Concussion rates are increasing in high school sports.
The current rates per 100,000 athletic exposures (an AE is one athlete participating in one organized high school athletic practice or competition, regardless of the amount of time played), according to the two most recent studies [8,10] are as follows:
- Football: 64 -76.8
- Boys' ice hockey: 54
- Girl's soccer: 33
- Boys' lacrosse: 40 - 46.6
- Girls' lacrosse: 31 - 35
- Boys' soccer: 19 - 19.2
- Boys' wrestling: 22 - 23.9
- Girls' basketball: 18.6 - 21
- Girls' softball: 16 - 16.3
- Boys' basketball: 16 - 21.2
- Girls' field hockey: 22 - 24.9
- Cheerleading: 11.5 to 14
- Girls' volleyball: 6 - 8.6
- Boys' baseball: Between 4.6 - 5
- Girls' gymnastics: 7
- Girls' swim/dive: 2
- Girls' track/field: 2
- Boys' track/field: 2
- Boys' swim/dive: 1
Football players most at risk
- High school football is consistently shown in studies to be the sport with the greatest proportion of concussions (47.1%  to 56.8% ) and the highest concussion rate (6.4 to 7.6 concussions per 10,000 athletic exposures)* [8,10].
- There are approximately 67,000 diagnosed concussions in high school football every year. 
- Anecdotal evidence from athletic trainers suggests that only about 5% of high school players report suffering a concussion each season , but numerous formal studies over the period 2004 to 2013 suggests that the number is much higher, with close to 50% saying they have experienced concussion symptoms  and fully one-third reporting two or more concussions in a single season.
- Between 1931 and 2011, 678 high school football players died, two-thirds from helmet-to-helmet contact. 
- According to the National Center for Catastrophic Sport Injury Research,  there were no direct fatalities in high school, college or youth football in 2012. It was the first year with no fatalities in high school football since 1990. According to unofficial newspaper reports, there have been at least 6 football fatalities from helmet-to-helmet contact (as of October 18, 2013) during the 2013 football season (including spring practice).
- According to a 2007 study: 
- Football players suffer the most brain injuries of any sport;
- An unacceptably high percentage (39%) of high school and collegiate football players suffering catastrophic head injuries (death, nonfatal but causing permanent neurologic functional disability, and serious injury but leaving no permanent functional disability) during the period 1989 to 2002 were still playing with neurologic symptoms at the time of the catastrophic event.
Girls more prone to concussion?
- Some studies suggest that girls have higher concussion rates than boys and that concussions represent a greater proportion of all injuries in girls than in boys, but the trend in peer-reviewed studies appears to be towards finding no significant gender differences.
- A study published in the Winter 2007-2008 Journal of Athletic Training  suggested that girls were much more susceptible to concussions in sports like soccer and basketball than boys,
- Two more recent studies suggested that, while the concussion rate for girls in soccer was higher (33.0 per 100,000 AEs versus 19.2 per 100,000 AES in the 2009-2010 school year),  the concussion rate for basketball was actually higher for boys (21.2) than girls (18.6).
- A more recent study of high school sports  found that the concussion rate for girls' basketball (21) was higher than that in boys' basketball (16) and soccer (34 versus 19).
- Whether female high school athletes are more likely than male athletes for have symptoms that persist longer than 7 days is also unclear. While a 2011 study  found such a gender gap, a 2010 study,  reported no gender difference in the time symptoms took to clear or in the time athletes took to return to play. A study conducted by researchers at Vanderbilt published in late 2012  found that girls did not appear to be worse off after sports-related concussion than boys, either in terms of concussion symptoms or on neurocognitive tests measuring reaction time and visual memory. The only significant gender-related difference the study identified was that female high school soccer players reported a greater number of post-concussion symptoms, although their total symptom score, when the symptoms were ranked on a 6-point scale for severity, were not statistically different from those of the male athletes.
The reason for the higher concussion rate for girls, if one exists at all, are unknown, although some have theorized that female athletes have weaker neck muscles and a small head mass than male athletes [5,10,17,18] or that male athletes are more reluctant to report concussions for fear of being removed from competition, which may result in the well-documented underestimation of the incidence of concussion among boys [6,15-18] and that female athletes may be generally more honest about reporting injuries than male athletes, a reporting bias resulting in a greater proportion of boys' concussions going undiagnosed than girls', thereby misrepresenting girls as having higher concussion rates. [10,17,18] A third explanation for gender differences in concussion may be possible hormonal factors, such as the protective effect of estrogen in males. [17,18]
- The percentage of high school athletes sustaining a concussion who had previously sustained a sports-related concussion either that season or in a previous season is holding steady at about 11%:
- Two studies released in 2011, the first  covering the 11-year period from 1997 to 2008 at high schools in one large suburban school district, each with an athletic trainer, and the second  covering the 2009-2010 school year for a representative sample of U.S. high schools with athletic trainers, both found that 11% of concussions in the high school sports studied were repeat concussions;
- the most recent study of concussions in high school sports  reported that 11.5% of concussions were of the recurrent variety.
- almost 20% of concussions in boys' wrestling were recurrent concussions. 
- Once an athlete has suffered an initial concussion, his or her chances of a second one are 3 to 6 times greater than an athlete who has never sustained a concussion.
- Slightly more than a third of high school players in one recent survey who reported two or more concussions within the same school year. 
- High school athletes who suffer 3 or more concussions are at increased risk of experiencing loss of consciousness (8-fold greater risk), anterograde/post-traumatic amnesia/PTA (reduced ability to form new memories after a brain injury) (5.5-fold greater risk), and confusion (5.1-fold greater risk) after a subsequent concussion.
- Children who are seen in a hospital emergency room for a head injury, concussion, skull fracture or intracranial injury) are more than twice as likely to sustain a subsequent head injury of similar type within 12 months as are children seeking care for an injury not related to the head, regardless of their age.
- A 2013 study by researchers at Boston Children's Hospital  found that concussion symptoms lasted twice as long for patients with a history
of previous concussion as those without such a history (24 versus 12
days); that the median symptom duration for those with a multiple
concussion history and who had sustained a concussion within the past
year was 2 and 1/2 times longer (28 days) and nearly three times (33
days) longer respectively, compared with patients without such risk
- The finding linking multiple previous concussion history and prolonged symptom duration is consistent with a 2005 study  led by MomsTEAM's expert sport concussion neuropsychologist, Rosemarie Scolaro Moser, PhD, which found that high school athletes with two or more concussions performed
more poorly on cognitive measures than those athletes with one or no
previous concussions, and a 2011 study  which revealed
that youth athletes with multiple concussions reported more cognitive,
emotional, physical and sleep complaints than peers who had sustained no or only one concussion.
- A more recent study,  however, reported that adolescent athletes with one or two or more prior concussions did not have significantly worse neurocognitive functioning on computerized neurocognitive tests than those with no previous concussions, although those with two or more prior concussions reported significantly more symptoms than those with no or one prior concussion. Adolescents with multiple previous concussions also had higher level of baseline symptoms.
- The finding linking multiple previous concussion history and prolonged symptom duration is consistent with a 2005 study  led by MomsTEAM's expert sport concussion neuropsychologist, Rosemarie Scolaro Moser, PhD, which found that high school athletes with two or more concussions performed more poorly on cognitive measures than those athletes with one or no previous concussions, and a 2011 study  which revealed that youth athletes with multiple concussions reported more cognitive, emotional, physical and sleep complaints than peers who had sustained no or only one concussion.