Drop-Jump Landing Varies With Baseline
Neurocognition: Implications for Anterior Cruciate Ligament Injury Risk and

Herman DC,
Barth JT. Am J Sports Med. 2016 Sep;44(9):2347-53. doi: 10.1177/0363546516657338.
Epub 2016 Jul 29.

Take Home Message: An athlete
with low baseline neurocognitive scores is likely to produce knee movement
patterns that are associated to anterior cruciate ligament (ACL) injury.

athlete with a low neurocognitive test score or poor neuromuscular control is
more likely to experience an anterior cruciate ligament (ACL) injury. During sport activity, an athlete may have altered visual
processing, movement planning, and reaction time due to external stimuli. Neuromuscular
screening protocols are used to identify at-risk individuals to implement
injury prevention programs. It may be beneficial to know if neurocognitive testing,
which many athletes complete, can also serve as an injury screening tool. If
relationships exist between these tests, then commonly administered
neurocognitive tests may be used to help identify athletes at-risk of injury. The
authors aimed to determine if differences exist in neuromuscular landing performance
during a challenging athletic task between athletes with high or low
neurocognitive performance. A total of 123 recreational athletes were
administered the
Concussion Resolution Index (CRI)
to identify 20 high performers and 17 low performers. The CRI comprised three
indices that were used in the study: Simple Reaction Time, Complex Reaction
Time, and Processing Speed. The authors defined high performers as athletes
that scored above the 80th percentile in 1 index and no lower than
the 60th percentile in the other two. The low performers were
identified by as athletes that scored below the 40th percentile in
one index and no higher than the 70th percentile in the other two or
athletes who had two index scores below the 30th percentile. These participants
then underwent an unanticipated jump landing task. The participants jumped
forward off a 30-cm box onto a forceplate before jumping at maximum effort to a
second target. The second target was either directly in front, 45 degrees to
the left, or 45 degrees to the right. The arrow that prompted the second target
was randomly presented 250 milliseconds before the initial landing. At initial
landing, the low performers demonstrated higher peak proximal anterior tibial
shear force, higher peak vertical ground-reaction force, a greater knee
abduction angle, and a lower truck flexion angle.

the authors found neuromuscular patterns that are associated with ACL injury among
healthy recreational athletes with low neurocognitive scores. The unanticipated
landing task may be able to simulate sport competition by demanding fast
cognitive processing to execute a desired function. The results of this study may
provide neurocognitive characteristics about athletes who are at risk for a
noncontact ACL injury. The relationship between neurocognitive scores and
neuromuscular performance may help explain why an athlete is at greater risk
for an injury during the first year after a concussion. However, these authors
looked at the relationship between neurocognitive scores and neuromuscular
performance and not actual risk of injury. Despite this limitation, this study
offers evidence that commonly used neurocognitive tests may provide important
information about a person’s risk of ACL injury. For patients returning back to
sport activity, clinicians may be able to address these neuromuscular and
neurocognitive concerns by providing dual-attention tasks. Dual tasks with cognitive
(counting backwards from 100 by 7) and physical (ball toss during a single leg
balance stance) tasks may offer a greater challenge to a patient by limiting direct
focus on the rehabilitation task. Clinicians may also consider using computerized
testing of reaction time and processing speed as an additional screening tool to
identify individuals at a greater risk for injury.

Questions for Discussion:
With computerized baseline concussion tests commonly being administered, should
clinicians use reaction or processing scores as a screening tool for injury?

by: Stephan Bodkin
by: Jeffrey Driban


Herman, D., & Barth, J. (2016). Drop-Jump Landing Varies With Baseline Neurocognition: Implications for Anterior Cruciate Ligament Injury Risk and Prevention The American Journal of Sports Medicine, 44 (9), 2347-2353 DOI: 10.1177/0363546516657338