Zach Jamison is 13 years old and Isabela Brown-Soler is only 8. But hardly a day goes by when they don’t experience the nagging pain of arthritis.

“It’s constant and when it’s really bad, it radiates down from [my] head to my knees,” said Zach. “Sometimes it’s an aching pain. Sometimes it’s stiffness and sometimes it’s a sharp pain in one spot.”

Contrary to popular belief, arthritis isn’t just some trivial side effect of aging.

About 300,000 children age 16 and under have some form of juvenile arthritis, a chronic condition that causes inflammation in one or more joints, according to Dr. Patience White, vice president of public health for the Arthritis Foundation and a pediatric rheumatologist.

“Most people equate arthritis with the elderly but one in 1,000 children will get juvenile arthritis,” said White. “It’s a myth that’s very hard to break.”

In Georgia, 1 in 4 people live with arthritis including some 10,000 children like Isabela and Zach, both of whom will participate in Saturday’s Atlanta Arthritis Walk, one of 200 events happening across the country this spring.

Isabela was diagnosed with arthritis shortly after she lost the use of her legs and while she was celebrating her first birthday, said her mother Robin Brown-Soler of Stone Mountain.

Brown-Soler said emergency room doctors wrapped her knees and sentthe family to an orthopedic specialist who told them they needed to see a rheumatologist.

That doctor told them Isabela was suffering from one of three things: sepsis, leukemia or arthritis.

“We prayed, of course, that it was arthritis,” Robin recalled the other day.

Although Isabela’s condition has stabilized since that diagnosis seven years ago, her life has been a constant round of doctor’s appointment and pain killers.

“She’s in what’s called medicated remission,” Brown-Soler said.

In many ways, she said their family is lucky because Isabela got her diagnosis early.

That, however, is rarely the case.

Because even some doctors aren’t aware children can suffer from arthritis, they often go undiagnosed for years.

Zach suffered from multiple epiphyseal dysplasia, a rare form of Juvenile Arthritis, for nearly a year before doctors pinpointed the disease at age 6.

“Knowing is half the battle,” he said.

Still, the Woodstock eighth-grader said arthritis is three things: life-changing, life-threatening and unacceptable.

“It’s life-changing because you can’t do anything normal kids can do," said Zach, this year's Arthritis Foundation Arthritis Walk National Honoree. “It’s life-threatening because it can kill you. And it’s unacceptable because no one should have to live with it.”

That’s why he and his 57-member team will hit the pavement this week, hoping to raise $5,000 for Saturday’s walk, held annually to generate funds for arthritis research and education and life-improvement programs in 250 communities across the country.

Although there are many different types of juvenile arthritis, White said they are all extremely painful and debilitating and can rob otherwise fit and healthy youth of their independence and the simple pleasures of walking and playing.

“The pain and cost to young children and their families are quite high but we have unbelievably good treatment,” she said. “They don’t have to live a lifetime to pain.”

If you go:

What: 2011 Arthritis Walk

When: 9 a.m. registration; 10 a.m. walk, Saturday

Where: Concourse Office Park at Perimeter in Atlanta

For more information, log onto www.arthritis.org