Newswise — LOS ANGELES (Oct. 17, 2018) - On a warm and windy October evening at a football stadium in Torrance, California, a group of 70 teenage girls is being taught to "keep their knees straight" as they run. They tackle a series of squats, planking exercises and stretches—followed by sprints across the field.  

It may look like a typical pregame warmup, but this is an injury prevention session for female soccer players from the Beach Futbol Club U.S. Development Academy, led by Cedars-Sinai Kerlan-Jobe Institute orthopaedist Natasha Trentacosta, MD.  

Trentacosta's goal is to teach the girls how to protect a crucial part of their knees: the anterior cruciate ligament, or ACL.

"An ACL tear is a devastating injury that can keep many young women from achieving their athletic potential," said Trentacosta. "ACL injuries can put a player out of action for up to a year, which is especially serious for girls who are working toward careers in elite soccer." 

ACL injuries have become more common over the decades, especially among female athletes, who are three-and-a-half times more likely than males to suffer from ACL tears, according to a study in Current Reviews in Musculoskeletal Medicine

The reason? While many theories exist, most point to biomechanical and physical differences between male and female athletes, said Trentacosta, an expert in adolescent sports injuries. 

"As women, when we run and jump, our knees tend to fall into the midline of the body—known commonly as knock knees—which puts an extra strain on the knee," she said. 

"Women also tend to land with a stiffer leg, which can cause ACL injuries. Deep bending is more protective of the knee when jumping as it dissipates the force to the surrounding muscles—that's the kind of positive habit we want to instill through this training." 

Beach Futbol Club Coach Jeffrey Joyner sees the impact of ACL injuries firsthand. Within the club's development academy, the top tier of youth soccer in the U.S., three players have suffered serious ACL injuries within the last two seasons, he said. 

"College recruiting is getting younger and younger, and if the girls get injured, they are missing some really important opportunities," said Joyner, the development academy director. 

Christina Palacios, a 17-year-old midfielder, watches from the sidelines as her teammates take part in training drills with the Cedars-Sinai experts. 

"This is part of the grieving process," said Palacios, who wears a full-length leg brace. On May 17, during a game, the high school senior felt her knee shift and then felt a "weird" pain. 

For two months, she went about her daily activities as usual; despite the pain, she felt she had narrowly avoided a major injury. But an MRI of her knee revealed the extent of the problem: Palacios had torn her ACL. 

"When I first got the diagnosis, I cried because I thought I would miss the whole season," said Palacios, who has been playing soccer since age four and hopes to one day join the Women's Premier Soccer League. 

Fortunately, Palacios suffered a partial tear and should be back in the game by the new year. But this type of injury highlights the need for ACL injury awareness and avoidance techniques in addition to technical expertise, said Joyner. 

Enter the Cedars-Sinai team. During the inaugural training session on Oct. 1, Trentacosta was joined by orthopaedic physician Carlos Uquillas, MD, sports neurology physician Ilan J Danan, MD, and certified athletic trainers Sidney Jones and Emily Pastoors. 

After an introductory talk about the causes and risks of ACL injuries, the Cedars-Sinai experts presented the international soccer governing body FIFA's 11+ injury prevention program. This popular program has been found to reduce the injury risk in soccer players by 30 percent by focusing on correct posture and good body control, including straight leg alignment, knee-over-toe position and soft landings. 

"I think the most important thing I learned is to not let my knees 'buckle,' and that it's key to have proper form when landing a jump and slowing down from a sprint," said Samantha Encarnado, a 17-year-old midfielder, after the session. "I'll definitely be integrating the exercises into my workout."

Next month, Trentacosta and the team will return to answer questions, provide guidance and ensure the exercises are working out in practice.  

"We really hope to see tangible results as measured by a reduction in ACL injuries within the club," said Trentacosta.

Joyner is also positive about the long-term impact of the session. Asked when he plans to integrate the program into his team's practices, his answer was simple: "Tomorrow," he said.

"If we do everything in the training and it stops even one kid getting injured in a season, it's a win." 


  • One of the four major ligaments of the knee, an anterior cruciate ligament (ACL) is a band of tissue that connects the thigh bone to the shin bone.
  • An ACL injury occurs from overstretching or tearing the ligament, often caused by changing direction quickly, landing incorrectly from a jump, stopping suddenly or direct contact from a collision.
  • An estimated 200,000 ACL injuries are reported in the U.S. each year, most commonly among female athletes.


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