Last night, at the Lynn Woods Summer Cross Country Races, I wore long sleeves for the first time all season. Yes, it?s that time of year again.The first day of fall is Sunday (we had a harvest moon last night). That means colorful New England foliage, shorter days … and, for us runners, cooler temperatures.It hasn?t become sweatpants weather just yet, although I did bring a pair of sweats just in case. But in the Woods, on the short race up the Middle Road of Steel Tower, the long sleeves came in handy. (Next week, by the way, is the last week for the free Wednesday-night Woods cross country races.) I layered up, wearing the long-sleeved shirt over a T-shirt. If I got too hot, I could have tied the long-sleeve shirt around my waist like I saw a fellow runner doing yesterday morning.Of course, the nights are arriving earlier, too. While this means earlier opportunities to see the moon like the gorgeous one in the sky last night, it also means runners accustomed to summer-evening runs need to be aware that now, in the words of Yogi Berra, “it gets late early out here.”Autumn in New England also means getting ready for the gusts of wind that cheerfully blow away the leaves that people have raked into piles … the same gusts that make things challenging for high school soccer and football players. Hold on to your hats!Today is the seventh annual Clock to the Rock 5K, which starts in Central Square at 6 p.m. Race-day registration is $20. The course includes part of Lynn Shore Drive, so runners will get to see the Atlantic coastline.Several runners I know are running their second race in two days, having run the Lynn Woods course on Wednesday. I wish them all good luck. Who knows, maybe I?ll join them!Joe Abelon of Lynn is helping out with the scoring for both races. I asked him about running back-to-back courses.?In the national NCAA championships, (you could run) one day in the 5,000 meters and the second day in the 10,000 meters,” Abelon said. “Indoors, it?s quite frequent. In a two-to-three-day meet, you can double in an event. In the distance medley relay, you run the anchor leg of the mile, (then) the qualifying heat of the mile, then the final.”Abelon added, “You can run back-to-back if you?re in shape. Then you can start recovery. Or, if not, you run the first race moderately and in the second race, you run harder.?In the Woods, some people just go out and run under control. You don?t beat yourself to death. You go 70, 80 percent. The next day, you?re able to do it again.”Of course, there are limits to running back-to-back.?I?m not going to run a half-marathon and the next day something else,” Abelon said. “Usually it?s a 5K, 5-mile that you?ll double up on. I wouldn?t run a half-marathon or marathon and come back and run the next day.”In Wednesday?s Lynn Woods Summer Cross Country races, Michael Smith of Beverly won the Out and Back via Middle Road (4.6 miles) race in 30:16. Greg Esbitt of Salem was second (30:43) and Michael McKie of North Andover, third (31:34). Nakri Dao was the top Lynn finisher, taking seventh (33:59). Susan Collins of Rowley was the top female finisher (12th, 36:54).In the Steel Tower via Middle Road (2.3 miles) race, Doug Wilson of Lynn took first (15:16), followed by Paul Hennessey of Melrose (17:46) and Ted Kennedy of Swampscott (18:18). Kate Swails of Salem was the top female finisher, taking seventh (20:05) with Paula Clancy of Lynn grabbing 10th (21:03).In the 1.59-mile Kids Race, Emma Carney of Winthrop took first (13:31). Joseph Carney of Winthrop, second (16:29), Olivia Ford of Essex, third (17:29) and Sabrina Armstrong of Lynn, fourth (18:58).