Shoulder rotator torque and wheelchair dependence differences of National Wheelchair Basketball Association players


Nyland, J.; Robinson, K.; Caborn, D.; Knapp, E.; Brosky, T.

Archives of Physical Medicine and Rehabilitation 78(4): 358-363

1997


Objective: Shoulder rotator muscle imbalances can contribute to subacromial impingement. The forces and movement patterns of wheelchair locomotion may contribute to these imbalances. This study attempted to determine whether National Wheelchair Basketball Association players of differing classifications had significant differences (p ltoreq .05) in concentric isokinetic peak shoulder rotator torque and torque ratios, and wheelchair locomotion dependence. Design: Fifty-seven (class 1 = 12, class 2 = 24, class 3 = 21) of 117 total tournament participants (class 1 = 25, class 2 = 49, class 3 = 43) served as the convenience sample of volunteers for the survey portion, and 33 of these subjects (class 1 = 11, class 2 = 12, class 3 = 10) also entered the isokinetic portion of this study. Setting: National wheelchair basketball tournament. Results: Class 1 and 2 players had greater wheelchair dependence than class 3 players (p ltoreq .05). Peak torque or torque ratios generally did not differ among player classifications or with other populations. Class 1 players had weaker nondominant shoulder external rotator torque production at 60 degree /sec (p ltoreq .03) compared with other classes and at 180 degree /sec compared with class 3 players (p = .02), suggesting an inability to develop the "attenuation of dominance" noted among other groups. Diminished torque-producing capacity at 60 degree /sec related to greater wheelchair dependence among class 1 players (p = .034). Conclusions: Class 1 players failed to demonstrate the acquired shoulder external rotator torque symmetry evident among class 2 and 3 players (with specific weakness of the nondominant shoulder external rotators). This torque symmetry difference was related to their greater dependence on wheelchair locomotion.

358
Shoulder
Rotator
Torque
and
Wheelchair
Dependence
Differences
of
National
Wheelchair
Basketball
Association
Players
John
Nyland,
EdD,
PT,
Kevin
Robinson,
MS,
PT,
David
Caborn,
MD,
Elizabeth
Knapp,
BS,
Tony
Brosky,
PT,
SCS.
ABSTRACT.
Nyland
J,
Robinson
K,
Caborn
D,
Knapp
E,
Brosky
T.
Shoulder
rotation
torque
and
wheelchair
dependence
differences
of
National
Wheelchair
Basketball
Association
play-
ers.
Arch
Phys
Med
Rehabil
1997;78:358-63.
Objective:
Shoulder
rotator
muscle
imbalances
can
contrib-
ute
to
subacromial
impingement.
The
forces
and
movement
patterns
of
wheelchair
locomotion
may
contribute
to
these
im-
balances.
This
study
attempted
to
determine
whether
National
Wheelchair
Basketball
Association
players
of
differing
classi-
fications
had
significant
differences
(p
.05)
in
concentric
isokinetic
peak
shoulder
rotator
torque
and
torque
ratios,
and
wheelchair
locomotion
dependence.
Design:
Fifty-seven
(class
1
=
12,
class
2
=
24,
class
3
=
21)
of
117
total
tournament
participants
(class
1
=
25,
class
2
=
49,
class
3
=
43)
served
as
the
convenience
sample
of
volun-
teers
for
the
survey
portion,
and
33
of
these
subjects
(class
1
=
11,
class
2
=
12,
class
3
=
10)
also
entered
the
isokinetic
portion
of
this
study.
Setting:
National
wheelchair
basketball
tournament.
Results:
Class
1
and
2
players
had
greater
wheelchair
depen-
dence
than
class
3
players
(p
.05).
Peak
torque
or
torque
ratios
generally
did
not
differ
among
player
classifications
or
with
other
populations.
Class
1
players
had
weaker
nondominant
shoulder
external
rotator
torque
production
at
60°/sec
(p
.03)
compared
with
other
classes
and
at
180°/sec
compared
with
class
3
players
(p
=
.02),
suggesting
an
inability
to
develop
the
"attenuation
of
dominance"
noted
among
other
groups.
Diminished
torque-producing
capacity
at
60°/sec
related
to
greater
wheelchair
dependence
among
class
1
players
(p
=
.034).
Conclusions:
Class
1
players
failed
to
demonstrate
the
ac-
quired
shoulder
external
rotator
torque
symmetry
evident
among
class
2
and
3
players
(with
specific
weakness
of
the
nondomi-
nant
shoulder
external
rotators).
This
torque
symmetry
differ-
ence
was
related
to
their
greater
dependence
on
wheelchair
locomotion.
©
1997
by
the
American
Congress
of
Rehabilitation
Medicine
and
the
American
Academy
of
Physical
Medicine
and
Rehabili-
tation
O
RGANIZED
COMPETITIVE
wheelchair
athletics
date
back
to
1948
and
were
developed
originally
as
a
means
to
rehabilitate
disabled
war
veterans.'
Individuals
with
congenital
From
the
University
of
Kentucky
Sports
Medicine
Center
Submitted
for
publication
March
8,
1996.
Accepted
in
revised
form
September
6,
1996.
No
commercial
party
having
a
direct
or
indirect
interest
in
the
subject
matter
of
this
article
has
or
will
confer
a
benefit
upon
the
authors
or upon
any
organization
with
which
the
authors
are
associated.
Reprint
requests
to
John
Nyland,
EdD,
PT,
K437
Kentucky
Clinic,
University
of
Kentucky
Sports
Medicine
Center,
Lexington,
KY
40536-0284.
©
1997
by
the
American
Congress
of
Rehabilitation
Medicine
and
the
American
Academy
of
Physical
Medicine
and
Rehabilitation
0003-9993/97/7804-3934$3
.00/0
deformities
such
as
spina
bifida,
diseases
such
as
polio,
and
traumatic
injuries
such
as
spinal
cord
injury
or
amputation
are
often
active
participants
in
wheelchair
athletics.
The
number
of
disabled
athletes
participating
in
competitive
sports
has
rapidly
increased,
and
wheelchair
sports
have
evolved
from
a
rehabilita-
tion
process
to
competitions
on
local,
state,
national,
and
inter-
national
levels.
2-5
Competitive
wheelchair
athletes
from
6
to
18
years
of
age
form
one
of
the
fastest
growing
areas
of
wheelchair
athletics.'
Increased
and
earlier
participation
in
wheelchair
ath-
letics
raises
further
concern
over
the
prevention
of
sports-related
injuries
among
this
population.
THE
BENEFITS
OF
WHEELCHAIR
ATHLETICS
Disabled
individuals
who
assume
sedentary
lifestyles
often
have
diminished
functional
capacity,
rehabilitation
potential,
and
overall
quality
of
life.'
A
sedentary
lifestyle
can
place
the
disabled
individual
at
greater
risk
for
the
development
of
cardio-
pulmonary
disease,
adult-onset
diabetes,
and
hypertension'
Regular
endurance
activities
for
individuals
who
depend
on
a
wheelchair
as
their
primary
method
of
locomotion
may
delay
the
progression
of
these
diseases,
reduce
the
incidence
of
respi-
ratory
infection,
counter
the
development
of
osteoporosis,
and
decrease
the
risk
of
calculi
formation.'
Increased
habitual
activ-
ity
can
also
improve
self-image'
and
have
a
positive
impact
on
other
health
behaviors
such
as
smoking
or
alcohol
consump-
tion.'
SHOULDER
INJURY
OCCURRENCE
Dependence
on
a
wheelchair
for
locomotion
(wheeling)
and
repeated
lifting
of
body
weight
during
transfers
place
demands
on
the
upper
extremities
of
the
disabled
that
exceed
those
of
able-bodied
persons.
11
•'
2
Wheelchair
athletes
rely
on
their
upper
extremities
for
both
propulsion
and
weight
bearing
during
daily
living
and
sports
activities.'
The
integrity
of
the
upper
extremi-
ties
is
believed
to
be
a
major
determinant
regarding
the
ultimate
level
of
functional
independence
of
wheelchair
athletes.'
With
increased
numbers
of
participants,
and
increased
levels
of
competition,
sports-related
injuries
among
this
population
have
also
increased.
In
a
1972
survey
conducted
among
Ameri-
can
wheelchair
athletes,
72%
of
respondents
reported
at
least
1
injury
as
a
result
of
sport
participation,
with
soft
tissue
injuries
such
as
sprains,
strains,
tendinitis,
and
bursitis
being
the
most
commonly
reported.'
Hoeberigs
and
Verstappen"
reported
that
42%
of
wheelchair
basketball
athletes
developed
upper
extrem-
ity
soreness
during
tournament
play,
with
34%
reporting
sore-
ness
in
the
deltoid
region.
Among
National
Wheelchair
Athletic
Association
(NWAA)
athletes,
61%
of
total
injuries
occur
at
the
upper
extremity,
with
40%
of
these
injuries
occurring
at
the
shoulder
joint.'
Shoulder
injury
and
pain
are
also
common
among
wheel-
chair-dependent
nonathletes."
5
16
Bayley
et
al
l
'
reported
that
33%
of
wheelchair-dependent
paraplegic
persons
had
chronic,
Arch
Phys
Med
Rehabil
Vol
78,
April
1977
Ca
0—
(
I?
C1
C2
C3
C4
CS
6
C7
C8
T1
T2
T3
T4
T5
I-
18
T9
T10
S1
S2
S3
S4
Cs
Cs
rn
S5
T6
T7
T11
T12
L1
L2
L3
L4
WHEELCHAIR
BASKETBALL
SHOULDER,
Nyland
359
Class
I
Complete
motor
loss
at
T7
or
above
or
comparable
disability
where
there
is
total
loss
of
muscle
function
originating
at
or
above
T7.
Class
H
Complete
motor
loss
originating
at
T8
and
descending
through
and
incuding
L2
where
there
may
be
motor
power
of
hips
and
thighs.
Also
included
in
this
class
are
amputees
with
bilateral
hip
disarticulation.
A
Class
III
----- -------
------
All
other
physical
disabilities
as
related
to
lower
extremity
paralysis
or
paresis
originating
at
or
below
L3.
All
lower
extremity
amputees
are
included
in
this
class
except
those
with
bilateral
hip
disarticulation
(see
Class
II).
9
Fig
1.
NWBA
player
classifications.
persistent
shoulder
pain
that
was
clinically
diagnosed
as
sub-
acromial
impingement
syndrome.
Despite
being
recognized
as
a
common
and
disabling
problem,
little
has
been
written
regard-
ing
the
cause,
prevention,
or
treatment
of
shoulder
problems
among
wheelchair
athletes.'
WHEELCHAIR
ATHLETIC
SUBACROMIAL
IMPINGEMENT—MUSCULAR
IMBALANCE
RELATIONSHIP
The
primary
cause
of
overuse
injury
or
pain
involving
the
shoulders
of
wheelchair
athletes
is
believed
to
be
subacromial
impingement.'
Overuse,
lack
of
proper
warm-up,
glenohumeral
and
scapulo-thoracic
dyskinesia
(muscular
imbalances),
lack
of
dynamic
lumbo-pelvic
postural
control,
axial
weight
bearing
forces,
poor
shoulder
flexibility,
repetitive
overhead
arm
posi-
tioning,
and
fatigue
may
all
contribute
to
subacromial
impinge-
ment
syndrome
among
wheelchair
athletes,
3,6,11.12,15-21
Exaggerated
glenohumeral
internal
rotation
and
scapular
pro-
traction
with
downward
rotation
positioning
is
common
for
wheelchair
athletes
both
at
rest
and
during
aggressive
wheeling.'
Repetitive
function
with
the
shoulder
girdle
in
this
position
reportedly
promotes
subacromial
impingement
in
other
ath-
letic'
'
4
and
nonathletic
populations.'
When
upper
extremity
weight
bearing
increases,
as
during
wheelchair
locomotion,
changes
in
muscular
agonist-antagonist
torque-producing
ratios
similar
to
those
noted
after
intensive
conditioning
programs
may
occur,
often
leading
to
greater
torque
production
symmetry
("nondominance")
between
Fig
2.
Isokinetic
Test
Positioning:
(A)
maximal
internal
rotation;
(B)
maxi-
mal
external
rotation.
extremities
and
imbalances
between
opposing
muscular
groups:
9
'
26
Shoulder
muscle
imbalances
with
humeral
head
de-
pressor
weakness
(infraspinatus,
teres
minor,
subscapularis,
long
head
of
biceps
brachii)
in
combination
with
repetitive
axial
subacromial
space
loading
from
weight
bearing
may
further
exacerbate
subacromial
impingement
among
wheelchair
ath-
letes.
2
'
19
Wheelchair
propulsion
selectively
promotes
the
devel-
opment
of
glenohumeral
joint
internal
rotator
(pectoralis
major,
teres
major,
latissimus
dorsi,
subscapularis)
and
scapular
pro-
tractor
(serratus
anterior)
torque-producing
capacity,
thereby
creating
muscular
imbalances.
227
Dysfunctional
sitting
posture
resulting
from
neurological
deficits
or
simply
poor
habits
can
adversely
affect
the
glenohu-
meral
joint
through
changes
in
scapulo-thoracic
articulation
ori-
entation.
Subtle
changes
in
glenoid
fossa
alignment
can
evoke
compensatory
muscular
stabilization
demands
that
eventually
promote
joint
degeneration.
Paraplegic
persons
with
complete
Table
1:
Subject
Demographics
Wheelchair
Basketball
Duration
of
Playing
NWBA
Disability
Experience
Height
Weight
Classification
Age
(yrs)
(yrs) (yrs) (cm)
(kg)
Class
1
(n
=
12)
35.7
±-
4
14.3
±
5
11.0
±
5
183
±
10
80
±
18
Class
2
(n
=
24)
35,8
±
8
17.8
±
11
11.9
±
8
180±
11
74±15
Class
3
(n
=
21)
34.4
±
7
19.2
±
11
11.8
±
6
184
±
10
88
17
Characteristics
presented
as
mean
±
SD.
p
>
.05.
Arch
Phys
Med
Rehabil
Vol
78,
April
1997
360
WHEELCHAIR
BASKETBALL
SHOULDER,
Nyland
Table
2:
Wheelchair
Dependence
NWBA
Wheelchair
Dependence
Classification
(mm)
Class
1
(n
=
12)
93.1
±
15.0*
Class
2
(n
=
24)
76.2
±
35.4*
Class
3
(n
=
21)
30.2
±
30.6
Values
presented
as
mean
±
SD.
*
Overall
F
=
26.7
(p
=
.0001);
Class
1
and
Class
2
>
Class
3
(p
.05).
spinal
cord
lesions
below
the
second
thoracic
(T-2)
spinal
nerve
root
level
can
achieve
partial
sitting
postural
compensation
for
decreased
erector
spinae
muscle
group
function
by
increased
latissimus
dorsi
and
upper
trapezius
muscle
activation.'
When
dynamic
trunk
control
is
compromised,
these
muscles
may
serve
more
as
postural
stabilizers
for
the
trunk
than
as
prime
movers
for
the
upper
extremity,
thereby
further
promoting
glenohu-
meral muscular
imbalances.'
The
ability
to
dynamically
control
sitting
posture
is
vital
for
proper
scapulo-thoracic
and
glenohu-
meral
function
and
efficient
performance
of
functional
tasks
with
the
upper
extremities.'
Spinal
cord
injured
subjects
tend
to
sit
with
their
pelvis
tilted
15°
more
posteriorly
than
normal
subjects
to
enhance
sitting
balance
in
the
absence
of
effective
dynamic
lumbo-pelvic
control.'
This
sitting
posture
further
pro-
motes
inefficient
scapulo-thoracic
and
glenohumeral
position-
ing,
motion,
and
torque-producing
capacity.
25
NWBA
RATING
SYSTEM
According
to
a
study
performed
in
1984,
the
National
Wheel-
chair
Basketball
Association
(NWBA)
includes
approximately
1,950
players
on
more
than
165
men's
and
women's
teams
in
27
conferences.
13
The
NWBA
is
the
oldest
organization
in
the
United
States
representing
athletes
with
locomotor
impair-
ments.'
To
be
eligible
for
NWBA
participation
individuals
must
have
permanent
severe
leg
disability
or
paralysis
of
the
lower
portion
of
the
body,
as
well
as
the
potential
for
benefiting
from
participation
in
wheelchair
basketball,
and
must
be
denied
the
opportunity
to
otherwise
play
basketball
were
it
not
for
the
wheelchair
adaptation.
The
NWBA
favors
a
functional
classifi-
cation
system
for
its
participants
based
on
the
quality
and
quan-
tity
of
active
muscle
and
the
ability
to
perform
specific
tasks
such
as
trunk
rotation
and
picking
a
basketball
up
from
the
floor.
This
functional
classification
system
generates
three
player
categories,
ranging
from
relatively
higher
spinal
cord
injured
athletes
(class
1),
who
are
almost
exclusively
wheelchair
dependent,
to
any
of
a
wide
variety
of
other
medical
conditions
that
generally
do
not
result
in
as
great
a
wheelchair
dependence
(class
3).
Class
3
players
often
leave
their
wheelchairs
courtside
at
the
completion
of
play
and
walk
around
with
or
without
other
assistive
devices. Player
classifications
are
denoted
in
figure
1.
30
Although
studies
have
assessed
shoulder
muscle
torque-produc-
ing
capability
2
-
'
26
and
relative
wheelchair
dependence,
6
'
15
com-
parison
of
wheelchair
basketball
players
based
solely
on
their
NWBA
classification
has
not
been
performed.
The
purpose
of
this
study
was
to
determine
if
NWBA
player
classification
resulted
in
statistically
significant
differences
(p
.05)
in
(1)
concentric
Table
3:
Peak
Shoulder
External
Rotator
(ER)
and
Internal
Rotator
(IR)
Torque
ER
Peak
IR
Peak
ER
Peak
IR
Peak
Torque
Torque
NWBA
Torque
Torque
(Nm),
(Nm),
Classification
(Nm),
60
°
/sec
(Nm),
60°/sec
180°/sec
180°/sec
Class
1
(n
=
11)
45.8
9.8
74.7
±
11.7
36.9
9.2
64.8
±
9.4
Class
2
(n
=
12)
42.2
±
13.6
69.4
±
14.9
31.3
±
12.1
58.0
±
13.0
Class
3
(n
=
10)
41.4
±
9.4
70.2
±
13.3
31.2
±
7.2
61.3
±
9.2
Values
presented
as
mean
±
SD.
p
>
.05.
isokinetic
peak
torque
of
the
shoulder
internal
and
external
rota-
tors,
(2)
the
ratio
of
dominant
and
nondominant
concentric
isoki-
netic
peak
torque
of
the
shoulder
internal
and
external
rotators,
and
(3)
wheelchair
dependence
for
locomotion.
Peak
torque
and
torque
ratios
were
also
compared
and
con-
trasted
with
other
populations.
METHODS
Procedures
Informed
consent
was
obtained
from
each
participant
in
the
study.
Data
collection
took
place
during
the
13th
Annual
Blue-
grass
Invitational
Wheelchair
Basketball
Tournament.
Data
col-
lection
was
coordinated
by
the
primary
investigator.
The
NWBA
classification
was
verified
from
tournament
registration
applications
at
the
conclusion
of
the
tournament.
Subjects
The
study
population
was
sampled
from
the
117
participants
(class
1
=
25,
class
2
=
49,
class
3
=
43)
in
the
basketball
tournament.
Fifty-seven
(class
1
=
12,
class
2
=
24,
class
3
=
21)
players
volunteered
to
participate
in
the
questionnaire
por-
tion
of
this
study,
which
attempted
to
determine
wheelchair
dependence
as
the
primary
mode
of
transportation.
The
follow-
ing
question
was
used
to
determine
wheelchair
dependence:
"Excluding
motorized
vehicles,
I
use
a
wheelchair
as
my
pri-
mary
method
of
transportation
?
percent
of
the
time."
Re-
sponses
could
range
from
"Never"
to
"All
the
Time."
Before
answering
this
question,
subjects
completed
a
trial
question
un-
der
the
supervision
of
the
principle
investigator
to
become
fa-
miliar
with
the
visual
analog
scale
(VAS)
format
and
to
increase
measurement
reliability.'
Additional
information
was
obtained
regarding
the
duration
of
disability,
wheelchair
basketball
play-
ing
experience,
height,
and
weight.
Of
these
subjects,
33
(class
1
=
11,
class
2
=
12,
class
3
=
10)
players
volunteered
to
participate
in
the
isokinetic
portion
of
this
study.
Only
subjects
who
were
asymptomatic
for
upper
extremity
or
trunk
pain
par-
ticipated
in
this
portion
of
the
study.
Isokinetic
testing
was
performed
using
a
Cybex
II
isokinetic
dynamometer
and
dual
channel
recorder'
and
a
Biodex
Upper
Extremity
Chair.
b
The
Biodex
chair
was
used
for
its
hydraulic
lift
capability,
which
enabled
greater
ease
of
transfer
while
simultaneously
enabling
replication
of
the
test
position
described
by
Cahalan
et
al.
32
Table
4:
Dominant
(DOM)
and
Nondominant
(NONDOM)
Shoulder
External
Rotator
(ER)
and
Internal
Rotator
(IR)
Peak
Torque
Ratios
NWBA
DOM
ER/IR
Peak
Torque
NONDOM
ER/IR
Peak
Torque
DOM
ER/IR
Peak
Torque
NONDOM
ER/IR
Peak
Torque
Classification
Ratio,
60°/sec
Ratio,
60°/sec
Ratio,
180°/sec
Ratio,
180°/sec
Class
1
(n
=
111
.66
±
.11
.57
±
.05
.58
±
.08
.54
±
.06
Class
2
(n
=
12)
.60
±
.13
.59
±
.11
.53
±
.11
.53
±
.12
Class
3
In
=
101
.58
±
.08
.59
±
.12
.50
±
.10
.54
±
.13
Values
presented
as
mean
±
SD.
p
>
.05.
Arch
Phys
Med
Rehabil
Vol
78,
April
1977
WHEELCHAIR
BASKETBALL
SHOULDER,
Nyland
361
Table
5:
Nondominant
(NONDOM)/Dominant
(DOM)
External
Rotator
(ER)
and
Internal
Rotator
(IR)
Peak
Torque
Ratios
NWBA
NONDOM/DOM
ER
Peak
Torque
NONDOM/DOM
IR
Peak
Torque
NONDOM/DOM
ER
Peak
Torque
NONDOM/DOM
IR
Peak
Torque
Classification
Ratio,
60°/sec
Ratio,
60°/sec
Ratio,
180°/sec
Ratio,
180°/sec
Class
1
(n
=
11)
.77
±
.11*
.91
.14 .84
±
.14
°
.93
±
.14
Class
2
In
=
12)
.97
±
.24
1.0
±
.16
1.04
±
.24
1.04
±
.18
Class
3
(n
=
10)
1.0
±
.13
.98
±
.19
1.16
±
.30
1.0
±
.17
*
NONDOM/DOM
ER
Peak
Torque
Ratio,
60°/sec,
overall
F=
4.9
(p
=
.011.
Differences
from
Class
2
(p
=
.03),
Class
3
(p
=
.02).
NONDOM/DOM
ER
Peak
Torque
Ratio,
180°/sec,
overall
F
=
4.5
(p
=
.04).
Differences
from
Class
2
(p
=
.11),
Class
3
(p
=
.02).
Torso
and
forearm
stabilization
straps
were
used.
Test
position-
ing
and
motion
pattern
are
presented
in
figure
2.
During
isoki-
netic
testing,
the
upper
extremity
which
was
tested
first
was
randomly
selected.
Before
determination
of
peak
shoulder
inter-
nal
or
external
rotator
torque,
each
subject
performed
three
submaximal
practice
repetitions.
Following
this,
each
subject
was
instructed
to
perform
five
repetitions
with
maximal
effort.
This
procedure
was
performed
initially
at
60°/sec
and
then
at
180°/sec.
Standard
recorder
settings
were
used
for
damping,
chart
speed,
and
torque
scale.'
This
procedure
was
then
re-
peated
for
the
opposite
upper
extremity.
Following
completion
of
isokinetic
testing,
peak
torque
values
were
manually
mea-
sured
per
manufacturer's
protocol.'
Statistical
Methods
Means
and
standard
deviations
were
calculated
for
each
vari-
able.
Median
and
range
values
were
also
determined
for
the
wheelchair
dependence
variable.
One-way
analysis
of
variance
(ANOVA)
tests
were
employed
to
determine
whether
significant
differences
existed
among
the
mean
torque
variables
and
wheel-
chair
dependence
values
of
each
NWBA
classification.
When
a
significant
F
value
occurred,
Tukey
Honest
Significant
Differ-
ence
post
hoc
comparisons
were
employed
to
specify
how
the
groups
differed
from
each
other.
A
probability
level
of
p
.05
was
chosen
for
all
statistical
procedures
to
demonstrate
statisti-
cal
significance.
RESULTS
Age,
duration
of
disability,
wheelchair
sports
experience,
height,
and
weight
were
not
significantly
different
among
player
classifications
(table
1).
Class
1
and
2
players
depended
on
wheelchairs
as
their
primary
mode
of
transportation
to
a
greater
extent
than
class
3
players
(p
5_
.05)
(table
2).
Comparisons
of
peak
shoulder
external
or
internal
rotator
torque
at
60°/sec
and
180°/sec
failed
to
reveal
statistically
sig-
nificant
differences
among
player
classifications
(table
3).
The
dominant
upper
extremity
was
defined
as
that
which
the
subject
preferred
to
use
while
shooting
a
basketball.
Comparisons
of
dominant
or
nondominant
peak
shoulder
external/internal
rota-
tor
torque
ratios
at
60°/sec
and
180°/sec
failed
to
reveal
signifi-
cant
differences
among
player
classifications
(table
4).
Comparisons
of
nondominant/dominant
peak
shoulder
exter-
nal
and
internal
rotator
torque
ratios
at
60°/sec
and
180°/sec
found
statistically
significant
decreases
in
external
rotator
torque
on
the
nondominant
shoulder
for
class
1
players
compared
to
class
2
and
3
players
at
60°/sec,
and
compared
to
class
3
players
at
180°/sec
(table
5).
Comparisons
of
nondominant/dominant
peak
shoulder
external
rotator
torque
and
NWBA
player
classi-
fication
by
wheelchair
dependence
found
significant
differences
at
60°/sec
between
class
1
players
and
other
classes
(table
6)
(fig
3).
DISCUSSION
Comparisons
were
made
among
peak
shoulder
external
and
internal
rotator
torque
(table
3),
dominant
and
nondominant
shoulder
external/internal
rotator
peak
torque
ratios
(table
4),
and
nondominant/dominant
shoulder
external
and
internal
rota-
tor
peak
torque
ratios
(table
5).
Comparisons
were
also
made
with
other
studies''''''
for
peak
shoulder
external
and
inter-
nal
rotator
torque
(table
7),
dominant
and
nondominant
shoulder
external/internal
rotator
peak
torque
ratios
(table
8
),22,23,32,34-39
and
nondominant/dominant
shoulder
external
and
internal
rota-
tor
peak
torque
ratios
(table
9).22,23,32,3436
Studies
were
chosen
that
used
similar
isokinetic
testing
procedures
and
positions
including
shoulder
positioning
(although
slight
differences
in
shoulder
flexion
and
abduction
angles
did
occur,
and
varying
isokinetic
devices
were
used).
Peak
shoulder
rotator
torques
reported
in
this
investigation
compared
favorably
with
previous
reports
of
wheelchair
athletes
and
other
populations
(table
7).
Peak
dominant
and
nondomi-
nant
shoulder external/internal
rotator
torque
ratios
(table
4)
also
compared
favorably
with
previous
studies
of
wheelchair
athletes,
and
other
populations
(table
8).
Nondominant/dominant
peak
shoulder
external
rotator
torque
results
for
class
1
wheelchair
basketball
players
revealed
statisti-
cal
differences
when
compared
to
class
2
and
3
players
(table
5)
and
when
compared
to
other
athletic
populations
(table
9).
These
results
indicate
that
although
class
1
wheelchair
basket-
ball
players
fail
to
demonstrate
significant
differences
in
peak
torque
capacity
compared
to
class
2
or
3
players,
they
demon-
strate
a
lack
of
the acquired
bilateral
shoulder
external
rotator
torque
symmetry
(attenuation
of
dominance)
reportedly
com-
mon
among
other
wheelchair
athletes
2
'
26
with
weaker
nondorni-
nant
shoulder
external
rotators
(table
8).
Comparisons
of
non-
dominant/dominant
peak
shoulder
external
rotation
torque
at
60°/sec
and
NWBA
player
classification
by
wheelchair
depen-
dence
provided
further
evidence
of
differences
between
class
1
players
and
other
player
classes
(table
6)
(fig
3).
Although
not
primarily
assessed
in
this
study,
faulty
sitting
posture
may
contribute
more
to
the
development
of
glenohu-
meral
joint
muscular
imbalances
among
class
1
players
more
than
other
wheelchair
basketball
players.
Lesions
at
or
above
Table
6:
Class
Comparisons
of
Wheelchair
Dependence
Versus
Nondominant/Dominant
External
Rotator
Torque
Ratios
at
60°/sec
Source
Wheelchair
Dependence
Sum-of-Squares
Degrees
of
Freedom
F
Ratio
Class
1
External
Rotator
Ratio
(n
=
11)
95.6
±
4.4
78.2
6.3
.034"
Class
2
External
Rotator
Ratio
(n
=
12)
66.9
25.9
1953.4
3.6
.086
Class
3
External
Rotator
Ratio
(n
=
10)
23.9
±
16
9.941
.035
.86
Wheelchair
dependence
values
presented
as
mean
±
SD.
"
p
s
.05.
Arch
Phys
Med
Rehabil
Vol
78,
April
1997
p.
2
4
362
WHEELCHAIR
BASKETBALL
SHOULDER,
Nyland
affect
both
intrinsic
and
extrinsic
shoulder
girdle
muscle
torque
producing
capacity.
When
normal
innervation
is
compromised,
scapulo-thoracic
and
glenohumeral
muscular
imbalances
may
result,
increasing
susceptibility
to
subacromial
impingement.
Because
of
their
greater
wheelchair
dependence,
and
potentially
more
impaired
dynamic
trunk
control,
class
1
wheelchair
bas-
ketball
players
may
be
especially
susceptible
to
subacromial
impingement
from
glenohumeral
joint
muscular
imbalances.
0
a
a
cit)
CZ>
O
a
(5>
O
cBC)
0
0
5
I
*OD
Fig
3.
Relation
of
wheelchair
dependence
and
nondominant/dominant
external
rotator
torque
at
60°/sec
to
player
classification.
the
seventh
thoracic
(T-7)
spinal
nerve
root
level
(class
1
by
definition)
can
produce
greater
and
more
variable
dynamic
trunk
control
and
shoulder
mobility
deficits
than
either
of
the
other
two
player
classifications.
Concurrently,
any
loss
of
normal
neural
function
above
the
T-7
spinal
nerve
root
level
may
also
CONCLUSIONS
This
study
found
that:
1.
Differences
did
not
exist
among
the
concentric
isokinetic
peak
shoulder
rotator
torque
or
nondominant/dominant
torque
ratios
of
differing
NWBA
player
classifications
or
other
populations;
2.
Differences
did
exist
in
nondominant/dominant
external
rotator
torque
ratios,
with
class
1
wheelchair
basketball
players
failing
to
demonstrate
the
symmetry
of
external
rotator
torque
(attenuation
of
dominance)
demonstrated
by
class
2
or
3
wheelchair
basketball
players
or
other
populations,
with
specific
weakness
of
the
nondominant
glenohumeral
joint
external
rotators;
3.
Class
1
wheelchair
basketball
players
were
more
depen-
dent
on
wheelchairs
as
their
primary
mode
of
transporta-
tion
than
either
class
2
or
3
players,
and
this
dependence
related
to
differences
in
nondominant
external
rotator
torque-producing
capacity.
Athletic
examinations
and
conditioning
programs
of
wheel-
chair
basketball
players
before
participation
should
place
partic-
ular
emphasis
on
functionally
evaluating
the
entire
shoulder
joint
complex,
with
emphasis
on
glenohumeral
external
rotator
and
scapular
retractor
function
as
integrated
members
of
a
global
kinetic
chain
that
has
an
origin
primarily
from
a
sitting
position.
Class
1
players
may
be
at
greater
risk
for
developing
glenohumeral
muscular
imbalances
than
their
class
2
or
3
coun-
terparts
because
of
greater
wheelchair
dependence,
inherently
Table
7:
Peak
Shoulder
External
Rotator
(ER)
and
Internal
Rotator
(IR)
Torque
Comparisons
ER
Peak
Torque
(Nm),
IR
Peak
Torque
(Nm),
ER
Peak
Torque
(Nm),
IR
Peak
Torque
(Nm),
Reference
Citations
60°/sec
60°/sec
180°/sec
180°/sec
Brown
et
a1
34
(Male
Baseball)
NA
Cahalan
et
a1
32
(Healthy
Adults)
35.3
±
8.1
Hageman
et
al
l'
(Healthy
Adults)
30.6
±
5.3
Leroux
et
al'
s
(Healthy
Adults)
32.1
±
1.9
McMaster
et
a1
22
(Healthy
Males)
(Male
Water
Polo)
NA
McMaster
et
a)
23
(Healthy
Males)
(Male
Swimmers)
NA
NA
62.4
±
19.0
48.6
±
11.0
43.6
±
4.0
NA
NA
39.7
±
7.1
27.1
±
5.4
26.7
±
7.1
29.3
±
2.1
37.1
±
8.7
46.8
±
10.7
37.1
±
8.7
38.6
±
10.8
56.9
±
9.9
54.2
±
17.6
42.3
±
8.3
39.0
±
3.7
56.7
±
12.7
89.3
±
23.3
56.7
±
12.7
89.9
±
27.1
Values
presented
as
mean
±
SD.
NA
=
not
applicable.
Table
8:
Dominant
(DOM)
and
Nondominant
INONDOM)
External
Rotator
(ER)
Internal
Rotator
(IR)
Peak
Torque
Ratio
Comparisons
DOM
ER/IR
Peak
Torque
Ratio,
60°/sec
NONDOM
ER/IR
Peak
Torque
Ratio,
60°/sec
DOM
ER/IR
Peak
Torque
Ratio,
180°/sec
NONDOM
ER/IR
Peak
Torque
Ratio,
180°/sec
NA
NA
.70
.72
.56
.60
.48
.54
.82
NA
NA
NA
.63
NA
.59
NA
.74
.80
.72
.80
NA NA
.65
.66
.55 .56
NA
NA
.65
.66
.45
.55
.60
NA
.61
NA
.63
NA
.60
NA
Reference
Citations
Brown
et
a1
34
(Male
Baseball)
Cahalan
et
a1
32
(Healthy
Adults)
Greenfield
et
al'
(Healthy
Adults)
Hageman
et
a1
35
(Healthy
Adults)
Leroux
et
a1
36
(Healthy
Adults)
McMaster
et
a)
22
(Healthy
Males)
(Male
Water
Polo)
McMaster
et
a1
23
(Healthy
Males)
(Male
Swimmers)
Soderberg
et
a1
38
(Healthy
Males)
Walmsley
et
a1
35
(Healthy
Females)
Mean
values
presented.
NA
=
not
applicable.
Arch
Phys
Med
Rehabil
Vol
78,
April
1977
WHEELCHAIR
BASKETBALL
SHOULDER,
Nyland
363
Table
9:
NONDOM/DOM
External
Rotator
(ER)
and
Internal
Rotator
(IR)
Peak
Torque
Ratio
Comparisons
Reference
Citations
NONDOM/DOM
ER
Peak
Torque
Ratio,
60°/sec
NONDOM/DOM
IR
Peak
Torque
Ratio,
60°/sec
NONDOM/DOM
ER
Peak
Torque
Ratio,
180°/sec
NONDOM/DOM
IR
Peak
Torque
Ratio,
180°/sec
Brown
et
al'
(Male
Baseball)
NA
NA
.98
.93
Cahalan
et
a1
32
(Healthy
Adults)
1.0
.93
1.05
.93
Leroux
et
a1
36
(Healthy
Adults)
1.0
.92
1.05
.94
McMaster
et
a1
22
(Healthy
Males)
(Male
Water
Polo)
NA
NA
.93
.90
.88 .85
McMaster
et
a1
23
(Healthy
Males)
(Male
Swimmers)
NA
NA
1.12
.99
1.01
.91
Mean
values
presented.
NA
=
not
applicable.
less
trunk
control,
and
a
lack
of
acquired
shoulder
external
rotator
torque
symmetry
(as
noted
among
class
2
and
3
players)
with
specific
weakness
of
the
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research
is
necessary
with
greater
subject
numbers
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attempting
to
establish
the
clinical
significance
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functional
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