Advances in Anthropology
2013. Vol.3, No.4, 229-236
Published Online November 2013 in SciRes (http://www.scirp.org/journal/aa) http://dx.doi.org/10.4236/aa.2013.34032
Open Access 229
Human Postural Adaptation to Earthly and Atypical
Gravitational Environment Effects of Sport Training on
Stabilometric Parameters
Luisa Pizzigalli1*, Margherita Micheletti Cremasco2, Elena Cremona1, Alberto Rainoldi1
1Department of Medical Sciences, School of Exercise and Sport Sciences, SUISM,
University of Turin, Turin, Italy
2Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
Received June 6th, 2013; revised July 8th, 2013; accepted August 4th, 2013
Copyright © 2013 Luisa Pizzigalli et al. This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
Earthly gravitational environment has been conditioned organisms evolutional transformations. Mankind
evolution in acquiring the upright posture changed functional anatomical characteristics behaved in an
almost stable environment (g = 9.81 m/s). Technological environment, up to the microgravity conditions,
faces peculiar gravitational conditions that may affect locomotion, working capabilities and living situa-
tion. To understand human adapting capacities, some systematic knowledge may come from the study of
trained persons such as those practising sports in different postures and environments. The aims of this
study are to investigate whether long-term practice of a physical activity, in which body attitude and pos-
tural regulation are organized in different ways, can influence postural control and generate a “postural
memory”. Three groups of male athletes (average age: 22 ± 3 years, weight: 69 ± 9 kg, height: 179.6 ± 5.5
cm) were studied in 26 athletes (runners, bikers and swimmers). The protocol consisted of balance tests
with eyes open (EO) and closed (EC) in bipodalic and monopodalic conditions. Bikers showed a mean
velocity lower than swimmers both in EO (p = .004) and EC condition (p = .03). Also for mean velocity
in M-L plane (p = .02) and for perimeter length (p = .003) during EO condition, bikers showed lower re-
sults. Moreover, bikers showed a more posterior position of the centre of pressure when compared to
runners with EO (p = .02) and with EC (p = .03). These findings suggested that sport-specific physical
training induce postural modifications on upright stance. Within the main results concerning the gravita-
tional aspects appears paramount that swimming, the most 0 g sport (water is the best terrestrial 0 g simu-
lator environment) gives the smallest postural memory conditioning. The studies about human postural
control in normal condition, about postural modifications and memory induced by specific physical train-
ing in normal versus atypical gravitation setting, open a new perspective in anthropological studies on
postural adaptations, ability and performance in extreme environments.
Keywords: Human Posture; Postural Memory; Environmental Adaptations; Athletes
Introduction
Evolutional Relationship between Posture and
Environment
Gravitation has played an important role in influencing the
evolutionary processes that led to the actual human characteris-
tics (mainly the ones related to by the labyrinth function). Our
postures, in terrestrial environment, and even more our locomo-
tion and movement control is the product of a progressive ad-
aptation of the body structures and the functional and control
capabilities in relationship to the contrast with the gravitation
driving force.
Reconsidering the studies of A. Delattre and R. Fenart (De-
lattre & Fenart, 1960) ensues the evidence that Vertebrate laby-
rinth, the semicircular canals and the whole equilibrium organ,
were physiologically oriented in the evolution to detect the
direction of the gravitation field, regardless of bodies in shape,
size and postural orientation, ground-dwelling, water swim-
ming or air flight. Earthly Gravity, the “little g” (g), which is
the local gravitational field at the terrestrial surface, is equiva-
lent to the free-fall acceleration (9.81 m/s). It is certainly a
component of the environment and it may be perceived at a first
approximation as a physical constant, something like and fre-
quently confused, with Newton’s universal gravitational effec-
tive constant, the “big G”. At the Earth’s surface, the gravita-
tional field shows only instrumental variations, with virtually
no effect on the living. Gravity is a weak force (a small magnet
attracts a nail against the mass of the planet), nevertheless, the
force of gravity has an absolute influence in determining the
survival of live animals or plants: no species can survive if it is
not adapted to the gravitational environment.
This allows us to discuss Delattre’s proposed gravitation and
in particular its effect on the equilibrium organ, the “inner ear
vestibule”, as one of the main factors of the human form evolu-
*Corresponding author.

L. PIZZIGALLI ET AL.
tion and its fundamental meaning in the humanization process.
The so-called “vestibular plane” (inclined so that when hori-
zontal, the traditional “Frankfort Plane” downslides about 28˚)
gives us a comfortable and safe vision of the ground ahead
within the evolution of human postural adaptation as an impor-
tant, but not unique, step in the complicate “bush-like” pattern
of the Primates evolution from the original vertebrate horizontal
posture to upright human locomotion and arboreal anthropoid
dwelling (Harmon, 2013).
Today in the study of the man/environment changes mainly
concern the “living environment” which is increasingly artifi-
cial and technology dependant. The new environments, parti-
cularly the extreme ones, lead to the possibility of experi-
encing human capabilities in conditions other than the gravita-
tional ones that have characterized our evolution, as we may
experience situations in micro/macro gravity and in the absence
of gravity in the Outer Space (Masali et al., 2010a, 2010b).
Fundamentally, to live in the Space environment, a different
process of adaptation needs to be applied, one being the apti-
tude-based selection and training applied by the agencies, an-
other being the adaptation of the environment to support human
life in the effort to create a sustainable and Earth-autonomous
habitat. In cases where the environment cannot be adapted,
there is a third possibility: exaptation. Exaptation, first pro-
posed by Gould and Vrba (1982), means that the “archetypal”
structures developed by an organism for a specific need are
co-opted by the new environment to evolve into new functions
(Gould & Vrba, 1982; Gould, 1990, 2010) as “different adap-
tive patterns may derive from unusual environmental conditions.
This approach may be the challenge for extraterrestrial adapta-
tion of Earthly organisms”.
Ergonomic research to study the elements of the built envi-
ronment become paramount to better support human activities
in Space and in conditions other than 1 g but also takes care to
investigate further possible changes or functional postural ad-
aptations. Man may encounter these new conditions. Here
comes the importance of studies in reduced gravity, in real or,
when possible, in simulated conditions such as “neutral buoy-
ancy” or “virtual simulation” (Andreoni et al., 2000) or “para-
bolic flights” (Schlacht et al., 2009a, 2009b, 2009c) simula-
tions of gestures with actions, etc. Most studies on the ground
in the sporting arena (Tinto et al., 2012; Rosato et al., 2012) and,
as in our study the behavior of balance, control and postural
memory etc. which follow the practice of sport activities in ex-
treme environmental conditions and different postures and for
sport practitioners, whether a sport-specific balance oriented
training can modify athlete strategies during control of static
postural balance in different sensory conditions. A persuasive
approach to the significance of unconventional gravity condi-
tions and motor activity occurs from some experience of our
research team in an ESA Student Parabolic Flight Campaign,
during the color perceptive experiment “CROMOS” in which
some gymnastics actions were performed by Irene Schlacht and
Henrik Birke, during some void parabolas (Schlacht et al.,
2009a, 2009b, 2009c). However mostly of our knowledge ori-
gins from the encounter with the choreographer, dance educator
and researcher Kitsou Dubois in the course of one of her per-
formance in Chambery (Masali et al., 2010a). Kitsou Dubois
worked for ten years with the space research on gestures and
process orientation and perception in weightlessness. She ex-
perienced weightlessness aboard parabolic flights proposed by
the French Space Research (CNES) between 1990 and 1994, a
flight to Star City in Russia in September 2000 opening a new
program with the agency Arts Catalyst-Science which proposed
an astronaut training from dance techniques. She was able to
participate in more than a dozen parabolic flights and experi-
ence weightlessness. K. Dubois is the first artist in the choreog-
rapher world who works with the Space research weightless
gesture (Dubois, 1994).
Moreover, for sport practitioners, whether a sport-specific
balance oriented training can modify athlete strategies during
control of static postural balance in different sensory conditions.
A relationship exists between balance ability and sport training:
athletes of different sports develop specific postural adaptations
since specific is the physical activity. Training feedback re-
quires a gravitational stimulation as human adaptation to up-
right posture is mostly by antagonism to gravity force.
A peculiar aspect of gravitational adaptation is the self per-
ceiving in relationship to space and time.
Postural Control and Physical Activity
The position of the body in relation to force gravity and the
surround is controlled by combining visual, vestibular and pro-
prioceptive inputs (Manchester et al., 1989). Vision is the sys-
tem primarily involved in planning animal and human locomo-
tion and in avoiding obstacles along way. The vestibular system
can be considered as a “naturally embedded gyroscope”, since
it senses linear and angular accelerations. The somatosensory
system can be described as a multitude of sensors which sense
the position and velocity of all body segments, their contact
(impact) with external objects (including the ground), and the
orientation of gravity vector (Winter, 1995).
Professional activity modifies postural strategy and this issue
is particularly evident in sportsmen (Arkov et al., 2009). As
well known, regular sport training induces structural and or-
ganic modifications in human body. Moreover, human balance
control in an upright position depends not only on the innate
reflex, but also on training capacity (Ustinova et al., 2001).
Sport training increases the ability to use somatosensory and
otholitic information, improving postural capabilities (Bringoux
et al., 2000), which are different according to the practiced
sport (Davlin, 2004; Perrin et al., 2002). A study dated 2008,
identified the types of the postural subsystems involved in bal-
ance control and assessed the magnitude of their activities dur-
ing classical dressage, show jumping, vaulting, and versatility
riding (Schwesig et al., 2008). In general, the higher the level of
practice, the more appropriate the sensory organization, and
thus the higher the postural performance (Paillard et al., 2006;
Vuillerme et al., 2001). Previous work suggested that both the
level of activity and the type of sport may have a major impact
on postural control (Schwesig et al., 2009). Several studies com-
pared different athletes, in order to determine whether sports
improved balance performance and postural control (Bressel et
al., 2007; Calavalle et al., 2008; Hugel et al., 1999; Matsuda et
al., 2008; Paillard et al., 2006; Weinkam et al., 2008).
Postural Characteristics in Running, Cycling and
Swimming
To the knowledge of the authors, scientific evidence of the
influence of the training effects among running, cycling, and
swimming on stabilometric postural performances is lacking.
To bridge such a gap, the authors tested the hypothesis that these
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L. PIZZIGALLI ET AL.
specific types of sport have specific effects on static balance.
The herein presented study tested three groups of participants
who practiced physical activities in which body attitude and
postural regulation were organized in different ways. In fact,
run, swim and bike training referred to environmental condi-
tions in which feet and visual axes were used differently. Run-
ning is characterized by a movement pattern with head hold in
vertical position and a sequence of foot contacts with ground.
This kind of discipline is characterized by an alternation be-
tween a flying phase and a phase characterized by an alternated
support of the two lower-limbs. Lower limbs work both in open
and closed kinetic chain, whereas arms work always in open
kinetic chain. Runners performed their physical activity on land,
and they make extensive use of anti-gravity muscles during
training. Moreover, they must frequently support their body
weight with one leg; for these reasons they may be expected to
have better one-leg stance stability than other athletes.
In contrast, swimmers work in a net condition of micrograv-
ity and in open kinetic chain: they train predominantly in water
having few occasions to train anti-gravity muscles because of
water buoyant force. During locomotion in water, head and
body are in horizontal position and no fixed supports and ref-
erence points are available. When running, propulsion phase is
provided by lower-limbs whereas arms act to balance; the op-
posite occurs in swimming. Foot loading reduction of swim-
mers could alter their proprioceptive system. In water posi-
tion-sense receptors were activated while load-sense dependent
receptors were inactivated (Kelly et al., 2000). As a conse-
quence, swimmers could show a decrease in stance stability
with respect to other athletes. Postural water conditioning could
be comparable to those in 0g situation as demonstrated in stud-
ies on Neutral Buoyancy (Andreoni et al., 2000; Toscano et al.,
2004). In Space research Neutre Buoyancy Test Facility (NBTF)
are conducted quite to simulate weightlessness/microgravity
conditions testing activities, equipment and procedures for “er-
gonomic” design (ALTEC, 2012).
Finally, bikers, differently from the other two groups of ath-
letes, maintained a sit position constrained to the bike on three
fixed points (hands and pelvis) and two movable points (pedals).
These athletes work in a closed kinetic chain and their plantar
flexion is in the range 90˚ - 120˚ degrees only supported by the
metatarsus. Both upper and lower-limbs muscles were used du-
ring running and cycling but adopting different motor scheme
and contraction time. For instance, the propulsion phase during
cycling is based on a concentric contraction of the lengthening
kinetic chain, whereas during running requires its elastic char-
acteristic dues to the stretch shortening cycle. Literature has not
yet compared these kinds of athletes in terms of their own pos-
tural strategies.
It is evident that postural control had an important role in all
these physical activities (run, swimming, and cycling), but con-
sidering that each sport used lower limbs differently and re-
ceived different sensorial information it is of interest to show if
and how the practice of these sports induces any modification
on stance stability. Hence, the aim of this study was to investi-
gate and compare the impact of these conditioned trainings on
the sensorial systems (visual, vestibular and somatosensory) of
postural control.
Materials and Methods
The authors examined 26 healthy athletes, 10 runners, 10
swimmers and six bikers at a competitive level. The average
age of athletes was 22 ± 3 years, weight 69 ± 9 kg, height 179.6
± 5.5 cm and 275 mm foot length (ISO 9407:1991, Mondo-
point). Participants practised their sport for at least three years.
All the participants gave informed consent before data collec-
tion; the tests were carried out in the Motor Science Research
Centre of the University of Turin, School of Exercise and Sport
Science and the research was approved by the ethical com-
mittee. All the participants filled in a questionnaire aimed to as-
sess their anthropometric parameters (age, weight, height, foot
size) and practice and training characteristics (age of sport be-
ginning, years of physical activity and training hours/week).
Each subject was free from any known pathology of the cen-
tral nervous system and did not show any orthopaedic disorders
either of the trunk or of the lower limbs that could affect pos-
tural performance. Since inter-subjects differences of the pos-
tural response are linked not only to individual biomechanical
characteristics but also to the confidence they have with the
proposed postural protocol, the recruited participants never per-
formed postural exercises before this research to counteract this
biasing factor.
A four cell platform with a sampling frequency of 20 Hz
(Tecno-body PROKIN PK 214 P, Bergamo, Italy) was used.
The calculated variables were: the average movement of the
centre of pressure (COP) in the frontal plane (mm), the average
movement of the centre of pressure in the sagittal plane (mm),
the average speed in anterior-posterior direction (mm/s), the
average speed in medio-lateral direction (mm/s), the 90% el-
lipse area (mm2), and the sway path (SP) (mm) described by
COP position during the test.
Participants were tested in a stabilometric position. In order
to quantify postural control quality, the researchers chose to
measure the COP displacements, which are the trajectory in
time of such a point.
Participants were tested wearing their usual clothes and with-
out shoes. Four tests were performed, two lasting 30 seconds
(Gribble et al., 2007) in unipedal stance (dominant leg as a
support), one with eyes open and the other with eyes closed;
and two lasting 60 seconds (Nishiwaki et al., 2000; Raymakers
et al., 2005) in bipedal stance with and without visual inputs.
During two-leg stance tests, the subject was barefooted (with
heels touching and metatarsal phalangeal joints were in contact),
with the arms along the hips. During one-leg stance tests one
leg was used as a support and the other one maintained with
knee flexed at 90˚. During measurement with eyes open par-
ticipants were asked to fix their gaze at a target point in the
form of a black point on a white sheet located at a distance of 2
m at the vertical plane corresponding to eye level (Rogind et al.,
2003). To minimize external disturbances, all measurements
took place in a quiet, well lit room reserved for this purpose.
Statistical Analysis
Statistical analysis of the results was made with GraphPad
Prism 4.0 (San Diego, California, USA). All data were reported
as mean ± standard deviation. The differences between the
three groups were determined by Kruskal-Wallis test. The post
hoc Dunn’s tests were performed when necessary to isolate the
differences. Differences within groups were investigated with
the Wilcoxon test. The significance was set at a p level ≤ .05.
Finally, among stabilometric parameters, anthropometric and
training data, some correlations were done (both in the single
group, and in the total group of athletes), to evaluate if specific
types of sport generated specific effects on static balance.
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L. PIZZIGALLI ET AL.
Results
The results of Kruskal-Wallis test indicated no significant
differences in the anthropometric and training characteristics of
the recruited athletes (as reported in Table 1).
Statistical significant differences between groups were found
only for the variable “age of physical activity beginning” (p
< .05). This result showed that swimmers begun their sport
earlier at (8 ± 3 years), than the other two groups at (15 ± 6
years; p < .05). Other differences were reported for the variable
“number of training hours for week”, where bikers showed the
greatest value (19 ± 3 hours) (p < .01). No statistically signifi-
cant differences were observed, during monopodalic test in
eyes open (EO) and in eyes closed (EC) conditions among the
three groups, whereas some significant differences were ob-
served during bipodalic test with and without visual inputs.
Bikers showed more posterior (negative) sway of the COP,
in particular in comparison with runners both in EO condition
(p < .05) and in EC condition (p < .05). In fact they reported
greater negative median y COP values than others two groups,
as illustrated in Figures 1 and 2.
Moreover, bikers showed the best postural stability associ-
ated with the best body control in A-P direction and reported
average speeds lower than runners and swimmers both in EO
condition (p < .01) and in EC condition (p < .05). The best
body control in M-L direction in EO condition (p < .05) was
also observed in the bikers (as reported in Figures 3-5).
Perimeter length was found the shortest during tests with vi-
sual inputs for the bikers whereas swimmers showed the worst
body control during analysed stabilometric trials (p < .01) (as
illustrated in Figure 6).
Table 1.
Synthesis of anthropometric, practice and training characteristics of
analyzed athletes and the results of Kruskal-Wallis test among the three
groups. Post hoc statistical significant differences are evidenced by *(p
< .05) and by **(p < .01) and n.s. (not significant). R: (runners). S:
(swimmers). B: (bikers).
Age (months)
Weight (kg) Height (cm)
Foot length (mm)
Age of physical activity
beginning (years)
Years of physical activity
Training sessions/week
Training hours/week
Runners
Minimum
Maximum
Mean
Std. Deviation
218
333
253
±39
54
86
65
±10
174
189
179
±5
260
286
273
±1.5
8
17
13
±3
3
16
7.5
±4
3
11
5
±3
4.5 h
22 h
8.5 h
±5.0
Swimmers
Minimum
Maximum
Mean
Std. Deviation
226
367
285
±51
60
94
73
±9
173
192
1789
±5.51
254
286
267
±2
5
13
8
±3
6
24
15
± 6
3
10
6
±2
3.5 h
20 h
12 h
±6.0
Bikers
Minimum
Maximum
Mean
Std. Deviation
244
320
269
±27
67
77
71
±4
172
188
182
±6
257
279
273
±1.5
7
21
13
±6
4
15
9
±5
5.5
7
6.5
±.6
13.5 h
21 h
19 h
±3.0
Kruskal-
Wallis
Post hoc
p values n.s n.s. n.s.n.s.
R < S
*
R < S
* n.s R < B **
RUNNERS SWIMMERS BIKERS
-50
-40
-30
-20
-10
0
*
Y COP med (mm)
Figure 1.
Kruskal-Wallis test; differences between groups during
bipedal stance in E.O. condition for Y COP med variable.
Post hoc significance difference was evidenced by *(p
< .05).
RUNNERS SWIMMERS BIKERS
-50
-40
-30
-20
-10
0
*
Y COPmed (mm )
Figure 2.
Kruskal-Wallis test; differences between groups during
bipedal stance in E.C. condition for Y COP med variable.
Post hoc significance difference was evidenced by *(p
< .05).
RUNNERS SWIMMERSBIKERS
0
5
10
15
20
**
**
A-P Average speed (mm /s)
Figure 3.
Kruskal-Wallis test; differences between groups during
bipedal stance in E.O. condition for A-P average speed
variable. Post hoc significance difference was evidenced
by **(p < .01).
No statistically significant differences were reported among
the three groups for other stabilometric parameters.
The Wilcoxon test (Table 2) indicated statistically signifi-
cant differences between EO and EC trials within each group
both in bipodalic and in monopodalic tests. During EC trials all
groups reported their worst balance stability in comparison with
EO trials, but such a difference was less marked in bikers; in
fact for all the stabilometric variables this group showed less
differences between the two trials in different sensory condi-
tions (p < .05).
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L. PIZZIGALLI ET AL.
RUNNERS SWIMMERS BIKERS
0
5
10
15
20 *
A-P average speed (mm /s)
Figure 4.
Kruskal-Wallis test; differences between groups during
bipedal stance in E.C. condition for A-P average speed
variable. Post hoc significance difference was evidenced
by *(p < .05).
RUNNERS SWIMMERS BIKERS
0
5
10
15
*
*
M-L aver age speed (mm/s)
Figure 5.
Kruskal-Wallis test; differences between groups during
bipedal stance in E.O. condition for M-L average speed
variable. Post hoc significance differences were evidenc-
ed by *(p < .05).
RUNNERS SWIMMERS BIKERS
0
200
400
600
800
1000
*
**
Perimeter length (mm)
Figure 6.
Kruskal-Wallis test; differences between groups during
bipedal stance in E.O. condition for perimeter length va-
riable. Post hoc significance differences were evidenced
by *(p < .05) and by **(p < .01).
The analysis was carried out pooling together all the athletes
(bikers, swimmers and runners) (Tables 3 and 4). It was found
as follows:
1) Average speed in A-P plane was inversely correlated, in
bipodalic test in EC condition, with age of sport beginning (p
< .05) and, in monopodalic test in EO trials, with training hours
a week (p < .05). 2) Average speed in M-L plane was inversely
Table 2.
Wilcoxon test results. E.O. and E.C. conditions were compared within
each group in bipodalic and monopodalic tests. Statistical significant
differences were evidenced by *(p < .05), **(p < .01) and by n.s. (not
significant). All differences between variables recorded during E.O and
E.C. conditions were found greater in E.C. than in E.O. trials in all
groups.
Wilcoxon test
E.O. vs E.C.
conditions
Average Sp. A-P
Average Sp. M-L
Perimeter
length
Ellipse area
Bipodalic test ** ** ** n.s.
Runners
Monopodalic test ** ** ** **
Bipodalic test ** ** ** **
Swimmers
Monopodalic test ** ** ** **
Bipodalic test * * * n.s.
Bikers
Monopodalic test * * * *
Table 3.
Correlations among stabilometric parameters, anthropometric and train-
ing data during E.O. and E.C. bipodalic tests. Only parameters for which
were found significative correlation are reported in the table. A repre-
sents the whole group of 26 analysed athletes. R: runners. S: swimmers.
B: bikers. The first value represents the r value and the second one the p
value of the correlations.
Weight
Height
Age sport beginning
Years of physical activity
Training sessions/week
Training hours/week
Aver. Sp.
A-P
EC condition
A
−.421
.032
B
.845
.033
B
.921
.017
B
.921
.017
Aver. Sp.
M-L
EO condition
S
.706
.022
B
.845
.033
A
−.525
.005
Aver. Sp.
M-L
EC condition
A
−.439
.024
Perimeter
Length
EO condition
S
.669
.035
A
−.395
.046
S
−.654
.040
A
−.551
.004
S
−.719
.019
Perimeter
Length
EC condition
A
−.424
.031
Ellipse
Area
EO
condition
S
.650
.042
A
.408
.039
R
.741
.017
A
.576
.002
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L. PIZZIGALLI ET AL.
Table 4.
Correlations among stabilometric parameters, anthropometric and train-
ing data during E.O. and E.C. monopodalic tests. Only parameters for
which significative correlation were found are reported in the table. A
represents the whole group of 26 analysed athletes. R runners. S: swim-
mers. B: bikers. The first value represents the r value and the second
one the p value of the correlations.
Age (months)
Weight
Height
Foot length
Age sport beginning
Years of physical activity
Training hours/week
Aver. Sp.
A-P
EO
condition
R
−.757
.015
S
.651
.049
A
−.449
.021
Aver. Sp.
M-L
EO
condition
R
−.679
.035
A
−.462
.018
Perimeter
Length
EO
condition
R
−.663
.044
S
.683
.035
A
−.530
.006
Ellipse
Area
EO condition
A
.441
.024
S
.693
.031
A
.553
.003
S
.769
.013
Ellipse
Area
EC condition
R
.899
.001
R
−.821
.005
correlated, in bipodalic test with EO (p < .01), and in EC (p
< .05) and in monopodalic test with EO (p < .01), with training
hours a week. 3) Perimeter length was inversely correlated, in
bipodalic test with EO condition, with number of training ses-
sion a week (p < .05) and with hours of training session a week
(p < .01), and, this last variable was inversely correlated also in
bipodalic test with EC (p < .05) and in monopodalic test with
EO (p < .01). 4) Ellipse area was positively correlated with
weight (p < .05) and height (p < .01), both in bipodalic test and
in monopodalic test with EO.
When the analysis was carried out within each group:
In runners, it was found that: 1) age, in monopodalic test
with EO, was inversely correlated with average speeds in A-P
(p < .05), M-L (p < .05) and perimeter length (p < .05); 2) el-
lipse area, in bipodalic test with EO, was positively correlated
with height (p < .05), such as in Athletes group, whereas was
inversely correlated in bipodalic test with EC and, in monopo-
dalic test with EC, with age of sport beginning (p < .001) and
years of physical activity (p < .01).
In swimmers, it was found that: 1) average speed in A-P
plane, during monopodalic test with EO, was positively corre-
lated with foot size (p < .05); 2) average speed in M-L, during
bipodalic test with EO, was positively correlated with weight (p
< .05), such as in bikers. 3) Perimeter length was positively
correlated with height (p < .05), in bipodalic test with EO, and
with foot size (p < .05), in monopodalic test with EO, whereas
was inversely correlated with number of training sessions for
week (p < .05) and with training hours (p < .05), in bipodalic
test with EO, such as in athletes group. 4) Ellipse area, in bipo-
dalic test with EO, was positively correlated with weight (p
< .05), such as in the athletes group as a whole, whereas, in
monopodalic test with EO, with age of sport beginning (p < .05)
and with height (p < .05).
In bikers, it was found that: 1) average speed in A-P was po-
sitively correlated, in bipodalic test with EC, with years of phy-
sical activity (p < .05), number of training (p < .05), and with
hours of training sessions a week (p < .05). 2) Average speed in
M-L plane, in bipodalic test with EO was positively correlated
with weight (p < .05), such as in the swimmers group.
Discussion and Conclusion
The capacity to use sensory information varied among sub-
jects; in general, the practice of physical and sporting activities
(type and level of practice) improved postural balance (Davlin,
2004; Guskiewicz et al., 2001; Hugel et al., 1999; Paillard et al.,
2007; Perrin et al., 2002). Postural efficiency increased thanks
to the sensibility of the different sensors and to the development
of a sensory hierarchy related to proprioceptive preference
(Gauchard et al., 1999; Mesure et al., 1997; Perrin et al., 1998).
The herein study revealed that specific types of sport showed
specific effects on static balance which can be quantitatively
assessed. In fact, investigating the influence of three out of the
more played sport (such as running, cycling, and swimming) on
sensorial systems of postural control, findings showed that bik-
ers reported the best postural stability and swimmers the worst.
In 1999, some authors (Hahn et al., 1999) failed to demonstrate
an association between postural stability and work or leisure
activities in young people. They demonstrated that unipedal ba-
lance test was not associated with gender and age, but was po-
sitively associated with hours per week of sport activity (in that
case basketball). These findings are similar to the correlations
herein presented revealing that load training (number of train-
ing sessions, hours of training sessions) positively influences
stabilometric parameters of athletes group, in particular on M-L
average speed and on perimeter length with a correlation in all
tests with the only exception for monopodalic test with eyes
closed.
We shall remember that all the questions regarding the ef-
fects of postures in a gravitational field are related to what we
may call a “gravitational revolution” as the Primates spine ro-
tated appreciatively 90˚ in about 60 MY but only recently (≈ 4
MY) Hominids acquired the terrestrial upright posture. Such
change may be taken as a simulation of an adaptation to a quite
different gravity environment (Gamba et al., 2001).
In bikers, load training and the years of activity were found
to have a negative effect on A-P average speed without visual
inputs during bipodalic test, probably even if they showed the
best postural performances, these kind of athletes had a less
ability in body control in A-P direction, because in this plane
they were constrained on the bike with two fixed points (one on
saddle and the other on handle). Another explanation of this
finding could be the fact that bikers maintained balance by
watching the profile of the road, the back wheel, and the shoul-
ders of the cyclists in front of them (Lion et al., 2009). More-
over, the optimal position on bike is characterized by a load
distribution with 40% on anterior wheel and 60% on posterior
wheel. According to that, findings showed more posterior sway
of the COP in bikers, in particular in comparison with runners,
Open Access 234

L. PIZZIGALLI ET AL.
both in EO condition and in EC conditions. During bipodalic
test (in EO and EC conditions) statistically significant differ-
ences in COP sways, average speeds in A-P and M-L planes
and perimeter length were found, whereas during monopodalic
test no statistically significant differences were obtained in the
three analyzed groups.
This finding can be explained since the three analyzed sports
are symmetrical and characterized by cyclic actions; therefore,
bipodalic EO tests could be considered more specific for these
athletes than one-legged stance test. In fact, monopodalic static
stance cannot be considered a training position for these ath-
letes, and it was found the most stressful, in particular with eyes
closed. This finding was confirmed also by other authors
(Asseman et al., 2008; Paillard et al., 2006; Perrin et al., 2002).
During double stance test bikers showed more postural stability
than other athletes, in particular swimmers, with statistically
significant differences in A-P direction with and without visual
inputs, in M-L direction and in perimeter length with EO. Their
ability to maintain the bike in balance, in particular in M-L di-
rection, could explain such a specific postural performance.
Furthermore, maintaining an appropriate posture on bike seems
to be essential to ensure the highest performances (Duc et al.,
2008). The elimination of eyesight during the tests resulted in a
marked increase in postural sway on the force platform for all
athletes, diminishing visual feedback with eyes closed condi-
tions consistently decreased postural stability in comparison to
opened conditions.
Findings herein presented are similar to those from another
study (Riemann et al., 1999); moreover, data from bikers sug-
gested reduced differences between the two trials in EO and EC
conditions, supporting the fact that visual inputs were much
more important for swimmers and runners compared to the
bikers. The role of vision in bikers was studied in 2009 (Lion et
al., 2009). It was shown that balance-related visual informa-
tion was better used by bikers who mostly practiced on-road
cycling, whereas, proprioceptive information was better used
by mountain bikers, who mostly practiced off-road cycling. The
practice of swimming in elderly people (Hsu, 2010), was shown
to improve balance function in difficult conditions in contrast to
other elderly athletes. Contrary to that study, swimmers herein
showed the worst postural sways particularly in comparison
with runners. These findings may be related to the fact that par-
ticipants recruited in this study were younger and spent the
most part of their physical training in aquatic environment as-
suming horizontal position. Sensorial information to the cen-
tral nervous system was altered during swimming due to the
counter balanced force of gravity, the lack of uprightness and
ground support. These modifications induce a re-organization
of the sensorimotor system that provokes the development of a
specific aquatic coordination. In the present study considerable
differences were observed in the adaptability of postural control
during stabilometric trials between athletes from different dis-
ciplines. Such differences in postural control abilities may de-
pend on individual athletic background and consequently on
training characteristics.
These aspects modify postural balance capabilities respect to
postural demand typical of stable environment (g = 9.81 m/s)
that modify the capacity of managing the balance than required
by the simple force of gravity in a condition of static upright
posture. These results provide additional information in support
of the ability of stabilometric techniques to identify inter-sub-
ject differences. The current study provides evidence that sig-
nificant differences on stabilometric performances can be ob-
served and quantified in bikers, runners and swimmers. As a
consequence, the practice of different sport specialties can im-
pact in different way on balance control. Training induces mo-
difications on postural control mechanisms: athletes from dif-
ferent disciplines scored different stabilometric performances,
because each sport develops specific postural adaptations. Sports,
as extreme conditions of human activity, are one of the most
valid fields of experimentation for advanced physical Anthro-
pology researches.
Acknowledgements
The Authors are grateful to the participants in the experimen-
tal session. In particular we wish to thank the participants of
this study. A special acknowledgment goes to Prof. M. Masali
for valuable advice and openness to considerations on aspects
of the relationship between man and environment extragravita-
tional conditions! Finally, we wish to thank the company Tec-
nobody, Bergamo, Italy that provided the equipment used in
this investigation.
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