Many of the people who bicycle from place to place around Washington say they find it therapeutic. Now a new program will consider whether bicycling is effective therapy for people who may need it the most.

On the anniversary of its creation, the Capital Bikeshare program has embraced a study that will provide 20 mentally ill people with memberships, in part to help them get around town but also to see whether cycling improves their physical and mental health.

“The cool thing about the Bikeshare program is we’re going to know exactly how much people are actually using membership because we’ll get monthly reports on it,” said Yavar Moghimi, the psychiatrist who proposed the program. “Basically, we’ll have an estimate of how many miles people have ridden, how many calories they’ve burned. We’ll know the locations — where they picked up the bike and where they dropped off the bike.”

Moghimi said he hopes the year-long study will prove that enhanced mobility and physical activity improve the patients’ mental health.

The 20 people selected for the study group range from the chronically schizophrenic to those beset by depression, anxiety or post-traumatic stress. The only patients excluded from the program are those with cognitive disorders who might not be able to negotiate the bike.

“My hope is that there are unequivocal positive effects involving physical and mental health and that this project can be incorporated into other studies and sort of pave the way,” said Josh Moskowitz, one of the Bikeshare program’s managers.

The Bikeshare program has proved more popular than expected in the year since the cherry-red machines debuted on the streets of Washington and Arlington County. It now has 15,982 annual members, its bikes make an average of 4,000 trips each day, and the total number of trips taken hit 1 million Tuesday, on it’s one-year anniversary.

“It’s exceeded our expectations in terms of ridership, in terms of the core membership, and it’s personally a wonderful experience to be involved in such a great project,” Moskowitz said.

Almost 80 percent of the trips have been made by annual members, although there have been 66,534 24-hour and five-day memberships sold, according to Bikeshare data. The busiest Bikeshare docking station is where Massachusetts Avenue intersects with Dupont Circle, where more than 40,000 trips have originated.

Membership costs $75 for a year, $25 for a month, $15 for five days and $5 for 24 hours. Long-term members get a key to unlock a bike from the docking station; short-term members get a five-digit code to do it. The first 30 minutes of riding are free, but fees kick in after that until the bike is returned to another docking station.

The program will open 32 docking stations in new locations in the city this fall, increase the size of 18 existing stations and add 265 more bikes, bringing the total number to 1,365 in the District and Arlington. Arlington hopes to add 30 stations in the Rosslyn, Courthouse, Clarendon, Virginia Square and Ballston areas, and the program may expand to Rockville and Shady Grove next year.

The bikes have added another transportation option in the District, where more than a quarter of households do not own a car.

Moghimi, who works at Whitman-Walker Health, is developing the program in conjunction with the McClendon Center, a District facility that treats people with serious and persistent mental illness. He is funding it with grant money from the American Psychiatric Association.

The first patients enrolled in the Bikeshare study group received bike training Wednesday from instructors from the Washington Area Bicyclist Association. They also learned how the Bikeshare program functions and how to release and return a bike from one of the docking stations.

“Right now I spend a lot of time on Metro,” said Madwkaego Williams-Holliman, who works in Beltsville, lives in the District and visits a gym in Alexandria. “With the bike I’ll be able to just ride right across Memorial Bridge.”

It had been a year since Williams-Holliman, a former bike mechanic, last rode a bike. For Dorothy Williams, 52, it had been a lot longer.

“I got my first bike when I was 16 and sold it when I was 17 and learned how to drive,” she said as she prepared to climb onto one of the red Bikeshare machines for her first ride in Lafayette Park.

Many of the people in the program live below the poverty line, Moghimi said.

“Oftentimes they have a very difficult time getting around, missing appointments with potential job interviews, and a lot of people may have been involved with the legal system,” he said. “Just general getting around the city, if you only have five bucks in your wallet, you’re going to pick and choose the things that you have to go to.”

Even signing up for Bikeshare becomes problematic for people who do not have the computer or credit card needed to get a membership.

After six months of Bikeshare participation, the patients will swap places with a control group that will ride for the next six months.

“The hypothesis is that people who have been riding bikes for six months will have a greater sense that they are healthier,” Moghimi said. “They’ll have a greater sense of mobility, that things are accessible to them in the city that weren’t accessible before.”

Capital Bikeshare plans to celebrate its one-year anniversary, which occurred Tuesday, during the free Birthday Bash from 6 to 9 p.m. Thursday at Yards Park, on the Anacostia River near Nationals Park. There will be live music, moon bounces, food, games and prizes.