Danny Colaprico was hurting.
It was 2019, and the 27-year-old midfielder realized that a career in soccer was starting to catch up to her body.
She was introduced to CBD by some of her Chicago Red Stars teammates, and though she was skeptical, she decided to give it a try.
"As it kept growing and CBD got more and more popular, a lot of players in our league started using it," Colaprico told ESPN. "And in my head, I was like, 'OK, I may as well try it out.'"
But what are athletes actually putting in or on their bodies?
CBD, short for cannabidiol, is the chemical compound strain of cannabis that can be derived from the hemp or cannabis plant. It has been around for centuries but was not isolated from the plant -- from what causes the "high" -- until 1940 by a team from the University of Illinois. Then, in 2014, the Farm Bill was signed, allowing "institutions of higher education and state agriculture departments to start industrial hemp research and cultivation."
The past few years, CBD has often been touted as a cure-all of sorts. Manufacturers and users claim, mostly anecdotally, that it has given them relief from muscle soreness and swelling and helped curb stress and anxiety. What is actually known or proven by clinical trials is very little.
Hemp-based CBD is legal -- in various forms from ingestible oils to topicals -- in all but three states in the U.S. and is legal at the federal level. States have their own rules restricting or allowing CBD products to be sold, and in many states, CBD can be sold over the counter in drug stores. It remains unregulated by the Federal Drug Administration, however.
Colaprico is allowed to use CBD in the NWSL, but it is currently prohibited in the NFL, NBA, MLB and NHL. In February, MLB and the MLB Players Association announced that they "are working closely with NSF International to develop an independent testing and certification process for" hemp-based CBD products.
The NBA has also expressed interest in revising its bylaws against CBD use. In 2018, CBD was removed from the World Anti-Doping Agency's banned substances list.
Restrictions aside, CBD business is booming. A marketing report released in September found that the global market for CBD oil should grow from $967.2 million in 2020 to $5.3 billion by 2025. That is without CBD brands being allowed to directly advertise their products on social media.
Aaron Keay, chairman of The Alkaline Water Co., thinks the timing is right for athlete endorsements. In May, his company launched a new ingestible CBD product line, including CBD-water, capsules, tinctures and gummies.
"[I]f you look at the kind of the athlete adoption of it, it kind of coincides with how the world is taking it on and looking at it. But you have a few movers and shakers that are willing to take the risk and say: 'Look, CBD is going to become mainstream way ahead of cannabis and THC,'" Keay told ESPN.
It's certainly a business decision on some ends -- for example, Dwyane Wade openly promotes Alkaline's water -- but for others, it is also a health decision.
After nearly two decades on the soccer pitch, Colaprico had a lot of chronic pain, she said. She became more open to trying new ways for her body to recover better and more quickly. CBD, she asserts, became that for her -- and more.
"There are three very useful or beneficial sides to it for an athlete. No. 1, it is a potent anti-inflammatory. No. 2, it helps with sleep. And No. 3, there are lots of reports that show that it helps with anxiety," Dr. Ara Suppiah, a functional sports medicine expert who works with professional athletes, told ESPN.
Because cannabinoids fall under a group of products called adaptogens -- think of herbs such as ashwagandha, Rhodiola and ginseng -- they are able to give users the same benefits, Suppiah said. (Adaptogens, some research suggests, help your body deal with stress and have become more popular in recent years.)
Suppiah is PGA player Bubba Watson's doctor and has been vocal in encouraging the golfer to use CBD to alleviate the trouble he has sleeping before a final round.
"So for an athlete, if you're looking for the ability to recover and perform over and over again, it is a useful tool in the toolbox," Suppiah said.
That rings true for Colaprico, who says she can also feel the benefits of CBD on her high levels of stress and anxiety.
All of these claimed benefits come with cautions, especially because there is very little scientific evidence to back the purported advantages of CBD. The FDA lists a handful of potential harms, side effects and unknowns about CBD and believes that "[s]ome CBD products are being marketed with unproven medical claims and are of unknown quality."
But because much is still unknown about how CBD is delivered to the brain and how much of what is in the product goes elsewhere in the body, critics are concerned. For instance, the absorption and processing of CBD by a 12-year-old athlete and a 200-pound professional athlete are likely to be different.
"The FDA has seen only limited data about CBD safety, and these data point to real risks that need to be considered before taking CBD for any reason," the agency said in November.
Dr. Krista Lisdahl, the director of the University of Wisconsin-Milwaukee's Brain Imaging and Neuropsychology Laboratory, says she cannot recommend CBD usage to anyone for any of the issues its makers and sellers claim that it can address.
That, she told ESPN, is because of the lack of clinical trials that prove -- or disprove -- benefits and potential side effects. So far, in an evaluation study of CBD as a dietary supplement, there has been only evidence proving that CBD has anti-inflammatory properties in animals, with "some human evidence that it can reduce some of that inflammation."
"There needs to be more large-scale clinical trials where we can confirm that CBD is, in fact, effective." Dr. Krista Lisdahl
"There needs to be more large-scale clinical trials where we can confirm that CBD is, in fact, effective. So, for example, there have been a couple of clinical trials where we use a placebo-controlled, double-blinded design, where people are getting CBD or getting a placebo and they don't know which one they get, and then you actually test the effects of CBD on sleep in an objective way," said Lisdahl, who studies the neuroscience of addiction and drug effects. "Those studies have not found a significant effect on sleep and on healthy people."
Right now, the scientific evidence for sleep is only low-level, suggesting that CBD might increase sleepiness or decrease the time it takes for a person to fall asleep, she explained.
Further, there is no "direct evidence" in athletes to suggest that CBD helps muscle recovery and sport performance, Lisdahl said. Athletes who claim those benefits are promoting their "objective experience," she said, something that is neither proven nor disproven by science.
Those in the CBD industry hope that FDA approval will come sooner rather than later, especially because in 2018, the agency approved a prescription form of CBD for the treatment of two rare and severe forms of epilepsy. In late July, the FDA approved CBD for use in treating another seizure disorder, tuberous sclerosis complex.
If that approval happens, the industry's relationship with sports is bound to grow.
"[I]t'll probably get the stamp from the FDA and lawmakers, I'm guessing maybe within this election year or within the calendar year. I think you'll really start to see movement there, and that's why the athletes are starting to come out and get way more supportive than they ever were," Keay told ESPN.
The FDA in March said that it had "embarked on a comprehensive evaluation of [CBD] products, with a focus on educating the public about the risks and unknowns of these products, gathering the science needed to better understand both these safety concerns and potential benefits to inform our regulatory approach."
The FDA went on to state that it "recognize[s] the significant public interest in CBD and we must work together with stakeholders and industry to develop high-quality data to close the substantial knowledge gaps about the science, safety, and quality of many of these products."
Jay Hartenbach, the CEO of Medterra CBD, has found a handful of athlete endorsers, who are listed on the company's website, for his products outside of mainstream sports, such as surfers, cyclists and volleyball players. He says he has seen growth in three years that he "can't imagine" in another industry.
"The professional athletes, for us, are twofold: One, to just get general awareness and two, it's to show the league: 'Your athletes are supporting it. Why are you holding this back from your players?'" he said.
The endorsements and claims are appealing, especially for someone seeking pain relief or a restful night's sleep. But the message from those outside the CBD industry? Athlete recommendations do not trump medical ones.
Lisdahl told ESPN that she understands why CBD is "attractive" both to use and to promote.
"CBD is considered safe for the most part. People aren't going to experience a lot of negative side effects," she said. "So I could certainly see why people would try it. It is relatively cheap compared to the other interventions available to them."
But there are other proven treatments to help with muscle soreness, inflammation, stress and anxiety and to help athletes sleep better, she said.
"I personally wouldn't recommend CBD for any indications right now because it's not passing any of the clinical trials," Lisdahl said.