For the first five years of Kelly Madden's marriage, she politely encouraged husband, Bob, to exercise.
The 40-year-old Baltimore resident, who took yoga classes and ran several times a week, wanted him to regain the fitness he developed as a runner in his late 20s and during his stint in the Marine Corps in the late 1990s.
"He just wasn't interested," she said. "I didn't want to nag him about it. I said, 'You'll just get into it when you're ready.' "
But last August, after lots of subtle suggestions and little change, Madden stepped up her game and found an event they could do together: the Marine Corps Marathon 10K.
"For five years, I didn't want to do anything," said Bob Madden, 37. "I had to come to the right place in my mind where I was comfortable. Kelly was kind of that pusher, saying, 'Hey this is something you should do.' I think that really helped out."
New research from the Johns Hopkins Bloomberg School of Public Health shows the Maddens are not alone.
If one spouse improves his or her exercise regimen, the other is likely to do the same, said Laura Cobb, a Bloomberg doctoral student and co-author of the study looking at physical activity among married couples.
"Couples tend to change physical activity in the same direction," she said.
Cobb and her colleagues analyzed data from an Atherosclerosis Risk in Communities (ARIC) study, which followed adults ages 45 to 65 years old in the late 1980s and early 1990s. During the study, researchers asked more than 3,200 couples about their physical activity levels at two medical visits held about six years apart.
Using data from the ARIC study, Cobb and her colleagues found when a wife met the recommended exercise levels during both medical visits, her husband — who did not meet the recommended levels during his first visit — was 70 percent more likely than a husband with a less physically active wife to meet those levels by the follow-up visit.
Physically active husbands also positively influenced their nonactive wives. When a husband met the recommended exercise levels, his wife — who, again, did not meet the recommended levels during her first visit — was 40 percent more likely to meet those levels at the follow-up visit.
Cobb said there are several theories as to why.
Married couples share the same environment and have similar influences, she said. For example, couples living in walkable cities will have more chances for leisure-time physical activities like walking or commuting by bicycle than those living in a less walkable suburb, Cobb said.
In addition, spouses just tend to influence each other, she said.
Cobb added that while research also showed a slight indication that at inactive spouse could make his or her partner become less active, the numbers are not "statistically significant."
The American Heart Association recommends men and women perform at least 150 minutes a week of moderate exercise or 75 minutes a week of vigorous exercise to improve overall cardiovascular health.
Lynne Brick, president of Brick Bodies Fitness Services, said the research findings are no surprise. Brick and her husband, Victor Brick, often see women or men join one of their seven Baltimore-area Brick Bodies fitness centers, only to have their spouses join a few months later.
"It just happened the other day," Brick said. "My husband and I were in the club, and there was a member who had been a member of the women's club. She brought her husband in to join, and they joined the coed club together because they wanted to exercise together."
Social and cultural support, whether through a spouse, exercise buddy or even small-group training, is essential when it comes exercise adherence, she said.
"If your spouse is committed to changing their behavior, it is so much easier to do it together," Brick said.
Madden's commitment to running and fitness "definitely" motivated Bob Madden to get back in shape, he said.
"I can't be 37 and weighing 230 pounds, because the longer I stayed at this weight and [did] not exercise… it just gets harder and harder the older you get," he said.
With the October race date looming, Madden began running at least once a week and riding his bicycle outside or inside on the trainer four days a week. Along the way, he lost more than 35 pounds.
"I could have easily spent the next two years just sitting on the couch again," he said. "But it was the right time, and it was the right spouse."
Both Maddens completed the race, and since then, the tables have turned, Kelly Madden said. Her husband is already registered for a half-marathon in Ocean City in May and might participate in his first-ever triathlon in September.
"He's definitely a motivator for me now," she said. "We'll run together. He'll say, 'I ran at work yesterday. It's a nice day out, and we need to take advantage of it.' He didn't do anything for so long, and then he did, so it's almost like I have to stay in shape too, because he's working hard at it."