On most mornings, usually before the sun rises, you’ll find Julia Martinusen rowing gracefully across the waters of the Des Moines River in her boat, enjoying a sport that has caught the interest of dozens in the area, though it’s still largely unknown to most in the city.

“There are usually a few hardy souls out there with me,” she said.

Martinusen, a food editor at Meredith Corp., joined the Des Moines Rowing Club in 1990, and her interest in the sport took off from there. She enjoys the fitness benefits rowing provides, as well as the friendship and camaraderie.

On Saturday, the 150-member club will host the 21st annual Head of the Des Moines Regatta, the first “head race” of the fall rowing season and one that area rowers say is at the top of its class.

“For me, our regatta is like Christmas Day,” said Martinusen, who serves on the club’s board of directors. “I’m as busy preparing for it as I am Christmas Day. It’s a lot of time, but by the time the big day gets here, it’s all worth it.”

Along with her role in planning the regatta, Martinusen is preparing to compete in the women’s master 8 and women’s single events and will also be “coxing” two boats.

Bob Rennebohm will participate in his seventh regatta on Saturday with members of his eight-man boat, which will compete in the men’s master 8 event. He took up rowing at the urging of his daughter Molly, who competed in rowing at the University of Wisconsin-Madison.

“She kept saying, ‘Dad, this is a really cool sport. You ought to try it,’” Rennebohm said. So he started with the Des Moines Rowing Club’s novice program, which trains beginner-level rowers at Gray’s Lake before moving them to the Des Moines River.

Like Martinusen, Rennebohm has remained with his crew of eight since his novice class, though a few have come and gone, and they have gone on to compete in Des Moines, Rockford, Ill., the Quad Cities and Waterloo. The sport’s teamwork and concentration remains an attraction for him.

“I’d been an athlete in high school and college, so there’s kind of a feeling and anticipation you had and I didn’t feel like that until I got back into rowing,” said Rennebohm, who competed in football and swimming at the University of Wisconsin-Madison. “It re-stirs some of those old feelings you had when you were an athlete.”

Both Martinusen and Rennebohm agree that, unlike many other sports, rowing is suitable for athletes of all ages. Martinusen hopes she is still rowing when she turns 90.

“I think that one of the great things about the sport is that there’s no shock or stress on your joints like you’d have in running,” Rennebohm said. “This is a sport that really exercises all of the muscle groups but is not hard on you.”

Martinusen has incorporated rowing into a mix of athletic endeavors. She will compete in the Boston Marathon – her fifth marathon – in April and traveled with a group this spring to bicycle through France.

“I have the idea that I want to do something every day for about an hour,” she said. “I used to exercise because it was good for me. Now I do it because I enjoy it.”

Others in Greater Des Moines have latched onto rowing as a sport that is more fun than work, and interest has continued to grow. The club once trained a novice class that consisted of approximately two eight-person boats and has grown to train as many as nine eight-person boats in each class, although membership numbers in the club have remained fairly constant in recent years.

Rennebohm, owner of Heard Gardens in West Des Moines, said that, despite family and career obligations, as well as other commitments, his eight-person crew has not found it difficult to get together one or two nights each week to train.

“It seems in our boat everyone enjoys it so much they establish it as a priority,” he said. “For the most part, everyone’s there and looks forward to it.”

Martinusen has found an interesting dynamic between her rowing interests and her career at Meredith, which has been a source of new club members for a number of years.

“It’s a very visual sport,” she said. “And I’ve found a lot of our artists from Meredith are drawn to it. There’s something about the beauty and fluidity of it.”

The Des Moines-based publishing company has been supportive of the Des Moines Rowing Club and its employee members, supporting improvement efforts at Gray’s Lake, home to the club’s novice program, and again sponsoring the Meredith Mixed 8 race at Saturday’s regatta.

Approximately 600 rowers and 30 clubs and universities will compete in the Head of the Des Moines Regatta, which is a head race, meaning that the rowers compete against the clock rather than one another. These races are held in the fall, while head-to-head races, called sprint races, are held in the spring. Saturday’s races will begin at the Des Moines Botanical Center and will continue upstream past Prospect Park.

After putting in hundreds of volunteer hours preparing for the regatta, club members enjoy the festivities of the day and meeting rowers from throughout the region.

“That’s what I think rowing is all about is sportsmanship and enjoying the day,” Martinusen said. “If you get all caught up in the competition and try beating everyone, it’s just not fun.”