Structured abstract: Introduction: Maintaining balance while
walking is of utmost importance for individuals with visual impairments
because deficits in dynamic balance have been associated with a high
risk of falling. Thus, the primary aim of the study presented here was
to determine whether balance training effects the dynamic balance of
children with visual impairments. Methods: The study included 19
children with visual impairments (aged 8 to 14) from the school for
students with visual impairments in Isfahan, Iran, who were randomly
assigned to a balance-training (n = 9) or control (n = 10) group. The
balance-training group was required to participate in an eight-week
balance-training program, while the control group did not participate in
any organized balance-training program. The Modified Bass Test of
Dynamic Balance was used to measure the dynamic balance of the
participants. Both groups performed a pretest prior to the experimental
period and performed a posttest immediately after the experimental
period. Results: The scores on the pretest showed no significant
difference between the balance-training group and the control group.
However, after the balance-training group completed the balance-training
program, a between-group difference was found in the participants’
task scores, t (18) = 4.095, p < .05. Discussion: The findings
indicate that involvement in a balance-training program will
significantly improve the dynamic balance of individuals with visual
impairments relative to a control group. Implications for practitioners:
The study showed that if instructors require individuals with visual
impairments to perform balance-improving exercises, the result can be an
outstanding improvement in their dynamic balance. With improved balance,
individuals with visual impairments may encounter fewer falls and
experience a healthier lifestyle.
Balance has been defined as the ability to maintain one’s
equilibrium as the center of gravity shifts (dynamic balance), as in
walking and running, and while the center of gravity remains stationary
(static balance), as in standing or sitting (Gallahue & Ozmun,
2006). Several neural and biomechanical factors work together to achieve
balance. Among the components that play a vital role in the control of
one’s balance are the visual, vestibular, and somatosensory systems
(Woollacott & Shumway-Cook, 1990). Individuals with visual
impairments (that is, those who are blind or have low vision) are at an
increased risk of falls because vision, an important contributor to
balance, is disturbed (Cheung, Au, Lam, & Jones, 2008; Ray, Horvat,
Croce, Mason, & Wolf, 2008).
The lack of balance is one of the most profound problems observed
in children with visual impairments (Bouchard & Tetreault, 2000;
Buell, 1950; PortforsYeomans & Riach, 2008). Complications with
postural control and poor balance and a stiff and hesitant gait have
been found in children and adolescents with visual impairments (Bouchard
& Tetreault, 2000; Sleeuwenhoek, Boter, & Vermeer, 1995).
Moreover, investigators have reported that gait problems, balance
impairment, postural sway, and visual impairment are the most
significant risk factors for falls (Lord & Dayhew, 2001; Rubenstein,
Josephson, & Robbins, 1994). One area that has received attention
from researchers of visual impairments has been physical exercise-based
intervention programs (Blessing, McCrimmon, Stovall, & Williford,
1993; Campbell et al., 2005; Cheung et al., 2008).
The majority of studies on the prevention of falls have been
conducted among older adults (Maeda, Nakamura, Otomo, Higuchi, &
Motohashi, 1998; Province et al., 1995; Shumway-Cook, Gruber, Baldwin,
& Liao, 1997; Steinman, Nguyen, Pynoos, & Leland, 2011).
Furthermore, exercises have been designed to increase various
musculoskeletal systems and fitness factors in older individuals
(Fatouros et al., 2002; Shumway-Cook et al., 1997; Taaffe, Duret,
Wheeler, & Marcus, 1999). In these studies, balance has been
presented as a whole, not as specifically dynamic or static. However, it
seems that children with visual impairments also need training to
achieve better balance and postural stability to prevent falling.
To our knowledge, no study has used balance-improving exercises to
determine whether they result in an improvement in dynamic balance in
children with visual impairments. The purpose of the study presented
here was to examine whether balance-improving exercises would improve
the dynamic balance of children with visual impairments. The
experimental design chosen for the study was a two-grouped matched
pretest-posttest design. The primary hypothesis was that children with
visual impairments who were required to do balance-improving exercises,
compared to those who were not, would show improvements in dynamic
balance. We believe that improvement in dynamic balance can largely
affect stability in walking and therefore reduce falling among this
In the study, a student with a visual impairment was defined as one
who sustained a loss in vision (regardless of the cause) to such a
degree as to be beyond conventional corrective measures, such as
refractive correction, medication, or surgery (Arditi & Rosenthal,
1998). Each participant had been formerly diagnosed as having a visual
impairment (low vision or “legally blind”) by an
ophthalmologist. The students’ visual acuity was 20/70 or less in
the better eye after conventional correction. All the participants were
screened by an experienced physician and were found eligible to
participate in balance training.
[FIGURE 1 OMITTED]
Nineteen students with visual impairments (aged 8 to 14) from the
school of students with visual impairments in Isfahan, Iran, volunteered
to participate in the study. We did not include individuals who were
blind. None of the participants had previously experienced
balance-training programs. The participants were randomly assigned to a
balance training group (n = 9, 7 boys and 2 girls; 10.44 [+ or -] 1.59
years) or a control group (n = 10, 5 boys and 5 girls; 10.10 [+ or -]
2.13 years). They took part in the study after their scheduled classes.
All the participants were in reasonably good health and physical
condition except for their visual impairments. They and their families
all gave their informed consent. The Committee for Ethical
Considerations in Human Experimentation of the University of Isfahan
assessed and approved the experimental protocol.
APPARATUS AND TESTING PROTOCOL
An apparatus was designed to simulate the Modified Bass Test of
Dynamic Balance. Figure 1 presents the geometric dimensions of a mixed
wooden platform (3 inches high by 190 inches long by 25 inches wide). On
the surface, landing locations are marked as shown in Figure 1. For
better visibility, beneath each marking is a halogenic light that is
fixed inside the wooden surface.
The Modified Bass Test of Dynamic Balance was used to examine
dynamic balance. Reliability for this test was found to be r = 0.75. A
validity of r = 0.46 was found when the test was correlated with the
Bass Dynamic Balance Test (Johnson & Nelson, 1979). The Modified
Bass Test of Dynamic Balance was originally designed to assess dynamic
balance in school-aged children. Moreover, we asked a multidisciplinary
team (including a physician, three certified trainers, a certified
physical fitness judge, and an ophthalmologist) to watch some children
with visual impairments while performing the balance test. They
confirmed that the test was appropriate for children to test their
dynamic balance and that it does not hurt them. All the measurements for
all the participants were made by an experimenter (with an M.Sc. in
physical education and sport sciences) and an assistant (an
undergraduate student of the College of Physical Education and Sport
Sciences, University of Isfahan). Both the experimenter and the
assistant were trained before the experimental protocol began.
Prior to the experimental period, we organized an initial
instructional balance-training session in which the participants of both
groups were instructed in how to complete the dynamic balance test. At
the beginning of the test, the participant was required to stand
stationary on the sole of the right foot on the starting point light. He
or she then hopped diagonally on Point 1 with his or her left foot on
the mark. He or she was required to hold a stationary position for five
seconds and then to hop with his or her right foot to Point 2. The
participant then held a static position for another five seconds and
hopped to the next point. This process continued to Point 10 with
alternate hops and holding a static position for five seconds. For each
successful landing, the participants were awarded five points. For every
one second the balance was held on the mark, an additional one point was
awarded. Thus, the maximum points that could be attained by the
participant were 10 points for every mark and a total of 100 points for
the complete test.
Two kinds of errors were made in this test, landing errors and
balance errors. There was a five-point deduction if the following
landing errors occurred: (1) the heel of the foot or other parts of the
body touched the floor, (2) the sole of the foot did not cover the light
so that it could not be seen, and (3) the participant was unable to stop
on every mark after landing from a leap. There was a one
point-per-second deduction if the following balance errors occurred
before the participant completed five seconds on the mark: (1) the
participant was unable to hold a static position while his or her foot
was on the mark and (2) any part of the participant’ s body other
than the sole of the supporting foot touched the floor (Sports
Information and Science Agency, 2000). If the participant lost balance,
he or she had to go back to the proper mark and leap to the next mark.
The time for completion of each balance attempt was counted aloud in
seconds for the participant. Each participant made two attempts, and the
better score was considered the final measurement.
We organized a program in which balance exercises were
progressively set. To do so, we followed the principles of training
proposed in exercise physiology texts. The training program was found to
be specific, progressive, realistic, challenging, attainable, and time
limited according to three certified trainers of physical fitness
batteries. The trainers made some corrections to our balance-training
program and confirmed that the program was appropriately set. The
balance-training program was carried out in one group.
The balance-training program consisted of such movements as
standing still without rocking, movements from standing (swinging the
arms back and forth together rhythmically, bending and straightening the
knees), standing games, crawling (through a hoop, under a rope, and over
a rolled-up mat), rolling, walking (in straight lines, forward and
backward, then along curves and then with abrupt changes of direction,
walking through the space made by two facing benches), hopping,
skipping, and galloping, jumping, and bunny jumping over a straight line
from side to side (Macintyre, 2005). The training sessions consisted of
60 minutes of exercise, two times per week for eight weeks (16
sessions). For each session, there were 10 minutes of stretching and
warm-up exercises, 45 minutes of balance exercises, and 5 minutes for a
cool down. We held practice sessions in an appropriate schoolyard. The
participants took the pretest after the initial instructional practice
and the posttest immediately after the 16th session of practice.
We performed statistical analyses with an independent t test by
using SPSS software (Version 11.5). We expressed all data as the mean [+
or -] SD. We set the statistical significance at p < .05.
To confirm that the random assignment of participants produced
equally talented groups for dynamic balance, we compared the mean test
scores of the two groups in the pretest. The mean test scores of the
balance-training group and the control group were 11.11 and 11.5,
respectively. We found no significant difference.
Figure 2 illustrates the balance test scores for the experimental
and control groups throughout the experimental period. Typically, when
the scores of balance tests are interpreted, they are judged against
normative data. Since we did not find any normative values for the
Modified Bass Test of Dynamic Balance for children with visual
impairments, each participant’s pretest score was compared to the
same person’s score in the posttest. As can be seen in Figure 2,
the experimental group improved their dynamic balance scores
considerably (from 11.11 to 34.11). In addition, to investigate the
effects of balance training on the dynamic balance of children with
visual impairments, we compared the mean task score of the two groups in
the posttest. The mean test scores of the balance-training group and the
control group were 34.11 and 10.5, respectively. We found a significant
difference, t (18) = 4.095, p < .05.
Owing to their visual disabilities, individuals with visual
impairments spend less time on daily activities than do sighted
individuals, which may affect their capabilities, such as balance
(Graham & Reid, 2000; Lahtinen, Rintala, & Malin, 2007;
Seok-Min, Silliman-French, & Hyun-Su, 2010; Steinman, Pynoos, &
Nguyen, 2009). In addition, sustaining balance and stability are
necessary to avoid falls (Rubenstein et al., 1994; Steinman et al.,
2011). The study examined the effect of balance-improving exercises on
the dynamic balance of children with visual impairments. Previous
studies have shown that well-organized balance and strength-training
programs improve the balance of sighted individuals (Granacher,
Gollhofer, & Kriemler, 2010; Kahle, 2009; Province et al., 1995;
Shumway-Cook et al., 1997; Skelton, 2001). These results are in
accordance with the results of our study. We found that after going
through eight weeks of selected balance exercises, the children’s
dynamic balance had significantly improved.
As we mentioned earlier, various sensory processes contribute to
the development of stability and balance. To accommodate the inadequacy
of their visual capacities, individuals with visual impairments must
rely on their somatosensory and vestibular systems to maintain balance
and postural stability in everyday life, including physical activity
(Pereira, 1990). Although we did not directly assess the likely
adjustments in the somatosensory and vestibular systems, it is possible
that taking part in regular balance-improving exercises could improve
the efficiency of these structures in children with visual impairments.
Research has shown that certain physical activities improve
proprioception (an element of the somatosensory system) in particular
joints. Xu, Hong, Li, and Chan (2004) reported that long-term training
could improve proprioception in the knee and ankle joints. Jacobson,
Chert, Cashel, and Guerrero (1997) observed the same results on shoulder
proprioception. Because the somatosensory system in general and
proprioception in particular influence balance status, it is possible
that the kinesthetic senses in the children’s joints improved after
eight weeks of balance training. As a result of their likely increase in
their reliance on proprioception, we observed improvements in dynamic
balance of the children.
The vestibular system is another contributor to balance in
individuals with visual impairments. Seemungal, Glasauer, Gresty, and
Bronstein (2007) suggested that long-term training for persons who are
blind can affect navigation and orientation (a function of the
vestibular system). As we stated before, maintaining balance depends
partly on how the vestibular system operates. The results of the studies
mentioned earlier can explain the probable reasons for the improved
balance of the children in our study. It seems that as a consequence of
balance training, some aspects of vestibular performance could have been
positively enhanced in the children.
In summary, the study showed an improvement in the dynamic balance
of the children with visual impairments that could probably have been a
result of the increased use of proprioception and vestibular structures.
However, it should be noted that there was no direct method of
determining the exact changes in the function of the somatosensory and
vestibular systems in our study. Thus, we cannot confidently state that
our results were related to the mentioned adjustments. Further research
is needed on the role of sensory structures underlying the enhancement
of balance in children with visual impairments. In addition, most of the
research in the field of visual impairments and balance disorders has
been conducted on adults, rather than children. It is obvious that
physical exercise should begin at a young age to produce the best
outcome. Therefore, early “body preparation” can have a major
impact on the social lives of children with visual impairments. Thus,
through exercise and training, fewer falling incidents are likely to
occur, and the children can achieve a better lifestyle.
The children with visual impairments showed a significant
improvement in their dynamic balance after taking part in
balance-improving exercises for eight weeks. Because of the absence of
enough scientific support for the role of sensory adaptation to balance
training in individuals with visual impairments and the lack of a
physiological evaluation of the results of training in the study, the
fundamental reasons for the children’s improvement in balance could
not be completely detected. It is important to point out that the next
step in future research is to understand the supporting factors, such as
kinesthetic and proprioceptive cues, underlying the improvement in the
dynamic balance of children with visual impairments.
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Figure 2. Mean scores of the experimental
and control groups on the pretest and posttest.
Mean scores Pretest Posttest
Experimental 11.11 34.11
Control 11.5 10.5
Note: Table made from bar graph.