Winter is no reason to put an exercise routine on hold, local fitness experts say.

Adam St.Pierre, exercise physiologist at the Boulder Center for Sports Medicine at Boulder Community Hospital, said one of his favorite quotes comes from an L.L.Bean catalogue.

"There's no such thing as bad weather -- only bad clothing," he said. "With minor modifications in clothing, exercise is very feasible in the winter."

And, since Colorado's winters can be fairly mild, St.Pierre said local trails rarely are impassible.

Annie Sirotniak, a physical therapist in the Sports Medicine department of University of Colorado's Wardenburg Health center, said she encourages students to take advantage of the outdoor hiking trails in Colorado.

"It's the type of exercise that offers a great vertical gain," Sirotniak said.

Sirotniak said getting outside in the sun and being active, even if it's just for a short period of time, helps with seasonal affective disorder and the winter blues.

"It's important to get on a regular schedule and try to be consistent," said Sirotniak. "But don't put too much pressure on yourself. Stay positive and try to get in a few workouts each week."

St.Pierre, however, said winter does sustain one major obstacle.

"The hindrance to a fitness routine in the winter is the darkness," St.Pierre said.

The days are already getting shorter and, starting Sunday, Colorado will lose one hour of evening daylight.

"Avoid trails after dark because of the wildlife," St.Pierre said. "If you are going to run on a trail after dark, make sure you have adequate lighting or take a group with you. Don't go it alone."

St.Pierre said students' access to the Recreation Center on campus could remedy this problem.

He offered some tips for stretching:

Before any workout, the muscles need to warm up -- he recommends an aerobic activity like jogging outside.

Stretching before working out isn't necessary -- he said stretching a cold muscle doesn't tend to do much.

It's important to stretch the warmed muscles after the workout -- but make sure to warm-down indoors.

"Stretching outdoors after a hike is inviting illness if it's cold out," St.Pierre said.

Sirotniak said joint-loosening exercises can help get the body warmed up as well.