Increased fees to play school sports may have long-reaching health effects. As costs go up, participation goes down, leaving more kids sitting on the sidelines, a study has found.

A University of Michigan survey found a link between income and sports participation. While 51 percent of families earning more than $60,000 per year reported having a child in sports, only 30 percent of lower-income families had a child playing school sports.

Those disparities are worrisome for several reasons, said Sarah Clark, associate research scientist at the university’s Child Health Evaluation and Research Unit.

“Sports is one way that kids can be physically active in an enjoyable way,” she said. “They’re with their buddies. They’re learning teamwork.”

She said that school-based activities such as sports or music programs also help kids stay in school.

The poll found that the average school sports participation fee was $126 per child; when costs for equipment and travel were included, the average rose to more than $400.

The survey, referred to as the National Poll on Children’s Health, found that one in seven parents whose children were not in sports cited cost as a reason. That factor also might be increasingly important.

Sports participation among lower-income students decreased by 10 percent when compared with a 2012 poll on the same subject. Even among parents in higher-income households, nearly 10 percent of parents said their child had decreased sports participation because of cost — twice as high as reported in 2012.

The results are troubling, Clark said. Schools and parent groups try to help reduce costs for low-income students who demonstrate a desire to play sports, she said. But they often fail to consider students who never bother to try out for a team because they know cost will be an obstacle, she said.