ACL Injuries within Young Athletes: Gender Differences (part two)

Nov 7th, 2013

Category: Injury Prevention

ACL Injuries within Young Athletes: Gender Differences (part two)

ACL Injuries within Young Athletes: Gender Differences (part two)

Founder of Functional Muscle Fitness

Gender differences in neuromuscular abilities and risk of injury risk often emerge post-pubescent; more specifically, the differences most often occur between the ages of 15 and 18 (1). In fact, 1 in 20 female athletes will sustain a major ACL injury in high school (2). Therefore, a program designed to prevent ACL tears should be started during early childhood years.


Regardless, females are at a higher risk of ACL trauma than males (2). Below I have listed out six reasons for this fact:


1.     Little to no general strength.

Lack of muscular strength often results in ligament dominance. Ligament dominance is when ligaments become active before their supporting musculature during dynamic movements such as jumping, sprinting, running, cutting and stopping. Ligaments are meant to be supported by the surrounding musculature and not the other way around. In fact, one of the most high risk movement patterns during dynamic movements is ground reaction forces (GRFs). GRFs are when your lower extremities make ground contact during dynamic movements.


In part one I mentioned knee valgus as one of the major contributors to ACL tears. Knee valgus is when the knee collapse inward during squatting, jumping, etc… This particular movement pattern places excessive amounts of torque on the ACL and other knee ligaments.


2.     Lack of coordinative abilities.

During times of growth spurts coordination suffers because of a changing center body mass and bony lever system. These changes result in poor neuromuscular abilities. Training during this time becomes increasingly critical. Females typically suffer from coordinative abilities during times of non-growth as well. Therefore, it is critical to train fundamental athletic movements throughout their childhood while progressively increasing the level of difficulty. The athlete must be able to show the following abilities before moving to more difficult skills: general strength; stability within the lower extremities; core strength; mobility and static flexibility; and muscular symmetry.


3.     A weakened posterior chain.

A weak posterior chain (hamstrings and glutes) often result in unbalanced center mass and dominance from the quadriceps muscular group. Quadricepses, which are the primary knee extensors, are primarily responsible for the eccentric muscular action during dynamic movements. Dominant or prolonged activation of the quadriceps during dynamic movements increases the likelihood of overextended knees, which results in excessive torque on the knee / ACL.


From a performance standpoint a strong posterior chain leads to increased levels of athletic performance. The hamstrings and glutes are primarily responsible for the concentric muscular actions during dynamic movements. More specifically, the posterior chain is responsible for increasing speed and jumping abilities.


4.     Weak glute medius muscle.

The glute medius is primarily responsible for controlling the hip and lower extremities (i.e. providing stability). An inability to efficiently activate this musculature increases asymmetry, hip pain, knee injuries and lower back pain. All of these are a result of limited knee and hip control. It is critical that athletes, particularly the female athlete, develop this musculature. Some exercises that do so are single leg bridges, split squats and many others (more to come during part 3).


5.     Muscular asymmetry.

Individuals who suffer from muscular asymmetry greater than 15% are at high risk of injury. Therefore, unilateral or single side training must be emphasized. Females often suffer from side dominance (i.e. one leg stronger than the other). Side dominance places both the strong and weak side at risk of injury during dynamic movements. The weak side suffers from an inability to dissipate force whereas the strong side is subject to high force as a result of high dependence to account for its counterpart’s weaknesses.


6.     Insufficient core strength.

Insufficient core strength results in over trunk rotation, particularly in the frontal plane during change of direction and/or unilateral dynamic movements. This trait increases knee abduction and joint vulnerability (2). The core, which is “the center of all movement,” is primarily responsible for stabilization and transferring power during dynamic movements. If the core is weak the athlete will be left unbalanced and at risk of injury.


Gender differences are a critical factor in youth athletic training. A proper training program, which encompasses these six traits, must be incorporated into any young girl’s athletic training program. However, this program should also be incorporated into any young boy’s athletic training program.


Continues reading on to part 3 ACL Injuries within Young Athletes – Prevention, to learn how to properly develop young athletes.




  1. Yu B, McClure SB, Onate JA, Guskiewicz KM, Kirdkendall DT, and Garrett WE. Age and gender effects on lower extremity kinematics of youth soccer players. American Journal of Sports Medicine 33: 1360-1365, 2005.
  2. Hewett, TE, Stroupe AL, Nance TA, and Noyes FR. Plyometric training in female athletes: Decreased impact forces and increase hamstring torques. Am J Sports Med 24: 765-773, 1996.
  3. Henja WF, Rosenberg A, Buturusis DJ, and Krieger A. The prevention of sports injuries in high school students through strength training. National Strength Conditioning Association Journal 4: 28-30, 1982.
  4. Ebben WP, Fauth ML, Petushek EJ, Garceau LR, Hsu BE, Lutsch BN, and Feldmann CR. Gender-based analysis of hamstring and quadriceps muscle activation during jump landings and cutting. Journal of Strength and Conditioning Research 24: 410-415, 2010.


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