A smiling Ping Xiang Lin, a 45-year-old garment worker in a small factory here, swiveled on her new padded, adjustable chair. This unremarkable piece of dark gray furniture has ended her days of pain.

At KC Sewing, where Lin works, and two other East Bay garment shops, state and university health experts are attempting to spark an ergonomic transformation in an industry notorious for poor working conditions.

Their novel experiment has shown factories can achieve productivity gains by improving working conditions -sometimes as much as 20 percent, health expert say. Workers, meanwhile, said their knee, hand or foot pain ended or substantially subsided.

The results so aroused the curiosity of federal health researchers that they are embarking on a larger test in Southern California.

Garment manufacturing generates $13 billion a year in business in California. The state took over New York's role as the country's capital of clothing manufacturing in the 1970s after business owners fled westward in search of cheaper labor, said Kimi Lee, the director of the Garment Worker Center, a Los Angeles advocacy group.

In the vast majority of California's 7,500 garment factories, workers labor at primitive sewing stations that differ little in design from those used a century ago. They often sit on inflexible metal chairs, or sometimes stools or orange crates, working eight to 10 hours a day, five to six days a week.

The factories employ more than 140,000 people, most of them Chinese women in Northern California and Latina women in Southern California.

They complain of similar aches, pains and injuries: aching shoulders, backs and arms; pinched nerves; repetitive stress injuries to elbows, wrists and hands; and strained or even torn vertebral disks that may not heal, according to Ira Janowitz, an ergonomics expert with the University of California system.

Inside the crowded, narrow KC Sewing shop, about 30 women assemble designer evening gowns from piles of pink chiffon and black satin. Over the whir of sewing machines, Chinese opera music pours from mounted speakers.

Before workstations were transformed and metal chairs replaced, Lin said, her body ached almost constantly. After spending her days hunched over a sewing machine, sometimes she could barely lift her neck.

"It's like a pain inside the bone, every single bone," she said, speaking in Cantonese through a translator.

Despite the work-related injuries, Lin and others prize jobs that pay a steady, minimum-wage income, said Nan Lashuay, the director of the UC San Francisco community occupational health clinic in Oakland. As immigrants with marginal English skills, many have limited options.

Few dare to speak out about work-related pain or apply for workers' compensation. Lashuay said those who do often find themselves without a job or with curtailed work hours.

UCSF began studying the issue in 2000 and joined a coalition that sought federal, state and private funds for an experiment at the three Bay Area garment shops. Their findings have inspired the U.S. Centers for Disease Control and Prevention to replicate the study in an $850,000 project in 10 Los Angeles County garment shops.

Scheduled to end in 2005, the study will track the long-term health and productivity effects of the factory modernizations.

Lashuay and other UCSF health experts saw the need for ergonomic changes at garment shops after taking an informal health survey of garment workers at a free health clinic in Oakland's Chinatown.

Half the 100 workers visiting the clinic said job-related pain kept them awake at night, and 94 percent said it interfered with such daily activities as housecleaning, cooking and dressing.

"They were just so used to it," Lashuay said. "They didn't think anything could be changed."

But those who listened did: UCSF, the Asian Immigrant Women Advocates in Oakland, the California Department of Health Services and the University of California's Ergonomics Program formed a coalition to introduce modern ergonomic standards to garment shops.

Ergonomic experts descended on the three test shops - hammering extensions onto sewing tables, building footrests, padding the knee pedals used throughout the day, tilting the tables, pasting down a sticky surface to keep cloth from sliding, brightening the lighting, and making other small but significant changes.

The crowning enhancement was the padded, adjustable chair designed like one used by cello players, who also work in a forward-bending position.

The workers loved the upgrades, which cost about $250 per workstation. "They noticed the improvements within a week," said Kam Lin Chao, one of the owners of KC Sewing.

The ergonomics team estimated that nearly half the workers in the test shops reported that their neck, shoulder and back pains were gone, according to a 2002 study of the project. Almost all workers with knee, hand or foot pain reported it was gone or substantially reduced.

Stacy Kono, program coordinator for the Asian Immigrant Women Advocates, said she's hopeful that the East Bay and Los Angeles County projects will elevate industry standards.

"We've created a solution, so it really only makes sense that this gets spread throughout the industry," she said.

Ilse Metchek, the executive director of the California Fashion Association, which represents brand-name clothing manufacturers and designers, predicted that new data linking increased productivity with ergonomic upgrades would motivate garment factory owners to run to find the best chair.

"Those who want to be good guys keep their employees happy and maintain a better work force," Metchek said. "(They) certainly have less turnover and less medical problems."

The CDC wasn't the only government entity intrigued by the results of the ergonomic changes at the three factories.

The Oakland City Council in February reviewed the study and listened to workers' stories, then gave garment shop owners a financial hand to upgrade their factories ergonomically. The shops usually operate on thin profit margins in the highly competitive industry.

Jean Quan, an Oakland city councilwoman, said the council voted to set aside $25,000 to help garment factory owners acquire the chairs, using money from a fund created to keep jobs in the United States.

Ying Ci Cai, the owner of Harbor View Sewing in Oakland, applied for the funding administered by Asian Immigrant Women Advocates. The program requires the shop owners to pay a small share of the costs.

Cai, who said her 19 workers now sit on metal kitchen-style chairs, applied to get the new chairs because "I want my workers to work comfortably, and I want to provide better conditions for them."

Without the city's financial backing, Cai said she couldn't afford the new furniture.

For the program to expand in Oakland, factory workers had to learn to speak up and, in the case of the Chinese employees, overcome cultural prohibitions against petitioning authorities.

"People never go to see officials in China. It's taboo," explained Ken Fong, an organizer with AIWA. Consequently, those willing to speak out are becoming heroes in their communities.

Chi Yeung, a shy 50-year-old who spoke through a translator, told the Oakland City Council of the severe pain in her neck, back and shoulders that had crippled her. Like most garment workers, Yeung had no health insurance and went to a Chinese herbalist whose massage got her walking again and back to work.

While reluctant to discuss her accomplishments, Yeung finally shared that co-workers were amazed at her courage in asking city leaders for improvements.

"They admire us, that we got a chance to see them," Yeung said of her colleagues. "They ask, 'How can that happen?' "