Sunday, I woke up as sore as I’ve been in a long while. Not just leg sore from running, say, a half marathon, or riding a mountain century. And not the shoulder and arm sore from a long paddle. Full-body head-to-toe sore. That’s what a day of honest work will do.

Saturday, I observed National Trails Day with the Friends of Mountains-to-Sea Trail, sprucing up Section 20 of the MST along Falls Lake. The specific assignment of our eight-person detachment: pick up the acres of flotsam and jetsam that had accumulated along the trail during high tide. (In the case of Falls Lake, that would be when heavy rains raise the water level, pushing debris to higher ground, where it remains when the water recedes. If you’ve hiked Falls Lake, you’re no doubt familiar with this phenomenon.)

At 1.4 miles in length, Section 20 is one of the smaller sections of the 60-mile MST along Falls Lake. The first sign that we might have a long day was when Jeff Brewer, a vice president with the Friends of the Mountains-to-Sea Trail who was directing the overall NTD effort along Falls Lake, told us we’d been allotted 250 trash bags. Seemed like a lot; we would learn shortly just how many 250 truly was.

Before long, Eric Motzno, trail supervisor for Section 20 and our crew chief for the day, was leading us down the trail off Redwood Road in Durham County. Despite passing under I-85, then marching along side it for a couple hundred yards, Section 20 offers a nice escape typical of Falls Lake: passage through a maturing hardwood forest with occasional glimpses of Falls Lake and more occasional encounters with the hundreds of small creeks and freshets feeding into 28-mile-long Falls Lake. We didn’t get past the first creek, about a quarter mile in, before it was time to get out our orange plastic trash bags and dig in.

The low-lying creeks provide a natural path for trash trying to escape a swollen Falls Lake. Plastic pop bottles, glass liquor bottles, basketballs, soccer balls, a bocce ball, a ping-pong ball. Styrofoam cups, Styrofoam ice chests, pop cans, beer cans. Four tires, still mounted on their rims. Stuff I couldn’t identify, stuff I didn’t want to identify. For six hours: bend, scoop, deposit in orange trash bag, repeat. For a break, we’d haul the trash bags, each weighing 35 to 40 pounds, the quarter mile back up to the road. At one point it occurred to me that rolling the tires up the trail to the road might be fun, so I volunteered to shepherd all four. It was more backbreaking than hauling 80 pounds of bagged trash. I don’t know about my fellow volunteers on Section 20, but I took a perverse pride in realizing we had volunteered for the most physically demanding chore of the day. At day’s end, we had about 80 bursting orange trash bags to show for our efforts, and I had earned a good — and early — night’s sleep. It was the most demanding and rewarding day I’d spent on the trail in a long while.

I tried to get a handle on just how rigorous trail work can be. Libby Wile, who manages volunteer programs for the American Hiking Society, said they haven’t done research on just how physically demanding trail work can be. “Our trips vary in difficulty, in the amount of hiking involved and whether it’s trail maintenance or building a trail, so it’s hard to provide an average for them.”

She was referring specifically to AHS’s Volunteer Vacations. This year, AHS is sponsoring 70 Volunteer Vacations, which generally last a week. Each includes anywhere from 6 to 15 volunteers on trail work projects. Last year, Wile said 420 volunteers took part in their vacation program. The projects are pitched to AHS by various land management agencies (a good deal of them state parks) across the country. (Alas, there are no Volunteer Vacations scheduled in North Carolina this year.) Learn more about the program here. http://www.americanhiking.org/volunteer-vacations/

I didn’t need anyone to tell me that trail work was good exercise; my body was doing a great job of communicating that. I was curious, though, about the amount of energy I’d burned on National Trails Day. It was hard to find an online calorie calculator with this specific task. I did find one that came close: the About.com calorie calculator by occupation, covering everything from working in a bakery and bookbinding to steel mill fettling and forging. The closest activity to what I had done was “Forestry, General,” which for the typical 150-pound person (I’m about 20 pounds north of that) burns about 544 calories — or about 3,264 calories over our six-hour shift. That’s nearly twice what we need to power us through the typical day.

Losing weight and toning up while helping your favorite trail: Not a bad way to spend a Saturday. And you don’t have to wait a year until National Trails Day 2012 for the next session. Hiking clubs and groups such as the Friends of the Mountains-to-Sea Trail hold trail workdays regularly.

To find an upcoming workday near you, check out the hiking clubs list at our sister site, NCHikes.com. If you’re with a hiking club, a friends group or any other group or agency that that has a workday coming up, leave the particulars in our comment box below.

For more on our Saturday’s NTD workday on Falls Lake, I refer you again to our sister site, NCHikes.com.