BEIJING - Every morning at 6 a.m., Zhang Qiju climbs onto a pavilion, puts his hands on his hips, leans back and lets out a bellow that shatters the morning calm.

"Heeee!" he cries, forcing all the air from his stocky chest. Then he takes a deep breath.

"Ho!" he continues, this time throwing up his arms. "Ha, ha, ha, ha, ha!"

Soon other gray-haired men and women join the 76-year-old Zhang in the belly laughs, signaling the start of morning exercises in Ritan Park in central Beijing, a few miles from the Olympic Green.

Taking deep breaths of Beijing's polluted air may not seem like the pathway to health, but the people gathering in the park, which was built in 1530, think nothing of it.

The bellicose laughter is just their way of warming up for morning exercises, a ritual that plays out every day in tens of thousands of parks across China.

Ritan means altar of the sun, although most mornings in Beijing, there is very little sun, and a heavy layer of grayish gunk hangs over the city.

Within an hour of opening, nearly every open space and pathway in the park is occupied by Beijing residents doing all manner of exercise, the most popular being the traditional tai chi, often using swords. Others play a popular game called jian-zi, which is similar to hacky sack.

There's also, oddly enough, ballroom dancing.

Tai chi is not everyone's cup of tea, says Gao Lianyou, 72, who runs a popular dance program in the park's children amusement area.

"We have music. You can have a chat. You have no troubles when you are dancing," he says, as two dozen couples waltz next to the bumper-car ride.

The park also has a man-made lake, walking paths and a climbing wall.

Some, like 65-year-old Li Heng, perform amazing feats on horizontal and parallel bars. Li mounts the bars and begins swinging his legs back and forth. Suddenly, with one swift motion, he is upside down, locked in a steady handstand. A minute later he finishes with a flip.

"Chairman Mao said, 'We should civilize our spirits and be brutal on our bodies,"' says Li, a retired engineer who rides his bicycle to the park every morning. "We may be old, but we have a young person's spirit - and good health."