There's something new at Rock Creek Park, my friend said, and it's really worth the trip in from the suburbs.

My husband and I and three of our children put on warm-up suits, packed a picnic lunch and headed down to the park just below Calvert Street where the new "adult" obstacle course begins.

The course, designed by the Perrier Company of California, is spread out for about a mile along the creek. Directions and diagrams are posted to show novices how to use the 18 different exercise stations.

The children watched my fumbling attempts to walk the balance beam at the first stop. "Come on Mom, geez, can't you go any faster?" After a while they concluded that I couldn't, and made the obvious decision. "We'll meet you at the end" they called and raced away. We weren't exactly sorry to see them go. Being shown up by agile 14-, 12- and 9-year-olds isn't easy to take; with them gone we could move along at our own pace.

We did pushups and jumping jacks and leg stretches and chose to walk briskly between stations although the directions said to job.Most of the people (who would have thought that so many would be out exercising so early on a Sunday morning?) were doing just that: jogging along and even jogging in place while waiting to get on the equipment.

I especially liked the rings where you kind of hang on and make big body circles for a great stretch, and my husband liked the vaulting bar, which I couldn't manage at all. "Look, it's easy" he said as he and a few other exercisers demonstrated. "Just lean on the bar and kind of flip your legs over." All I could manage was to bang my knee and ankle in a kind of slow-motion hop. I redeemed mystelf at the sit-up station though. I did sit-ups for the entire chorus of "Blue Moon," which I hummed to myself as I bobbed up and down and up and down.

Each stop on the course has three levels of competence: "starting," "sporting" and "championship," with suggested repetitions for each. It is designed to give a person -- blooming athlete or fading also-ran -- a complete workout. The people doing the course were unusually friendly and helpful. "I couldn't do that either at first" one guy told me sympathetically as I tried to handwalk between two parallel bars. "And now watch." Wouldn't you know he did the whole thing backwards. "You'll get the hang of it soon, no pun intended," he said as he jogged away.

Almost everyone called out a "Hi" between huffs and puffs and, although it seemed a bit odd at first to lie down beside a perfect stranger in the middle of a park beside a bubbling brook and do pushups, by the end of the course it was perfectly natural. Bike riders whizzed by, and one guy jogged along playing the flute. My son was delighted to meet Kermit the Frog, who was riding along on a jogger's hand, the word "Hi" inscribed on his chest.

We caught up with our whiz kids at the chinning bar (another failure for me) and then the five of us hiked back through the park to get our picnic basket. It was a speedy picnic because there was a cool wind, and we were glad we had a thermos of coffee along with the chicken sandwiches.