Journal list menu
Effect of whole body vibration on clinical and metabolic outcomes in adults with type 2 diabetes: an observational pilot trial
Abstract
The objective of this trial was to evaluate the effect of 28Hz whole body vibration on glycaemic control and other metabolic parameters in adults with type 2 diabetes (T2D).
Twenty-four adults with T2D on oral antidiabetic agents, with a baseline glycated haemoglobin (HbA1c) 6.5–9.0% (48–75mmol/mol), were randomised into two groups. The control group (CG) was advised to adopt lifestyle modifications, and the intervention group (IG) received the same orientations plus a vibrating platform for daily use for 12 weeks.
Data from 22 patients were analysed (one from each group was excluded). Baseline characteristics of both groups were similar except for triglycerides, which were higher in the CG (111.8±39.9 vs 188.9±68.8mg/dL [1.26±0.45 vs 2.13±0.78mmol/L], p<0.05). After 12 weeks, there was a significant reduction in HbA1c in the IG (7.69±0.49 vs 7.17±0.77% [60.5±5.39 vs 54.9±8.74mmol/mol], p<0.05), not observed in the CG (8.05±0.98 vs 7.92±1.07% [64.5±10.78 vs 63.1±11.77mmol/mol], p=0.52). A non-significant trend for weight loss in IG was observed (78.14±10.47 vs 77.14±11.08kg, p=0.06). There were no significant differences between the groups regarding fasting blood glucose or any other clinical and biochemical variables analysed.
Daily use of the vibrating platform for 12 weeks resulted in improved HbA1c in adults with T2D. Further studies are needed to better define the role of whole body vibration as an adjuvant in T2D treatment. Copyright © 2021 John Wiley & Sons.
Introduction
Type 2 diabetes mellitus (T2D) is characterised by excess plasma glucose associated with the inability to produce and/or use insulin correctly, resulting in the difficulty of glucose access to target cells, especially muscle tissue.1, 2 This hyperglycaemia, together with the other alterations associated with insulin resistance, eventually cause several complications, both microvascular and macrovascular.1, 3-5
T2D treatment includes several strategies to achieve metabolic improvement and resultant reductions in complications associated with the disease.1 One pillar in the management of people with T2D is physical activity6 which, when performed regularly, is associated with increased insulin sensitivity, optimised mitochondrial function and enzyme oxidation, and improved cardiovascular benefit through blood vessel complacency and reactivity.7
However, as studies increasingly reinforce the importance of exercise for global health, there has been a concomitant reduction in these activities in recent years.2, 8 The introduction of new technologies into daily life, as well as lack of time and motivational barriers have mediated this effect. In addition, these patients often have functional limitations.9, 10
Alternative methods to conventional exercise have recently been studied to obtain positive metabolic effects in T2D. One such method is whole body vibration training.9-11 During muscle stimulation with body vibration, it is suggested an activation of muscle receptors and spindles occur that would enable metabolic improvement similar to physical activity, called ‘tonic vibration reaction’ with insulin-like effect.9 The use of a vibration platform would act in almost 100% of the musculature, while other exercise methods prioritise around 40–60%. The equipment is simple and can be used by frail individuals without prior physical training, who constitute a significant percentage of patients with T2D. An additional benefit is reduced execution time compared to other activities.9 Thus, several studies have demonstrated the role of body vibration as a non-pharmacological treatment alternative for these patients.9, 11, 12
In this context, the aim of the present study was to evaluate the effect of 28Hz whole body mechanical vibration on glycaemic control and other metabolic parameters in adult patients with T2D.
Subjects
A randomised, unblinded pilot clinical trial was performed. Since this was the first clinical trial to test this particular device, a sample of 12 patients per group was included, as described by Julious.13 Twenty-four subjects were consecutively included, of both sexes, aged between 40–70 years old who were diagnosed with diabetes according to the American Diabetes Association (ADA) criteria14 with outpatient follow-up at the Endocrinology and Metabolism Service of the Hospital Universitário Polydoro Ernani de São Thiago from the Universidade Federal de Santa Catarina (HU-UFSC). All patients were using oral antidiabetic agents only and there was no treatment modification for at least three months, with a basal glycated haemoglobin (HbA1c) between 6.5–9.0% (48–75mmol/mol).
Exclusion criteria were: use of insulin, weight over 150kg, altered balance in bipedal posture, arrhythmia, pregnancy, epilepsy, migraine, cancer, surgery less than six months ago, thrombosis, injury to the lower limbs, another disease or condition that contraindicates physical exercise. People with a history of nephrolithiasis or cholelithiasis were also excluded due to the potential risk of stone dislocation.15
The subjects were randomly divided into two groups: control group (CG; n=12) and intervention group (IG; n=12). Both groups underwent medical follow-up according to the standard HU-UFSC care protocol for patients with T2D, and the IG received the vibrating platform (28Hz) provided by the company SmartKopf do Brasil Ind. e Com. Ltda. and guidance on its use.
The study protocol complied with the ethical principles of the Declaration of Helsinki and was approved by the Ethics and Research Committee of the Universidade Federal de Santa Catarina (document No. 2.054.582). All subjects signed the Informed Consent Form.
Methods
All patients were evaluated by a member of the data collection team, formed by four physicians from the Endocrinology and Metabolism Service of HU-UFSC. Medical history and physical examination were performed on the first visit, and peripheral blood samples were collected after 12 hours of fasting to assess blood glucose, HbA1c, total cholesterol, HDL cholesterol, triglycerides, and creatinine. All subjects received guidance on diet and physical activity according to ADA recommendations.7 In addition, subjects allocated to the IG received a SmartWalk vibrating platform unit (Figure 1), with a fixed frequency of 28Hz, maximum intensity of 0.6g, capable of supporting up to 150kg and produced in accordance with ISO 2631 – the present international standard for human response to whole body vibration, which outlines methods for the measurement, evaluation and assessment of human exposure to multiple mechanical shocks.16 The equipment was made available to each IG subject by the company SmartKopf do Brasil Ind. e Com. Ltda. Subjects were instructed to stay on the platform in the biped position for a period of 20 to 30 minutes daily, with knee flexion at 30o (Figure 2), in order to minimise the vibratory effects to the head according to the described protocol.17
At the end of 12 weeks, all subjects underwent clinical and laboratory re-evaluation. All dosages were performed at the HU-UFSC clinical analysis laboratory. HbA1c was measured by the NGSP (National Glycohemoglobin Standardisation Program-USA) certified high performance liquid chromatography method. Glucose, total cholesterol, HDL and triglycerides were measured by the colorimetric enzymatic method and creatinine by the modified Jaffe's kinetic method.
The diagnoses of hypertension, dyslipidaemia and obesity were established according to current guidelines.18-20 LDL cholesterol was calculated by Martin's formula.21 Glomerular filtration rate was estimated by the CKD-EPI formula.22
Statistical analysis
To assess the normality of data distribution, the Shapiro-Wilk test was applied to the study variables. For those with normal distribution, Student's t-test was performed, and for those without normal distribution, the Mann-Whitney U test was applied.
For paired comparisons, Student's t-test for paired samples was applied to variables with normal distribution and Wilcoxon's t-test to non-normality cases.
For categorical variable evaluation, we applied the Chi-square test. When the assumptions of this test were broken, Fisher's exact test was used.
Results are presented as mean ± standard deviation for continuous variables, and as absolute numbers and percentages for categorical variables.
Analyses were performed by Statistica statistical software, Ultimate Academic version (TIBCO Software Inc., Palo Alto, CA, USA), with significance level α=0.05 and 95% confidence interval.
Results
Of the 24 subjects included in the study, two subjects were excluded: one from the CG due to loss of follow-up and one from IG due to therapeutic modification during the study period (Figure 3). Thus, data from 22 subjects (11 from each group) were analysed. All characteristics of the series are shown in Table 1.
| Variables | Total (n=22) | Control group (n=11) | Intervention group (n=11) | P-value* |
|---|---|---|---|---|
| Female gender | 15 (68.2%) | 8 (72.7%) | 7 (63.6%) | 0.99 |
| Diabetes time (years) | 11.32 (±6.24) | 11.36 (±4.92) | 11.27 (±7.59) | 0.97 |
| Hypertension | 17 (77.3%) | 10 (90.9%) | 7 (63.6%) | 0.31 |
| Dyslipidaemia | 20 (90.9%) | 11 (100%) | 9 (81.8%) | 0.47 |
| Obesity | 9 (40.9%) | 4 (36.4%) | 5 (45.5%) | 0.99 |
| Age (years) | 59.18 (±6.40) | 58.91 (±5.95) | 59.45 (±7.10) | 0.85 |
| 1 OAD | 2 (9.1%) | 1 (9.1%) | 1 (9.1%) | – |
| 2 OADs | 10 (45.5%) | 7 (63.6%) | 3 (27.3%) | – |
| >2 OADs | 10 (45.5%) | 3 (27.3%) | 7 (63.6%) | – |
- * Comparison between control group and intervention group. OAD: oral antidiabetic agent
There was a predominance of females in both groups, including seven women in the IG (63.6%) and eight women in the CG (72.7%). The mean age was 59 years, with no significant difference between the groups. Regarding the time of diagnosis of T2D, the mean was 11.32±6.24 years, with no difference between the groups. There were also no differences regarding diagnoses of hypertension, dyslipidaemia, and obesity.
Baseline HbA1c values in the IG and the CG were similar (7.69±0.49 vs 8.05±0.98% [60.5±5.39 vs 64.5±10.78mmol/mol], p=0.36), as well as fasting blood glucose (146.80±19.85 vs 166.55±45.06mg/dL, p=0.21) and all other variables analysed, except for triglycerides, which were higher in the CG (111.82±39.90 vs 188.91±68.76mg/dL [1.26±0.45 vs 2.13±0.78 mmol/L], p<0.05).
Results analysis after 12 weeks showed a statistically significant reduction in HbA1c after vibration platform use compared to baseline in the IG, with a mean at baseline of 7.69±0.49% (60.5±5.39mmol/mol) and at the end of 12 weeks of 7.17±0.77% (54.9±8.74mmol/mol) (p<0.05), not observed in the CG (8.05±0.98 vs 7.92±1.07% [64.5±10.78 vs 63.1±11.77mmol/mol], p=0.52). None of the groups showed significant change in fasting blood glucose (IG: 146.80±19.85 vs 157.10±28.15mg/dL, p=0.22; and CG: 166.55±45.06 vs 172.36±55.99mg/dL, p=0.70). Comparison of the results of all variables is shown in Table 2.
| Variables | Control group | Intervention group | ||||
|---|---|---|---|---|---|---|
| Pre | Post | P-value | Pre | Post | P-value | |
| Weight (kg) | 73.50±9.11 | 73.77±7.73 | 0.69 | 78.14±10.47 | 77.14±11.08 | 0.06 |
| Weight variation (%) | – | +0.51±2.74 | – | -1.35±1.75 | 0.06 | |
| Abdominal circumference (cm) | 98.14±6.51 | 98.42±7.13 | 0.80 | 101.62±11.04 | 100.37±9.88 | 0.32 |
| BMI (kg/m2) | 28.56±2.29 | 28.76±1.57 | 0.47 | 31.05±4.96 | 30.61 ±5.08 | 0.10 |
| Systolic blood pressure (mmHg) | 138.27±7.26 | 138.18±16.62 | 0.98 | 132.73±14.20 | 130.91±15.78 | 0.71 |
| Diastolic blood pressure (mmHg) | 81.20±5.77 | 81.00±11.00 | 0.99 | 81.82±7.50 | 78.18±8.73 | 0.23 |
| Fasting blood glucose (mg/dL) | 166.55±45.06 | 172.36±55.99 | 0.70 | 146.80±19.85 | 157.10±28.15 | 0.22 |
| HbA1c (%) | 8.05±0.98 | 7.92±1.07 | 0.52 | 7.69±0.49 | 7.17±0.77 | 0.01 |
| eGFR (ml/min/1.73m2) | 78.08±20.32 | 82.13±24.58 | 0.27 | 85.44 ±15.11 | 82.78 ±18.14 | 0.41 |
| Total cholesterol (mg/dL) | 197.09±47.31 | 180.64±52.27 | 0.16 | 161.09±42.91 | 159.91±39.19 | 0.88 |
| HDL cholesterol (mg/dL) | 45.50±12.44 | 47.10±13.26 | 0.44 | 51.18±39.19 | 49.55±11.57 | 0.57 |
| Triglycerides (mg/dL) | 188.91±68.76 | 214.55±149.62 | 0.50 | 111.82±39.90 | 131.91±59.13 | 0.24 |
| LDL cholesterol (mg/dL) | 118.56±41.33 | 104.22±33.92 | 0.23 | 88.73±32.78 | 87.09±27.26 | 0.78 |
- eGFR = estimated glomerular filtration rate; HDL = high density lipoprotein; LDL = low density lipoprotein.
A trend towards weight loss was observed in the IG, with an average weight loss of 1.35±1.75% in the IG and a gain of 0.51±2.74% in the CG, without reaching statistical significance (p=0.06). There was no significant change in waist circumference in either group. There was also no change in blood pressure, lipid profile, estimated glomerular filtration rate or any other variables that were analysed.
Discussion
This study evaluated the response of glycaemic control and other metabolic parameters of people with T2D using oral antidiabetic agents and daily use of a 28Hz vibration platform for 20 to 30 minutes for 12 weeks. Subjects undergoing the intervention showed a statistically significant reduction in HbA1c when compared to patients who did not use it. No changes were identified in other analysed metabolic and anthropometric parameters.
In our series, there was a 0.52% reduction in HbA1c with the use of the platform in just three months of follow-up, an effect comparable to that of aerobic or resistance exercise training6 and to some oral antidiabetic drugs.23 Importantly, the group of patients who participated in this study was relatively well controlled (mean baseline HbA1c of 7.69%). A greater magnitude of effect on HbA1c would be expected in a group of patients with higher baseline levels.
The significant improvement in HbA1c in the group that used the vibrating platform is in line with other studies,10, 17 but not all, perhaps due to different sample populations, follow-up time, device usage protocol and platform-specific characteristics.1, 9 Del Pozo-Cruz et al.17 reported a reduction of 0.55% in HbA1c after a 12-week whole body vibration based programme on a side-alternating vibration device when compared to the control group. The frequency was 12Hz for the first month, 14Hz for the second month and 16Hz for the last month. Unlike our study, participants were asked to perform eight different exercises while standing on the platform, which increases complexity and therefore may affect applicability in clinical practice. Using a similar protocol which consisted of eight different exercises performed against a swinging platform during 12 weeks, Baum et al.10 found a small non-significant reduction in HbA1c, despite a significant decrease in fasting blood glucose. The frequency was 30Hz from weeks one to nine and up to 35Hz during the last three weeks. Behboudi et al.9 did not find any significant reduction in HbA1c after an eight-week intervention, three sessions per week with a 30Hz vibration platform.
Several studies have investigated how vibration therapy could affect T2D, but the mechanisms are still uncertain.3, 24-27 The proposed mechanisms of action, summarised in Table 3, include increased glucose uptake by activating muscle contraction,1, 10, 26 attenuation of hepatic oxidative stress,24, 28 reduced adipose tissue inflammation, changes in the digestive tract microbiome24, 25 and osteoblasts stimulation with increased osteocalcin secretion, which also reduces inflammatory response and increases insulin sensitivity.27-31
| Reference | Proposed mechanism of action |
|---|---|
| Zaidell et al., 201326 | This study offers experimental evidence that supports the ‘tonic vibration reflex’ (TRV) as one of the mechanisms underlying the neuromuscular response to whole body vibration. TRV is a reflex muscular contraction that occurs during direct vibratory musculo-tendinous stimulation which can acutely increase muscle activation, lead to post-activation potentiation, and improve muscular performance |
| Yin et al., 20152 | A mouse model of type 2 diabetes (db/db) was used to investigate the anti-inflammatory and cytoprotective properties of whole body vibration. Besides improvement in HbA1c, pro-inflammatory changes were significantly reduced, as indicated by reduced IL-17 but increased Foxp3 expression. Whole body vibration also reduced gammaH2AX, which is suggestive of cytoprotective effect |
| Liu et al., 201624 | db/db mice were exposed to whole body vibration for 12 weeks, resulting in attenuation of hepatic oxidative stress level through increasing GSH content and the expression of GSH-Px. With the reduction of oxidative stress, the expression of SREBP1c was decreased and hepatic lipogenesis suppressed with improvement in liver steatosis and insulin resistance |
|
McGee-Lawrence et al., 201728 |
db/db mice were exposed to whole body vibration for 3 months, which reduced body weight, normalised muscle fibre diameter, attenuated adipocyte hypertrophy in visceral adipose tissue, reduced hepatic lipid content and increased circulating levels of osteocalcin. Osteocalcin can reduce the inflammatory response and increase insulin sensitivity,27, 29 and subjects with type 2 diabetes are known to have lower osteocalcin levels30, 31 |
| Yu et al., 201925 | Insulin resistance is associated with chronic inflammation, with macrophage infiltration in adipose tissue, which can be classified into functional subtypes M1 and M2: the former being characterised by the production of high levels of pro-inflammatory cytokines and the latter with anti-inflammatory properties. In patients with diabetes, there is a predominance of the M1 population, in addition to changes in the intestinal microbiota that also lead to an increase in the serum concentration of pro-inflammatory molecules. This study has shown that whole body vibration can cause macrophage polarisation from M1 towards M2, decreasing pro-inflammatory cytokines and increasing anti-inflammatory cytokines, while modifying the fecal microbiome in mice with type 2 diabetes |
Despite the difference in basal triglyceride levels between groups, no difference was observed after the end of the study. In the remaining lipid profile, no significant change was seen either. Del Pozo-Cruz et al.17 evaluated the effect of whole body vibration on serum lipids and showed a reduction in total cholesterol and triglycerides, but not in HDL and LDL cholesterol.
Although new drugs and therapeutic approaches have emerged, a high proportion of people with T2D have an HbA1c above the proposed individualised goals.4 A study conducted in Brazil estimated that the average annual cost of a T2D patient is US$1012, of which the largest amount is due to medication costs: around US$422/year.32 The vibration platform used in this study has an average cost of US$190 per unit. In addition, a cost-effectiveness analysis of the use of the vibration platform in patients with T2D for 12 weeks found it to be cost-effective for use in the primary care setting.12
Whole body vibration is a novel, simple, safe and relatively low-cost potential non-pharmacological measure which can be an attractive alternative to conventional physical exercise for some patients with T2D. Besides the reduced usage time, it does not require prior training or supervision and can be performed by the majority of the population with T2D, from diagnosis to the later stage of the disease when mobility may be restricted, facilitating adherence by these patients.1, 9, 10 Our study was the first to test the use of this particular device, with a protocol that can be easily followed in the patient's home.
As study limitations, we highlight the small number of participants and the short follow-up time. Furthermore, the use of the platform was not supervised and the assessment of adherence was based on patients’ reports. We also emphasise that the study was not blinded or placebo controlled. Thus, we cannot exclude that the observed effect, at least in part, is due to a greater adherence to other therapeutic measures by the intervention group, when feeling stimulated with the use of a new equipment.
In conclusion, daily use of the 28Hz vibration platform by patients with T2D for 12 weeks resulted in improved HbA1c, suggesting a possible beneficial effect on glycaemic control, without modification of other metabolic parameters. Further studies are needed with more patients and longer follow-up to assess the role of whole body vibration as an adjuvant in T2D treatment.
Acknowledgements and declaration of interests
We would like to thank everyone involved in this work, the HU-UFSC and especially the patients.
The vibrating platforms were provided by SmartKopf do Brasil Ind. e Com. Ltda. The sponsor had no involvement in study design, in the collection, analysis and interpretation of data, in the writing of the report and in the decision to submit the article for publication.
Key points
- Although physical exercise is an important strategy for the management of type 2 diabetes, patient compliance is generally low
- In this study, the daily use of a vibrating platform for 12 weeks led to an improvement in HbA1c in subjects with type 2 diabetes
- Whole body vibration is a simple, safe and relatively low cost potential non-pharmacological measure that could become a useful adjunct to other treatment modalities for type 2 diabetes
