Josiah Hesse, a journalist who lives in Colorado, never voluntarily exercised a day in his life until he turned 30, when he decided to start doing it for health reasons. But right away, he hated working out.

“When I first started running, I couldn’t run a single block,” he said. “It hurt and my lungs burned.”

Then one day he took a cannabis-infused edible before going out for a run and his previously excruciating workout felt euphoric. “I felt like I weighed 50 pounds,” he said. “Running up a hill became an easy, playful experience. With the right soundtrack it was so much fun. It became the highlight of my day.”

Soon, Mr. Hesse met other runners and athletes who described having similar experiences with cannabis. That led him to write “Runner’s High,” scheduled to be published in September, which explores what he calls the “hidden culture” of cannabis use among recreational and elite athletes who routinely engage in stoned workouts. For his book, Mr. Hesse interviewed bodybuilders and endurance athletes who rely on cannabis to stimulate their appetites so they can keep on weight. He spoke to athletes who have claimed it helps them recover from tough workouts, reduces their pain and improves their sleep. But the most common refrain from athletes who use cannabis was that it helped calm their nerves and alleviate anxiety.

“What I heard so often from athletes who use cannabis is the phrase ‘dialed in,’” he said. “They become myopically focused on the task at hand. Any anxiety that they have about thousands or millions of people watching them, about their careers being at stake, or whether that injury from last year is going to hold up — it all melts away.”

When Sha’Carri Richardson, the star American sprinter, was denied a spot in the Tokyo Olympics this month after testing positive for marijuana, it reignited the debate around cannabis and performance enhancement among elite athletes. More broadly, however, is there any value for the average person to mix exercise and pot?

Cannabis is not a performance enhancer.

Although marijuana is prohibited by the World Anti-Doping Agency, there’s no scientific evidence that it can make people bigger, stronger or faster athletes. If anything, cannabis — the scientific name for the hemp plant, from which marijuana is derived — has a reputation for decreasing athletic performance.

Research suggests that, for competitive athletes, cannabis can be a double-edged sword. In some of the earliest studies looking at its effects on exercise, scientists found that when they assigned healthy volunteers to smoke cannabis and then perform strength and exercise tests, the cannabis spiked their heart rates, increased their blood pressure levels and hampered their ability to exercise.

Many of the studies that followed were small, not very rigorous or performed on animals. But overall, their findings suggest that cannabis use does not improve strength or exercise endurance.

“If you look at any test of physical performance, there’s either no data, it’s a wash, or marijuana makes it worse,” said Dr. Michael J. Joyner, an exercise physiologist and anesthesiologist who studies elite athletes at the Mayo Clinic in Minnesota.

Dr. Joyner said there might be some objective but minor physical benefit of cannabis in certain sports. World Archery, the international federation for the Olympic sport of archery, bans alcohol from competitions because it could help to steady an archer’s hand. Cannabis could potentially offer a similar advantage in sports that require such feats. But there is no real data to support that.

For cannabis users, experts say consider the risks.

There are also some potential health concerns surrounding marijuana, experts say, especially for athletes who smoke it. According to the American Lung Association, marijuana smoke contains many of the same toxins and carcinogens as tobacco smoke. And since marijuana smokers tend to inhale deeply and hold their breath longer than people who smoke cigarettes, they can be exposed to more tar. “Smoking marijuana clearly damages the human lung,” the lung association states. “Regular use leads to chronic bronchitis and can cause an immune-compromised person to be more susceptible to lung infections.”

Scientists say there are mental health risks as well, especially for people who start using cannabis as teenagers or young adults. Studies suggest that early exposure to marijuana can lead people to experiment with harder drugs, and a 2017 report by the prestigious National Academy of Medicine concluded that cannabis use increases the risk of developing schizophrenia and other psychoses. Some people may be more susceptible because of genetics or other factors.

Studies show that cannabis can also worsen people’s reaction time and hamper their decision-making abilities. That can be dangerous in situations where there is a high risk of serious physical injury, whether it is driving a car, lifting heavy weights or cycling along the shoulder of a busy road.

So, why have marijuana workouts become popular?

Still, the potential health risks and lack of evidence for performance benefits have not deterred some athletes and exercise aficionados from exercising while high — and swearing that cannabis enhances their workouts.

In a 2019 study published in the journal PLOS One, 26 percent of 1,161 self-identified athletes, mostly runners, cyclists and triathletes, reported that they were current users of cannabis. Some smoked it, while others consumed it as edibles or rubbed it on their bodies as creams. Around 70 percent of the athletes said that it helped them sleep or alleviated pain stemming from tough workouts and other activities. Almost 60 percent said that it calmed them down.

In another 2019 survey, Angela Bryan, a professor of psychology and neuroscience at the University of Colorado Boulder, and her colleagues recruited about 600 regular cannabis users and quizzed them on their use of the drug. Dr. Bryan suspected that cannabis would make people less physically active. But to her surprise, roughly half of the people in the study said that cannabis motivated them to exercise. More than 80 percent of cannabis users said that they regularly used it around the time of their workouts. Seventy percent said that marijuana increased their enjoyment of exercise, and roughly 80 percent said that it helped them recover.

“It was a pretty strong relationship and pretty common to use cannabis either before or after exercise,” Dr. Bryan said. Studies suggest that cannabis may help some people fall asleep faster, and there is modest but limited evidence from clinical trials that it reduces pain and inflammation. “It’s probably not surprising that people are using it in that context,” she added.

For the most part, research on cannabis and its effects on exercise has been somewhat limited by its status as a Schedule 1 drug.

“The federal legal status means that we can’t have it on campus or prescribe it or even tell people what to use,” Dr. Bryan said. “We are not allowed to give them anything.”

That has constrained Dr. Bryan’s ability to examine more closely how cannabis influences exercise, metabolic health and inflammation, since she cannot bring people to her lab, give them an edible and run experiments on them.

She and her colleagues, however, have devised a way to get around this. Using a mobile lab, they drive to the homes of people who regularly use cannabis, taking blood samples from the subjects and running tests on them before and after they use the drug. “They tell us what they use and then we quantify the THC and CBD in their blood for an objective level,” she said.

Next, the subjects show up at the lab on different days to run on a treadmill, sometimes after they have used marijuana and other times after they’ve abstained. A few things Dr. Bryan and her colleagues are looking into is whether cannabis affects how much pain and pleasure people experience while exercising and whether it influences their perception of time.

“When we talk to endurance athletes who do a four-hour run or bike ride,” she said, “they tell us that cannabis makes the time go faster and it feels less boring.”

Anahad O'Connor

NyTimes