Willie James Jackson's business goes by a biblical name: King James Fitness. But his professional persona is a foul-mouthed mash-up of Richard Simmons and Snoop Dogg, the rapper.

In recent years, Jackson has helped hundreds of local African-American women lose weight. In coming weeks, he'll likely help dozens more who have made resolutions for 2012. How long those new clients stick with him depends on how they feel about his unorthodox methods.

A YouTube video shows Jackson cursing at several dozen clients, calling them derogatory nicknames, like Jell-O, and hitting them with a plastic baseball bat to get them to move faster. The video has been viewed nearly 178,000 times and spurred debates about whether he's a misogynist.

Fitness experts question his qualifications and worry that he's putting his clients at risk.

According to Jackson, who's polite and pleasant when he's not "King James," there's altruism behind his badness.

He has to be ornery, he said, if he's going to save black women from diabetes, heart disease and other health problems that plague African-American communities.

The U.S. Department of Health and Human Services estimates that four out of five African-American women are overweight or obese, more than any other group in the nation. About 18 percent of African-American adults have diabetes — twice the rate of whites — and two out of three of them will die of heart disease or stroke.

"I actually train my women like men," Jackson said. "I have the roughest, toughest women around, and they love it. I'm the one they call to say they're off high blood pressure medications, and they're in the mall shopping for new clothes and 'My husband can't keep his hands off me.' "

Jackson compares his rapport with his clients to that of brothers who trash talk each other. Outsiders, he said, just don't get it.

Yet behavioral experts insist that negative reinforcement doesn't work.

"If you say, 'How do we shape behavior?' the most successful way is through positive reinforcement," said Joseph Lenac, founder of Winning Edge Sports Psychology in St. Louis. "It's most successful from shaping children's behavior at school to adults in the work setting."

Even elite athletes perform better with positive reinforcement, he added. Negative reinforcement is usually short-lived. Yelling might get some people pumped up and emotionally aroused, but as a rule it works in very short bursts and for very specific reasons.

"If you overuse it, it loses its effectiveness," Lenac said.

Several experts in women's studies and African-American culture at Washington University declined to comment on King James' tactics after seeing his video. They were offended by it and didn't want to draw attention to him, they said.

Val Strang, owner of Rock Workout in midtown St. Louis, worries that Jackson is putting his clients' health at risk. After watching online videos of his classes, she rattled off a list of problems she saw, including:

• Obese, de-conditioned women jumping up and down off cinder blocks which puts added stress on their already compromised joints.

• The potential that insulin levels of those with diabetes could plummet or skyrocket from the women being overheated and over-exerted.

Strang is a registered personal fitness trainer with The National Board of Fitness Examiners which means she is certified to train other trainers.

"And if his videos are realistic, he has between 30 and 60 people at a time in his classes," she said. "You need at least three trainers in a class that large, walking around checking (biomechanics) form as you lead class, because you cannot see everyone all the time."

'WALL OF SHAME'

Two dozen women lined up one evening last month in King James Fitness in the basement of Five Star Cuts Barber Shop on West Florissant Avenue. Those who were most fit stood in front while newcomers and those with health conditions stood at the rear.

"Wall of Shame" was spray-painted on one hot pink wall; "Wall of Winners" was on another. Cinder blocks were lined against the walls and down the center of the room.

The women began by doing jumping jacks. Those in the back did modified ones by standing with their feet apart and clapping their hands above their heads.

"Switch!" yelled Jackson.

"Hut!" the women responded.

One by one, starting at the front, they peeled off to the center of the room where they stepped up and down off the row of cinder blocks, moving sideways from one end to the other at rapid speed.

Occasionally, Jackson stopped to admonish a client.

"Lay yo' (expletive) down," he yelled at a woman who did a sit-up too soon.

Areshia Williams sat nearby watching her mother.

"I took his class yesterday. It tore me up, girl," said Williams, 24, of Los Angeles, shaking her head. "I tell you, I thought I was in shape, too."

Jackson, 48, who moonlights as a stripper, said he began working as a fitness trainer at a local gym about 10 years ago. He was certified by the International Fitness Association, though that certification lapsed last year, said a spokesman for the group.

Initially his approach was gentler, more mainstream, he said. Then one day an African-American woman jumped up in his face and cursed him because she thought he was pushing her too hard.

"I came in the locker room the next day and heard guys whispering and laughing, and I said, 'That will never, ever happen again,' " Jackson said. "That's how I developed my style. African-American women don't want you to hold their hand. They want discipline; they want someone hard-core."

He quit the gym about seven years ago and launched Nu Gurl Fitness, marketing it almost exclusively to black women through radio commercials. He's moved his operation and changed its name several times over the years.

Jackson insisted he isn't as vulgar or abusive in class as he is on the YouTube video. He acted over the top, he said, to get people to watch it — and in hopes of getting a reality TV show.

"When you saw someone get whopped ... you were going to watch the whole thing," he said. "Even if you hate me, you watched it. I'm just a black guy being loud."

On the night a Post-Dispatch reporter and photographer were present, Jackson's demeanor was tamer than on his video. The plastic bat never made an appearance.

He strolled among his clients as they moved cinder blocks around the room, a bottle of juice in his hand and the letter "P" popping from his lips like verbal bullets: "Pick that brick up and shut up. Just pick it up. Turn to your (expletive) right every time. Pick it up! Take it back! Put it down! Now turn to the right!"

"How much does it weigh?" someone asked.

"It don't matter how much it weigh. Shut up!" he shot back.

He yelled at them to bend at the knees and keep their backs straight.

"G-string," he roared at one of them, "put it back, squat down and do it the correct way."

On and on they went, moving the blocks this way and that, jumping up and down on them, doing sit ups and whatever else Jackson commanded.

METHODS ARE DEBATED

Jackson is proud that he gives his clients a good workout with something as simple as a cinder block.

Strang was disturbed by it.

"It's one big lump of weight. It's not like a dumbbell where the weight is evenly distributed," she said. "We're talking about something that can be easily dropped on your foot because it's so cumbersome."

About 35 minutes after class began, it stopped abruptly.

Jackson instructed the women to sit on the floor in front of him. For the next half hour, he spoke.

He explained that he's so affordable even a homeless person can workout with him. For $10 a week, his clients can attend dozens of classes a week.

He told them that if they brought him a gift — some cologne from Walgreens, perhaps — he'd give them the gift of not weighing them over the holidays. But only if they brought him a gift. Typically, clients are required to lose three pounds a week or pay a $10 fine.

Soon, Jackson said, he'd begin taping the first workout DVD featuring plus-size African-American women. Who, he asked, wants to watch a skinny woman swinging her leg around?

"If you see somebody with back jelly and a fat ass doing it, you'll say 'I'll at least try it,' " he said.

"Mmmm hmmm," the women agreed.

Some critics believe Jackson is exploiting women who have low self-esteem and are used to being abused.

Robbie Buchanan, 30, worked out with Jackson three years ago before moving to Atlanta.

"His tone and the way he talked, I didn't think it was necessary," Buchanan said. "We're not wanting to be abused. I definitely don't. It hurts my stomach. My aunt stopped working out with him, because she said it gave her flashbacks of things she had gone through."

But many of his current clients are college-educated professionals, such as teachers, financial analysts and registered nurses.

Sherri "Handicap" Virdure, 39 of Florissant, has been taking Jackson's classes for two years and said she's lost 75 pounds. She's been hit with the bat and said she doesn't mind it a bit.

"If he thinks you're not giving your best, he will do that," she said. "But really, he's a big softy. He cares about the people he trains. He cares about what you eat and if you lose weight."

Michelle "Apple" Bunting, 40, of St. Louis heard about Jackson through word-of mouth and said she's lost 21 pounds since October.

"I was going from gym to gym, from trainers to boxing classes, buying all the equipment, a treadmill, a bike and nothing worked," she said. "I came here and lost the weight. I look forward to coming, because I see the success of the other women in here who are losing weight."

Several other women said they don't take Jackson's treatment personally; that's it's an act, albeit a highly motivating one.

After watching the YouTube video, Lenac came to the conclusion that Jackson's clients probably tolerate his treatment because it helps them lose weight and allows them to fit into a social dynamic.

"He has a very defined group of women who may have a lot of similarities; they're peers doing this together," Lenac said. "They see people just like themselves who have the same goals, they want to lose weight and get healthy."

Jackson knows he has critics. He doesn't care.

"I care about my clients and the joy they have now," he said. "Those (critics) are the same individuals who are not helping anyone; not saving any lives. They're not doing anything to help the situation.

"You may not like my technique, or how I go about it," he continued, "but tell that to the person who is off high blood pressure medication or has their diabetes under control."