A large study of adolescent soccer players in Michigan revealed key differences in concussion injury metrics among males and females, underscoring a need to develop sex-specific approaches to managing injury in the sport.
Dr. William Stewart
Sport-related concussion (SRC) is a specific concern in young female athletes, study authors Abigail C. Bretzin, PhD, and colleagues noted in their paper, which appears in JAMA Network Open. Previous surveillance studies on SRC at the high school and college level have reported higher rates of injury risk and longer recovery outcomes in female soccer athletes. Taking a deeper dive into these trends, the investigators explored whether sex-associated differences existed in SRC, addressing the mechanics, management, and recovery from SRC.
“This is an area that is remarkably underresearched,” William Stewart, MBChB, PhD, the study’s corresponding author, said in an interview. Prior studies of males and females have shown that female axons are thinner, with fewer microtubules or internal scaffolding than male axons. This potentially increases risk of shear injury in females. Limited research has also cited differences in concussion risk across the menstrual cycle in female athletes.
Reporting system targets four injury areas
The investigators conducted a high school injury surveillance project in 43,741 male and 39,637 female soccer athletes participating in the Michigan High School Athletic Association (MHSAA) Head Injury Reporting System. The study included students from 9th to 12th grade, spanning from the beginning of academic year 2016-2017 to the end of academic year 2018-2019. Since 2015, the state has mandated high schools to submit data to MHSAA.
MHSAA captures data on four categories: person-to-person contact, person-to-object contact, person-to-playing surface contact, or uncertain about cause of the event. Study outcomes included details regarding injury mechanism, immediate management, and return-to-play time for each documented SRC.
Investigators reported notable differences among male and female players. Documented SRC risk was 1.88 times higher among adolescent girls than boys across all academic years (RR, 1.88; 95% CI, 1.69-2.09; P < .001). They also cited inconsistencies in distribution of injury mechanisms among the sexes. Females were most likely to suffer injury from equipment contact such as heading a ball (41.9%), whereas male players commonly sustained SRC from contact with another player (48.4%). The authors suggested that “female soccer athletes have lower neck strength and girth, compared with male athletes, with these variables inversely associated with linear and rotational head acceleration after soccer ball heading.”
Boys had greater odds of immediate removal from play and but also returned to the sport 2 days sooner than girls. “The possibility exists, therefore, that this longer recovery time might, in part, be reflective of our observed differences in immediate care, in particular removal from play,” the authors wrote. Immediate removal from play was also more common in cases where an athletic trainer played a part in evaluating players for SRC.
Eliminating the one-size-fits-all approach
Current concussion management is based on a “one-size-fits-all” model, said Dr. Stewart. Male and female athletes are treated following a common concussion management protocol, covering concussion detection through to rehabilitation. “This model of management is based on research that is almost exclusively in male athletes.”
What the study showed is this one-size-fits-all approach may be flawed, letting down female athletes. “We should be pursuing more research in sex differences in concussion and, importantly, putting these into practice in sex-specific concussion management protocols,” he suggested.
Future studies should also look at the effects of athletic trainer employment on SRC metrics. “Although this was a large, statewide epidemiological study of reported SRC in adolescent soccer athletes, inclusive of high schools with and without access to athletic trainers, the Head Injury Reporting System did not include information on the whether there were athletic trainer services available at each school, including specific athletic training services for soccer,” wrote the investigators, in citing the study’s limitations.
Girls report symptoms more often
“The researchers are to be commended for taking a prospective approach to address this common observation in high school sports,” said Keith J. Loud, MD, MSc, FAAP, a sports pediatrician at Children’s Hospital at Dartmouth-Hitchcock in Manchester, N.H. The results are “entirely believable,” said Dr. Loud, who was not affiliated with the study. “We have long postulated differences in neurophysiology, neck strength, style of play, and tendency to report as explanations for the observation that girls in high school soccer are diagnosed with more concussions than boys.”
The findings suggest that boys play more aggressively, but sustain fewer concussions, he added. Girls in the meantime, are more likely to speak up about their injury.
“Concussion diagnosis still relies to a large degree on the athlete to report symptoms, which is one of our hypotheses as to why girls seem to sustain more concussions – they report symptoms more often. That could also be why they have a prolonged recovery,” offered Dr. Loud. A main limitation of this study is it can’t overcome this reporting bias.
Dr. Loud was also concerned that girls were less likely to be removed from game play, even though they apparently sustained more concussions. “Perhaps that is because their injuries are less obvious on the field, and they are diagnosed when reported after the games.”
Dr. Stewart reported receiving grants from The Football Association and National Health Service Research Scotland during the study. He also served as a nonremunerated member of the Fédération Internationale de Football Association Independent Football Concussion Advisory Group and the Football Association Expert Panel on Concussion and Head Injury in Football. None of the other authors had disclosures.