Prospective Study on the Effect of Sport Specialization on Lower Extremity Injury
Rates in High School Athletes

TA, Post EG, Hetzel SJ, Brooks MA, Trigsted S, & Bell DR. Am J Sport Med. 2017; Online Ahead of
Print July 23, 2017.  DOI:
Take Home Message: An athlete who specializes in sport is
more likely to have a lower extremity injury than an athlete with a low level
of sport specialization. 
Young athletes are beginning to play
one sport year round to focus on sport-specific skills and become a better
athlete within that one sport.  Prior investigators
have found that sport specialization may be related to a young athlete’s
landing mechanics, movement patterns, and history of injury.  However, without following athletes over time
it is hard to offer evidence that an athlete who specializes in a sport is more
likely to get injured.  Therefore, the
authors of this study prospectively
investigated lower extremity injuries over the course of a year among 1544
athletes in 29 Wisconsin high schools with various sport specialization
categories.  The authors categorized
athletes based on a 3-point scale that accounted for quitting another sport to
focus on a primary sport, considering the primary sport more important than
their other sports, and training more than 8 months per year in their primary
sport.  They found that 60% of the
athletes were low specialized (0 or 1 of the prior criteria), 27% were moderately
specialized (2 of the prior criteria), and 13% were highly specialized (all 3
criteria).  High school athletic trainers
recorded the number of coach-directed sessions (conditioning, practices, and
competitions) as well as any lower extremity injury (acute-, gradual-, or
recurrent) that occurred in an interscholastic-sport activity and required
medical attention. Soccer was reported to have more highly specialized athletes
than other sports.  Over the course of 1 academic
year, 235 athletes suffered 276 lower extremity injuries.  Sport specialization was found to be a risk factor
for lower extremity injury.  Athletes who
were highly specialized had an 85% higher incidence of lower extremity injury
than those who were categorized as low specialization. Athletes who were
moderately specialized had a 50% higher incidence than those who were low
specialization.  Based on injury
classification (acute or chronic), the authors revealed that chronic lower
extremity injuries were higher based on level of sport specialization.
These authors confirmed prior retrospective studies (see
below) that linked sport specialization to injury risk.  They found that as sport specialization
increased, so did the rate of injury. 
Interestingly, as the authors teased out acute versus chronic lower
extremity injuries the largest difference seemed to be with chronic lower
extremity injuries.  So the question
becomes, whether sport specialization increases the risk of injury because of a
lack of recovery/rest time instead of poor neuromuscular control?  Among highly specialized athletes, the same
muscles/joints get used in the same way for prolonged periods, which may prevent
those anatomical structures from having time to appropriately recover.  The method for sport specialization classification
seems appropriate as it is self-reported, and the authors also reported on
training volume based on the number of competitions over the interscholastic
year.  There are so many highly
specialized athletes that participate in non-school related sports teams or
leagues, such as AAU or Little League.  Unfortunately, most of these teams lack an
athletic trainer so there may be a significant number of injuries or exposures
that are not being captured among these athletes.  It would be interesting to see if there was a
way to monitor how much rest highly specialized athletes got over the course of
the year, as well as to possibly monitor patient reported outcomes or other
variables such as strength, balance, and fatigue over the course of that
year.  The authors of this study show us
that sport specialization is associated with higher injury risk, and that we
should be mindful of athletes’ specialization level in trying to prevent or
manage lower extremity injuries. 
for Discussion:  What do you think we can
do as clinicians about athletes’ increasing interest in sport
specialization?  Is there anything that
you do differently for athletes who you know are highly specialized in a sport?
by: Nicole Cattano
by: Jeffrey Driban