|
PRACTICAL
SIGNIFICANCE
This
investigation
demonstrated
that
landing
profiles
consistent
with
greater
anterior
cruciate
ligament
(ACL)
injury
risk may
be
predicted
using
biomechanical
factors
that are
modifiable;
and that
these
factors
should
be
specifically
targeted
in ACL
injury
prevention
programs.
STUDY
BACKGROUND
Greater
total
sagittal
plane
energy
absorption
during
the 100
ms
immediately
following
ground
contact
(INI EA)
is
indicative
of a
landing
profile
that
likely
results
in
greater
ACL
loading
due to
sagittal
plane
mechanisms.
However,
it is
unknown
if
modifiable
biomechanical
factors
are
predictive
of total
INI EA.
OBJECTIVE
To
identify
modifiable
biomechanical
predictors
of total
INI EA.
DESIGN
AND
SETTING
This was
a
cross-sectional
study
design
conducted
in the
Neuromuscular
Research
laboratory
at the
University
of North
Carolina
at
Chapel
Hill.
SUBJECTS
Seventy-seven
(40
males,
37
females)
healthy,
recreationally
active
volunteers
(Age =
20.8 ±
2.2
years;
Height =
174.4 ±
9.6 cm;
Mass =
70.3 ±
16.2
kg).
MEASUREMENTS
Peak
strength
and
electromyographic
(EMG)
amplitudes
were
measured
during
hip and
knee
extension,
knee
flexion,
and
ankle
extension
(plantarflexion)
maximal
voluntary
isometric
contractions
(MVIC).
Dominant
limb EMG
and
three-dimensional
kinematics
and
kinetics
were
assessed
using an
electromagnetic
motion
capture
system
and a
force
plate as
subjects
performed
five
double-leg
jump
landings.
During
this
task,
individual
joint
energy
absorptions
were
calculated
by
integrating
the
negative
portions
of the
net
power
curves
of each
joint (P
= M x ω)
during
the 100
ms
immediately
following
initial
contact
(IC).
These
joint
energy
absorptions
were
then
summated
to
compute
total
INI EA.
Sagittal
plane
hip,
knee,
and
ankle
angles
at IC;
sagittal
plane
angular
displacements
during
the
loading
phase;
and EMG
amplitudes
from 50
ms
before
to 100
ms after
IC,
normalized
to %MVIC,
were
also
calculated.
During
data
screening,
four
participants
were
identified
as
outliers
on at
least
one
outcome
measure
and
excluded
from
further
analysis.
Principal
components
analysis,
used to
perform
factor
reduction
of the
fourteen
biomechanical
measures
(i.e.
strength,
EMG,
angles
at IC,
and
angular
displacements),
identified
five
principal
components
for
which
component
scores
were
generated
and
entered
into a
regression
model to
predict
total
INI EA.
RESULTS
Greater
total
INI EA
was
predicted
by
greater
scores
for PC1,
characterized
by
greater
ankle
extension
and
lesser
knee and
hip
flexion
at IC,
and
greater
ankle
flexion
dis-placement
(Adjusted
R2
= 0.056,
p =
0.024).
CONCLUSIONS
Lesser
hip and
knee
flexion
at IC,
greater
ankle
extension
at IC,
and
greater
ankle
flexion
displacement
during
landing
is
predictive
of
greater
total
INI EA.
While
the
total
variance
explained
by this
model
was
small,
the
results
suggest
that
increasing
hip,
knee,
and
ankle
flexion
at IC
may be a
strategy
to
decrease
ACL
strain
resulting
from
sagittal
plane
loading
mechanisms
during
jump
landings.
|
Publication
&
Presentation
List:
-
Norcross MF, Lewek MD, Padua DA, Shultz SJ, Weinhold PS, Blackburn JT. Modifiable biomechanical factors predict total lower extremity initial energy absorption during landing. 2012 National Athletic Trainers’ Association Annual Meeting and Clinical Symposium, St. Louis, MO. Journal of Athletic Training 47(3), S82.
-
Norcross MF, Lewek MD, Padua DA, Shultz SJ, Weinhold PS, Blackburn JT. (In Press). Lower extremity energy absorption and biomechanics during landing. Part I: Sagittal plane energy analyses. Journal of Athletic Training.
-
Norcross MF, Lewek MD, Padua DA, Shultz SJ, Weinhold PS, Blackburn JT. (In Press). Lower extremity energy absorption and biomechanics during landing. Part II: Frontal plane energy analyses and inter-planar relationships. Journal of Athletic Training.
Grant Funding Received
2010
Funding
Provided
By
The NATA
Research
and
Education
Foundation
Doctoral
Grant
Program
Grant
Summary
Published
2013
|
|
|
|
Marc F. Norcross, PhD, ATC
Principal Investigator
|
Marc F. Norcross, PhD, ATC
106 Women’s Building
Oregon State University
Corvallis, OR 97331
Office: (541) 737-6788
Email: Marc.Norcross@oregonstate.edu
Marc Norcross received his doctorate in Human Movement Science (Biomechanics concentration) at the University of North Carolina at Chapel Hill in 2011 and is currently an Assistant Professor in the College of Public Health and Human Sciences at Oregon State University. He earned his undergraduate degree in Athletic Training from Boston University in 2001, and completed a Master's degree in Exercise and Sport Science (Athletic Training Specialization) from UNC-Chapel Hill in 2003. He then worked clinically as an Assistant Athletic Trainer at UCLA from 2003- 2007. His current research interests are to inform ACL injury prevention and rehabilitation programs by elucidating modifiable factors predictive of high risk landing strategies and to improve high school coaches’ implementation of injury prevention programs.
|
|
|
This
Grant
Information
Summary
may be
downloaded
in a
2-page
pdf file
from
http://www.natafoundation.org/wp-content/uploads/2013/07/Norcross-Mark.pdf |
Back to
September
12
eBlast
Newsletter
Send e-mail
to rachaelo@nata.org with questions
or
comments
about this web site. |
