Transcript Gender differences during declined walking with a heavy load - WCB 2014

Gender Differences in Frontal Plane Gait Biomechanics
During Declined Walking With a Heavy Load
Becky Krupenevich, Jake Ridings, Rachel Tatarski, Patrick Rider, Zachary J Domire, Paul DeVita
Department of Kinesiology, East Carolina University, Greenville, NC 27858
A
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Introduction
Results & Conclusions
Frequent hill-walking may present an injury risk due to
the increased stress imposed on the lower extremity.
Decline walking, in particular, substantially increases
knee joint loading, which can exacerbate knee joint
injuries [1]. Individuals in the military carry heavy loads
and often encounter hilly terrains when walking. Military
load carriage is associated with high rates of injury,
particularly in females. Previous investigations of gender
differences during load carriage used a relative load
normalized to body mass [2]. Due to anthropometric
differences between genders, this methodology may
mask gender differences in response to the load by
under-loading females compared to the absolute loads
all military personnel carry. An absolute, heavy load
would stress females more than males relative to their
mass. Therefore, we hypothesize an interaction effect
between gender and load carriage such that females
compared to males will respond differently to absolute,
heavy loads during declined walking. The purpose of this
study was to compare the effects of carrying an absolute
load on frontal plane gait kinematics and kinetics in
males and females during decline walking.
B
We found significant gender by load interactions in
peak hip and knee abduction joint moments
(p<0.05). Females compared to males had larger
increases in response to the load in hip (low: m=27%,
f=47%; mid: m=29%, f=45%) and knee (low: m=18%,
f=54%; mid: m=12%, f=42%) moments. Additionally,
we found significant gender and load effects for hip
moment, and a significant load effect for knee
moment (p<0.05). It is unlikely that these changes
were due to joint position differences, which did not
show significant gender by load interactions or
significant main effects of gender or load in the
frontal plane at either joint (p>0.05).
Methods
C
We recruited 8 males and 8 females to participate in this
study. Subjects wore standard ROTC boots during testing
and a MOLLE rucksack containing 22kg (U.S. Army
fighting load) during loaded conditions. Subjects
performed several walking trials on a ramp declined 10
degrees at a standard speed of 1.5m/s. Three load
conditions (unloaded, mid-back position, and low-back
position) were tested. Kinematic data were captured
using an eight camera Qualisys motion tracking system.
An AMTI forceplate fitted into the ramp was used to
capture force data. Data were analyzed using Visual 3D.
Frontal plane hip and knee internal, abducting joint
moments were calculated with inverse dynamics. Peak
moments were analyzed using a 2x3 (gender by load
condition) repeated measures ANOVA, p<0.05. Post hoc
tests were run on significant interactions.
Figures: A) Peak hip abduction moment, B) Maximum hip adduction
position, C) Peak knee abduction moment, D) Maximum knee
adduction position (#gender by load interaction, *different from
unloaded, †gender effect, p<0.05)
Increased knee abduction moment has been
correlated with patellofemoral pain syndrome and
degeneration at the knee joint [3]. It is therefore
possible that the observed gender differences in hip
and knee abduction moments in response to heavy
loads may serve as an underlying mechanism for
higher injury rates in female vs. male military
personnel.
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References
1. Lay et al. J. Biomech. 39, 1621-1628 (2006).
2. Silder et al. J. Biomech. (2013).
3. Stefanyshyn et al. Am. J. Sports. Med. 34(11), 18441851 (2006).
D
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