When you sit

on a FitBall Exercise Ball at work, you can't completely relax your muscles

like you can when you sit in an office chair. That's because the ball

isn't stable. So, when you sit on a FitBall, your back muscles along your

spine must make tiny adjustments to balance, which helps strengthen your

core muscles while you work.

Sitting on

the ball also helps increase blood flow to key muscle groups, helping

business people stay more alert, work longer and feel better. The balls,

which come in different sizes and colors, range in price from $23 to $30

and are available online at www.fitball.com .

"For proper

posture when sitting on the ball, make sure your knees are at a 90-degree

angle," said Merry Lester, president of Denver Physical Therapy,

who treats patients with orthopedic and sports-related injuries. A recommended

FitBall size chart is as follows:

Height 4'8" to 5'3"

Ball size

55cm

Height 5'3"

to 6'0"

Ball size

65 cm

Height 6'0"

to 6'7"

Ball size

75 cm

In addition

to providing back-friendly seating at work, the FitBall Exercise Ball

is an inexpensive and easy-to-use exercise tool for core strength training.

The American

Council on Exercise predicts that core strength training exercises will

increase in popularity this year, as exercisers recognize their value

for weight management, osteoporosis and overall health.

Here are three

ways to strengthen your core muscles.

Crunch and

Punch: Sit down on the ball and put the small of your back against

it with your arms extended out in front of you. Then, contract those ab

muscles and crunch forward while you pull your elbows back. Next, sit

straight up on the ball and move your fists up to your face as if you're

blocking a punch. Then, finish off with a right jab in front of you. Repeat

10 times, alternating your punches. This exercise is guaranteed to work

out your upper abs, tough-to-isolate lower abs and obliques all at the

same time.