The sound bounces off the fitness studio's walls.

Thwack! ... Thwack! ... Thwack!

Leah Biskup, cancer survivor, is pivoting on her right foot and kicking a padded training bag with her left. It scoots an inch or two with each foot strike, metal stand and all.

"Sometimes she moves it across the room, and I have to keep moving it back," says Val Strang, owner of ROCK Workout in midtown St. Louis.

Historically, health experts have recommended that cancer survivors and patients rest and avoid activity. But last month, the American College of Sports Medicine stated that "to the extent they are able, cancer patients and survivors should adhere to the 2008 federal Physical Activity Guidelines for Americans, which recommend at least 150 minutes per week of moderate-intensity aerobic activity."

The recommendations came out of a scientific conference at the Siteman Cancer Center in June 2009.

This week, the National Cancer Institute awarded a $348,109 grant to Dr. Laura Rogers, associate professor of internal medicine at Southern Illinois University School of Medicine in Springfield, to study exercise after breast cancer. The grant is the second of its kind for Rogers, who hopes to get a better understanding of the kind and amount of exercise certain breast cancer survivors may need.

Kate Wolin, assistant professor of surgery at Washington University, said several attendees at last year's conference presented data showing that patients who exercise experience fewer side effects, such as fatigue, than those who are sedentary.

The data also indicated that exercise might reduce the risk of recurrence and improve survival rates, Wolin added.

Then there are the emotional benefits: exercise boosts morale, helps patients regain some control over their bodies and restores normal daily living.

"There are a lot of patients and clinicians who operate under the assumption of rest and recovery, because cancer treatment is an incredibly debilitating process," she said. "But the evidence points the other way. It's showing that it has benefits despite that pervasive myth. So, we're just now where cardiac rehab was several years ago."

Nine years ago, Biskup, 24, of Brentwood, was a highly competitive athlete. She ran cross country, was on a diving team and played with a select softball team.

She collapsed one day during her freshman year of high school. Eight months later, after blood from a leak in her brain cleared up, she was diagnosed with cancer. She was in remission in 2004 when it returned.

Biskup is in remission again, but the multiple tumors that grew in the left side of her brain, the two surgeries to remove them, and the rounds of radiation and chemotherapy that followed left her with peripheral neuropathy.

The right side of her body is numb, tingly and weaker than it once was — though you wouldn't know it by watching her kickbox.

Biskup credits Strang with that.

"Sometimes, I try to knock Val over," she said, giggling.

chronic disease

Thirty years ago the primary goal of doctors was to get people to live five years, Wolin said. Today, they view cancer more as a chronic disease with a host of systemic residual effects, ranging from balance issues and bone loss to nerve pain and heart muscle damage.

Breast cancer survivors often must deal with lymphedema, an excessive build up of lymph fluids from damaged lymph nodes. It often causes the arm, chest and breast to swell.

But experts maintain that there are ways to work around those issues and perhaps even correct and prevent them with exercise.

For instance, women who've had mastectomies often can't reach things in a cupboard, scratch their back or blow-dry their hair, said Andrea Leonard, founder of the Cancer Exercise Training Institute in West Linn, Ore.

"Many patients don't realize that there are corrective exercises," she said. "They think, 'Oh, thank God, I'm cured of cancer. I guess I should be happy with this.' That's not the case at all. They're suffering needlessly."

Two years ago, Biskup was so weak and wobbly that she couldn't stand upright on air-filled balance cushions. Now she takes part in ROCK's various group classes, including yoga, pilates, boot camp and even TRX Suspension Training, a hardcore resistance program created by U.S. Navy Seals. But she had to work up to it under Strang's watchful eye and tutelage.

Strang is the only local trainer to have advanced qualification for working with cancer patients through the Cancer Exercise Training Institute.

Since 2004, Leonard said, more than 3,000 trainers worldwide have attended her workshops and received advanced qualification to work with clients who have battled 25 types of cancer.

'My goal before the day I leave this earth is to have a cancer exercise specialist in every city in every state," said Leonard. "I look at this not only as a business person but as a (thyroid) cancer survivor who knows what it's like to feel like your life is out of control. We help people reclaim their lives."

'every day is different'

The American College of Sports Medicine began certifying trainers to work with cancer clients 18 months ago, and has since certified 135 of them, though none are in the metro area.

Richard Cotton, national director of certification at the organization, expects that number to increase dramatically in coming years.

"The one challenge with cancer, especially during treatment, is that every day is different depending on how you feel," Cotton said. "It's very important for the trainer and the patient to not overdo it. To be consistent, but to allow you to be in the shape that you are on a given day."

Strang analyzes her cancer clients thoroughly when she meets them. Then she has them start with simple, fundamental exercises that set them up for success. Progress naturally follows.

Strang sterilizes her studio for those with weakened immune systems.

She calls Biskup a cancer conqueror.

"To survive, all you have to do is eat, drink and breathe," she said. "To conquer, you have to start to live again." Biskup said she'll never be as strong, fast and agile as she once was. But she's way more fit than she could have imagined two years ago.

"It's nice," she said, "because I feel like when I'm with friends, I can do some of the stuff they do."