Heading the ball in soccer is popular with fans. Like a showy dunk in basketball or a devastating overhead smash in tennis, it demonstrates a player has advanced skills.

But a new study shows that repetitive headers and accidental head impacts in soccer lead to changes in blood patterns.

Norwegian researchers analyzed blood samples taken from professional soccer players during match play and training that involved heading the ball — which means, as one might surmise, directing the ball with one’s head rather than kicking it with one’s feet.

According to U.S. Soccer, players age 11 and under should not head the ball, period. And players 11 to 13 can practice heading no more than 30 minutes a week.

Beyond that, heading is allowed, although it continues to generate controversy in the sport, played by millions of people around the globe.

The researchers drew blood samples from professional soccer players at rest. More samples were taken one and 12 hours later after three scenarios: accidental head impacts during a match, repetitive headers during training and high-intensity exercise.

Following head impacts and headers, the samples showed “specific alterations” in microRNAs, blood biomarkers associated with signaling pathways that suggest brain changes. But the microRNAs were unaffected by other high-intensity exercise.

Scientists hope the findings will help shed light on brain injury severity and the damage caused by head impacts in soccer.

While the voices questioning heading in soccer are growing louder, it may never leave the game completely. Use your head — pardon the pun — and be sure your soccer coach has your safety top of mind.