Joel Wiens is in his element in winter, but winter doesn't last all year.

The founder of Wiens Sports International for nearly 30 years has made underwear and other inner clothing that kept athletes, hunters, skiers and other outdoor enthusiasts warm but not overheated.

The company, based in Eagan and known as WSI, even supplies some cold-weather gear for NFL teams, including the Vikings, Jaguars, Patriots and Eagles.

But Wiens wants to end the slowdowns that happen at other parts of the year. Now the company is developing a consumer line using its thin- but-warm fabrics that seem to cling to the body.

"It's like going back to the days of 'Star Trek,' " he said. "The clothing is streamlined, like a natural extension of your body."

Wiens, 50, has been interested in comfortable athletic clothing since middle school. "I took a T-shirt and made compression shorts out of it with a head hole for the waist and arm holes for my legs," he said. "My mom and grandma sewed it."

His first big hits when he started his company in 1990 were a protective short for hockey players and a sliding short for baseball players.

Matt Strahm, a pitcher for the San Diego Padres, said he has been wearing WSI's compression gear and slider shorts since his mom found them when he was a kid growing up in Fargo. "I'm still wearing the brand," he said. "It's the most comfortable I've found."

Wiens sent him a slightly thicker pair of sliders when his former team, Kansas City, played its opening game at Target Field in April. "They definitely did their job," he said.

Wiens also developed a high-tech body map shirt with one of the pitching coaches for the Chicago Cubs.

"He asked me if I could keep the arms, back and chest a little warmer than the rest of the body," Wiens said. "It's where pitching mechanics come in. It's crossed over well into other sports."

WSI is small, with annual revenue of about $2 million, but it has caught the attention of investors and venture capitalists at times. "We've been approached to sell the company, add shoes, and grow to be like Nike and Under Armour," he said. "I look at the big companies and see a lot of headaches. I want to do one thing really well."

Bill Welle, who founded the Wellefast sports performance program in Hopkins, said that what makes WSI gear different is how it's made.

"The quality of the sewing is awesome," he said. "You're lucky to get through one season with some of the other brands, but I know athletes who still have a WSI shirt from 2006."

Wiens listens to athletes, trainers and equipment managers about what's needed and then gets it made.

The Super Arctic Shield for $200 is a favorite of one of this year's Super Bowl players, who has a contract with a more famous apparel brand. It is made of a super thin, lightweight fabric that functions like a windstop but also has gussets for breathability under the arms. "We don't sell it to the consumer," Wiens said.

He buys some fabrics from a few Minnesota companies, such as Minnesota Knitting in Mendota Heights. But most are made in mills on the East Coast. None of the fabric originates from outside the U.S. All of it is then cut and sewn in Minnesota.

Many of the sewers are Hmong residents who operate out of their homes. With a large number of them retiring, Wiens is starting to add some automation, especially for cutting.

"WSI is a tried-and-true Minnesota company," said Janet Miller, creative director at Love From Companies in Roseville, including Love from Minnesota stores. "We wanted to work with WSI because it's local, but his line works so well in the cold," she said. The eight Twin Cities stores sell WSI's base layer pieces, socks, gaiters, mittens and a special hat for women or men with hair in a bun.

Wiens said that sales of his high-tech apparel is split evenly between men and women, but he thinks the growth in his women's apparel line shows more potential. WSI also has a group of about 40 social influencers around the country who are hunters, many of them women. Both Love From Minnesota stores and Sun & Slope in Wayzata have purchased pieces designed specifically for their customers, including a women's Alpine team.

Wiens creates special orders for many clients, whether it's a pant with built-in knee support for Joe Mauer when he had a knee injury to a shirt with built-in rib protection for the Green Bay Packers.

"I was the first one to make a protective shirt that was less than one-half inch thick," he said.

WSI's latest concepts include photo real apparel with images of Minnesota made for a Super Bowl ice-fishing event, including the Duluth Lift Bridge, the Walker Art Center's Spoonbridge and Cherry, and the Capitol. "I'm hoping he puts the Minnecentric MVP [most valuable parka] winter coats into wider production," said Welle.

The company's revenue is divided evenly among sports teams, hunters and individuals in snow sports. While 75 percent of it comes from cold weather, Wiens is expanding his line into warm-weather apparel with bamboo fabric that has natural wicking properties and is antimicrobial.

He added the line for spring and summer to try to keep his sewers busy year round.

Competing with established sportswear companies such as Nike and Under Armour won't be easy, but Wiens wants to focus on wearable technology 12 months of the year. 612-673-7633