For some married couples, doing something active together means going for an afternoon hike in the mountains or maybe playing a friendly game of tennis.

But for Bruce and Cristina Worrilow of Marina del Rey, it means competing in triathlons.

The three-sport activity has been a way for the Worrilows not only to stay physically fit but to test themselves together.

The couple, who have been married nearly six years and have two daughters, aged five months and two years, don’t take on the grueling challenge separately. They do it as a team, with Bruce starting out the first two stages of swimming and cycling, and Cristina closing the competition with the running stage.

“It’s a fun thing to be able to share and it’s a fun bonding experience,” said Bruce Worrilow, 47, of doing triathlons with his wife. He is an editor and post-production film supervisor at UCLA. “It feels like we’ve done something together.”

Cristina Worrilow, 35, a Web designer who is originally from Rio de Janeiro, said her husband introduced her to triathlons and the sport has kept her in shape.

“It’s just a fun atmosphere to be competing with other people,” she said.

The Worrilows have also achieved some success with their couples activity. Two years ago, when competing in the co-ed sprint-distance relay at the Los Angeles Triathlon, they won in their division, much to their surprise.

“We were completely stunned,” Bruce Worrilow said of the victory.

“We had no idea we had won. It was a lot of fun,” added Cristina, noting that the couple learned of their victory two days later, when they saw the race results online.

The Marina del Rey couple plans to tackle the Los Angeles Triathlon co-ed sprint relay race again at the ninth annual event Sunday, September 7th. The sprint distance of the race involves a 0.4-mile swim, a 20-mile bicycle ride and a 3.1-mile run.

The Kaiser Permanente Los Angeles Triathlon, presented by Herbalife, begins with the swim stage at Venice Beach, with the professionals starting at 6:45 a.m. and all divisions starting at 7 a.m. The race will end at the Nokia Plaza in downtown Los Angeles.

Late event registration will still be accepted Friday and Saturday, September 5th and 6th, at the Marina del Rey Marriott, 4100 Admiralty Way.

Information, www.latriathlon .com/, or (714) 978-1528.

Cristina Worrilow will take on the final stage of a 3.1-mile run, as Bruce, who had double-hip replacement surgery last year, says he is better suited for the swimming and cycling stages. While Bruce says he is able to run again following the surgery, he notes that “running is so much harder on your body.”

Jan Fambro, a spokeswoman for the L.A. Triathlon, said relay teams are typically represented by a different competitor in each of the three phases, but the Worrilows will only have two on their team, with Bruce swimming and biking.

Bruce Worrilow is no stranger to trying athletic competitions, as he has run a number of marathons, participated in numerous Olympic-distance triathlons, and even competed in three Iron Man races, which are essentially elevated triathlons.

He says he has been “hooked” on the three-sport activity ever since entering his first race in Malibu ten years ago.

Cristina has also done her share of competitions, from windsurfing to triathlons, but she notes that her husband is the real competitive type.

“I made him promise not to get upset if I don’t run fast,” she joked.

While the two were pleased with their victory two years ago, they say they entered this year primarily to have fun.

“We’re going out to have fun,” Bruce Worrilow said.

Referring to the activity they share, the Worrilows said they have not come across any other couples who have merged triathlons with their marriage.

Some couples enjoy traveling together or some other shared experience, Bruce Worrilow says, “We just like to do triathlons together.”