The Midweek Hikers are the geriatrics of the Washington trekking community, but though they are old, they definitely are not feeble.

This is the sort of thing you figure out when you traipse the mountains alongside a 74-year-old woman in tennis shoes and find the conversation increasingly dominated by her and the heavy breathing increasingly dominated by you.

The Midweekers are an informal arm of the 55-year-old Potomac Appalachian Trail Club, granddaddy of Washington's hiking groups. They hike every Wednesday, except in raging sleet storms, and while the six- to 10-mile mountain courses they travel are not as demanding as the Wanderbirds Hiking Club, which enjoys forced marches of up to 20 miles in full battle array every weekend, the Midweekers are no Wednesday strollers, either.

"My wife Kim really founded the club," said Bill Hutchinson, 68, who coordinates the weekly treks, as he led five carloads of hikers west to the Catoctin Mountains on a sparkling day last week.

"Potomac Appalachian Trail Club used to have once-a-month midweek hikes, but they were very easy," he said. "About seven years ago we came back from an exciting series of hikes in Austria and then went out with the Wednesday group. Kim said, 'Wouldn't it be nice if we could do something like this every week, and make it a little more energetic?' "

These days, the Midweekers attract 12 to 20 hikers a week to their gatherings in the Maryland and Virginia mountains, mostly retired folks with a median age somewhere over 60 if you don't count Daisy, the three-legged dog who accompanies former agronomist Jack Meiners.

Last week, 17 turned out for an eight-mile jaunt over two peaks near Thurmont, Md. Hutchinson said it would be easy to spot the group in the parking lot of the Gaithersburg Holiday Inn where they convened, and he was right.

He and his wife were resplendent in buttercup-yellow hiking caps. Dave Brownlie, 75, had a patch-bedecked daypack. Alice Ruddimer, 74, wore weathered sneakers and a floppy hat. Carmelo Caruana, a bear of a man from Malta, had his trousers stuffed into nine-inch boots. And Meiners was nuzzling Daisy. A half-dozen others milled around, looking like anything but Holiday Inn guests.

On the ride to the mountains, Hutchinson said he'd picked the Catoctin route hoping early spring wildflowers would be out. "Last Saturday, we saw the early flowers past their prime in the Potomac Valley, and on Sunday, they were out along the Appalachian Trail in Maryland. It seems to me, therefore, that we should get a nice range here from the low ground to high."

But where he found time to chronicle the wildflowers was a bit of a puzzle. When the walk began near Cunningham Falls State Park, the pace was swift and stayed that way, with only occasional breaks for the laggers to catch up.

It took Hutchinson's practiced eye to spot the tiny blooms as we barreled along the blue-blazed trails. "Rue anemone," he would call out. "Bluets over here. Trailing arbutus. Bloodroot."

Hiking in groups always has seemed odd to me, since walking is one sport you can do all alone. Hutchinson said the appeal is social, with a medium-sized group providing plenty of different people with whom to chat, without being unwieldy. "We tend to end up walking in twos," he said, "but you can switch around."

I wound up switched around to Ruddiman on a long, rocky stretch. She is a tiny woman who races up hills like a mountain goat. At 74, she said she's been hiking seriously for nearly 20 years. The Catoctin walk was a leg-stretcher to her.

"This weekend the Wanderbirds are doing what they call a marathon," she said. "You can go seven, 14 or 21 miles. I'll try 21."

In front of us and from behind, we could hear the murmurings of other conversations through the woods -- discussions of European hiking trips, comparisons of shoes, talk of injuries.

"Do you ever worry," I asked Hutchinson later, "that with all these older people out in the woods, someone might get sick or hurt and you'd have a bad situation on your hands?"

"No," he said. "I had heart surgery myself eight years ago, and every time I go to my cardiologist, he says, 'One of these days you're going to have a cardiac arrest out in the wilderness and die.'

"And then he says, 'What a way to go!' "

The Midweek Hikers charge nothing and welcome new hikers. For information about their trips and other activities of the Potomac Appalachian Trail Club, write to PATC, 1718 N St. NW, Washington, D.C. 20036.