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DOI: 10.1177/1938640010374981. From the Department of Dance, University of California, Irvine (JAR); Department of Orthopaedic Surgery and Family Medicine,
University of California, Irvine (DWK); School of Sport, Performing Arts and Leisure, University of Wolverhampton, Walsall, UK (AMN, YK, MAW); and the Department of
Exercise Sciences, University of Thessaly, Trikala, Greece (YK). Address correspondence to Jeffrey A. Russell, PhD, ATC, University of California, Irvine, Department of Dance,
300 Mesa Arts Building, Irvine, CA 92697-2775; e-mail: jeff.russell@uci.edu.
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Copyright © 2010 The Author(s)
〈 Clinical Research 〉
Measurement of the
Extreme Ankle Range of
Motion Required by
Female Ballet Dancers
Jeffrey A. Russell, PhD, ATC,
David W. Kruse, MD,
Alan M. Nevill, PhD,
Yiannis Koutedakis, PhD,
and Matthew A. Wyon, PhD
Abstract: Female ballet dancers
require extreme ankle motion, espe-
cially plantar flexion, but research
about measuring such motion is lack-
ing. The purposes of this study were to
determine in a sample of ballet danc-
ers whether non–weight-bearing ankle
range of motion is significantly differ-
ent from the weight-bearing equiva-
lent and whether inclinometric plantar
flexion measurement is a suitable sub-
stitute for standard plantar flexion
goniometry. Fifteen female ballet danc-
ers (5 university, 5 vocational, and
5 professional dancers; age 21 ± 3.0
years) volunteered. Subjects received
5 assessments on 1 ankle: non–weight-
bearing goniometry dorsiflexion (NDF)
and plantar flexion (NPF), weight-bear-
ing goniometry in the ballet positions
demi-plié (WDF) and en pointe (WPF),
and non–weight-bearing plantar flex-
ion inclinometry (IPF). Mean NDF was
significantly lower than WDF (17° ±
1.3° vs 30° ± 1.8°, P < .001). NPF (77°
± 2.5°) was significantly lower than
both WPF (83° ± 2.2°, P = .01) and
IPF (89° ± 1.6°, P < .001), and WPF
was significantly lower than IPF (P =
.013). Dorsiflexion tended to decrease
and plantar flexion tended to increase
with increasing ballet proficiency. The
authors conclude that assessment of
extreme ankle motion in female ballet
dancers is challenging, and goniometry
and inclinometry appear to measure
plantar flexion differently.
Levels of Evidence: Diagnostic,
Level II
Keywords: ankle; goniometry; incli-
nometry; dance; ballet
Female ballet dancers require large
ranges of motion in dorsiflexion
and plantar flexion.1-3 This is par-
ticularly exemplified by the plantar flex-
ion needed to rise en pointe (Figure 1).3-6
Such extremes challenge ankle range-
of-motion assessment in ballet dancers
because the motion is greater than nor-
mative data reported for the ankle using
goniometry.7,8 In light of this, the stan-
dardization of methods to measure ankle
range of motion in female ballet dancers
is important for improved understanding
of the demands of ballet on this joint and
surrounding structures and for measure-
ment of ballet dancers’ ankle range of
motion during rehabilitation from ankle
injury or surgery.
Figure 1.
A ballet dancer standing en pointe.
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While various studies have mea-
sured ankle range of motion in ballet
dancers,3,5,9-16 none could be found com-
paring different measurement techniques
nor evaluating motion in the weight-
bearing positions of demi-plié (maximum
dorsiflexion) and en pointe (maximum
plantar flexion). Therefore, the primary
aims of this project were to determine
whether non–weight-bearing ankle range
of motion is significantly different from
weight-bearing ankle range of motion
in demi-plié and en pointe and whether
inclinometric plantar flexion measure-
ment as proposed by Novella5,6 is a suit-
able substitute for standard plantar
flexion goniometry.
Materials and Methods
Subjects
Power calculations were performed to
estimate sample sizes required for this
study. A desired power value of 0.90
was used. For comparing non–weight-
bearing and weight-bearing dorsiflexion,
6 subjects were required. For comparing
non–weight-bearing and weight-bearing
plantar flexion, the required sample size
was 9. For a comparison of non–weight-
bearing goniometry plantar flexion to
non–weight-bearing inclinometry plan-
tar flexion, a minimum of 11 subjects was
needed.
Fifteen female ballet dancers (mean
age, 21 ± 3.0 years) volunteered. Of
these, 5 were university dancers, 5 were
vocational (ie, preprofessional training)
dancers, and 5 were professional bal-
let dancers. All subjects completed a
demographic questionnaire that included
information about their years of dance
participation and their years of experi-
ence dancing en pointe. Mean age and
ballet participation data for the subjects at
each level of ballet are given in Table 1.
The right ankle was studied unless
a subject reported a substantial previ-
ous injury or any current injury to that
ankle. In such a case, the left ankle was
studied. Three of the 15 ballet dancers
reported a prior ankle sprain; although
they indicated that their symptoms had
resolved, the uninjured
left ankles of these 3
subjects were used to
ensure that previous
injury did not affect the
data. The appropriate
research ethics commit-
tee approved the study
protocol, and all
subjects gave their
informed consent.
Non–weight-bearing Goniometry
After completing the demographic
questionnaire, subjects warmed up their
ankles and feet in their customary way
until they felt comfortable standing en
pointe. Following this warm up, each
subject was seated on an examination
table with her feet bare and her knees
flexed between approximately 45° and
60°17 to prevent the gastrocnemius mus-
cle from limiting dorsiflexion.18
All goniometric measurements were
made by a single examiner using a stan-
dard 30-cm goniometer to measure non–
weight-bearing active dorsiflexion (NDF)
and plantar flexion (NPF). The proximal
arm of the goniometer was aligned with
the fibula, the distal arm was aligned par-
allel to the fifth metatarsal, and the rota-
tional axis was slightly below the distal
tip of the lateral malleolus.8 The con-
vention was followed of neutral position
being 0°7,8 and ankle motion being the
number of degrees of angular movement
from that position in either a dorsal or
plantar direction.
Non–weight-bearing Inclinometry
Maximum plantar flexion was then
assessed with a bubble inclinometer
(Fabrication Enterprises, White Plains,
New York). The device incorporates a
gravity-mediated spirit level containing a
bubble that aligns with a dial gradated in
degrees. The inclinometer plantar flex-
ion (IPF) technique was adapted from
the method of Novella.5,6 Novella used
the tendu ballet position (ie, his sub-
jects stood holding their lower extremity
with slight hip flexion, knee extension,
and plantar flexion). However, for this
research, the identical seated position
was selected as that used for the plantar
flexion goniometry.
The subject was barefoot and asked
to maximally plantar flex the ankle and
hold it still until tibial and dorsal foot
inclinometry measurements were com-
pleted (less than 30 seconds). The first
placement of the inclinometer was along
the anterior border of the distal tibia,
where the inclinometer dial’s zero mark
was aligned to the bubble. Then the
Table 1.
Age and Dance Participation (Mean ± SD) of the Subjects According to Ballet
Proficiency Level
Parameter
University
(n = 5)
Vocational
(n = 5)
Professional
(n = 5)
All Subjects
(N = 15)
Agea,y 20 ± 0.9 23 ± 3.3 22 ± 3.6 21 ± 3.0
Years dancinga15 ± 3.0 18 ± 4.5 17 ± 2.5 17 ± 3.5
Years dancing
en pointeb 3 ± 1.3 10 ± 4.4 11 ± 4.0 8 ± 4.8
aNo significant differences among levels of proficiency.
bSignificant differences between university and other levels: vocational (P = .03), professional (P = .01).
. . . the standardization of methods to
measure ankle range of motion in female
ballet dancers is important for improved
understanding of the demands of ballet on
this joint and surrounding structures . . . .”
“
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inclinometer was repositioned on the
dorsal foot across the distal talus and
navicular. The procedure is shown in
Figure 2.
Then, the reading of the inclinome-
ter in degrees was recorded. The differ-
ence between the inclinometry value of
the dorsal foot and that of the distal tibia
indicated the subject’s plantar flexion.
A difference of 0° indicated that the ballet
dancer’s tibia and dorsal foot described a
180° angle (corresponding to plantar flex-
ion of 90°). A positive difference indi-
cated that the angle between the tibia
and foot was greater than 180° (plantar
flexion greater than 90°). A negative dif-
ference indicated this angle to be less
than 180° (plantar flexion less than 90°).
Weight-bearing Goniometry
Following the non–weight-bearing
range-of-motion assessments, subjects put
on their pointe shoes in their usual way.
No attempt was made to standardize the
shoes by either brand or relative new-
ness; this allowed each ballet dancer to
use the shoes most comfortable and suit-
able for her. Subjects were instructed to
stand on a platform to allow the goniom-
eter to be placed appropriately alongside
her foot and ankle in the positions of
demi-plié and en pointe (Figure 3).
First, weight-bearing dorsiflexion (WDF)
was measured in demi-plié. Subjects were
instructed to lower into as deep a demi-
plié as possible. Parallel position of the
feet was used because the limited sup-
port surface area available on the appara-
tus did not allow externally rotated lower
extremity positions; the parallel posi-
tion coincides with other authors’ pro-
tocols.9,19-22 Using the same anatomical
landmarks and measuring conventions as
in the non–weight-bearing goniometry,
the angle of dorsiflexion was recorded.
Then, the subject stood en pointe, and
weight-bearing plantar flexion (WPF) was
similarly recorded.
Total Range-of-Motion Calculation
Finally, to obtain total ankle range of
motion (TAROM), a ballet dancer’s dor-
siflexion measurement was added to her
plantar flexion measurement. Scores for
both non–weight-bearing goniometry
and weight-bearing goniometry in the
ballet positions were accomplished this
way. That is,
TAROMNWB = NDF + NPF
and
TAROMWB = WDF + WPF.
Figure 2.
Inclinometric measurement of ankle plantar flexion. (Left) Tibial position where the
dial is set to 0°. (Right) Position of the inclinometer where the dorsal foot reading is
taken.
Figure 3.
Goniometric measurement of ankle range of motion in weight bearing. (Left) Demi-
plié dorsiflexion. (Right) En pointe plantar flexion.
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Reliability of the Goniometric
and Inclinometric Measurement
Techniques
To establish the intratester reliability of
the clinician in the present study, a sep-
arate group of 6 uninjured ankles were
measured for clinical non–weight-bearing
dorsiflexion and plantar flexion accord-
ing to the same standard method used
throughout the present study.8 Three tri-
als were accomplished on each ankle.
Three observations of the same 6 ankles
also were obtained with the inclinometry
technique.6
To assess the reliability of the exam-
iner’s technique, these data were ana-
lyzed with 1-way analysis of variance
with repeated measures. Intraclass cor-
relation coefficients (ICCs) were calcu-
lated from the mean square values in
the analysis of variance (ANOVA) sum-
mary table.23 ICCs for the reliability data
were 0.99 for both goniometry and incli-
nometry, showing that the examiner was
reliable in executing the required mea-
surements. Coefficients of variation (CVs)
for these data also show good agreement
among the examiner’s trials: dorsiflexion
CV = 10%, plantar flexion CV = 7%, incli-
nometry CV = 1%.
Data Analyses
Repeated-measures ANOVA, with 1 fac-
tor between (proficiency level of ballet
dancer) and 1 factor within (measure-
ment method) subjects was used to
determine if differences existed between
methods of measuring dorsiflexion,
among methods of measuring plantar
flexion, and among levels of dance pro-
ficiency for dorsiflexion and plantar flex-
ion. A Student t test for dependent pairs
was used to analyze TAROM data for
differences between the non–weight-
bearing and weight-bearing ballet posi-
tion range of motion. One-way ANOVA
assessed each type of TAROM among
the different dancer proficiency levels.
Following the ANOVAs, Tukey’s post hoc
test was employed to assess pairwise dif-
ferences. In addition, CVs were deter-
mined for dorsiflexion and total range of
motion (2 measurement conditions each)
and plantar flexion (3 measurement
conditions). An alpha value of .05 was
used for all analyses.
Results
Overall, mean NDF was significantly
different from WDF (P < .001), with val-
ues of 17° ± 1.3° and 30° ± 1.8°, respec-
tively. The 3 plantar flexion methods
were significantly different from one
another, and post hoc analysis indicated
that mean NPF of 77° ± 2.5° was signifi-
cantly less than both mean WPF of
83° ± 2.2° (P = .01) and mean IPF of
89° ± 1.6° (P < .001). In addition, mean
WPF was significantly less than IPF
(P = .013). Range-of-motion data for all
subjects appear in Table 2.
The range-of-motion data are bro-
ken down by ballet proficiency level in
Table 3. Interestingly, dorsiflexion abil-
ity decreased with increasing ballet
proficiency; the university ballet danc-
ers’ mean dorsiflexion was significantly
greater than that of the professional bal-
let dancers (P = .01 for both non–weight-
bearing and demi-plié values). Plantar
flexion showed the tendency to increase
with increasing ballet proficiency level,
although there were no significant
differences among NWB goniometric
plantar flexion values. Plantar flexion in
the university dancers was significantly
different from the professional dancers
for both en pointe and inclinometric plan-
tar flexion (P = .03).
Table 3 also contains the TAROM
data. There was a significant difference
between TAROMNWB and TAROMWB
(P < .001). Not surprisingly, the lat-
ter was always the greater of the two.
However, no significant differences were
found among the dance proficiency lev-
els for either method of TAROM mea-
surement. The professional ballet dancers
had the smallest TAROM of the 3 groups,
with clinical measurement and the largest
TAROM of the 3 groups when measured
in the ballet positions.
The coefficients of variation revealed
that dorsiflexion was the most variable
of the measurements undertaken
(CV = 24%). CV was 9% for both plantar
flexion and total range of motion.
Discussion
The primary aims of this research were
to determine in female ballet dancers
whether non–weight-bearing ankle range
Table 2.
Range-of-Motion Values in Female Ballet Dancers’ Ankles
Measurement Method
Mean ± SD
Dorsiflexion
Mean ± SD
Plantar Flexion
Active non–weight-bearing
goniometry
NDF = 17° ± 1.3°NPF = 77° ± 2.5°
Differences vs WDF: P < .001 vs WPF: P = .01
vs IPF: P < .001
Active non–weight-bearing
inclinometry
NA IPF = 89° ± 1.6°
Differences vs NPF: P < .001
vs WPF: P = .013
Weight-bearing goniometry WDF = 30° ± 1.8°WPF = 83° ± 2.2°
Differences vs NDF: P < .001 vs NPF: P = .01
vs IPF: P = .013
Abbreviations: IPF, non–weight-bearing inclinometry plantar flexion; NDF, non–weight-bearing
goniometry dorsiflexion; NPF, non–weight-bearing plantar flexion; WDF, weight-bearing dorsiflexion in
demi-plié; WPF, weight-bearing plantar flexion en pointe.
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Foot
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of motion is different from weight-
bearing ankle range of motion in demi-
plié and en pointe and whether inclino-
metric plantar flexion measurement is
an accurate substitute for standard plan-
tar flexion goniometry. We found that
weight-bearing range of motion was
greater than non–weight-bearing range
of motion; this was true for dorsiflexion,
plantar flexion, and total range of ankle
motion. This comparison between weight
bearing and non–weight bearing has
been reported previously for dorsiflex-
ion.24 Intuitively it is expected because of
the ability of a ballet dancer to apply her
body weight to the lever system of the
lower extremity, thereby incorporating
increased mechanical advantage in demi-
plié and en pointe. In demi-plié, the ballet
dancer applies her body weight to press
the leg-foot linkage into greater dorsiflex-
ion. During the rise en pointe, the forces
around the ankle and foot25,26 may accen-
tuate the loading of the foot’s longitudi-
nal arches in the dorsal direction with a
resultant forcing of the ankle and foot
into plantar flexion. Consequently, both
of these conditions would allow the bal-
let dancer to attain a greater angle of
ankle movement in weight bearing.
We further found that dorsiflexion
decreased with increasing dance profi-
ciency level while plantar flexion tended
to increase with increasing dance profi-
ciency. These results may stem from the
extra years that professional ballet danc-
ers have spent trying to improve plan-
tar flexion flexibility.3 It is also presumed
that higher level ballet dancers typically
spend more rehearsal and performance
time plantar flexed on demi-pointe and
en pointe than they do dorsiflexed in
demi-plié while fulfilling the requirements
of their ballet employment.
Another reason some higher level bal-
let dancers exhibit decreased dorsiflex-
ion may relate to the presence of anterior
impingement exostoses on the anterior
edge of the tibial plafond and the dor-
sal sulcus of the talar neck. These are
propagated by the repeated forced dor-
siflexion ballet dancers undergo in demi-
plié and can limit dorsiflexion range of
motion.27-31 Although it is a weakness
of the available medical literature that
studies report an empirical reduction in
dorsiflexion accompanying anterior exos-
tosis impingement without supplying
actual range-of-motion data, it has been
reported that anterior exostoses were
present in 59.3% of ballet dancers and
only 4% of nondancers.30
Our data for dorsiflexion and plan-
tar flexion of ballet dancers were greater
than data of some researchers who used
similar protocols14 but less than the data
reported by others.3,16 Hamilton et al3
studied a variety of musculoskeletal char-
acteristics in professional ballet dancers,
including ankle range of motion. Their
non–weight-bearing dorsiflexion value
in females compares favorably with the
value for the female professionals in our
study (means were virtually equal), but
their mean plantar flexion value was sub-
stantially greater (113° vs 80°). The mean
age of their ballet dancers was 29.3 years,
somewhat older than the professional
ballet dancers in our research (mean age
22 years). This may translate to addi-
tional years of professional experience
that could conceivably result in the larger
plantar flexion they reported.
Average en pointe plantar flexion val-
ues of 52.9° for the right ankle and 53.8°
for the left have been reported using
a motion capture protocol with classi-
cal ballet dancers.12 These values are
substantially lower than our data and
those of other investigators.3,14,16 Several
methodological issues may provide an
explanation for these researchers’ low
measurements. They attempted to mea-
sure plantar flexion from reflective mark-
ers placed at various points on the leg,
ankle, and foot, but they did not spec-
ify what position of the ankle they con-
sidered to be the 0° starting position.
Furthermore, one of the foot markers was
placed, by their description, between the
second and third metatarsophalangeal
joints. From an anatomical viewpoint, this
placement is not precise when a dancer
is wearing a pointe shoe. Depending on
its actual location, it may have contrib-
uted to their lower values.
With regard to the inclinometric plan-
tar flexion measurement method of
Novella,5,6 we found this method to be
Table 3.
Range-of-Motion Data by Ballet Level (Mean ± SD)
Measurement
University
(n = 5)
Vocational
(n = 5)
Professional
(n = 5)
NDFa22° ± 5.3°18° ± 3.6°10° ± 6.1°
WDFb35° ± 7.9°27° ± 7.3°26° ± 5.1°
NPFc70° ± 12.0°81° ± 11.7°80° ± 3.1°
WPFd74° ± 6.1°86° ± 7.2°90° ± 11.7°
IPFe83° ± 7.1°88° ± 8.3°95° ± 1.9°
Total NWB ankle motionf92° ± 15.0°98° ± 8.2°90° ± 5.7°
Total WB ankle motionf109° ± 13.7°113° ± 8.7°116° ± 10.4°
Abbreviations: IPF, non–weight-bearing inclinometry plantar flexion; NDF, non–weight-bearing
goniometry dorsiflexion; NPF, non–weight-bearing plantar flexion; NWB, non–weight bearing;
WB, weight bearing; WDF, weight-bearing dorsiflexion in demi-plié; WPF, weight-bearing plantar
flexion en pointe.
aUniversity and professional significantly different, P = .01.
bUniversity and professional significantly different, P = .01.
cNo significant differences among proficiency levels.
dUniversity and professional significantly different, P = .03.
eUniversity and professional significantly different, P = .03.
fTotal NWB versus total WB significantly different for all proficiency levels, P < .001.
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not comparable to goniometric mea-
surement of plantar flexion. Values
obtained by this inclinometry technique
require a conversion to compare them
to traditional goniometry values, a task
accomplished by adding 90 to the incli-
nometric plantar flexion values. This
conversion presumes that 0° of plantar
flexion is the position at which the foot
and leg are perpendicular to one another,
or ankle neutral position.7,8,32 Novella5
regarded parallel alignment of the tibia
and dorsal talonavicular region as 0°, so
his plantar flexion values were negative
on the dorsal side of 0° and positive on
the plantar side of 0°. His reported values
ranged from –12° to +25°, with a mean of
+8°.6 Converting these according to our
described calculation yields a range of
78° to 115°, with a mean of 98°.
Novella’s mean plantar flexion value
was more than 11° greater than our clin-
ical measurement technique and more
than 5° greater than our en pointe mea-
surement technique. Measuring active
range of motion with the limb in an
open kinetic chain as he recommended
(hip slightly flexed, knee fully extended,
and ankle maximally plantar flexed)
may introduce error if the subject can-
not remain completely still. In our study,
we modified the testing position to cor-
respond to the position used for active
goniometry17 (subject seated, knee flexed
45°-60°, ankle maximally plantar flexed)
as it has been previously reported that
different patient positions during plan-
tar flexion assessment do not decrease
measurement reliability.33 In addition, the
relative amount and compressibility of tis-
sue along the anterior border of the tibia
may be a source of error in this inclinom-
etry method due to variability in the sup-
port surface for the instrument. We noted
that even small changes in the position of
an inclinometer can create concomitant
changes in angular readings.
As far as we can determine, goniometry
of weight-bearing ankle motion in ballet
dancers en pointe has not been reported
previously. In establishing this method, it
is reasonable to assume that the present
study contained underlying limitations.
Chief among these were the practical
matters of measuring ankle movement in
the most extreme positions possible using
a goniometric procedure that is standard-
ized to substantially smaller ranges of
motion and trying to do so with the foot
encased in a pointe shoe. Although this
was an initial study into the topic and
statistical power calculations indicated
that we had enough subjects overall, the
sample size of 5 dancers in each of the 3
dance proficiency levels limits generaliz-
ability within these categories. Also,
in inclinometry of ballet dancers’ plan-
tar flexion, the potential for variability
inherent in the technique may have
introduced variability.
In conclusion, goniometric and incli-
nometric measurement of ankle range of
motion in female ballet dancers is chal-
lenging, particularly for the extreme
amount of plantar flexion required to
dance en pointe. Most studies of plantar
flexion in ballet dancers, including ours,
reveal a range much larger than the nor-
mative value of 50°. Thus, standard goni-
ometry may not be the best method of
assessing this motion in ballet dancers.
In addition, goniometry and inclinome-
try appear to evaluate ankle plantar flex-
ion differently. We recommend adoption
of inclinometry for ankle range-of-motion
assessment because it incorporates land-
marks that are easier to consistently locate
than those of goniometry and does not
require estimation of a joint axis. However,
normative values for inclinometry must be
ascertained with future research, as they
do not currently exist.
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