee brace (or perhaps sleeve) is cost-effective over immediate knee replacement. So you don’t need to have germanium and charcoal infusions in your sleeve to get some benefits if you’ve got knee OA. In considering how future studies could build on their results, they suggest
A study that considers the inclusion of a third group treated only with the soft knee brace would be particularly desirable.
Could I suggest a third group which has a standard knee sleeve/brace, to be compared against a group with an Incrediwear one? That would be really helpful.
All of which means..
Does the inclusion of germanium and charcoal in Incrediwear’s sleeves make a difference to pain management and healing? I’d love to say we have an answer, but we don’t. None of these three studies tells us, because none is designed in a way that would answer the question. Certainly it seems to reduce effusion if you’ve had a total knee replacement. Wearing one also seems to lead to less pain in the knee than not wearing one if you’re having magnetotherapy—but wearing a knee sleeve of any sort is also good at reducing pain.
To get to the social warming bit of this, it should be noted that Novak Djokovic has an absolutely rabid fanbase on social media. For them, nothing he does can possibly be wrong, and anything that any other player does which impinges on him (or doesn’t) is almost certainly wrong.
So when I expressed doubt about how and whether the sleeves worked because of the infused elements, I got, well, some reactions.
Policing what people say about Djokovic really is a large part of some people’s online lives. One wonders what they’ll do when he actually does hang up his rackets for good. Probably just police what people say about his modern comparators: it’s a game they can’t lose, and which never has to end.
But look, for all the critiques I’ve done above, maybe there’s a better explanation in Incrediwear’s own video?
Ah, well, maybe not.
Yet for all that, I’d say it’s almost certain that Incrediwear’s sales are going to rocket in the near future. Being able to put Djokovic’s face on sales material is a huge selling point; and tennis player and other athletes are always in need of sleeves to get them past an injury. The Incrediwear sleeves also look fairly nice, though the prices—£45.95 for an elbow sleeve—are a bit steep compared to the £9 I paid a while back for an elbow sleeve from Amazon.
To finish (m’lud), let me be quite clear what I am, and am not saying.
• I am not saying that Novak Djokovic is trying to deceive the public or potential investors. I’m certain he derived benefit from using an Incrediwear knee sleeve.
• I am not saying that Incrediwear is trying to deceive the public or potential investors. People have derived benefits from using its knee sleeves.
• I am saying that the studies don’t—and can’t—tell us whether the inclusion of germanium and charcoal (aka carbon) in the sleeves makes any difference to the healing or pain relief. It would be great to see some which did. But at the time of writing, there are only the three studies on PubMed.
I’m sure, though, that Incrediwear won’t let it rest there. There must be other studies in the pipeline. Mustn’t there?
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Cue outrage from people with very high opinions of their own opinions and too much time on their hands ...