THE IMPORTANCE OF THE GREAT TOE IN BALANCE PERFORMANCE
Hsin-Yi Kathy Cheng1,2, Chun-Li Lin1, Shih-Wei Chou2,3,4, Yan-Ying Ju2,3, Yin-Chou Lin4, May-Kuen Wong2,3,4
1Graduate Institute of Mechanical Engineering, Chang Gung University, Tao-Yuan, Taiwan
2Department of Physical Therapy, Chang-Gung University, Tao-Yuan, Taiwan
3Graduate Institute of Rehabilitation Science, Chang-Gung University, Tao-Yuan, Taiwan
4Department of Physical Medicine and Rehabilitation, Chang-Gung Memorial Hospital, Tao-Yuan, Taiwan
[email protected] , [email protected] , [email protected] , [email protected] ,
[email protected] , [email protected]
ABSTRACT
The objective of this study was to evaluate
function of the great toe in maintaining human static and
dynamic balance. Correlation among the great toe length,
body height and balance performance parameters were
also investigated. Thirty female subjects (aged 22.1±1.87
years) were tested in two great toe conditions,
unconstrained and constrained. Balance testing was done
in the orders listed: 1) static balance, single leg stance
with right/left foot, eyes open and closed; 2) static balance,
both feet, eyes open and closed; 3) dynamic balance,
rhythmic weight shifting, left/right and forward/backward;
4) dynamic balance, target reaching test, eight targets
within 90% limit of stability (LOS). The results
demonstrated significant differences in sway velocity
between the two toe conditions with either eyes open or
closed in single leg standing (p<0.05). No difference was
found between the two toe conditions while standing with
both feet. For the rhythmic weight shifting, significant
differences in movement velocity were found both in toe
conditions and in weight-shifting directions (p<0.05).
Significant interaction was also found between the toe
conditions and the weight-shifting condition. As to target
reaching, significance was only noted in directional
control scores but not in reaction time (p=0.689) and
movement velocity (p=0.17). Correlation results revealed
the great toe length was only linearly correlated with
s
u
bj
e
c
t
’
sh
e
i
gh
t(
r
=0.
553,p<0
.
05)bu
tn
ott
h
eot
h
e
r
s
.Ou
r
results indicated that constrained great toe deteriorated the
s
u
bj
e
c
t
s
’s
i
n
gl
el
e
gs
t
a
n
c
epe
r
f
or
ma
n
c
ea
n
dworsened the
directional control ability during forward/backward
weight shifting. Great toe amputation individuals will be
recruited in future testing for a more conclusive summary
of the importance of the great toe in human balance.
KEY WORDS
Great toe, Balance, Foot, Sway velocity
Introduction
Balance is vital for people to accomplish daily
tasks. Impairment in balance would interfere with the
acquisition of motor skills, thus lead to deterioration in
performance quality and cause higher incidence of falls
and injuries. The plantar surface of the foot provides
direct contact of human body to the surrounding
environments. It is the most distal joint in the lower
kinetic chain in maintaining standing balance [1]. During
locomotion such as walking and running, the foot serves
as a propulsive lever and a shock absorber. Therefore,
proper arthrokinematics within the foot influences the
body
’
sa
bi
l
i
t
yt
oa
t
t
e
nu
a
t
et
h
e
s
ef
or
c
e
s
[1]. Dysfunction of
foot biomechanics caused by diseases or injuries would
interfere lower extremity biomechanics, posing extra
pressure onto some other joints.
Within the foot structure, the great toe seems to
play an important role in the biomechanical function of
the foot. In standing, the great toe exerts more pressure
than those of the five metatarsal heads and the heel 3. It
also poses a pressure about twice of the total pressure of
the other four toes [2]. During walking, as the great toe is
passively dorsiflexed, the longitudinal arch of the foot is
raised, the rearfoot supinated, the leg externally rotated,
and the plantar aponeurosis tensed [3]. This so-called
windlass mechanism is of great importance since it tenses
the plantar fascia thus forming a rigid lever of the foot for
push-off. If the mechanism is altered, the timing and
effectiveness of push off would be affected. Therefore,
disorders of great toe would cause inevitable changes in
s
u
bj
e
c
t
’
ss
t
a
t
i
ca
n
ddy
n
a
mi
cba
l
a
n
c
e
.
Tot
h
ea
u
t
h
or
s
’kn
owl
e
dg
e
,non
eoft
h
eba
l
a
n
c
e
studies had directly evaluated the great toe influence onto
balance performance. Tanaka et al., 1996[2], tested
s
u
bj
e
c
t
s
’s
i
ng
l
el
e
gs
t
a
n
c
eon amovi
ng pl
a
t
f
or
ma
n
d
measured their sway responses and the peak pressure
under the toes. The results demonstrated that body sway
was more significantly correlated with the peak
anteroposterior sway component than with lateral sway,
and the peak pressure value of the great toe was
significantly greater than the sum of the peak values of
the other four toes for both sides. Moreover, the maximal
great toe pressure in the elderly group was significantly
greater than that in the young group6. Similar results were
found by Ducic et al. [4][5] in a group of patients with
peripheral neuropathy. These results indicated that big toe
may influence the balance performance.
Furthermore, Beyaert [6] analyzed children
(aged 6.5-12.5 years) 5 years after removal of one or two
second toes for digital reconstruction. They found
maintenance of balance and rate of displacement of the
center of pressure when standing on one foot with eyes
closed were significantly altered for operated limbs
compared with non-operated limbs. This result revealed
the importance of the second toe in balance function.
Since the great toe is the largest among all toes, it is likely
to demonstrate an important function in maintaining
balance.
Great toe amputation was also found to affect
i
n
di
v
i
du
a
l
’
sf
ootbon
es
t
r
e
s
s
.Ba
r
c
ae
ta
l
.(
19
95)[7] found
that patients who received microsurgical reconstruction of
the thumb with great toe transfer exhibited an overload of
central and lateral metatarsal bones. This indicated great
toe amputation significantly altered the weight
distribution pattern within the foot structure. This
a
l
t
e
r
a
t
i
onwou
l
di
n
e
v
i
t
a
bl
ya
f
f
e
c
ts
u
bj
e
c
t
’
sba
l
a
n
c
e
.
Due to the scant information regarding the role
the great toe plays in human balance performance, the
purpose of this study is to evaluate the function of the
great toe in maintaining human static or dynamic balance.
It was hypothesized that subjects with unconstrained great
toe would perform better during single leg stance in eyes
open or eyes closed condition. For dynamic standing tasks,
we predicted constraint of the great toe would deteriorate
t
h
es
u
bj
e
c
t
’
sba
l
a
n
c
epe
r
f
or
ma
n
c
epa
r
a
me
t
e
r
s
.I
na
ddi
t
i
on
,
the relationships among the length of great toe, body
height and balance ability would also be investigated.
Material and Method
Thirty female aged 18-24 years volunteered for the
study. The participation of subjects was in accordance
with Institutional Review Board procedures at the ChangGung Memorial Hospital. Descriptive statistics regarding
s
u
bj
e
c
t
s
’a
g
e
,h
e
i
g
ht
,bodywe
i
gh
t
,a
n
dg
r
e
a
tt
oel
e
ng
t
h
were listed in Table 1. Length of the big toe was
measured from the first metatarsal joint line to the most
distal part of the phalange. All subjects were right-leg
dominant. Subjects signed the informed consents before
their participation.
Table 1. The descriptive statistics of subjects age,
height, body weight, and great toe length
MEAN ± SD
MINIMUM
MAXIMUM
AGE (years)
22.10 ± 1.87
18.37
24.88
HEIGHT (cm)
161.11 ± 4.78
152.00
170.00
BODY WEIGHT
(kg)
GREAT TOE
LENGTH (cm)
57.02 ± 6.48
48.50
77.00
6.48 ± 0.45
5.60
7.50
Subjects were tested in two great toe conditions,
unconstrained or constrained. In condition of constraint,
s
u
bj
e
c
t
’
sg
r
e
a
t toe was constrained in 30° dorsiflexion
with a special designed splint to mimic the situation
without great toe. In condition with two legs standing,
both great toes were constrained. The splint held the great
toe in a position so that it could not contact the ground.
Fifteen subjects performed the unconstrined toe condition
first and the others constrained toe condition first. The
orders of the great toe conditions were randomly assigned.
Subject rode a stationary bike for three minutes and
then performed designed lower extremity stretching
exercises. The following testing conditions were recorded
in the orders listed: 1) static balance, single leg stance
with right/left foot, eyes open and closed; 2) static balance,
both feet, eyes open and closed; 3) dynamic balance,
rhythmic weight shifting, left/right and forward/backward;
4) dynamic balance, target reaching test, eight targets
within 90% limit of stability (LOS). After the series of
testing, subject sat and rested for ten minutes then
performed the whole series of testing again with the next
big toe condition.
Balance parameters were measured by a
commercially available balance machine, the Smart
Balance Master v5.0 from Neurocom International Inc,
U.S.A.. In condition of the static balance testing, subject
stood with her eyes leveled with the computer screen. In
single leg stance, subject placed her foot in the middle of
the force plate. For the next condition, subjects stood with
both feet about shoulder width apart (the actual width
depended on the body height of the subjects). The
recording time was 20 seconds. Both conditions were
tested with eyes open and then eyes closed. Eyes open and
eyes closed were treated as independent testing conditions.
The sway velocity of center of pressure was recorded.
Sway velocity was calculated by the averaged movement
velocity between the 5%-95% movement distance.
Two-way analyses of variances were used with
repeated measures on the two independent variables. The
two independent variables were toe (unconstrained and
constrained) and leg (left and right) for static single leg
stance with eyes open or eyes closed; toe and direction
(left/right and forward/backward) for weight shifting
condition; toe and target (front, right front, right, right
back, back, left back, left, left front) for target reaching
test. Paired-t test of toe condition was used for static two
leg stance with eyes open or closed. Pairwise comparison
was used when a significant interaction was found
between two independent variables. The significance level
wa
ss
e
ta
t0.
0
5.Pe
a
r
s
on
’
sc
or
r
e
l
a
t
i
on c
oe
f
f
i
c
i
e
ntwa
s
calculated to represent the correlation between great toe
length and body height, great toe length and balance
parameters, and the body height and balance parameters.
Results
Effects of great toe onto static balance
In condition with single leg standing, significant
difference was seen in sway velocity between the two toe
conditions with either eyes open or closed (p<0.05), but
not between right and left legs. No interactions were
shown between toe and leg conditions with eyes open or
closed. The sway velocities were smaller with the great
toe unconstrained than constrained (Fig 1). However, the
sway velocity in static standing with both feet did not
show significant differences between the two toe
conditions (p=0.29) (Fig 2).
87
directional control (%)
86
2
1.6
1.4
1.2
unconstrained great toe
83
constrained great toe
82
81
79
0.8
forward/backward
left/right
w e i g h t s h i f t i n g d i re c t i o n
0.6
0.4
0.2
0
open
close
e y e c o n d i ti o n
Unconstrained great toe
Constrained great toe
Fig 1. Sway velocity (degree/second) during single leg
standing between the two toe conditions with both eyes
open and closed.
0.5
mean movement velocity (deg/sec)
84
80
1
0.45
0.4
Fig 3. Directional control scores (%) during rhythmic
weight shifting between the two toe conditions in
forward/backward
and
left/right
directions.
Significant difference (p<0.05) was noticed between
the two toe conditions in forward/backward direction.
As to the target reaching, there were no significant
differences in the reaction time (p=0.689) or movement
velocity (p=0.17) with the great toe either constrained or
unconstrained. Significance was only noted in directional
control scores (p<0.05). Paired t-test showed a significant
difference between the two toe conditions in the
directional control score in target position front, right
front and left front (Fig 4). Subject demonstrated a better
directional control when the great toe was unconstrained.
0.35
0.3
unconstrained great toe
0.25
constrained great toe
0.2
0.15
0.1
0.05
0
open
close
e y e c o n d it io n
Fig 2. Sway velocity (degree/second) during two leg
stance between the two toe conditions with both eyes
open and closed.
Effect of great toe onto dynamic balance
For the rhythmic weight shifting, statistical analysis
revealed significant differences both in toe conditions and
in weight-shifting directions (p<0.05). Subjects
demonstrated a better directional control when the toe is
unconstrained. Their directional control was better in
left/right than forward/backward direction. A significant
interaction was found between the toe conditions and the
weight-shifting directions. Pairwise comparisons revealed
that the sway direction in forward/backward was
significantly different between different toe conditions
(p<0.05), but not in left/right (Fig 3). This indicated the
great toe played a significant role in forward/backward
weight shifting balance. In addition, during the
forward/backward weight shifting, subjects demonstrated
a better directional control with their great toe
unconstrained. Pairwise comparisons also revealed a
significant difference between forward/backward and
left/right sway regardless of the toe conditions.
directional control scores (%)
mean movement velocity
1.8
85
90.00
85.00
unconstrained
80.00
75.00
constrained
70.00
65.00
front
right-front
right
right-back
back
left-back
left
left-front
target position
Fig 4. Directional control scores (%) of eight target
positions for target reaching test. Paired t-test
revealed significant differences in directional scores
for target position front, right-front, and left-front
(p<0.05).
Correlation between great toe length and body height /
balance performance
Pe
r
s
on
’
sc
or
r
e
l
a
t
i
onc
oe
f
f
i
c
i
e
n
twa
sus
e
dt
oa
n
a
l
y
z
e
t
h
ec
or
r
e
l
a
t
i
onofg
r
e
a
tt
oel
e
n
gt
hwi
t
hs
u
bj
e
c
t
’
sbody
height, static balance performance with single leg support
(eyes open or closed), static balance performance with
both feet (eyes open or closed), dynamic left/right weight
shifting, dynamic forward/backward weight shifting,
dynamic target reaching reaction time, dynamic target
reaching movement velocity, and dynamic target reaching
directional control. The results indicated that great toe
l
e
n
gt
hwa
sonl
yl
i
n
e
a
r
l
yc
or
r
e
l
a
t
e
dwi
t
hs
u
bj
e
c
t
’
sbody
height (r=0.553, p<0.01), but not the others.
Correlation between body height and balance
performance
No significant correlations were found between the
s
u
bj
e
c
t
’
s body h
e
i
g
h
ta
n
dt
h
ea
bov
el
i
s
t
e
d ba
l
a
n
c
e
parameters (p>0.05).
Discussion
The purpose of this study is to investigate the
functional role of the great toe in maintaining static and
dynamic balance. Results of our study revealed the
importance of great toe in standing balance. The
constraint status of the great toe did make a significant
di
f
f
e
r
e
n
c
ei
ns
u
bj
e
c
t
’
ss
wa
yv
e
l
oc
i
t
ydu
r
i
ngs
i
ng
l
el
e
g
standing but not in standing with both feet. This supported
our hypothesis that subjects demonstrated a better single
leg stance performance with the unconstrained great toe.
These results can be interpreted with the biomechanical
(muscle function) point of view. In standing
,body
’
s
center of gravity passes through femoral greater
trochanter and falls in front of the ankle joint. The gluteus
maximus and the posterior shin muscles contract to hold
the body in position. During single leg stance, the base of
support is relativel
ys
ma
l
l
e
r
.I
nor
de
rf
ort
h
ebody
’
sc
e
n
t
e
r
of gravity to fall within the supported foot, more muscles
need to join in to assist this task. Other than the activities
from the above mentioned muscles, gluteus medius
contracts to prevent the body from sideway leaning. Foot
muscles are also of great importance while standing in
this condition. Menz et al. [8] found that toe plantar flexor
muscles are significant predictors of balance and
functional ability. With a constrained great toe, the
functions of great toe plantar flexors would be limited.
In addition, great toe is the biggest toe above all. It
serves as the insertion for some of the foot extrinsic and
intrinsic musculatures, and also the insertion of the arch
maintaining structure-plantar aponeurosis. Malfunction of
the great toe would inevitably cause foot function
deterioration, therefore interfering with balance
performance especially in challenging conditions such as
single leg stance.
Our study also showed directional control deficits
during forward/backward weight shifting in constrained
great toe condition, but not during left/right weight
shifting. Winter [9] indicated that during quiet standing,
the center of pressure (COP) excursion in
forward/backward direction is primarily controlled by the
foot plantar- and dorsi- flexors, while the COP excursion
in left/right direction is mainly adjusted by hip abductors
and the foot invertors and evertors. The constrained great
toe condition in our study limited functional control of
foot, not hip; therefore the weight shifting performance in
forward/backward direction might be deteriorated more
obviously. Tanaka et al [10] also pointed out the amount
of forward/backward sway during single leg stance is
more obvious than the amount of left/right sway. This
result again indicated that left/right sway, which is
controlled by larger hip abductors, is more stable than the
forward/backward sway-which is adjusted by foot dorsiand plantar- flexors.
No significant difference was found in reaction time
and movement velocity in the target reaching test
regardless the conditions of great toe. This might be
because the target reaching movement was mainly
generated by the large lower extremity muscles in order to
move the COP, and the muscles in great toe are primarily
for fine motor control. Therefore, whether the great toe is
constrained or not did not cause significant difference.
Similar explanations apply to the findings of movement
velocity. Since the COP movement velocity is mainly
controlled by the contraction of large muscle groups, the
conditions of great toe were not of great influence either.
On the other hand, significant differences were
noticed in the directional control during target reaching
between two toe conditions. When the great toe was
constrained, subject demonstrated a worse directional
control. The worse performance is directional specific to
front, right front and left front target position. Limitation
of foot dorsi- and plantar- f
l
e
x
or
swou
l
da
f
f
e
c
ts
u
bj
e
c
t
’
s
forward/backward sway performance. In addition,
considering plantar pressure distribution, the great toe
itself sustains about 2.4% of the total load carried by the
foot during regular stance[11]. According to the above, it
is reasonable to infer that subjects with the great toe
constrained in a dorsiflexed position would encounter
difficulties while shifting forward—including the front,
right front, left front target reaching tasks.
Test of correlation found that great toe length is
h
i
gh
l
yc
or
r
e
l
a
t
e
dwi
t
ht
h
es
ubj
e
c
t
’
sbodyh
e
i
gh
t, but not
with any other balance parameters. This indicated that in
general, the ones who are tall have longer great toes;
however the long great toes do not positively or
negatively affect their balance performance.
Our results also found no correlations between the
s
u
bj
e
c
t
’
s body h
e
i
gh
ta
n
dt
h
e ba
l
a
n
c
e pa
r
a
me
t
e
r
s
measured. Different body characteristics would affect the
balance ability differently; however the exact mechanism
is not clear. Inconsistent results had been published
regarding this issue. Era [12] pointed out that as the body
height of subjects increases, the postural sway increases.
In contrast, the study by Davis et al. [13] found that the
older women who were shorter demonstrated a poorer
balance ability and more prone to falls. On the other hand,
Keionen et al [14] found no relationships between the
s
u
bj
e
c
t
s
’body h
e
i
gh
ta
n
dt
h
e
i
rba
l
a
n
c
e pe
r
f
or
ma
n
c
e
.
Therefore, the mechanism of how body height influence
balance performance remains unclear.
Conclusion
This study pointed out the importance of the great toe
in static and dynamic standing balance. Constrained great
t
oei
n
t
e
r
f
e
r
e
dwi
t
hs
u
bj
e
c
t
’
sba
l
a
n
c
epe
r
f
or
ma
n
c
edu
r
i
ng
single leg stance. It also worsened the directional control
ability during forward/backward shifting. Since the great
toe flexors were restricted while the toe was constrained,
they can not participate fully in balance adjustment. This
might be one of the reasons why balance performance
differs with a constrained great toe. Further research is
needed to clarify whether the balance deteriorations come
from the deficits of foot supporting surfaces, great toe
flexor muscle activities, or sensory functions. Individuals
with great toe amputation will be recruited for testing in
the future for a more conclusive summary of the
importance of the great toe in human balance.
References
[1] R Donatelli, editor. The Biomechanics of the Foot
and Ankle. Philadelphia: F.A. Davis Company; 1990.
[2] T Tanaka, N Hashimoto, M Nakata, T Ito, S Ino, T
Ifukube. Analysis of toe pressures under the foot while
dynamic standing on one foot in healthy subjects. Journal
of Orthopaedic and Sports Physical Therapy 23, 1996,
188-93.
[3] JH Hicks. The mechanism of the foot. II. The plantar
aponeurosis and the arch. Journal of Anatomy, 88, 1954,
25-30.
[4] I Ducic, KW Short, AL Dellon, JJ Disa. Relationship
between loss of pedal sensibility, balance, and falls in
patients with peripheral neuropathy. Annals of Plastic
Surgery, 52, 2004, 535-40.
[5] I Ducic, NS Taylor, AL Dellon. Relationship between
peripheral nerve decompression and gain of pedal
sensibility and balance in patients with peripheral
neuropathy. Annals of Plastic Surgery, 56, 2006,145-50.
[6] C Beyaert, S Henry, G Dautel, N Martinet, F
Beltramo, P Lascombes, et al. Effect on balance and gait
secondary to removal of the second toe for digital
reconstruction: 5-Year follow-up. Journal of Pediatric
Orthopaedics, 23, 2003,60-4.
[7] F Barca, A Santi, PL Tartoni, A Landi. Gait analysis
of the donor foot in microsurgical reconstruction of the
thumb. Foot and Ankle International, 16, 1995,201-6.
[8] HB Menz, ME Morris, SR Lord. Foot and ankle
characteristics associated with impaired balance and
functional ability in older people. Journals of
Gerontology - Series A Biological Sciences and Medical
Sciences, 60, 2005, 1546-52.
[9] DA Winter, editor. The Biomechanics and Motor
Control of Human Gait: Normal, Elderly, and
Pathological. 2nd ed. Ontario: Waterloo Biomechanics;
1991.
[10] T Tanaka, N Hashimoto, H Takeda, S Ino, T Ifukube.
Influence of the the pressure and tactile sense of the great
toe on dynamic standing balance in healthy subjects.
Journal of Human Movement Studies, 30, 1996,35-53.
[11] YK Jan, SJ Lee, SW Yang, LY Chao, CC Lin, WF
Cheung. Foot pressure analysis in normal young Chinese
adults. Journal of the Physical Therapy Association of the
ROC, 22, 1997, 1-9.
[12] P Era, M Schroll, H Ytting, I Gause-Nilsson, E
Heikkinen, B Steen. Postural balance and its sensorymotor correlates in 75-year-old men and women: A crossnational comparative study. Journals of Gerontology Series A Biological Sciences and Medical Sciences
1996;51.
[13] JW Davis, PD Ross, MC Nevitt, RD Wasnich. Risk
factors for falls and for serious injuries on falling among
older Japanese women in Hawaii. Journal of the
American Geriatrics Society, 47, 1999, 792-8.
[14] P Keionen, K Kauranen, H Vanharanta. The
relationship between anthropometric factors and bodybalancing movements in postural balance. Archives of
Physical Medicine and Rehabilitation, 84, 2003, 17-22.