Lower Extremity
Stiffness Changes after Concussion in Collegiate Football Players

DF., Herman DC., Jones DL., Tillman SM., Clugston JR., Pass A., Hernandez JA.,
Vasilopoulos T., Horodyski M., Chielewski TL. Medicine & Science in Sport
& Exercise. 2016; 49(1):167-172.

Take Home Message: An
athlete with a recent concussion has altered lower extremity stiffness at the
leg, hip, and knee, which could increase their risk for musculoskeletal injury.

when an athlete meets concussion return-to-play criteria they may be at an
increased risk for musculoskeletal injury. This may be due to unresolved
neuromuscular impairments, which can affect lower extremity stiffness. However,
few researchers have looked at the effect of concussion on lower extremity
stiffness. Therefore, the authors compared pre- to post-season changes in
stiffness during a jump-landing task in a cohort of 39 Division I football athletes
(13 with a history of concussion and 26 matched [age, position, season]
controls with no history of concussions]). All athletes completed a
jump-landing task starting with the left leg. The jump-landing task consisted
of hopping off a 25 cm step with hands on hips and eyes facing forward. A test
trial was successful if the athlete made solid foot contact with force plate and
maintained balance on test leg for 3 seconds. Testing was repeated until a
successful trial was obtained, and then repeated with the right leg. Then, the
authors calculated leg, hip, knee, and ankle stiffness. Concussed athletes
completed the post-season jump-task test ~50 days  after the concussion. The authors found no
differences between preseason or postseason values for hip, knee, ankle, and
leg stiffness between groups. However, when the authors compared change in
stiffness from preseason to postseason they found that the concussed athletes
exhibited decreased stiffness at the leg and knee, and increased hip stiffness compared
with the non-concussed athletes. There was no difference between groups for
change in ankle stiffness.

authors demonstrated that concussed athletes have altered lower extremity
stiffness from pre- to post-season when compared with non-concussed athletes. Specifically,
leg and knee stiffness decreased and hip stiffness increased in the concussed
athletes. The authors suggest that stiffness in the lower extremity is
controlled by the neuromuscular system, and this data provides further evidence
of neuromuscular dysfunction after return to play from concussion. These
changes in lower extremity stiffness could alter how an athlete lands, runs,
and performs other movement patterns, which places them at risk for a
musculoskeletal injury. Medical professionals should be aware of these changes in
stiffness within the lower extremity. Additionally, clinicians need to
recognize that an athlete is at greater risk for lower extremity injury after a
concussion, and therefore should consider whether return to play guidelines
need to be improved to include a high demand neuromuscular task. Lastly,
medical professionals may need to consider implementing neuromuscular tasks in
the concussion rehabilitation protocol to reduce the risk of subsequent
injuries following a concussion.

Question for
Discussion: Do you perform any neuromuscular tasks prior to releasing an
athlete to full return to play? What type of tasks do you think should be
incorporated into a concussion return to play protocol?

by: Jane McDevitt, PhD
by: Jeff Driban


If You Don’t Let Your Head Heal Your Knee May Be Next

Dubose DF, Herman DC, Jones DL, Tillman SM, Clugston JR, Pass A, Hernandez JA, Vasilopoulos T, Horodyski M, & Chmielewski TL (2017). Lower Extremity Stiffness Changes after Concussion in Collegiate Football Players. Medicine and science in sports and exercise, 49 (1), 167-172 PMID: 27501359