"Many of us tend to think cardiovascular disease hits in older age, but arteries begin to stiffen when we are very young," said study lead author Nicole Proudfoot from McMaster University in Canada.
"It's important to start any kind of preventative measures early. We need to ensure that small children have many opportunities to be active to keep their hearts and blood vessels as healthy as possible," Proudfoot said.
For the study, more than 400 children between the ages of three and five years were involved. Over the course of three years, the researchers measured and analysed key markers of heart health cardiovascular fitness, arterial stiffness and blood pressure.
The researchers calculated cardiovascular fitness by measuring how long the children could last on a treadmill test and how fast their heart rates recovered after exercise.
They measured arterial stiffness by how fast their pulse travelled through their body and used ultrasound images to measure the stiffness of the carotid artery. They also measured blood pressure.
The research team tracked physical activity each year by having the children wear an accelerometer around their waist for one week, allowing researchers to determine the amount and intensity of their activity each day.
The researchers determined that while arteries stiffen over time, the process is slower in young children who have been more active.
Those kids also showed more endurance on the treadmill, suggesting they had better cardiovascular fitness and their heart rates came down faster after exercise.
While the study showed overall physical activity had favourable effects on cardiovascular health, more intense physical activity was more beneficial.