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Professional athletes in sports ranging from football to bicycling to long-distance running are increasingly using cannabis to reduce their pain from post-game injuries and help them recover more quickly.

However, despite the many anecdotal reports of the purported benefits of cannabis, empirical evidence is scant.

The National Football League (NFL) is hoping to change that by funding a novel clinical trial that will assess the therapeutic efficacy, as well as any possible adverse effects, of delta-9-tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis; cannabidiol (CBD), the second most prevalent active ingredient in cannabis but not psychoactive; and a combination of the 2 for treating post-competition pain caused by soft tissue injury compared with placebo.

The investigators hypothesize that:

• THC and the THC/CBD combination will prove superior to CBD and placebo for pain reduction
• CBD alone will prove superior to placebo

“Real-World Model”

The randomized, double-blind trial will involve testing and monitoring of professional rugby players. This sport was chosen for the first trial because the types of injuries experienced by professional rugby players approximate the injuries experienced by NFL players.

“An innovation of this research is using a ‘real-world model’ of the NFL’s competitive injury burden with a group of elite athletes who experience similar injuries,” said Thomas Marcotte, PhD, one of the co-principal investigators. He is a professor of psychiatry at University of California School of Medicine and co-director of the Center for Medicinal Cannabis Research (CMCR) at UC San Diego.

“It’s a first-of-its-kind randomized trial to examine the possible practical efficacy of cannabinoids on post-competition pain.”

4 Study Groups

The primary goal of the trial will be to evaluate pain relief and recovery. Secondary goals include assessment of any effects on physical function, sleep, cognition, and mood.

Participating athletes who report post-game pain that meets a specific threshold will have a blood sample drawn. They will then be assigned to vaporize 1 of the following up to 4 times per day over the course of 48 hours:

• 4% THC
• 12% CBD
• A combination of THC and CBD at those percentages
• Placebo

Participants will also be asked to self-report pain scores via a cell phone application at regular intervals during those 48 hours. A second blood draw will be taken the day after each game.

Therapeutic Window of Analgesia

Cannabis has been used for medical purposes for centuries around the world. Increasingly, there are efforts to develop and promote it as a safer pharmacological alternative to other forms of pain relief and there is some scientific research suggesting that THC is effective in relieving certain types of pain.

Co-principal investigator Mark Wallace, MD, has integrated the use of medical cannabis into clinical practice. He is a pain management specialist and director of the Center for Pain Medicine at UC San Diego Health, as well as a professor of anesthesiology and chief of the Division of Pain Medicine at UC San Diego School of Medicine.

“Much of the knowledge we used for dosing medical cannabis in our pain clinic came from the studies supported by CMCR, which showed there is a therapeutic window of analgesia, with low doses of THC reducing pain and high doses worsening pain,” he said.

“We will build on the CMCR research and our clinical experience to translate efficacy and safety for sports injury recovery.”

The trial will be conducted following regulatory reviews by the US Food and Drug Administration, the Drug Enforcement Administration, the UC San Diego Institutional Review Board, and the Research Advisory Panel of California.