Alki Beach became Muscle Beach yesterday as athletes in tight shirts and spandex suits went bicep to bicep in a power-lifting competition.

While some of the young and bulked-up lifters drew gasps from spectators by pumping well over 400 and even 500 pounds, there were also a fair number of less-predictable participants: older athletes out to stay healthy and have fun.

Trainer Bull Stewart, who ran the event, said about 70 percent of the 80 competitors were in the older divisions, known as "masters."

"It's definitely an upward trend," said trainer Matt Spies of Pro Sports Club in Seattle. As people enter their 70s and 80s, Spies said, their flexibility, mobility and strength can deteriorate, hindering common daily activities such as walking or playing golf.

Keeping in shape and beginning strength training at 50 or 60 can help stave off those problems, Spies said. "The only big limitations that they're going to have to worry about is making sure they're working within their appropriate ranges."

Stewart's father, Walter Stewart, was the competition's oldest lifter at 69.

"Since I retired, I didn't have anything to do and got bored," the elder Stewart said. He began lifting two years ago after moving to Seattle from Mississippi, and says he has dead-lifted a personal best of 250 pounds.

"Some people my age tell me I'm crazy," he said. "And I guess I am, but I enjoy doing it."

Robert Mattison, 68, is from Northern California and has bench-pressed a personal best of 245 pounds. He got seriously into lifting four years ago after his legs grew weary after three decades of running.

"I have this urge to push myself," Mattison said. "I think [older] people are realizing that you can enjoy yourself and be healthy."

His wife, Anita Mattison, says her husband's lifting first struck her as crazy, but she's since come around. "I think it's good for him. It reinforces a healthy diet."

Juana Mangaoang said she started lifting about a year ago because her children were doing it. Now the 50-year-old and her daughters, who are 25 and 29, often wind up at the gym together, joking and having a good time.

"Any kind of weight training is really good to increase your bone mass," Mangaoang said. A side benefit, she said, is that lifting at an older age has also helped her focus on herself — something many busy women find difficult to do.

"We spend our whole lives taking care of everybody," she said. "And we don't spend a lot of time taking care of ourselves."

Tim Sinnett, a trainer at Sound Mind and Body Gym in Fremont, said would-be lifters, especially older ones, should contact a doctor first and avoid fast or excessive programs, which can result in strains and tendinitis.

Ari Bloomekatz: 206-464-2540 or abloomekatz@seattletimes.com