The Effect of Visual Feedback on Body Sway in the Elderly with Diabetes Compared to Elderly without Diabetes: Randomized Clinical Trial

Balance is a complicated mechanism aiming to maintain body
posture during the presence of static and dynamic stressors...

is rapidly increasing in the United States (US). According to the Department of Health and Human Services, in the year 2009, the number of people who were 65 years or older was 39.6 million.
However, by the year 2030, the projected number of people who are 65 years or older will be around 72.1 million [3].
Balance disorders are presented more in the elderly compared to young people due to the aging process and high incidence of diseases such as diabetes [4][5][6]. Aging involves many physiological changes in the sensory, visual, vestibular, motor, and central nervous systems (CNS) resulting in poor postural control [4].
A previous study has shown a significant indirect relationship between visual dysfunction and body stability [7]. This can be seen either as increased body sway, decreased postural control, or sustained falls among the elderly [2]. Studies have demonstrated a direct relationship between increasing body sway in the elderly and the risk of falling [2,8]. . Uncontrolled diabetes affects body balance significantly by affecting sensory inputs, brain function, and/or motor control [12]. The prevalence of peripheral neuropathy is between 60-70% among people with diabetes [12]. Loss of sensory input or muscle strength in peripheral neuropathy affects the postural stability and body balance significantly [2,13,14]. Kim and colleagues reported that 60% of patients with diabetic neuropathy develop vestibular disorders [15]. Another study showed that the vestibular disorders increased the risk of falls over 2 fold in people with diabetes [16].
Song and colleagues [17] examined the effect of an exercise program on balance and proprioception in the elderly participants with peripheral neuropathy. They used a balance training program for 60 minutes twice a week for 8 weeks. They found a significant reduction in postural sway following the training program [17].
Cawsey and colleagues [18] tested the effect of center of pressure (COP) magnification using visual feedback on standing sway.
They found that the standing sway on incompliant and compliant surfaces decreased significantly with COP magnification [18]. In summary, body balance is affected by the aging process and the high incidence of disease in the elderly. The impact on body sway is more among the elderly with diabetes due to damage in the CNS, PNS, vestibular system, vision, and musculoskeletal system. Body sway is worse in balance disorders and studies showed a direct relationship between body sway and the incidence of falling in the elderly. Current regimen in balance training requires a long duration and increased repetition which could be challenging to the elderly due to limited fitness and presence of disease and health disorders. Therefore, the purpose of this study was to examine the effect of a single 6 minutes of visual feedback training on body sway in the elderly participants with or without diabetes.

Participants
Fifty-one participants were enrolled in this study. They were recruited using fliers and telephone calls from physical therapy centers, senior homes, sport centers, and Loma Linda University.
The participants were included if they are 65-90 years of age, either having no diabetes or a type 2 diabetes, and having balance deficits presented by a complaint of instability. Subjects were divided into 2 groups; an elderly group without diabetes and an elderly group with diabetes. Then the participants were assigned randomly into 2 different interventions using a block design. One of these interventions was the visual feedback. Therefore, there were 13 participants in the elderly group with diabetes and 16 participants in the elderly group without diabetes receiving visual feedback. Participants were excluded if they had cognitive disorders, central nervous system disorders, alcohol/substance abuse, took medications that affected body balance, vestibular pathology, unable to stand for 10 minutes continuously, or enrolled in balance training that interfered with the provided intervention within the last month. All participants were screened with a 10-g monofilament test for neuropathy, and none of them failed the test.
All protocols and procedures were approved by the Institutional Review Board of Loma Linda University and all participants signed a statement of informed consent. The rights of human subjects were protected. The baseline demographics of each group are shown in Table 1. There was a significant difference in weight between the 2 study groups.

Study Design
A single blinded randomized clinical trial design was used. The participants were assigned randomly using a block design into visual feedback or another intervention. For the purpose of this paper, we are focusing on the effect of visual feedback on body sway.

Measurements of Body Sway
Measurements of body sway were conducted by a licensed physical therapist that had 5 years of experience in using

Design of Visual Feedback Intervention
The center of pressure (COP) was presented at the screen as

Data Analysis
The general characteristics of 16 elderly participants without diabetes and 13 elderly participants with diabetes were summarized using means and standard deviations for quantitative variables, and frequencies and relative frequencies for categorical variables. There was no attrition in the study. A 2x3 mixed factorial analysis of variance (ANOVA) with adjustment to the BMI were used to examine the difference in mean body sway between and within participants for the variables which were normally distributed.
The differences between post and pre intervention measurements were compared between the two groups using independent t-tests.
Effect sizes (Cohen's d) were calculated from the mixed models.
Nonparametric analyses using Friedman and Wilcoxon Signed Rank tests were used to examine the difference in mean body sway within groups for the variables which were not normally distributed. The level of significance was set at p≤.05.

Results
There were no significant differences in mean body sway between the elderly group without diabetes and the elderly group with diabetes on any of the tasks pre intervention, post intervention, 1.8±.9; p=.02, Figure 4). Also, the average body sway decreased significantly in the elderly group without diabetes when standing on foam with feet apart and eyes closed post intervention when compared to pre intervention (1.9±.9 vs. 3.4±1.8; p=.00, Figure 5).
However, there was no significant difference in mean body sway

Discussion
Body balance diminishes with aging. This is due to the normal aging process and the high incidence of diseases that interfere with body balance [4][5][6]20]. Balance disorders result in increased body sway, decreased postural control, and increased incidence of falls [2,21].

Diabetes can significantly affect peripheral sensory input and
can result in peripheral neuropathy. A study has shown association between peripheral neuropathy and vestibular disorders [16]. The results of this study indicated better improvement in body sway in the elderly group with diabetes when compared to the elderly without diabetes while standing on foam with eyes open but not with eyes closed. This finding could be attributed to many reasons.
As cited previously, vision predominates the somato sensory and vestibular systems in body balance in healthy people [23]. We would expect that vision will be involved more in controlling body balance in people with diabetes, compared to healthy people, due to limited peripheral somato sensory and vestibular inputs [16,23].
This might explain the reason that the elderly with diabetes, in this study, achieved better improvement than the elderly without diabetes in the situation involving standing on foam with eyes open. They could have learned a strategy to control their body sway using their visual input since they have to rely on the vision more than somato sensory and vestibular systems.
These findings are supported by a previous study that examined the effect of tactile feedback on body sway [24]. The elderly group without diabetes had more improvement than the elderly group with diabetes. This suggests that the participants in the elderly group without diabetes responded better to tactile feedback because they had better peripheral somato sensory input than the participants in the elderly group with diabetes [24]. Petrofsky and colleagues conducted a study to assess the motor control during balance tasks in participants with diabetes [25]. They found more activation in parietal cortex of the cerebrum in participants with diabetes compared to elderly without diabetes or young participants doing the same task. Also, the activation of parietal area increased with increasing the complexity of task such as eliminating vision or decreasing the somato sensory input in people with diabetes.
This finding suggests possible deficits in the sensor motor process and the integration of sensory inputs in people with diabetes. Their findings support the findings of this study that the participants in the elderly group with diabetes were able to learn new strategy to improve body sway in the situations involved eyes open because it makes the sensor motor process and sensory integration in parietal area less complex.
Other studies support the findings of this study [26,27] Positive effect of visual feedback on body balance in frail elderly women was reported by Sihvonen et al. [27]. In the same study, the compliance with visual feedback among participants was high 97.5% and participants were motivated to participate in the training. In another study, visual feedback training helped in decreasing the incidence of fall among frail older women [26]. This suggests a promising future for visual feedback to be a useful training tool in physical therapy or rehabilitation centers to improve body balance in the elderly people. The limitations of this study were the small sample size, the intensity of treatment, and the lack of measurements of carryover effects. Future studies are recommended to study multiple visual feedback training sessions on a larger sample size and to have follow up measures to examine the carry over effect of the intervention.

Conclusion
Visual feedback provides an additional approach for training elderly people with or without diabetes to improve their body stability and balance. It requires less time and effort than the conventional balance training.