A season-ending sports injury can happen in the blink of an eye. In recent years, more and more athletes have ended their seasons, or even their careers, after seemingly tripping on thin air. To some, it can look like a car blowing out a tire; an athlete sprinting at full speed collapses under their own weight without anyone nearby.
Frustrated athletes are quick to blame the surface beneath them, and one common culprit in particular: artificial turf. According to Mark Cote, PT, DPT, MSCTR, a Mass General Brigham Sports Medicine researcher, these athletes make a compelling argument.
“I think they’re right — they have good reason to blame artificial surfaces — but there are a number of reasons why injuries occur, and turf isn’t the only one,” says Cote. “It’s a misconception to say natural grass is uniformly better than artificial surfaces for preventing injury, or vice versa.”
Cote serves as director of Outcomes Research for Sports Medicine & Orthopaedic Surgery at Massachusetts General Hospital. He explains the differences between turf and grass playing surfaces, the risks of playing on each, and how athletes can best protect themselves from non-contact injuries.
Non-contact lower body injuries are common in sports like football, soccer, field hockey, and lacrosse. Each sport involves sudden movements on indoor fields with artificial turf or on outdoor grass fields. Those sudden movements, which include running, jumping, or cutting, place great stress on a player’s joints.
How that stress affects the joints, and the rest of the lower body, often depends on the surface beneath.
Cote uses a yardstick as an example. Imagine jamming the yardstick into the ground, he says, like an athlete planting their leg mid-sprint. If jabbed into soft dirt, the bottom of the stick bends without breaking. Rather, it moves the dirt. Now, imagine jamming the stick into cement so it doesn’t move.
“That flimsy yardstick becomes so stuck in the earth that, when you push or run into it hard enough, you break it,” he says. “There is no wiggle room against the cement.”
Whenever an athlete plants their cleats into the ground, they expose muscles, tendons, and ligaments in their legs to similar forces affecting the yardstick. On a natural grass surface, their cleats disrupt dirt beneath the grass, creating a divot.
Those divots allow the foot to break free from the ground, reducing the force from sharp movements. However, natural grass can expose players to several hazards:
According to Cote, injuries can occur from slipping on natural grass. A player who loses their balance moving side to side can overextend muscles in the inner thigh, leading to a groin injury.
Artificial surfaces, such as turf and artificial grass, offer an even playing field — literally. They mimic the appearance of natural grass without the uneven bumps and holes created by divots. Some athletes credit turf for helping them run faster; they claim the surface feels easier to grip with their cleat, allowing them to accelerate.
Despite their durability and consistency, artificial surfaces act more like cement against Cote’s figurative yardstick. A cleat may fix itself into the surface without room to latch free.
“A natural surface accommodates the cleat; its ability to allow the cleat to move and break free decreases built-up force trying to leave the leg,” Cote says. “On a turf surface, the cleat can’t move as well, so that force has nowhere else to go, except back up the leg.”
Depending on which direction and how fast the cleat lands, several injuries to ligaments, tendons, and muscles can occur. These include straining or tearing the:
Not enough data exists to confirm whether turf alone definitively causes more non-contact injuries than natural grass. Many variables affect an injury, such as:
Often, players simply end up at the wrong place at the wrong time. That said, he does believe the materials used to create artificial grass or turf increase the likelihood of a non-contact injury occurring.
The devil lies in the details, he says, especially when examining two common types of turf:
Lower body injuries cost professional athletes millions of dollars every year. In 2023 alone, more than 20 National Football League players were sidelined due to ACL or Achilles tears and other serious leg injuries. More than half of those injuries occurred on turf, or partially-turf playing surfaces, Forbes reports. The injuries affected some of the league’s brightest stars, including New York Jets quarterback Aaron Rodgers.
Rodgers, who tore his Achilles on MetLife Field’s artificial playing surface, suggested NFL stadiums switch their surfaces to natural grass the year before his injury. Other NFL players share a similar sentiment. For years, the NFL Players Union has asked the league to switch its 15 artificial playing surfaces to natural grass, often citing non-contact injuries on artificial surfaces.
Cote says the physicality of football can explain why players may prefer natural grass more than artificial surfaces. Tackling and bouncing off players heightens the amount of stress rebounding from the turf into the lower body.
“They’re not only exposed to forces from running and cutting, but those forces are compounded by players weighing more than 200 to 300 pounds landing on you,” he says. “Even without them coming into contact with you, it’s several players chasing and dodging one another with split-second turns.”
A 2018 study underscores the risks of playing football, and other sports, on turf. The study assessed more than 4,800 NFL foot and leg injuries during regular season games between 2012-2016. It found that, had every game been played on a grass surface, at least 300 fewer foot and leg injuries would have been expected.
Turf fields also appeared to significantly increase the likelihood of non-contact injuries. About 20% more non-contact injuries occurred per play on a turf surface than a grass surface.
Both findings align with 2015 research examining 19 American football cleats against natural grass and artificial playing surfaces. Almost every cleat, when propelled by the same amount of force, created a divot into the natural playing surface. When applied to an artificial playing surface with the same force, all but one cleat held fast to the turf.
Still, Cote cautions against drawing too many conclusions. After all, athletes who play on natural grass are not immune to injury either. A cleat fixed into a surface can sometimes benefit a player. Players who lose their footing on slick or bumpy natural grass can land awkwardly and tear a muscle, ligament, or tendon anywhere in their lower body.
“I don’t think we’re at a point yet where we can say an injury would have been avoided because a field is turf or natural grass, nor are we at a point where should immediately switch every field in America to natural grass,” he says. “We can easily reverse the argument and say, ‘Well, what about all the injuries turf may have prevented from unkept natural grass fields?’”
To settle the debate over playing surfaces, Cote would like to see more data published. Future research will help validate several suspicions held by athletes about turf. These include:
Fortunately, you can protect yourself from non-contact injuries regardless of the surface you play on. Cote believes this starts with athletes reminding themselves of what they can and cannot control. More times than not, he says, you can’t change the surface you play on. But you can prepare your body to withstand awkward or sudden movements.
“Everyone wants to run faster, jump higher, and lift heavier weights,” says Cote. “If you look at the athletes who have long careers, they’re often those who pay attention to balancing performance-needed strength with pliability and other preventative measures.”
Flexible muscles and joints allow the body to support added strength. Stretching in addition to strength exercises trains muscles and joints not to overexert itself in the heat of the moment. Strength and conditioning coaches and athletic trainers can tailor specific stretches and exercises to athletes competing across a variety of competitive levels and sports, many of which can help prevent common exercise injuries.
“While I’d prefer my own children play on natural grass, I know an injury can happen on any surface without proper conditioning,” Cote adds. “At the end of the day, it’s a part of the sport.”