Anything that's fun, inexpensive and offers a good physical workout is bound to attract attention. It's even better when it peaks on a 28-day cycle.

Nordic skiing, commonly known as cross-country skiing, cycles in popularity in this region with our annual endowment of snow. In good (read "snowy") years, it attracts new recruits and rewards its stalwarts with adventure, camaraderie and aerobic action that can burn 900 calories in one hour of enjoyable effort. In "bad" winters (read "little snow") it recedes into the recreational background.

Veterans of the trails go where and when they must to find the glide. This year, snow has been scarce in the lowlands and valleys. But across the Lake Erie snow belt and on the ridges, from the Laurel Highlands south through West Virginia's high country, skiers have found relief from mild-winter syndrome.

Best of all, those wintry regions were blessed with snow during last week's full moon. Among cross-country enthusiasts is a subset of skiers who like to explore the winter nightscape. To their delight, January's full moon coincided with ideal conditions -- new powder atop a crusted base.

If temperatures were a little low when the moon was brightest, the devoted were not deterred. A little cold, they say, is part of the fun.

"It's like going out into an enchanted forest," said Mike Sayre, co-owner and manager of White Grass Ski Center in Davis, W.Va. White Grass is one of few ski facilities in the region focused entirely on cross-country.

"You're out there and it's so quiet. It's just your breath, your heartbeat and you," he said. "You're surrounded by a thousand points of light from every snowflake or tree branch that's angled to catch the moonlight. All of that is why night skiing appeals to me."

Sayre's not alone in his nocturnal attraction to the trails.

"We've got a whole crowd of people who come up here when the moon is full and they wait around all day for [night skiing]. When the moon comes up they just spread out across the trails."

A full moon can shed 10 times more light on the earth's surface than a quarter moon. When that light is reflected off snow, the effect is startlingly bright. Colors are easily distinguished in the kind of moonlight that bathed the trails last week.

"You can easily read a map off the moon without a head lamp," Sayre said.

The same full moon bathes Western Pennsylvania at night.

"It's kind of hard to explain the attraction, but it's like a little adventure," said Bob Ruppel, who owns Riversport Outfitters in Confluence. "It is just so beautiful how the moon glistens off the snow. It's quiet and kind of eerie, but it makes you want to be out there. How many people get to see the woods like that? Sometimes we see wildlife, mostly deer, and sometimes a bear track."

Ruppel also operates the cross-country ski rental concession at Laurel Ridge State Park on Route 653 atop Laurel Mountain. It's against regulations to ski in the park at night, but Ruppel says he knows many skiers who seek out other areas where they have permission or where there are no specific rules against night skiing.

Ruppel said it's always best to check regulations for public trails before venturing out at night.

Cross-country skiing is an inexpensive sport after the initial investment. Beginners can get good skis, boots and poles for under $200, and there are no lift ticket fees on most public trails. Private venues set up for cross-country skiing, such as White Grass, generally charge a modest fee for a day of skiing.

The health benefits of cross-country skiing are widely recognized. It's a wonderful cardiovascular workout that uses a large percentage of your muscle mass: lower extremities for propulsion and support, trunk for balance and support and upper extremities for propulsion.

But the benefits of cross-country skiing go beyond the physical, said Charlie Yerrick, a director of cross-country skiing at Trapp Family Center in Stowe, Vermont, who has family ties to Pittsburgh. "While the physiological benefits are clear, there is also a spiritual benefit," Yerrick said. "It's very helpful in clearing your head. I do some of my best thinking out in the woods."

Both Sayre and Ruppel advocate certain precautions when night skiing. Their advice boils down to knowing where you are, staying on marked trails, dressing in layers and being prepared for changing conditions.

"The weather can change quickly. If clouds move in, you can't see as well," Ruppel said. "Take a headlamp and some lightweight but warm extra clothes in a daypack."

Sayre added that it's best to ski with a group.

"You never know what could happen if you go out alone at night," he said. "Only go out on the trails as far as the weakest member can make it back. Think of it as sharing a special experience. Besides, it's more fun to have someone huffing and puffing beside you."