The 12,000 runners in Sunday's Twin Cities Marathon likely will shed about two tons of weight.

No, it's not the calories they'll burn, but the amount of clothing they will jettison along the way. Long-sleeve T-shirts and warm-up pants are the most-discarded items, along with sweatshirts, hats, gloves, socks -- worn by many runners in lieu of gloves -- and even the occasional jacket. All wind up in recycling trucks that trail the runners.

This massive clothes dump is a result of Minnesota's mercurial fall weather.

"The temperature changes so fast as the sun rises," said Elizabeth Schoenknecht of the St. Paul running club Team Salubrious. "It can be in the 30s or 40s when you start but quickly reach the mid-50s." That's not an issue at summer races, like Grandma's Marathon in Duluth, because runners don't need extra clothing to stay warm before the race. And at winter runs, including the Freeze Yer Gizzard Blizzard Run in International Falls, participants keep their protective gear on the entire way.

Some runners buy their stuff at charitable clothing stores with the intention of wearing it only a brief time. Others rifle through their clothes looking for well-worn things they won't mind discarding.

Not everyone is as frugal, however. In running five marathons, Schoenknecht has come across "brand-new, name-brand stuff -- sweatshirts and tech shirts [made from synthetic fabrics that pull sweat away from the skin] -- that must have cost $60 or more," she said. "I've actually thought about picking up some of it."

But that would have meant carrying it another 20 miles or more, which is why it got tossed aside in the first place.

Marathoners can assuage their sense of loss by reminding themselves that the clothes are going to a good cause. This is the fourth year that the marathon has arranged with USAgain (pronounced "use again") to gather the discarded clothing and recycle it.

"Knowing that the clothing is going to go to someone who can wear it makes it a little easier for the runners to toss it aside," said John Long, owner of Marathon Sports in Minneapolis.

At last year's marathon, USAgain filled two large trucks with 4,000 pounds of clothing, spokeswoman Jen Hirsch said. This year's tally -- and the size of the "drop zone" -- will depend on the weather. If it's relatively warm, the bulk of the clothing will be discarded within the first two miles, but if it's cooler, the drop pattern will be lengthened.

"Usually, we find most of the clothing downtown along 6th Street and Hennepin Avenue," said Virginia Brophy Achman, the race's executive director. "But we've found things as far out as Lake Calhoun, which is mile 6."

Finding a greener solution not only makes the race a better world citizen, but also a better neighbor. Except for the start in downtown Minneapolis and the finish in downtown St. Paul, the race is run through residential areas. Having the pickup crews go out on the heels of the last runners keeps residents from stepping outside Sunday, wondering if a laundromat exploded on their front lawn.

When Sharon Clark and Sheila Field take their mid-morning daily walk, they retrace the second and third mile of the marathon. They have nothing but praise for the route's cleanliness.

"We've never seen any problem," Clark said, to which Field added, "In fact, it if weren't for the portable toilets -- which they come and get Monday morning -- you wouldn't even know anything had happened here."

Jeff Strickler • 612-673-7392