The Female Athlete’s Epidemic
By
Will Hawkins
In 1998, the American Journal of Sports Medicine featured an article
titled, “The Association Between the Menstrual Cycle and Anterior Cruciate
Ligament Injuries in Female Athletes.” This article confirmed the suspicion that
many coaches already had, which is that hormonal as well as anatomical
predispositions were to blame for the seeming epidemic of female athlete ACL
tears. I’ve come to the conclusion that there are three major reasons why women
are more than four times more likely than men to tear their ACL’s playing sports
(1).
In order to make hypotheses about women’s increased susceptibility to ACL
tears, one must first understand the basic anatomy of the knee and the purpose
of the ACL. First, the knee is a joint comprised of four bones—the femur, the
tibia, the fibula, and the patella. The knee joint is padded by sections of
cartilage (menisci) on both the medial and lateral side. The ACL is one
of four major ligaments responsible for stability in the knee. The ACL
originates in the notch of the distal portion of the femur and inserts into the
tibia. Due to its origin and insertion, its primary purpose is to protect the
knee from too much anterior translation of the tibia.
The first portion of the hypothesis we will discuss is the hormonal reason
for women’s increased susceptibility to ACL tears. Dr. Kurt Spindle, an
orthopedic surgeon in Nashville, has done some of the most relevant research on
this portion of the female athlete’s epidemic. In his study, he discovered that
women were three times more likely to tear the ACL when they were having their
period. He explains this by stating that during a female’s period, the
luteinizing and follicle stimulating hormones are allowed to enter the
bloodstream. These hormones come into contact with the ACL’s recently discovered
active hormone receptors. It is believed that this spike in hormonal levels can
actually temporarily alter the composition of the ligament, therefore leaving
the ACL more prone to tearing. Dr. Spindle also cited that women who had been
taking oral contraceptives were less likely to tear their ACL. This is due to
the fact that oral contraceptives skyrocket estrogen and progesterone levels,
causing luteinizing and follicle stimulating hormones to not be released.
The second reason female athletes are at least four times as likely to tear
their ACL is because of the difference in the anatomy of the hip. The term
“q-angle” is defined as “a measurement of the angle between the quadriceps
(rectus femoris is usually used) and the patella tendon (3).” Q-angles in women
are generally at least five degrees larger than that in men, which causes an
increased tension on almost all of the ligaments of the hip and knee. The hip
structure that most women have is great for giving birth but not so great for
playing sports requiring lots of multidirectional movement.
The third reason for female ACL tears is an anatomical predisposition. The
intercondyler notch is a portion of the knee between the condyles that the ACL
glides through during extension and flexion of the knee. These condyles are two
rounded portions, one on each side of the notch. They provide a large source of
stabilization for the knee. Think of the condyles as your knuckles when you put
two fists (femur and tibia) together. One of the main purposes of the condyles
is to give the ACL additional support by preventing too much anterior movement
of the tibia. Women have smaller condyles (less knee stability) as well as a
smaller intercondyler notch. The fact that women typically have smaller condyles
is a distinct mechanical disadvantage that leaves women with less knee stability
in general. Additionally, the smaller intercondyler notch that women have can
lead to the ACL being pinched or torn inside the joint. So there are a host of
anatomical differences in the knee joint of women that leave them more
susceptible to ACL tears.
So what’s a girl to do? Should girls with wide hips avoid playing sports
requiring multidirectional movements? Should girls sit out from playing sports
when they’re having their period? Should collegiate athletic programs require
their female athletes to be on oral contraceptives to lower their chances of
season or career ending ACL tears? There are obvious legal and moral issues
involved with asking female athletes to take oral contraceptives, but it’s an
option I wouldn’t be surprised to see explored. However, my answer to this
question is a resounding no. A study done by the American Journal of Sports
Medicine declared that women who undergo lower extremities injury prevention
workouts are 62 percent less likely to suffer traumatic knee injuries (5). This
tells us that corrective/preventative exercises are definitely the way to go.
All three factors related to women’s relative knee instability are
intertwined with the fact that women typically have roughly 30 percent less
muscle mass than men. Muscle mass is one of the joints’ greatest stabilizers.
There is a stigma in the exercise science field about training for larger
muscles, but this stigma is largely unfounded. There is a belief that
flexibility and muscle mass are mutually exclusive qualities. This isn’t true.
Gratuitous amounts of muscle mass and flexibility, however, are mutually
exclusive.
Flexibility is defined as “the ability of your joints to move throughout a
full range of motion” (6). It’s discussed a lot in the athletic performance
field, but sometimes we forget that being super flexible isn’t always good.
Being too flexible can lead to joint instability because of the joints’
extremely large range of motion. This is why training for hypertrophy and
balanced muscle ratios is so important. By training to achieve a proper
quadriceps to hamstring strength ratio, female athletes can drastically decrease
the likelihood of ACL tears (4). Most females, just like their male
counterparts, are quadriceps dominant. Having strong quadriceps is great, but
the hamstring complex by virtue of its origin and its insertion helps to prevent
too much anterior translation of the tibia from occurring. This anterior
translation of the tibia is the reason most tears of the ACL occur. This is why
training your posterior kinetic chain, specifically your hamstrings, is so
important.
Additional forms of corrective exercises should include multidirectional
neural activation/enhancement drills. The quicker that muscles fire while an
athlete is making a cut, the quicker the joint will be stabilized. Oftentimes
ACL tears occur when an athlete plants a foot to cut and immediately the plant
leg is compromised by a collision. It isn’t speculation to say that if
surrounding musculature can fire quicker and stronger (more fibers), these plant
and twist tears would become less likely.
In conclusion, it’s an undeniable fact that female athletes are up to four
times more susceptible to ACL tears than their male counterparts. There are at
least three scientifically proved reasons for this and perhaps more that we
haven’t discovered. However, there is hope for the female athlete. There is a
vaccine available to aid in putting an end to the “female athlete’s epidemic.”
Through the combination of preventative exercises aimed at producing neural
adaptation and balanced hypertrophy, there can be more healthy knees out there
on the field of play.
1. Wojtys EM, Huston LJ, Lindenfeld TN, Hewett TE, Greenfield ML (1998)
“Association between the menstrual cycle and anterior cruciate ligament injuries
in female athletes.” The American Journal of Sports Medicine
26(5):614–19.
2. Spindler K (2002) “The Effect of the Menstrual Cycle on Anterior
Cruciate Ligament Injuries in Women as Determined by Hormone Levels.”
American Journal of Sports Medicine 30(2):182–88.
3. “The Q Angle.” The Virtual Sports Injury Clinic—Sports Injuries.
Accessed: Nov. 12, 2009. At:
http://www.sportsinjuryclinic.net/cybertherapist/front/knee/q-angle.php.
4. Pettineo, et. al. Female ACL Injury Prevention With a Functional
Integration Exercise Model. Strength and Conditioning Journal
26(1):28–33.
5. Joseph M (2008) Knee Valgus During Drop Jumps in National Collegiate
Athletic Association Division I Female Athletes: The Effect of a Medial Post.
American Journal of Sports Medicine 36(2):285–89.
6. Marieb EN. (2008) Essentials of Human Anatomy & Physiology (9th
Edition) (Essentials of Human Anatomy & Physiology (Marieb)). San Francisco:
Benjamin Cummings.
Will Hawkins is currently finishing his degree in human performance
studies and will soon begin his masters degree in human performance studies. He
has interned and worked at multiple athletic performance and wellness gyms.
Human performance is his true passion, and he looks forward to being on the
cutting edge of future breakthroughs. For more information about Will, visit his
blog at
www.willtoperform.blogspot.com.
Elite Fitness Systems strives to be a recognized leader in the strength
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