What Are the Red Circles on Athletes?

Those distinctive red or purple circles you see on the shoulders, backs, and legs of Olympic swimmers, basketball players, and MMA fighters are marks left by cupping therapy, an ancient practice that uses suction cups to pull the skin and underlying tissue upward. The marks look alarming but are essentially bruises created on purpose. Cupping gained massive global attention when swimmer Michael Phelps appeared at the 2016 Rio Olympics covered in circular welts, triggering what one review described as a 2,100% spike in Google searches for the therapy that year.¹ The practice has been around for thousands of years, but the science behind whether it actually helps athletic performance is still catching up to the enthusiasm.

How Cupping Creates the Marks

A cupping session involves placing glass, silicone, or plastic cups on the skin and creating negative pressure inside them, either by heating the air (traditional fire cupping) or using a hand pump or valve. That suction pulls the skin and the soft tissue underneath upward into the cup. The negative pressure stretches the skin, dilates the tiny blood vessels beneath it, and eventually ruptures capillaries, producing the circular bruise-like discoloration that doctors call ecchymosis.² The color ranges from light pink to deep purple depending on the amount of suction, how long the cups stay on, and individual factors like skin tone and blood flow in the area.

The marks typically fade within a few days to two weeks. They are not burns or scars; the skin itself is not broken in standard dry cupping. Think of it as a bruise that was produced by pulling rather than by impact. The pattern is always circular because the rim of the cup defines the border of the suction zone.

Why Athletes Choose Cupping

Athletes reach for cupping primarily as a recovery tool. The goals are familiar to anyone who has dealt with sore muscles after hard training: reduce stiffness, manage pain between sessions, and speed up the turnaround between competition days. In sports-medicine settings, practitioners often call the technique “myofascial decompression” to distinguish it from traditional Chinese medicine framing. The idea is that suction lifts and separates layers of fascia and muscle, counteracting the compression that comes from massage, foam rolling, and the training itself.³

Several proposed mechanisms get discussed in the research literature. One is that the suction increases local blood flow, which could help clear metabolic waste products from fatigued muscles. Another is that the controlled tissue damage from cupping activates the body’s healing response in the area. A third explanation draws on pain-gate theory, the idea that a new sensory stimulus (the pulling sensation of the cup) can temporarily override pain signals traveling from sore muscles to the brain.⁴ None of these mechanisms are fully confirmed. They are plausible stories that fit some of the data, not settled science.

Does Cupping Actually Help Recovery?

The honest answer is that the evidence is mixed and often frustratingly thin. A systematic review of randomized controlled trials on cupping in athletes found that cupping was reported as beneficial for perceptions of pain and disability, increased range of motion, and reductions in a muscle-damage marker called creatine kinase, but mostly when compared to groups that received no treatment at all. The majority of those trials had unclear or high risk of bias, and none reported on safety.⁵ That distinction matters a lot. Beating “doing nothing” is a low bar, because the act of lying down and receiving any hands-on treatment can improve how someone feels.

When researchers have compared cupping to sham cupping (cups placed on the skin with little or no actual suction), the picture changes. A meta-analysis of 18 trials covering over a thousand patients with chronic pain found large short-term pain reductions compared to no treatment, but no significant difference when cupping was stacked against the sham version.⁶ That is the result you would expect if the benefit were largely driven by placebo and the ritual of treatment rather than the suction itself.

Not all findings are negative, though. One study on biceps fatigue found no immediate effect from cupping, but a significant delayed improvement in recovery measures 24 hours later compared to a sham treatment.⁷ Another study found that 10 minutes of cupping at higher suction reduced deep-layer muscle stiffness in the triceps more effectively than a shorter session, suggesting that the “dose” of cupping matters and that the effects may be real but depend on getting the parameters right.⁸ These are small studies, though, and they need replication before anyone should treat them as proof.

The Problem with Blinding

One of the biggest obstacles to figuring out whether cupping works is that it is extremely hard to fake. A good clinical trial compares the real treatment to a convincing placebo so that participants do not know which group they are in. With cupping, you can feel the suction pulling on your skin and you can see the marks afterward. Researchers have developed sham cupping devices where the cups have tiny holes drilled in them so the negative pressure releases within seconds, and the cups are taped in place to mimic the sensation of being held by suction.⁹ Participants in both groups are told that the suction sensation may fade quickly because the skin adapts. It is a clever workaround, but it is not perfect. Many participants can probably tell whether they are being strongly suctioned or not, especially athletes who have experienced real cupping before.

This blinding problem is not unique to cupping. Acupuncture, massage, and chiropractic manipulation all face the same challenge. It does mean, however, that any study showing cupping beats “no treatment” should be taken with a grain of salt. The relevant question is whether cupping beats a convincing fake version of itself, and on that score the data so far is underwhelming for pain but slightly more promising for specific recovery measures like muscle stiffness and delayed fatigue.

Cupping and Inflammation After Exercise

One line of research looks not at how athletes feel but at what is happening in their blood. A pilot study on martial arts athletes measured inflammatory markers before and after vigorous exercise, comparing sessions with and without cupping beforehand. Athletes who received cupping showed lower levels of two key inflammatory proteins immediately and 30 minutes after the cupping intervention. In the exercise-only group, those same markers spiked after training, as expected. Even in the group that received both cupping and exercise, certain inflammatory markers still rose, but the overall pattern suggested that cupping blunted the inflammatory response to hard training.¹⁰

This is interesting but far from conclusive. It was a small pilot study, and a lower inflammatory response is not automatically a good thing. Inflammation after exercise is part of how muscles repair and adapt. Blocking it entirely, the way some anti-inflammatory drugs can, may actually slow down long-term training adaptations. Whether cupping’s apparent dampening of inflammation helps or hinders athletic development over time is a question nobody has answered yet.

Cupping for Chronic Pain Beyond Sports

Athletes get the headlines, but a larger body of cupping research involves people with chronic musculoskeletal pain. An evidence-mapping study found that the best available evidence supports cupping for neck pain, low back pain, and knee osteoarthritis, though most of that evidence ranged from moderate to very low quality.¹¹ A separate systematic review focused specifically on neck pain found that cupping significantly reduced pain and improved function compared to both no-intervention groups and active-treatment groups, with patients also reporting better quality of life.¹²

These findings are more encouraging than the athlete-specific trials, possibly because chronic pain patients have more room for improvement or because pain perception is especially responsive to hands-on therapies. But the same blinding issues apply, and many of these trials were small or had methodological weaknesses. The overall picture for cupping and chronic pain is “probably helpful, hard to say how much of that is placebo.”

Dry Cupping vs. Wet Cupping

What athletes typically use is dry cupping: cups applied to intact skin with suction only. Wet cupping, also known as hijama in Arabic medical traditions, adds a step. The practitioner makes small superficial incisions or punctures in the skin before applying the cup, and the suction draws out a small amount of blood. Dry cupping itself encompasses several sub-types, including slide cupping (where oiled cups are moved across the skin like a massage), fire cupping (where flame is used to heat the air inside a glass cup before placement), and pull cupping (standard stationary cup placement).¹³

In elite sports, dry cupping dominates. Wet cupping raises hygiene and infection concerns that make it impractical in most athletic training rooms, and the additional skin trauma would be counterproductive for athletes who need to train the next day. Silicone cups and pump-valve plastic cups are the most common tools in Western sports-medicine practice because they allow precise control over suction pressure without the risks of open flame.

Safety and Side Effects

For dry cupping, the side-effect profile is relatively mild. The marks themselves are the most obvious consequence, and some practitioners argue they should not even count as an adverse event since they are an expected and intentional result of the treatment. A review of systematic reviews found that the most commonly reported adverse events were bruising, increased pain at the site, and occasionally burns from fire cupping or blisters from excessive suction.¹⁴ A systematic review of adverse events from cupping studies in Korea reported that anemia was the most frequently observed problem in observational studies, though this was linked to wet cupping performed repeatedly over time. Herpes viral infections were also reported in a small number of cases. Across randomized trials, adverse events were infrequent.¹⁵

The real safety concern with wet cupping is infection. A case report documented a disseminated bacterial infection after scarification wet cupping, even in a person with a healthy immune system. The authors emphasized that high hygiene standards are essential for any cupping practice, particularly when the skin barrier is broken.¹⁶ For athletes, the practical takeaway is that dry cupping from a trained practitioner using clean equipment carries low risk, while wet cupping introduces infection risk that most sports-medicine professionals consider unnecessary.

How Cupping Compares to Other Recovery Tools

Athletes have no shortage of recovery options: foam rolling, massage guns, compression garments, ice baths, and more. How does cupping stack up? One study compared cupping (referred to as myofascial decompression) head-to-head with self-myofascial release using a foam roller for hamstring problems. Both treatments improved passive range of motion and subjective flexibility scores after a single session. However, patients in the cupping group reported feeling a greater perceived benefit.³ That gap between similar objective outcomes and stronger subjective improvement is a recurring theme in cupping research. Athletes consistently feel better about the treatment than the measurable differences would predict.

This is not necessarily a knock against cupping. In competitive sports, confidence and perceived readiness matter. If an athlete believes they have recovered well and feels less stiff going into a competition, that psychological edge can translate into real performance gains. The placebo effect is sometimes dismissed as “not real,” but in the context of athletic competition, feeling recovered and feeling confident are functional advantages regardless of the mechanism producing them.

What the Mark Color Tells You (and Does Not)

In traditional Chinese medicine, practitioners have long interpreted the color of cupping marks as diagnostic information, with darker marks supposedly indicating areas of greater stagnation or pathology. Modern research suggests this interpretation is mostly wrong. A cross-sectional study found that the two factors most strongly associated with cupping mark color were sex and health status: women tended to have lighter marks than men, and people with fibromyalgia had lighter marks than healthy volunteers. Factors like body-mass index, age, and traditional Chinese medicine constitution type were not associated with mark color.¹⁷ So the darkness of a mark has more to do with individual biology than with how “sick” or “tight” the underlying tissue is. Athletes with more vascularized or thinner skin tend to mark more dramatically. A deep purple circle does not mean the muscle underneath is more damaged.

Why Cupping Remains Popular Despite Weak Evidence

Walk through the training room of any professional sports team and you will find cupping kits alongside ice baths and massage tables. The persistence of cupping in elite athletics, despite evidence that is at best inconclusive, probably comes down to a few factors. First, the treatment feels like something is happening. The strong suction sensation and the visible marks afterward give athletes a tangible sense that their body has been worked on. Second, the risks are genuinely low for dry cupping. Unlike anti-inflammatory drugs, which can interfere with muscle adaptation and carry gastrointestinal side effects with repeated use, cupping’s worst-case scenario for most athletes is an ugly bruise. Third, elite athletes are willing to try anything that might give them even a marginal edge. When you are competing at a level where hundredths of a second separate gold from silver, a treatment that helps even slightly, or that improves your mental state before competition, has value.

Cupping also benefits from the halo effect of celebrity endorsement. After 2016, the therapy was no longer an obscure alternative practice; it was something the most decorated Olympian in history was visibly using. That association with elite performance is more persuasive to most athletes than any systematic review. Whether the science eventually catches up to the enthusiasm or reveals the whole thing to be an elaborate placebo wrapped in tradition, those red circles are not going away from competitive sports anytime soon.

Cupping Duration and Pressure Dosing

One reason the evidence on cupping is so inconsistent may be that studies use wildly different protocols. How long the cups stay on and how much suction is applied varies enormously, and these parameters likely matter. Research on triceps stiffness found that 10 minutes of cupping at higher negative pressure was significantly more effective at reducing deep-layer muscle stiffness than a 5-minute session, providing the first evidence that cupping has a dose-response relationship.⁸ The deep layers of muscle also responded more than the superficial layers, suggesting that the effects are not just skin-deep. Until standardized dosing guidelines exist, comparing one cupping study to another is a bit like comparing a study that gave patients half a pill to one that gave them four pills and wondering why the results are different. If cupping does have a real physiological effect beyond placebo, nailing down the right pressure and duration for specific muscle groups is probably the key to finding it.