Active preschool kids have healthier hearts: McMaster study

The benefits of physical activity on heart health show up as early as preschool, says a new study out of McMaster University.

Important for kids to have time for active play, says researcher

Nicole Proudfoot and Hilary Caldwell, PhD candidates in Kinesiology, with one of the study participants, Freddie Warriner. (Submitted by McMaster University)

The benefits of physical activity on heart health show up as early as preschool, says a new study out of McMaster University.

The study, published in the peer-reviewed journal Pediatrics, looked at 418 young children in the Hamilton-Burlington area over the course of three years.

Each year — starting at age three to five — researchers measured the children's activity level in their daily lives, as well as markers of cardiovascular health: cardiovascular fitness, blood pressure and artery stiffness.

The children who were more active had better endurance on a treadmill test, the study found, and their heart rate slowed down faster afterward.

Less active children also had stiffer arteries, researchers found.

Doing more vigorous activity was linked to greater health benefits. The children's ateries stiffened over the years, but this happened more slowly for kids doing more intense activity.

This physical activity may also have long-term benefits, Proudfoot said.

"[We] would predict that if they continue to be physically active through childhood, it would put them at a lower risk of heart disease as adults," said lead author Nicole Proudfood, a PhD candidate in Kinesiology at McMaster. 

Proudfoot says it's important for daycares and classrooms to give young children time for active play. (Paul Smith/CBC)

Doing more vigorous physical activity was also associated with slower increase in blood pressure over time in girls.

"The protective effects of physical activity on cardiovascular health begin early in childhood," the study suggests. 

Make time for play

The findings highlight the power of physical activity and importance of getting kids active, said Proudfoot.

"It doesn't need to cost money," said Proudfoot. "Kids can dance around — that's going to get their heart rates up — tag, a lot of those typical childhood games that kids often play when they're outside."

Doing more vigorous physical activity was also associated with a slower increase in blood pressure over time in girls.

Proudfoot was still somewhat surprised, even though they predicted the results.

"The children were so young and we didn't know if we'd actually be able to see changes," she said, adding that daycare and Kindergarten facilities should also give kids plenty of breaks for active play.

This is the first study to show the benefits of physical activity on blood vessel health in early childhood, Proudfoot said. Future research should examine whether these positive effects carry on into later childhood and adulthood, the authors write.

Nicole Proudfoot, the lead author on the study, is a PhD candidate in Kinesiology at McMaster University. (Submitted by McMaster University)

What researchers measured

Once a year, the researchers measured the amount and intensity of the children's physical activity by asking them to wear an accelerometer over their hip for seven days during all the time they were awake (except during prolonged water activity). The study looked at total physical activity, as well as "moderate to vigorous physical activity."

To measure cardiovascular fitness, the researchers ran treadmill tests, seeing how long the child could run on a treadmill that was gradually getting steeper and speeding up. They also measured how quickly the participants' heart rates slowed down after the treadmill test, which also indicates autonomic function.

The study measured arterial stiffness by how fast the children's pulse traveled through their body, Proudfoot said, and used ultrasound imaging to look at carotid artery health.

The study was funded by the Canadian Institutes of Health Research.

Only 13 per cent of participants were non-white, and 22 per cent came from families below the areas median income, the authors said, potentially limiting the study's generalizability.