Everybody’s Sport: What soccer really asks of the body

When Atlanta Stadium welcomed fans for eight FIFA World Cup matches this summer, including a semifinal on July 15, it was not introducing soccer to a city that didn’t know it. It was handing a megaphone to a city that was already shouting its love for the “beautiful game.”

“We are claiming it,” says R. Amadeus Mason, an orthopaedic sports medicine physician at Emory Healthcare. “We are now the center for soccer in the United States.” Mason has a close view of that rise. He serves as chief medical officer for Atlanta United FC and formerly served as the medical director for USA Track and Field, a combination of roles that puts him inside professional sports in a way few academic physicians can match.

What Mason and his Emory colleagues also know, from years of treating players at every level, is that the sport’s growth comes with a physical price. The game is a demanding one, and the gap between what it looks like from the stands and what it asks of the body is wider than many realize.

Chess at full speed

“Soccer is like working out and playing chess at the same time,” Mason says. “It demands everything at once.”

The sport asks something of the body that almost no other game does, he says: continuous, unpredictable, full-body movement for 90 minutes, with few sustained breaks. A professional outfield player covers six to eight miles per match, but the mileage alone doesn’t capture it. Woven into that distance are explosive sprints, hard decelerations, lateral cuts, backward runs, jumping, landing and kicking, all strung together in response to a game that is constantly changing.

“Soccer is the only sport where you are moving consistently,” Mason says. “You don’t have a break. And even when you don’t have the ball, you’re having to move to get into position to facilitate the ball.”

That cognitive layer is part of what separates soccer from other running-based sports. A defender clearing the ball isn’t just kicking. They’re reading the field, finding a midfielder, calculating the next two or three passes, and moving to create space for a teammate who may never receive the ball. All of it happens in real time, at speed, for the entire match.

That blend of constant motion and constant decision-making is what makes soccer so beautiful to watch, and so hard on the body.

What breaks, and why

The injury Mason sees most often in professional soccer is not the one most fans would guess.

“Hamstring, hamstring, hamstring,” he says.

Ankle contusions are another frequent problem. ACL tears, while feared and sometimes career-altering, are not the most common injury in the sport, but they are among the most consequential.

The hamstring problem comes down to what soccer asks of that muscle group. Players don’t run in straight lines at predictable speeds. They accelerate, decelerate and change direction constantly, reacting to a game that doesn’t announce its next move. A right winger making a run doesn’t know whether the ball is coming inside or wide. They have to adjust in an instant, and the hamstrings take much of the strain.

“It is the change in speed and change of direction that has to be done so frequently,” Mason says. “If you think about football, a running back has a predetermined route. A right winger, they don’t know how their midfielder is going to service the ball. They just know they’re going to make a run. So it’s more of a responsive thing as opposed to something predetermined.”

Ankle sprains follow their own pattern. A typical outside ankle sprain, the most common, may improve enough for light activity within a week or two. But pain higher up or toward the front of the ankle can signal a more serious problem.

“Any pain you have in front, get in and get seen,” he says. “Those ligaments can take a lot longer to heal, and there are things we can do early that can get you back more quickly.”

Mason also cautions against judging an injury’s severity by appearance alone. “Don’t just look at it as, oh, it looks terrible. How are you responding? That’s the big thing.”

What pro sports medicine looks like

On matchday for Atlanta United, Emory Healthcare’s sports medicine team is at work well before kickoff. Athletic trainers arrive hours early. Physicians, trainers and performance staff move through the final checks that keep players ready and safe. GPS data from the week’s training sessions has already been reviewed, including each player’s distance, acceleration load and “freshness,” a measure of how recovered a player is relative to their individual baseline.

“You want somebody to be fit, but you also want them to be fresh,” Mason says. GPS data gives his team something no amount of watching can replicate. It measures every player across the roster at the same time. “When we’re watching a player sprint toward the goal, we don’t see what our center back is doing. But we need to know that information so that when he comes off, we can say, you covered this much distance sprinting, and that means tomorrow we need to do XYZ to help you recover.”

That infrastructure includes GPS vests and diagnostic ultrasound available at training, as well as a roster of support professionals: exercise science PhDs, sports nutritionists and physical therapists. It represents a level of medical support far beyond what most recreational soccer players ever see.

What all players can do to prepare

So what about the adult enthusiast who plays pickup on Sunday afternoons? Or the 13-year-old on a club team three days a week?

Mason’s advice for recreational players preparing for the pitch is straightforward—build your fitness first.

“Unlike other sports where you’re able to stop, soccer requires you to keep moving,” he says. “Get your fitness up where you can be out there running for 30 or 45 minutes. Without that basic fitness, the buck stops there.”

On stretching, a near-universal pre-game ritual, he offers a clarification.

“It has been proven that stretching does not prevent injury,” he says. What a warmup can do, though, is activate muscles, raise body temperature and improve performance, which may indirectly reduce risk. But the solid link many people assume between pregame static stretching and injury prevention is not well supported by the research.

Preparation for a sport as demanding as soccer, then, is more of a long-term fitness level than a 10-minute warmup.

The debate over headers

When Morgan Heinzelmann-Weisbaum watches a soccer match, she’s not watching like a regular fan.

“A lot of times people will see the header, but they might miss the player’s head going head to head, or head to body,” says Heinzelmann-Weisbaum, an assistant professor of orthopaedics and neurology at Emory School of Medicine who specializes in sports neurology. “I think that’s something that is misunderstood with regard to what causes the concussions.”

Heading is involved in roughly a quarter to a third of diagnosed concussions in U.S. high school soccer players, but many of those happen during contested headers, when players collide going for the same ball, rather than from clean contact with the ball itself. Player to player contact accounts for roughly half to two-thirds of concussions overall. This distinction matters because it shifts where attention and prevention efforts should go.

When a concussion occurs, the brain can move rapidly inside the skull, which Heinzelmann-Weisbaum describes in plain terms as “sloshing.” The brain sits in cerebrospinal fluid, but that fluid cannot fully cushion the sudden force of a hit. The brain may bounce or twist inside the skull, potentially stretching or damaging brain cells and triggering chemical changes that produce concussion symptoms.

A more contested question is what repeated sub-concussive impacts do over a career of deliberate headers. These hits do not cause diagnosable symptoms on their own. Heinzelmann-Weisbaum says the research is concerning but not yet conclusive. One recent study linked frequent heading to brain imaging changes and poorer performance on a verbal learning task. But she’s careful not to overstate what that means.

“The studies are pointing toward concern,” she says. “But there’s still work to be done on the long-term studies, for sure.”

One area where the data is more consistent is that female soccer players sustain concussions at higher rates than male players, and they often report more symptoms and greater severity. Researchers have looked at differences in neck strength and stability, brain structure, hormonal factors and the possibility that female athletes may be more likely to report symptoms accurately.

Less is known about impact on female players

What makes this disparity particularly important is that much of the foundational concussion research was conducted on male athletes. When Heinzelmann-Weisbaum prepared a talk on concussion in female athletes last year, she reviewed the Concussion in Sport Group’s consensus paper and noticed how rarely female athletes appeared in the discussion. In the statement, the word “female” appears only a handful of times, mostly in places where the authors note limited data or call for more research in female athletes.

“It’s a huge gap right now,” she says, “and an important one that we need to keep addressing.”

On the question of what to do when a concussion occurs, she is clear. The old approach of complete rest in a dark room until symptoms resolve has been replaced by evidence supporting active recovery. After 24 to 48 hours of relative rest, athletes progress through a structured, stepwise protocol that moves from light aerobic exercise to sport-specific movement, then non-contact training, and finally full contact practice, with each stage carefully monitored against symptoms. She prints the protocol out for athletes who don’t have athletic trainers available to guide them through it.

In professional soccer, MLS now allows teams one permanent concussion substitution per match, which does not count against the team’s standard allotment of substitutions. But the rule comes with a limitation. Once a player is removed under the concussion substitution protocol, the player cannot return. Critics of permanent concussion substitutions argue that this can create pressure to keep players in rather than remove them for a full evaluation, a tension Heinzelmann-Weisbaum sees as unresolved.

“When in doubt, sit them out,” she says.

 

The case against doing one thing

Neeru Jayanthi, an Emory sports medicine physician, professor of orthopaedics and family medicine at Emory School of Medicine, and co-director of Emory Youth Sports Medicine, has spent 20 years studying what youth sports specialization does to young athletes, and his work helped establish one of the most widely used definitions in the field.

Early sports specialization, as he defines it, means answering yes to three questions.

·       Does your child have a main sport?

·       Do they train or compete in it more than eight months a year?

·       Have they quit all other sports to focus on it?

In his research, the more specialized young athletes are, the higher their injury risk appears to climb. Those who meet all three criteria have shown up to twice the risk of serious overuse injuries compared with less specialized peers. Stress fractures. Growth plate injuries. Tendon problems that look like adult overuse injuries in bodies that are not yet fully grown.

Jayanthi is careful to note that a soccer-specific study he co-authored did not show the same strong link seen in his broader research across youth sports. Young soccer players in that study specialized early, often before age 10, but specialization was not associated with greater odds of previous injury in that elite male soccer sample.

The overall pattern still concerns him. His broader research has linked higher levels of specialization with greater injury and overuse injury risk. When a growing body repeats the same movement patterns year-round, without the variation and recovery that multi-sport participation can provide, developing muscles, tendons and joints may pay the price.

“A kid looks great,” he says. “They have adult-level skills in a child’s body. And you forget that they may be developing and still just beginning their rapid growth spurts.”

The concept he returns to most often is free play, the kind of movement that happens without organized coaching, adult instruction or structured outcomes. Children direct it themselves. They make the rules. They decide when they are tired. They stop when something hurts. There is no coach pushing them through a drill, no schedule telling them to keep going.

“What we lack in America, especially in soccer, is free play,” Jayanthi says. “How often do you see a bunch of kids playing soccer for fun in Atlanta, like we do in other countries that we often lose to in the World Cup?”

His research suggests that children with more free play in their routines are less likely to sustain serious overuse injuries. Part of the benefit is variety. Part of it is control. In kid-directed play, children decide when to sprint, when to slow down and when to stop.

For parents navigating the competitive pressure of club soccer, Jayanthi’s message is not to opt out. It’s to sequence more carefully. Pre-adolescent children, generally under 12, benefit most from sampling multiple sports and accumulating unstructured movement. Specialization becomes safer to consider in mid-adolescence, after the body has had more time to grow and adapt before the training load intensifies.

He also offers a simple rule of thumb based on his research. Children should not spend more hours per week in organized sports than their age in years. For a 9-year-old, that means no more than nine hours of organized soccer a week. It’s a guideline that gives families a practical framework.

“Try to find opportunities for your kids to play for fun,” he says. “Play soccer with your friends. You’ll love it, at all levels. And you don’t have to focus on always getting better. You can just play.”

Written by Jacob Gnieski, illustration by Chris Gash, design by Peta Westmaas.