About 25 local residents with Parkinson's disease gather in a Mountain View gym three mornings a week donning boxing gloves for a workout with a professional boxing coach.

Ranging in age from 40 through 80 — and with widely varying symptoms of the neurodegenerative disease — participants stretch, jog, jump, kick, jab, punch and shout their way through a rigorous 90-minute workout under the upbeat tutelage of coach Freddy Silva.

This local "Rock Steady Boxing" group is part of a fast-growing movement across the country to adapt boxing and other challenging exercise regimens to fight the tremors, unsteady gait, speech issues and other symptoms that often accompany Parkinson's.

Nearly as important as the workout, say participants, is the camaraderie and fellowship that develop among them as they sweat together while fighting a common enemy.

"For me, this has been my happy place," said Chrystal Kafka of Palo Alto, a former Pilates instructor who began experiencing Parkinson's symptoms in her early 40s more than a decade ago.

"We don't feel like Parkinson's patients going into physical therapy to deal with our disease," she said. "We're just going in to do our training — and by lucky happenstance, we feel a whole lot better."

Silva, a San Mateo-based personal trainer and boxing coach, first heard about non-contact boxing as a therapy for Parkinson's in 2014 and soon began volunteering in a Parkinson's boxing gym in San Francisco. Within months he traveled to Indianapolis to become certified in the Rock Steady Boxing program.

Founded by a former Indiana county prosecutor with Parkinson's who noticed his health significantly improved after boxing workouts, the nonprofit Rock Steady Boxing has grown to more than 300 affiliates in the U.S. and abroad since 2006. Growth boomed after a 2015 CBS Sunday Morning report by journalist Lesley Stahl on how boxing had reduced the Parkinson's symptoms in her husband, writer Aaron Latham.

While there's no cure for Parkinson's, research has shown regular exercise can reduce stiffness and improve mobility, posture, balance and gait in patients, according to the Parkinson's Disease Clinic and Research Center at UCSF. Silva said many participants in his Rock Steady Boxing programs — dubbed "fighters" — come to him on the advice of their physicians.

Adapting traditional boxing training to Parkinson's patients was not difficult, said Silva, who also trains professional boxers. "I really haven't had to change that much," he said.

"A lot of the things we learn in boxing — agility, footwork, balance, flexibility and rhythm — happen to be really helpful to people with Parkinson's. Boxing requires a lot of cognitive skill — it's not just punching, not just trying to hurt somebody. It requires a lot of coordination, knowing where your center is. Your neurotransmitters are making connections — it's almost like a dance," he added.

Indeed, Silva plays music throughout the workout, starting with golden oldies and working up to fast-paced Latin salsa.

Many of the Parkinson's "fighters" are able to complete Silva's workout on their own. Others do the drills with support from a spouse or caregiver.

"Some might be in a wheelchair or need to be seated part of the time," Silva said. "These fighters have really taught me that you're going to face some adversity in your life, but keep your mind open to the options.

"It takes a lot of guts for people 60-plus to come in and learn to throw punches. These boxers are fighting for quality of life, for their dignity."

Ray Ostby, a Saratoga resident who attends Rock Steady three times a week, said he's noticed significant improvement in his strength, stamina, balance, agility and overall health.

"There are several exercises that I couldn't do at first that are now relatively easy," said the 70-year-old, who was diagnosed with Parkinson's at 67 after having noticed symptoms for at least four years. "For example, I could not jump rope at all and now I can do eight to 10 turns at a time. I couldn't move laterally, and now I can."

In addition to boxing workouts, Ostby regularly attends a Mountain View YMCA Parkinson's program, walks on the treadmill and to the post office and also walks the dog each evening, but called Rock Steady the core of his Parkinson's therapy.

"I enjoy the sessions, the coaches, the other participants and even the exercises," he said.

Los Alto resident Clarence Kellogg, 71, said he'd never exercised before his Parkinson's diagnosis several years ago. "I never wanted to — it wasn't my thing," he said. "But they convinced me it better be my thing if I want to have the maximum chance of living a comfortable life. The medical profession has identified (exercise) as something that can do some good if you do it seriously, and I have to think that is correct."

Kellogg also has taken "less intense" classes elsewhere to help Parkinson's patients deal with daily tasks such as getting in and out of a car or up and down from furniture.

Though it's "a lot of work," the three-times-a-week boxing workout is "valuable and I don't dislike it," Kellogg said. "In fact, I kind of enjoy the boxing more so than the mechanical exercises. There's a certain niceness about having the 20 or 30 other people in the room validating what I'm trying to do, and I'm validating for them what they're trying to do."

After the workouts, he said, "I feel exhausted, and I can get to sleep (for a nap) real quick."

Silva said he's gratified by "all this love" he gets from Parkinson's boxers, particularly when they begin noticing improvements in their daily lives.

"One of the symptoms (of Parkinson's) is feeling apathetic," he said. "To hear people say, 'That's changed, I get up off the couch because I know I'm going to do boxing.' Or 'Hey Freddy, I'm not just doing boxing any more — I went over to the Parkinson's Institute, and now I'm taking this class.' Or 'I took my dog for a walk with my wife and we walked a mile and a half.' Or 'I played with my grandchildren for a half an hour.'

"Besides getting married three years ago," said Silva, "this is the greatest thing that's ever happened to me."

To learn more about Rock Steady Boxing in Mountain View, go to siliconvalley.rsbaffiliate.com, call 415-385-5668 or email siliconvalley@rsbaffiliate.com.