A Therapeutic Insole Device for Postural Stability in Older People With Type 2 Diabetes. A Feasibility Study (SENSOLE Part I)

Acute Effects of Vibrating Insoles on Dynamic Balance and Gait Quality in Individuals With Diabetic Peripheral Neuropathy: A Randomized Crossover Study

OBJECTIVE

This study investigated the effects of vibrating insoles on dynamic balance and gait quality during level and stair walking and explored the influence of vibration type and frequency in individuals with diabetic peripheral neuropathy (DPN).

RESEARCH DESIGN AND METHODS

Twenty-two men with DPN were assessed for gait quality and postural and dynamic balance during walking and stair negotiation using a motion capture system and force plates across seven vibratory insole conditions (Vcs) versus a control (Ctrl) condition (insole without vibration). Vibration was applied during standing and walking tasks, and 15-min rest-stop periods without vibration were interposed between conditions. Repeated measures test conditions were randomized. The primary outcomes were gait speed and dynamic balance.

RESULTS

Gait speed during walking significantly improved in all Vcs compared with Ctrl (P < 0.005), with Vc2, Vc4, and Vc6 identified as the most effective. Gait speed increased (reflecting faster walking) during stair ascent and descent in Vc2 (Ctrl vs. Vc2 for ascent 0.447 ± 0.180 vs. 0.517 ± 0.127 m/s; P = 0.037 and descent 0.394 ± 0.170 vs. 0.487 ± 0.125 m/s; P = 0.016), Vc4 (Ctrl vs. Vc4 for ascent 0.447 ± 0.180 vs. 0.482 ± 0.197 m/s; P = 0.047 and descent 0.394 ± 0.170 vs. 0.438 ± 0.181 m/s; P = 0.017), and Vc6 (Ctrl vs. Vc6 for ascent 0.447 ± 0.180 vs. 0.506 ± 0.179 m/s; P = 0.043 and descent 0.394 ± 0.170 vs. 0.463 ± 0.159 m/s; P = 0.026). Postural balance improved during quiet standing with eyes closed in Vc2, Vc4, Vc6, and Vc7 (P < 0.005).

CONCLUSIONS

Vibrating insoles are an effective acute strategy for improving postural balance and gait quality during level walking and stair descent in individuals with DPN. These benefits are particularly evident when the entire plantar foot surface is stimulated.

The effects of vibrating shoe insoles on standing balance, walking, and ankle-foot muscle activity in adults with diabetic peripheral neuropathy

BACKGROUND

Peripheral neuropathy is one of the most common complications of type 2 diabetes, which can lead to impaired balance and walking. Innovative footwear devices designed to stimulate foot sensory receptors, such as vibrating insoles, could offer a new route to improve motor impairments in people with diabetic peripheral neuropathy (DPN).

RESEARCH QUESTION

Does wearing vibrating insoles for the first time alter measures of balance, walking, and ankle-foot muscle activity, in people with DPN?

METHODS

A randomised cross-over study was conducted with 18 ambulant men and women with a diagnosis of DPN. Participants performed tests of standing balance (Bertec® force platform) under four conditions (foam/firm surface, eyes open/closed) and level-ground walking (GAITRite® instrumented walkway), whilst wearing vibrating and non-vibrating (control) insoles on two separate occasions (one insole/session). Electromyography (EMG) was used to assess soleus, medial gastrocnemius, tibialis anterior, peroneus longus activity during balance tests. Outcomes included centre of pressure (CoP) sway, EMG amplitude, spatiotemporal gait patterns, and Timed Up and Go test. One sample t-tests were used to explore %differences in outcomes between insole conditions.

RESULTS

Wearing vibrating insoles led to a reduction (improvement) in CoP elliptical area, when standing on a foam surface with eyes closed, relative to non-vibrating insoles (P=0.03). Applying perceptible vibrations to the soles of the feet also reduced the EMG amplitude in soleus (P=0.01 and P=0.04) and medial gastrocnemius (P=0.03 and P=0.09) when standing with eyes closed on firm and foam surfaces.

SIGNIFICANCE

Our findings of signs of improved balance and altered muscle activity with suprasensory vibrating insoles provides new insights into how these devices can be used to inform innovative rehabilitation approaches in individuals with DPN. This will be strengthened by further research into possible clinical benefits of these devices - given that the effects we detected were small with uncertain clinical meaning.

Effectiveness and safety of subthreshold vibration over suprathreshold vibration in treatment of muscle fatigue in elderly people

Muscle fatigue is common in many populations, particularly elderlies. Aging increases the incidence of muscle fatigue and delays its recovery. There is a huge debate about the current treatments for muscle fatigue, particularly in elderlies. Recently, it has been discovered that mechanoreceptors have an important role as a sensory system in sensing muscle fatigue which could enhance the body's response to muscle fatigue. The function of mechanoreceptors could be enhanced by applying either suprathreshold or subthreshold vibration. Although suprathreshold vibration improves muscle fatigue, it can cause desensitization of cutaneous receptors, discomfort, and paresthesia, which are barriers to clinical use. Subthreshold vibration has been approved as a safe and effective method of training for mechanoreceptors; however, its use and effectiveness in muscle fatigue have never been tested or explained. Possible physiological effects of subthreshold vibration in the treatment of muscle fatigue include: (1) Enhancing the function of mechanoreceptors themselves; (2) Increasing the firing rate and function of alpha motor neurons; (3) Increasing blood flow to fatigued muscles; (4) Decreasing the rate of muscle cell death in elderlies (sarcopenia); and (5) Driving motor commands and allow better performance of muscles to decrease fatigue incidence. In conclusion, the use of subthreshold vibration could be a safe and effective treatment for muscle fatigue in elderlies. It could enhance recovery from muscle fatigue. Finally, Subthreshold Vibration is safe and effective in treating muscle fatigue in comparison to suprathreshold vibration.

Effects of badminton insole design on stress distribution, displacement and bone rotation of ankle joint during single-leg landing: a finite element analysis

Previous research has reported that up to 92% of injuries amongst badminton players consist of lower limb, whereby 35% of foot fractures occurred at the metatarsal bone. In sports, insoles are widely used to increase athletes' performance and prevent many injuries. However, there is still a lack of badminton insole analysis and improvements. Therefore, this study aimed to biomechanically analyse three different insole designs. A validated and converged three-dimensional (3D) finite element model of ankle-foot complex was developed, which consisted of the skin, talus, calcaneus, navicular, three cuneiform, cuboid, five metatarsals and five phalanges. Three existing insoles from the market, (1) Yonex Active Pro Truactive, (2) Victor VT-XD 8 and (3) Li-Ning L6200LA, were scanned using a 3D scanner. For the analysis, single-leg landing was simulated. On the superior surface of the skin, 2.57 times of the bodyweight was axially applied, and the inferior surface of the outsole was fixed. The results showed that Insole 3 was the most optimum design to reduce peak stress on the metatarsals (3.807 MPa). In conclusion, the optimum design of Insole 3, based on the finite element analysis, could be a justification of athletes' choices to prevent injury and other complications.

A Therapeutic Vibrating Insole Device for Postural Instability in Older People with Type 2 Diabetes: A Randomized Control Study

INTRODUCTION

Frail older people with diabetes often present with or develop walking impairments, in part due to lower-limb sensory-motor neuropathy. Several studies suggest a possible improvement of balance control using somatosensory stimulation. We undertook a novel randomized control trial, the aim of which was to observe whether use of this device for 1 month improves walking speed as measured in the 10-m fast walking speed test standardized to body size at month 1 (M1) (FWS). Secondary outcomes were the differences between intervention (VS) and control (C) in the 10-m normal walking speed test, step length, short physical performance battery, timed up and go test, and posturographic measures.

METHODS

Subjects were aged ≥ 70 years and had had type 2 diabetes for at least 2 years. The intervention (VS) at home consisted of 22-min daily vibrating sequences with noise intensity set at 90% of the tactile threshold for each foot. The same device was used in group C but noise was set to 0. Compliance was retrieved from the device.

RESULTS

Among 56 subjects, 27 were in the VS group and 29 in the C group; 35 subjects were frail, 15 were prefrail ,and 6 were non-frail. Bilateral neuropathy was present in 17 subjects. More than half of sessions were done in 36 subjects with no discernible difference according to intervention. At M1 there were no discernible differences in FWS between the groups [VS: 0.96 (0.53) cm s-1 cm-1, C: 0.94 (0.47) cm s-1 cm-1]. There were also no discernible differences in other outcomes, irrespective of the presence of bilateral neuropathy.

CONCLUSION

In a cohort of frail, prefrail, or non-frail older subjects with diabetes, a 1-month intervention using a vibrating insole device did not alter measures of walking speed and related measures. Larger studies with longer term and different stimulation protocols are required to test this hypothesis more fully.

Applying Supra- or Sub-Threshold Plantar Vibrations Increases the Toe Clearance While Stepping over an Obstacle

This study aimed to investigate the effect of plantar vibrations on obstacle negotiation. Nineteen healthy young adults were randomly instructed to step over an obstacle without, with sub-, or with supra-threshold vibration via three vibrotactile tactors. The spatial-temporal gait parameters, the lower extremity joint angles, the foot integrated pressure, and the foot integrated area were recorded. Results indicated that sub-threshold and supra-threshold vibration increased the toe clearance of both leading leg and trailing legs. Additionally, the vibrations also increased the foot integrate pressure and the hip angels during toe clearance on both sides. These findings were devoted to the further understanding of the processes underlying motor control when plantar sensation was manipulated. These observations could further be used for developing a rehabilitation protocol for patients who suffered the loss or deterioration of the somatosensory system.

Immediate effects of footwear with vibration applied to the swing phase of the gait cycle on dynamic balance in patients with diabetic peripheral neuropathy

Sensory and sub-sensory foot vibration have beneficial effects on the static and dynamic balance of patients with diabetic peripheral neuropathy (DPN). Previous foot vibration during walking was applied at sub-sensory threshold in both stance and swing phases of the gait cycle in DPN. This study aimed to investigate the effects of footwear with vibration above the sensory threshold applied to the swing phase of the gait cycle on the dynamic balance of DPN. Fifteen patients with DPN and 10 matched healthy control participants were enrolled in this study. Dynamic balance assessment was investigated by the sit to stand and turn tests while electromyography activity (root mean square, RMS) of the vastus lateralis (VL), tibialis anterior (TA), and peroneus longus (PL) muscles were recorded at baseline, after 10 min of wearing the vibratory sandal without vibration, and after 10 min of wearing the sandal with vibration. Repeated measure analysis of variance was conducted for data analysis. Wearing the vibratory sandal slightly increased the speed of weight transfer in both groups and COP sway in DPN (P > 0.05), and close to significant decrease of turn sway (P = 0.07) in both groups. There were significant differences of the PL RMS in turn test (P = 0.03) in DPN and peak RMS of the PL after 10 min of wearing the sandal with vibration in both groups (P < 0.05). The results of the present study demonstrated that PL activity was significantly influenced by the vibratory sandal as its tendon passing across the sole and in direct contact with the source of the vibration.