Effects of repeated treadmill testing and electrical stimulation on post-stroke gait kinematics

Article (PDF Available)inGait & posture 37(1) · July 2012with91 Reads
DOI: 10.1016/j.gaitpost.2012.06.001 · Source: PubMed
Abstract
Improvements in task performance due to repeated testing have previously been documented in healthy and patient populations. The existence of a similar change in performance due to repeated testing has not been previously investigated at the level of gait kinematics in the post-stroke population. The presence of such changes may define the number of testing sessions necessary for measuring a stable baseline of pre-training gait performance, which is a necessary prerequisite for determining the effectiveness of gait interventions. Considering the emergence of treadmills as a popular tool for gait evaluation and retraining and the common addition of functional electrical stimulation (FES) to gait retraining protocols, the stability of gait kinematics during the repeated testing of post-stroke individuals on a treadmill, either with or without FES, needs to be determined. Nine individuals (age: 58.1±7.3 years), with hemi-paresis secondary to a stroke (onset: 7.3±6.0 years) participated in this study. An 8-camera motion analysis system was used to measure sagittal plane knee and ankle joint kinematics. Gait kinematics were compared across two (N=9) and five (N=5) testing sessions. No consistent changes in knee or ankle kinematics were observed during repeated testing. These findings indicate that clinicians and researchers may not need to spend valuable time and resources performing multiple testing and acclimatization sessions when assessing baseline gait kinematics in the post-stroke population for use in determining the effectiveness of gait interventions.
Full
length
article
Effects
of
repeated
treadmill
testing
and
electrical
stimulation
on
post-stroke
gait
kinematics
§,§§
Louis
N.
Awad
a,b,
*
,
Trisha
M.
Kesar
c
,
Darcy
Reisman
a,b
,
Stuart
A.
Binder-Macleod
a,b
a
Department
of
Physical
Therapy,
University
of
Delaware,
Newark,
DE
19716,
USA
b
Graduate
Program
in
Biomechanics
and
Movement
Sciences,
University
of
Delaware,
Newark,
DE
19716,
USA
c
Division
of
Physical
Therapy,
Department
of
Rehabilitation
Medicine,
Emory
University,
Atlanta,
GA
30322,
USA
1.
Introduction
Over
7.7
million
Americans
are
currently
living
with
post-
stroke
disabilities.
Many
of
these
disabilities
are
life-altering
and
necessitate
physical
rehabilitation.
Walking
dysfunction
is
one
such
disability,
and
has
been
linked
to
delayed
hospital
discharge
to
home
[1],
delayed
return
to
work
[2],
and
limited
community
participation
[1].
For
the
vast
majority
of
stroke
survivors,
improved
walking
ability
is
thus
the
ultimate
goal
of
rehabilitation
[3].
Accordingly,
considerable
time,
effort,
and
resources
are
spent
on
gait
retraining
during
conventional
post-stroke
rehabilitation.
However,
residual
gait
deficits
often
still
remain,
and
compensa-
tions
such
as
‘‘stiff-legged’’
[4]
and
circumduction
gait
[5,6]
eventually
result.
These
gait
deficits
often
increase
energy
expenditure,
diminish
endurance,
and
increase
the
likelihood
of
falls
[6–9].
Novel
gait
retraining
interventions
have
recently
been
intro-
duced
to
address
these
residual
gait
deficits
[7,10–13].
In
this
study,
we
explore
two
such
interventions:
treadmill
walking
and
functional
electrical
stimulation
(FES),
which
is
a
popular
targeted
intervention
for
the
treatment
of
foot
drop
[14–17].
Appropriate
use
of
these
interventions
is
contingent
upon
evidence
for
their
effectiveness.
An
evaluation
of
an
intervention’s
effectiveness
necessitates
at
least
two
testing
sessions,
typically
in
the
form
of
pre-
and
post-intervention
testing.
Evidence
for
an
intervention’s
effectiveness
requires
not
only
the
use
of
valid
and
reliable
outcome
measures,
but
also
on
knowledge
of
the
effect
that
repeated
testing
may
have
on
performance.
Indeed,
if
mere
repeated
testing
yields
systematic
changes
in
performance
across
testing
sessions,
then
the
likelihood
that
post-intervention
performance
changes
are
not
therapy-related,
but
are
merely
artifacts
of
repeated
testing,
is
increased.
Consequently,
additional
testing
sessions
may
be
necessary
before
stabilization
of
baseline
performance
can
occur
and
post-intervention
performance
changes
can
be
considered
an
accurate
reflection
of
an
interven-
tion’s
effect.
Gait
&
Posture
xxx
(2012)
xxx–xxx
A
R
T
I
C
L
E
I
N
F
O
Article
history:
Received
9
March
2012
Received
in
revised
form
25
May
2012
Accepted
7
June
2012
Keywords:
Treadmill
Repeated
testing
Functional
electrical
stimulation
(FES)
Kinematics
Stroke
A
B
S
T
R
A
C
T
Improvements
in
task
performance
due
to
repeated
testing
have
previously
been
documented
in
healthy
and
patient
populations.
The
existence
of
a
similar
change
in
performance
due
to
repeated
testing
has
not
been
previously
investigated
at
the
level
of
gait
kinematics
in
the
post-stroke
population.
The
presence
of
such
changes
may
define
the
number
of
testing
sessions
necessary
for
measuring
a
stable
baseline
of
pre-
training
gait
performance,
which
is
a
necessary
prerequisite
for
determining
the
effectiveness
of
gait
interventions.
Considering
the
emergence
of
treadmills
as
a
popular
tool
for
gait
evaluation
and
retraining
and
the
common
addition
of
functional
electrical
stimulation
(FES)
to
gait
retraining
protocols,
the
stability
of
gait
kinematics
during
the
repeated
testing
of
post-stroke
individuals
on
a
treadmill,
either
with
or
without
FES,
needs
to
be
determined.
Nine
individuals
(age:
58.1
7.3
years),
with
hemi-paresis
secondary
to
a
stroke
(onset:
7.3
6.0
years)
participated
in
this
study.
An
8-camera
motion
analysis
system
was
used
to
measure
sagittal
plane
knee
and
ankle
joint
kinematics.
Gait
kinematics
were
compared
across
two
(N
=
9)
and
five
(N
=
5)
testing
sessions.
No
consistent
changes
in
knee
or
ankle
kinematics
were
observed
during
repeated
testing.
These
findings
indicate
that
clinicians
and
researchers
may
not
need
to
spend
valuable
time
and
resources
performing
multiple
testing
and
acclimatization
sessions
when
assessing
baseline
gait
kinematics
in
the
post-stroke
population
for
use
in
determining
the
effectiveness
of
gait
interventions.
ß
2012
Elsevier
B.V.
All
rights
reserved.
§
This
study
was
supported
by
the
following
National
Institutes
of
Health
grants:
NR010786,
HD038582,
S10
RR022396-01,
K01HD050582,
and
T32HD007490.
§§
The
study
sponsors
were
not
involved
in
the
design
of
this
study;
in
the
collection,
analysis
and
interpretation
of
the
data
presented;
in
the
writing
of
this
manuscript;
nor
in
the
decision
to
submit
this
manuscript
for
publication.
*
Corresponding
author.
Tel.:
+1
5514044054.
E-mail
address:
louawad@udel.edu
(L.N.
Awad).
G
Model
GAIPOS-3608;
No.
of
Pages
5
Please
cite
this
article
in
press
as:
Awad
LN,
et
al.
Effects
of
repeated
treadmill
testing
and
electrical
stimulation
on
post-stroke
gait
kinematics.
Gait
Posture
(2012),
http://dx.doi.org/10.1016/j.gaitpost.2012.06.001
Contents
lists
available
at
SciVerse
ScienceDirect
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&
Posture
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ep
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see
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matter
ß
2012
Elsevier
B.V.
All
rights
reserved.
http://dx.doi.org/10.1016/j.gaitpost.2012.06.001
While
few
studies
in
both
healthy
and
patient
populations
have
provided
direct
evidence
for
either
the
existence
or
absence
of
an
effect
of
repeated
testing
on
performance,
it
is
often
anticipated
and
controlled
for
[18–20].
Researchers
have
used
the
better
[18],
the
average
[19],
or
the
second
[20]
of
two
collected
measures
when
conducting
baseline
measurements
of
variables
such
as
maximal
force
[18–20],
gait
velocity
and
stair-climbing
power
[19]
to
minimize
improvements
due
to
repeated
testing.
These
methods
are
common,
and
while
it
is
clear
that
an
accurate
reflection
of
baseline
performance
is
their
purpose,
the
criterion
by
which
they
are
selected
is
not
identified
[18–20].
In
both
able-bodied
individuals
and
various
patient
populations,
improvements
in
task
performance
have
been
observed
with
the
repeated
testing
of
the
six-minute
walk
test
(6MWT)
[20–24].
These
improvements
in
performance
across
testing
sessions
have
ranged
from
5%
to
33%,
with
incremental
increases
occurring
across
three
sessions
in
healthy
adults
[20],
and
across
two
sessions
in
patients
with
fibromyalgia
[23]
and
chronic
cardiac
and
pulmonary
disease
[24].
The
underlying
mechanisms
of
this
phenomenon
are
unknown,
but
researchers
have
postulated
that
these
improvements
may
result
from
improved
coordination,
finding
optimal
stride
length,
or
even
overcoming
anxiety
[25].
Because
the
6MWT
is
correlated
with
walking
ability
and
function
in
the
post
stroke
population
[26],
these
previous
findings
may
have
significant
implications
on
the
number
of
testing
sessions
that
may
be
necessary
to
achieve
a
stable
baseline
of
post-stroke
gait
performance.
It
is
currently
unknown
whether
repeated
gait
testing
on
a
treadmill,
either
with
or
without
the
addition
of
FES,
has
any
effect
on
the
gait
kinematics
of
the
post-stroke
population.
With
the
increased
prevalence
of
treadmills
as
tools
for
gait
evaluation
and
retraining,
it
is
important
to
determine
the
effects
of
repeated
treadmill
testing
on
gait
performance.
Also,
considering
the
common
addition
of
FES
to
post-stroke
gait
retraining
protocols
[14–17],
understanding
the
effects
of
electrical
stimulation
on
the
consistency
of
post-stroke
gait
is
also
warranted.
Thus,
the
purpose
of
this
study
was
to
determine
if
the
mere
repeated
testing
of
post-
stroke
gait
during
treadmill
walking,
with
and
without
the
addition
of
FES
for
dorsiflexor
assist,
produced
immediate
changes
in
knee
and
ankle
kinematics.
2.
Methods
Nine
subjects
with
hemiparesis
secondary
to
a
stroke
participated
in
this
study
(Table
1).
Inclusion
criteria
included
at
least
six
months
followin g
a
stroke
involving
the
cerebral
cortical
regions,
the
ability
to
walk
for
five
minutes
at
a
self-
selected
walking
speed,
and
sufficient
passive
ankle
ROM
to
allow
the
ankle
to
be
dorsiflexed
to
within
five
degrees
of
a
neutral
position
(i.e.
five
degrees
of
plantarflex ion ).
Exclusion
criteria
included
substantial
cognitive
deficits,
severe
aphasia,
cerebellar
involvement,
and
any
preexisting
conditions
affecting
walking
function.
All
nine
subjects
participated
in
two
testing
sessions
(2-session
group).
Due
to
scheduling
con flicts,
only
five
of
these
nine
subjects
were
able
to
participate
in
an
additional
three
testing
sessions
(5-session
group).
Subjects
were
asked
to
walk
on
a
treadmill
with
and
without
FES
delivered
to
the
ankle
dorsiflexor
musculature
during
the
swing
phase
of
gait.
All
subjects
signed
informed-consent
forms
previously
approved
by
the
human
subjects
review
board
of
the
University
of
Delaware.
In
this
paper,
we
report
data
collected
under
two
different
walking
conditions:
(1)
treadmill
walking
without
FES
(noFES)
and
(2)
treadmill
walking
with
dorsiflexor
muscle
FES
(FES).
A
single
testing
session
consisted
of
18
treadmill
walking
trials
of
20–40
s
each.
Rest
intervals
of
5–10
min
were
provided
between
consecutive
trials.
The
noFES
data
collection
always
occurred
at
the
beginning
(1st
trial)
of
each
testing
session.
The
FES
data
collection
occurred
during
a
subsequent
walking
trial,
but
the
trial
number
was
randomized.
Gait
speed
during
each
walking
trial
was
set
at
the
participant’s
self-selected
over
ground
walking
speed.
Data
collection
commenced
a
few
seconds
after
the
target
treadmill
speed
was
reached;
thus
subjects
were
provided
with
an
opportunity
to
practice
taking
several
steps
on
the
treadmill
before
data
were
collected.
For
safety,
subjects
held
onto
a
handrail
located
on
the
front
end
of
the
treadmill
while
walking.
All
subjects
wore
a
harness
that
was
connected
to
overhead
support;
no
body
weight
was
supported
by
the
harness.
The
data
presented
in
this
paper
are
part
of
a
larger
study
previously
completed
in
our
laboratory;
greater
detail
of
our
experimental
methodology
can
be
found
in
a
previous
paper
[27].
Surface
electrical
stimulation
electrodes
(2
in.
2
in.;
TENS
Products,
Grand
Lake,
CO)
and
a
Grass
S8800
stimulator
in
combination
with
a
Grass
model
SIU8TB
stimulus
isolation
unit
was
used
to
deliver
the
electrical
stimulation
(Grass
Instrument
Co,
Quincy,
MA).
An
8-camera
motion
analysis
system
(Vicon
5.2,
Oxford,
England)
was
used
to
collect
marker
data
at
100
Hz
during
walking,
with
and
without
dorsiflexor
FES,
on
a
split-belt
treadmill
instrumented
with
two
6
degrees
of
freedom
force
platforms
(AMTI,
Watertown,
MA).
2.1.
Data
processing
Marker
trajectories
and
ground-reaction
force
data
were
low
pass
filtered
(Butterworth
fourth
order,
phase
lag)
at
6
and
30
Hz,
respectively,
with
the
use
of
commercial
software
(Visual
3D;
C-Motion,
Rockville,
MD).
Vertical
ground-
reaction
forces
were
used
to
determine
gait
events.
2.2.
Dependent
variables
Because
an
increase
in
swing
phase
ankle
angle
is
the
primary
kinematic
goal
of
the
FES
provided
in
this
study,
and
because
we
have
previously
shown
that
changes
in
swing
phase
knee
angle
occur
with
FES
[27],
peak
swing
phase
ankle
dorsiflexion
and
knee
flexion
angles
were
our
variables
of
interest.
For
each
subject,
an
equal
number
of
consecutive
strides
(at
least
nine)
were
used
across
sessions
to
compute
an
average
peak
knee
flexion
and
peak
ankle
dorsiflexion
angle
for
each
session.
Peak
knee
flexion
and
ankle
dorsiflexion
angle
stride-to-stride
standard
deviation
were
also
computed
for
each
session,
and
stride-to-stride
variance
was
subsequently
calculated
as
the
square
root
of
this
stride-to-stride
standard
deviation.
2.3.
Statistical
analysis
An
a
priori
power
analysis
using
the
G
Power
3
software
showed
that
with
nine
subjects,
at
a
=
.05
we
would
have
92%
power
to
detect
a
.5
(medium)
effect
size.
Thus,
statistical
analysis
was
performed
using
SPSS
for
the
2-session
group
(N
=
9),
and
consisted
of
two-way
repeated
measures
ANOVAs
to
assess
main
effects
of
stimulation,
session,
and
an
interaction
between
stimulation
and
session
for
peak
knee
angle,
ankle
angle,
and
stride-to-stride
variance.
For
the
5-session
group
(N
=
5),
because
of
the
small
sample
size,
only
descriptive
statistics
were
assessed.
In
addition,
peak
knee
angle,
ankle
angle,
and
stride-to-stride
variance
changes
across
sessions
(across-session)
were
compared
to
known
minimal
detectable
change
(MDC)
values
[28]
to
determine
significance.
Table
1
Subject
characteristics.
Subject
Gender
Age
(years)
Time
since
stroke
onset
(years)
Side
of
hemiparesis
Gait
speed
(m/s)
Fugl
Meyer
(score)
Lesion
S
36
F
58
21.3
L
0.2
23
R
CVA
S
37
F
51
1.9
L
0.3
20
R
CVA
S
53
M
72
6.1
R
0.5
18
L
CVA
S
38
M
58
9.9
R
0.7
21
L
CVA
S
39
M
60
5.8
R
0.8
25
L
CVA
S
1
M
66
2.4
L
0.9
24
R
CVA
S
15
M
52
6.3
L
0.6
20
R
CVA
S
40
M
49
9.3
R
0.9
28
R
CVA
S
67
M
57
2.7
R
0.7
22
L
CVA
Average
58.1
7.3
0.6
22.3
St
dev
7.3
6.0
0.2
3.0
L.N.
Awad
et
al.
/
Gait
&
Posture
xxx
(2012)
xxx–xxx
2
G
Model
GAIPOS-3608;
No.
of
Pages
5
Please
cite
this
article
in
press
as:
Awad
LN,
et
al.
Effects
of
repeated
treadmill
testing
and
electrical
stimulation
on
post-stroke
gait
kinematics.
Gait
Posture
(2012),
http://dx.doi.org/10.1016/j.gaitpost.2012.06.001
3.
Results
Complete
data
sets
were
collected
for
eight
of
nine
subjects
(Figs.
1
and
2).
Due
to
problems
with
data
collection
during
testing
session
one
for
subject
36,
data
for
the
noFES
condition
from
another
trial
within
the
testing
session
were
substituted
for
data
for
the
noFES
condition
from
the
beginning
of
the
testing
session.
3.1.
2-Session
data
(N
=
9)
Analysis
of
peak
ankle
angle
data
revealed
a
main
effect
of
stimulation
(FES
increased
ankle
angle)
(p
=
.03),
no
main
effect
of
session
(p
=
.89),
and
no
interaction
effect
(p
=
.72)
(see
Fig.
1).
Similarly,
for
peak
knee
angle,
a
main
effect
of
stimulation
was
observed
(FES
decreased
knee
angle)
(p
=
.04),
but
neither
a
main
effect
of
session
(p
=
.64)
nor
an
interaction
effect
(p
=
.43)
were
found.
For
peak
ankle
angle
stride-to-stride
variance,
a
main
effect
of
stimulation
was
observed
(FES
decreased
variance)
(p
=
.005)
and
an
overall
effect
of
session
was
observed
(greater
ankle
angle
variance
during
the
2nd
session)
(p
=
.04).
No
interaction
effect
(p
=
.07)
was
found.
Similarly,
for
peak
knee
angle
stride-to-stride
variance,
a
main
effect
of
stimulation
was
observed
(FES
decreased
peak
knee
angle
stride-to-stride
variance)
(p
=
.05),
but
neither
a
main
effect
of
session
(p
=
.73)
nor
an
interaction
effect
(p
=
.46)
were
found.
3.2.
5-Session
data
(N
=
5)
MDC
values
have
been
reported
for
peak
ankle
(4.98)
and
peak
knee
angle
(5.78)
but
not
for
peak
ankle
and
peak
knee
stride-to-
stride
variances
[28].
For
both
the
FES
and
noFES
conditions,
the
average
across-session
kinematic
changes
for
peak
ankle
angle
and
peak
knee
angle
were
not
greater
than
the
known
MDCs
(see
Fig.
2).
No
consistent
changes
were
present
for
peak
ankle
and
knee
angle
stride-to-stride
variance.
Inspection
of
individual
subject
data
revealed
no
systematic
across-session
changes.
4.
Discussion
The
determination
of
an
intervention’s
effectiveness
is
typically
made
after
comparison
of
pre-
and
post-intervention
performance
measures.
However,
the
mere
repeated
testing
of
gait
could
produce
either
improvements
or
declines
in
gait
performance.
These
performance
changes
could
lead
to
false
conclusions
of
either
effectiveness
or
ineffectiveness.
Thus,
an
accurate
appraisal
of
effectiveness
requires
a
stable
pre-intervention
measurement
of
baseline
gait
performance,
which
may
necessitate
multiple
testing
sessions.
Hence,
the
purpose
of
this
study
was
to
determine
if
the
repeated
exposure
to
two
novel
gait
retraining
interventions
(1)
treadmill
walking
and
(2)
treadmill
walking
combined
with
dorsiflexor
FES
produced
systematic
changes
in
post-stroke
gait
kinematics,
and
if
these
changes
were
stabilized
with
additional
testing
sessions.
Our
results
show
that
whether
measured
across
two
or
five
testing
sessions,
no
systematic
changes
in
peak
knee
and
ankle
angle
means
and
variances
were
observed
except
for
an
overall
increase
in
ankle
angle
variance
across
two
sessions.
However,
this
finding
did
not
persist
across
five
testing
sessions
as
no
consistent
patterns
of
change
emerged
across
subjects.
Our
study,
therefore,
demonstrates
that
post-stroke
knee
and
ankle
gait
kinematics
do
not
exhibit
systematic
changes
across
multiple
treadmill
walking
sessions.
This
stability
of
post-stroke
knee
and
ankle
gait
kinematics
is
further
supported
by
our
similar
finding
of
no
systematic
changes
in
gait
kinematics
across
testing
sessions
even
with
the
addition
of
FES
during
walking.
This
finding
of
no
systematic
changes
in
kinematic
performance
across
multiple
testing
sessions
for
post-stroke
individuals
is
in
contrast
to
the
learning
effects
produced
during
the
repeated
testing
of
the
6-minute
walk
test
(6MWT)
in
young
healthy
adults
[20],
individuals
with
down
syndrome
[21],
patients
with
fibromyalgia
[23],
and
those
with
chronic
cardiac
and
pulmonary
disease
[24].
Furthermore,
our
finding
calls
into
question
whether
the
many
precautionary
actions
taken
by
researchers
in
anticipa-
tion
of
an
interaction
between
testing
and
performance,
such
as
Fig.
1.
The
mean
values
for
peak
ankle
and
knee
angles
(panels
A
and
B)
and
variances
(panels
C
and
D)
for
the
2-session
group
(N
=
9).
Each
panel
(A–D)
presents
across-
session
changes
for
both
the
FES
and
noFES
conditions.
*
denotes
a
main
effect
of
stimulation
between
conditions
(p
.05).
y
denotes
a
main
effect
of
session
for
a
condition
(p
.05).
L.N.
Awad
et
al.
/
Gait
&
Posture
xxx
(2012)
xxx–xxx
3
G
Model
GAIPOS-3608;
No.
of
Pages
5
Please
cite
this
article
in
press
as:
Awad
LN,
et
al.
Effects
of
repeated
treadmill
testing
and
electrical
stimulation
on
post-stroke
gait
kinematics.
Gait
Posture
(2012),
http://dx.doi.org/10.1016/j.gaitpost.2012.06.001
those
described
earlier
in
this
paper
[18–20],
are
indeed
necessary
without
direct
evidence
for
such
an
interaction.
The
lack
of
systematic
changes
in
gait
performance
due
to
repeated
testing
that
were
observed
during
this
study
may
be
explained
by
the
lack
of
knowledge
of
results
provided
to
the
subjects
during
testing.
Force
production
testing,
velocity
testing,
and
6MWT
studies
all
inherently
provide
some
knowledge
of
results
as
subjects
are
generally
aware
of
their
performance
even
without
external
feedback,
and
thus
some
learning
is
expected.
However,
individuals
are
typically
not
aware
of
their
gait
kinematics
during
walking;
thus,
without
external
feedback,
no
knowledge
of
results
is
provided
during
testing
and
any
possibility
of
learning
is
minimized.
Exploration
of
an
interaction
between
post-stroke
gait
testing
and
performance
when
knowledge
of
results
is
provided
may
be
an
interesting
direction
for
future
study.
The
lack
of
systematic
changes
in
performance
due
to
repeated
testing
that
were
observed
in
this
study
may
also
be
due
to
the
nature
of
gait
testing.
An
individual’s
initial
performance
on
any
given
outcome
measure
may
be
negatively
impacted
by
factors
such
as
lack
of
familiarity
with
the
testing
procedures
and
anxiety.
These
factors
can
be
overcome
with
practice
that
can
be
provided
via
several
testing
or
acclimatization
sessions.
Improvements
in
performance
that
may
emerge
during
these
subsequent
sessions
likely
do
not
represent
motor
learning;
rather,
these
improve-
ments
may
reflect
the
emergence
of
true
baseline
abilities
that
were
hindered
by
the
lack
of
familiarity
with
the
procedures
or
anxiety.
However,
as
was
described
in
the
methods
section
of
this
paper,
for
the
present
study
subjects
had
the
opportunity
to
familiarize
themselves
with
the
procedures
by
taking
several
practice
steps
immediately
before
data
began
to
be
recorded.
This
may
explain
why
multiple
testing
sessions
may
not
be
necessary
for
gait
testing
on
a
treadmill,
while
still
necessary
for
measures
such
as
force
production
and
6MWT
performance.
This
is
fortunate
as
the
considerable
time
and
resources
necessary
to
conduct
Fig.
2.
The
mean
values
(left)
and
corresponding
individual
subject
data
(right,
indicated
by
arrows)
for
peak
ankle
and
knee
angles
(panels
A
and
B)
and
variances
(panels
C
and
D)
for
the
5-session
group
(N
=
5).
Each
panel
(A–D)
presents
across-session
changes
for
both
the
FES
and
noFES
conditions.
For
the
individual
subject
graphs,
each
subject
is
given
a
unique
symbol.
L.N.
Awad
et
al.
/
Gait
&
Posture
xxx
(2012)
xxx–xxx
4
G
Model
GAIPOS-3608;
No.
of
Pages
5
Please
cite
this
article
in
press
as:
Awad
LN,
et
al.
Effects
of
repeated
treadmill
testing
and
electrical
stimulation
on
post-stroke
gait
kinematics.
Gait
Posture
(2012),
http://dx.doi.org/10.1016/j.gaitpost.2012.06.001
multiple
sessions
of
motion
analysis
are
significantly
higher
than
those
needed
to
repeat
the
6MWT
or
re-measure
maximal
force
production.
Thus,
our
findings
may
be
of
substantial
clinical
and
research
value
as
they
suggest
that
there
is
little
advantage
to
collecting
more
than
one
testing
session
when
determining
post-
stroke
treadmill
walking
ability,
with
or
without
the
addition
of
FES.
The
absence
of
systematic
changes
in
performance
due
to
repeated
treadmill
testing
in
the
present
study
may
also
be
related
to
a
decreased
motor
learning
ability
in
post-stroke
and
possibly
other
neurologically
impaired
patient
populations.
In
the
young,
healthy
population,
improvements
in
6MWT
performance
due
to
repeated
testing
were
maintained
for
as
long
as
two
months,
and
additional
improvements
were
observed
after
another
round
of
repeated
testing
[20].
This
finding
in
a
healthy
population,
as
compared
to
a
neurologically
impaired
population,
suggests
that
some
populations
may
have
higher
motor-learning
thresholds
as
compared
to
their
neurologically
unimpaired
counterparts.
Indeed,
a
restricted
learn-
ing
capacity
was
postulated
as
a
reason
for
the
absence
of
a
learning
effect
in
some
adults
with
Down
syndrome
[21].
Another
possible
reason
for
our
observation
of
no
changes
in
gait
performance
during
repeated
treadmill
testing
is
our
small
sample
size;
however,
the
results
of
our
power
analysis
indicate
that
this
study
was
adequately
powered.
Furthermore,
because
we
were
able
to
detect
the
modest
differences
that
were
present
between
the
FES
and
noFES
conditions
(see
Figs.
1
and
2),
we
are
confident
that
our
equipment
and
evaluation
methodology
were
both
highly
sensitive
and
reliable,
and
that
we
would
have
been
able
to
detect
changes
in
performance
due
to
repeated
testing
if
they
had
existed.
Thus,
while
future
studies
with
a
larger
sample
size
may
increase
the
generalizability
of
our
results,
we
do
not
believe
they
will
contradict
our
findings.
It
should
be
noted
that
while
this
study
has
demonstrated
that
no
systematic
changes
occur
in
post-stroke
gait
kinematics
across
testing
sessions,
random
variations
do
exist
for
individual
subjects
(see
Fig.
2).
This
random
variability
which
has
been
ascribed
to
test-retest
errors,
and
the
increased
inherent
day-to-day
variability
in
post-stroke
walking
patterns
as
compared
to
neurologically
unimpaired
individuals
[28–30]
can
effectively
be
accounted
for
through
the
use
of
MDC
scores
[28].
Specifics
regarding
the
appropriate
use
of
MDC
scores
can
be
found
in
a
previous
paper
from
our
lab
[28];
however,
if
repeated
testing
did
produce
changes
in
gait
performance,
relying
solely
on
MDC
scores
to
determine
‘‘real
change’’
would
be
insufficient
as
changes
in
performance
due
to
repeated
testing
may
be
greater
than
the
MDC,
thus
yielding
a
false
impression
of
an
intervention’s
effectiveness.
Our
finding
of
no
interaction
between
post-stroke
gait
testing
and
performance
therefore
affords
clinicians
and
researchers
the
confident
use
of
MDC
scores
when
determining
the
effectiveness
of
post-stroke
treadmill
walking,
with
and
without
the
addition
of
FES.
Conflict
of
interest
None
declared.
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  • [Show abstract] [Hide abstract] ABSTRACT: [Purpose] The purpose of the study was to design and implement a multichannel dynamic functional electrical stimulation system and investigate acute effects of functional electrical stimulation of the tibialis anterior and rectus femoris on ankle and knee sagittal-plane kinematics and related muscle forces of hemiplegic gait. [Subjects and Methods] A multichannel dynamic electrical stimulation system was developed with 8-channel low frequency current generators. Eight male hemiplegic patients were trained for 4 weeks with electric stimulation of the tibia anterior and rectus femoris muscles during walking, which was coupled with active contraction. Kinematic data were collected, and muscle forces of the tibialis anterior and rectus femoris of the affected limbs were analyzed using a musculoskelatal modeling approach before and after training. A paired sample t-test was used to detect the differences between before and after training. [Results] The step length of the affected limb significantly increased after the stimulation was applied. The maximum dorsiflexion angle and maximum knee flexion angle of the affected limb were both increased significantly during stimulation. The maximum muscle forces of both the tibia anterior and rectus femoris increased significantly during stimulation compared with before functional electrical stimulation was applied. [Conclusion] This study established a functional electrical stimulation strategy based on hemiplegic gait analysis and musculoskeletal modeling. The multichannel functional electrical stimulation system successfully corrected foot drop and altered circumduction hemiplegic gait pattern.
    Full-text · Article · Dec 2015