It's not the cold that's to blame for so many golfers, bikers and runners spending winter on the couch. It's the lack of light.

At least that's what Stacy Ingraham says. According to the exercise physiologist at the University of Minnesota, "Winter is a sunlight issue. The fact there is less of it affects our motivation."

Ingraham said it's essential for everyone, at every fitness level, to stay plugged into their warm-weather pursuits all year long. How? By continuing to focus exercise on the body parts that allow you to participate in the first place.

Golfers, for example, can lift weights to strengthen their backs and do exercises that power them through shots. Runners and cyclists, who tend to have well developed quad muscles, can use the off-season to zero in on the often underused glutes and hamstrings.

As for finding the motivation in our low-light season, well, there are ways to get help with that.

"Find a support system, group or workout buddy," said Ryan Sonnenburg, a certified personal trainer at Life Time Fitness.

While some people prefer to work out alone and tap into their inner trainer, others need a gym setting and expertise to keep them involved. "Relationships can be such a valuable tool," Sonnenburg said.

Still, Ingraham cautions that some summer sports enthusiasts, especially those who compete, might need to lower their expectations for their winter workouts. Consider them a way to set the stage for fitness, she advises. "At least you have a starting point when spring comes."

The golfer A person could set a watch by Erik Rasmussen's warm-weather routine. From the end of March to the end of November, the Shoreview golfer has had the first tee time Saturdays at North Oaks Golf Club -- for 15 years and counting.

Rasmussen, 47, also likes to "sneak in nine holes" one or two nights a week or find an hour to swing through a bucket of balls to keep sharp. And when he golfs, he walks.

With the unseasonably mild weather the past few years, Rasmussen's season has been extended. "I golfed the Saturday before Thanksgiving," he said. "It's not like 10 years ago when it was unheard of to play in November or March. ... Still, it's important to get ready."

How can he get ready for golf when the course is covered in snow? Rasmussen heads to the Shoreview Community Center for a full-body workout. Several times a week, he spends about an hour on core-stability and strength-training workouts.

Mainly on machines, he cycles through lat pulldowns, abdominal exercises and leg presses and curls, all geared to helping him swing a 9-iron or bend over a tricky putt.

By focusing on exercises that directly align with golf, Rasmussen is taking the right approach to his off-season. And he's confident he'll be in game shape for his annual May golfing trip.

The cyclist Andy Tetmeyer's world seems like it's always spinning. During the outdoor cycling season, he's a gravel-road racer. And his body is keenly aware of the rigor required. Races can last several hours.

To keep in shape, the St. Paul resident rides the 13 miles to and from work at Shoreview's Hed Cycling Products, where Tetmeyer makes state-of-the-art cycling wheels. In the summer, the bike commute takes about 40 minutes each way. In winter, it can be as long as 90 minutes if the roads are thick with snow and ice. Tetmeyer, 46, packs it in and drives to work if the temperature drops to zero or below.

In addition to biking, he also tries to build his endurance by lifting weights and occasionally swimming laps.

Still, he knows that even with his winter routine, he'll have to pick it up in spring if he wants to win any of those road races.

"The intensity drops because you just can't maintain what you can in summer," he said.

The runner Amy Schmidt, 27, of Lakeville has been hitting the pavement for 10 years. But winter never has been a good companion. When the weather forces her indoors, she dreads the monotony of a treadmill.

A few years ago, a tough winter "messed up" her running schedule -- and changed her ideas about how to stay fit during that season.

"I felt like running was the only way to get a good workout," she said, "but some of my friends opened my eyes to other exercises."

Those other exercises included working her stomach and back muscles for stability and doing yoga at least once a week, including hot yoga in winter.

"Since then, I've embraced winter," she said.

She also has attained some running milestones: Schmidt ran the Twin Cities Marathon in 2010 and 2011 and hammered out at least 10 half-marathons plus a few shorter races.

"Winter is nice, but I don't focus on running as much," said Schmidt, who logs 10 to 20 miles per week. "But when February and March come, they're awesome. It's a new environment. ... My mind is healthier, and my body is healthier."

Bob Timmons • 612-673-7899