Whole-body vibration (WBV) has gained prominence in the rehabilitation of individuals with chronic obstructive pulmonary disease (COPD) because it is a safe and low intensity exercise that promises beneficial effects on physical performance and quality of life. However, its effects on plasma cytokine levels in COPD are still unclear. The aim of the current study was to investigate the acute effects of WBV on inflammatory biomarkers in people with COPD. Twenty-six participants, COPD people (n=13) and healthy controls (n=13), were included. Both groups performed WBV at amplitude of 2 mm and frequency of vibration of 35 Hz, during six series of 30 seconds. They were assessed for lung function, body composition, 6-minute walking test (6MWT), handgrip strength test, plasma concentrations of interleukin (IL), IL-6, IL-8, and IL-10, and soluble tumor necrosis factor alpha (TNF-
Chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by chronic airflow obstruction associated with an inflammatory lung response to particles and/or toxics gases [
Pulmonary inflammation markers released into the circulation are known as important factors explaining high cytokine levels in blood, characterizing a low-grade systemic inflammation [
In this context, treatments for COPD should aim to decrease the low-grade systemic inflammation. Although previous studies have acknowledged that physical exercise may be effective on systemic inflammation related to COPD, which specific types of exercise, duration, and intensity have greater benefic effect sizes is still unclear [
According to Brown et al. [
Whole-body vibration (WBV) emerges as an interesting physical exercise modality for patients with COPD because it is frequently classified as a mild stimulus demanding less muscle and cardiorespiratory effort than other modalities. Previous studies found benefic effects of WBV on muscle strength, physical performance, and quality of life for patients with COPD [
This was a pilot study including a convenience sample of 26 participants, thirteen participants with COPD and thirteen healthy controls, both sexes, recruited from the local community of Diamantina, in Brazil. To be included in the study, participants had to meet the following criteria: aged 45-80 years; no history of physical exercise in the last 3 months; no flare-up in the last 4 weeks; postmenopausal period for females; body mass index (BMI) < 30 kg/m2; no current usage of systemic corticosteroids; no severe comorbidities or self-reported contraindications for WBV (e.g., deep vein thrombosis, metal implants, pacemaker, epilepsy, tumors, arterial aneurysm, and arrhythmia). All participants were paired for sex, age, and BMI.
This study followed the Declaration of Helsinki [
Pulmonary function of all participants was assessed using spirometry, following the American Thoracic Society (ATS) and the European Respiratory Society (ERS) [
Body composition (i.e., weight, lean mass, fat mass, fat percentage, and bone mineral density) was assessed by dual-energy X-ray absorptiometry (DXA, GE Lunar, Madison, Wisconsin, USA). BMI was calculated dividing the body mass by the square of the body height [
The history of smoking was assessed for smokers and former smokers using a self-report questionnaire. Number of pack-years was assessed, calculated as the number of smoked cigarettes per day/20, and multiplied by the number of years of smoking [
The exercise capacity was assessed using the six-minute walking test (i.e., 6MWT). The 6MWT was performed according to the guidelines of the ERS/ATS [
The peripheral muscle strength was assessed using a hand dynamometer (SH5001, Saehan, Korea). Peak handgrip strength (KgF) was measured at the dominant side, with the elbow in a 90° flexion and the forearm and wrist in neutral position [
Blood samples were collected at rest and immediately after the intervention. The plasma cytokine levels (i.e., IL-6, IL-8, and IL-10) were measured using the cytometric bead arrays kit (BD Bioscience, San Jose, CA, USA), according to the manufacturer’s protocol. Samples were acquired in a FACSCanto flow cytometer (BD Biosciences, San Jose, CA, USA) and analyzed using the FCAP array v1.0.1 software (Soft Flow Inc.). The detection limits were 1.6 pg/mL for IL-6, 1.2 pg/mL for IL-8, and 2.8 pg/mL for IL-10. Plasma soluble TNF-
WBV was performed using a synchronous vibratory platform that produces vertical sinusoidal vibrations (
During the protocol, the oxygen consumption (VO2) was continuously monitored through open circuit spirometry by the K4b2 gas analyzer (COSMED), as well as heart rate (Polar FT7) and oxygen saturation (Nonin Onyx 9500). All participants had a preliminary session to familiarize with the vibrating platform and materials, avoiding any possible effect of anxiety, placebo, or attention control on physiological variables. This preliminary session was performed 24 hours before the intervention.
Data were analyzed using the Graph-Pad Prism, version 5.0 (Inc., USA). Normality was tested using the Shapiro-Wilk test. Categorical variables were presented as absolute frequency, and these variables were compared using the chi-square test. Continuous variables were presented as means ± standard errors (SE), and these variables were compared using the independent
Characteristics of healthy and COPD participants are presented in Table
Characteristics of participants (n=26).
Characteristics | Healthy controls | COPD participants | P-value |
---|---|---|---|
Sex (M/F) | 9 /4 | 9 / 4 | 1.00§ |
Age (y) | 63.4 ± 6.9 | 65.2 ± 7.6 | 0.52¥ |
BMI (kg/m2) | 24.3 ± 2.6 | 22.6 ± 3.4 | 0.17¥ |
% Fat | 28.9 ± 7.9 | 27.0 ± 7.8 | 0.53¥ |
Lean body mass (Kg) | 41.7 ± 8.3 | 39.2 ± 8.4 | 0.44¥ |
Fat body mass (Kg) | 16.9 ± 4.8 | 14.5 ± 4.3 | 0.19¥ |
Bone mass (g/cm2) | 1.1 ± 0.1 | 1.0 ± 0.1 | 0.23£ |
FEV1 (l) | 2.6 ± 0.3 | 1.5 ± 0.6 | |
FVC (l) | 3.4 ± 0.5 | 2.1 ± 0.8 | |
| 99.6 ± 12.5 | 58.1 ± 19.2 | |
FEV1/FVC (%) | 76.9 ± 3.5 | 57.6 ± 9.1 | |
6MWT (m) | 574.3 ± 18.8 | 445.7 ± 25.6 | |
Handgrip strength# (KgF) | 34.3 ± 2.4 | 34.8 ± 2.9 | 0.9 |
Pack-years (n) | 12.5 ± 4.2 | 35.9 ± 6.3 | |
Means ±SD. §Chi square test; ¥unpaired
About inhaled medication, 8 participants with COPD used bronchodilators and corticosteroids only. Although there are no significant differences in handgrip strength between groups, a moderate and significant inverse correlation was found between handgrip strength and IL-8 concentration (r= -0.43, p= 0.04) for participants with COPD.
Regarding the intensity of WBV, there was no difference in the oxygen consumption (p = 0.66, df = 22), with mean values of 6.5 (2.2) and 6.2 (1.1) ml.kg−1.min−1, between healthy and COPD participants, respectively. Thus, for both groups, the exercise was classified as “very light” intensity (<2 METS) according to the American College of Sports Medicine guidelines) [
Plasma levels of IL-6, IL-10, IL-8, and soluble TNF-
After WBV, participants with COPD showed higher levels of IL-10 (p = 0.003, d = 0.94, power = 0.87, df = 24) compared with at rest, however, reaching values similar to values of healthy controls at rest (p = 0.89). In the COPD group, levels of IL-6, IL-8, sTNFR1, and sTNFR2 did not change after WBV [IL-6 (p = 0.08, df = 12); IL-8 (p = 0.25, df = 12); sTNFR-1 (p = 0.38, df = 12); and sTNFR-2 (p = 0.37, df = 12)]. Furthermore, after WBV, controls did not show significant differences in all analyzed markers (p> 0.05).
The present study shows that stable COPD participants compared with healthy controls have different inflammatory rest state, with higher circulating levels of IL-8 and lower levels of IL-10. Furthermore, this study reported for the first time that WBV increases circulating levels of IL-10 in participants with COPD.
Systemic inflammation is considered a relevant characteristic and an important etiological factor of extrapulmonary manifestations in COPD [
In line with our results, previous studies have demonstrated that levels of IL-8 are increased in people with COPD [
Few studies have investigated the role of IL-10 in the systemic inflammation of people with COPD. Similar to our results, recent studies have demonstrated that COPD people show reduced plasma levels [
Although no between-group differences were found for sTNFRs and IL-6, previous studies found changes on these markers in people with COPD [
Physical exercise is the basis of the pulmonary rehabilitation of people with COPD. Although benefits are reported for the cardiovascular and muscular systems, exercise also stimulates proinflammatory cytokines, such as TNF-
Studies investigating the acute effect of WBV in healthy people are scarce. Hazell
Several studies have investigated the response of cytokines to exercise in COPD people, but results are diverse. The main finding of Rabinovich
As revised by Brown
It has been showed that the strenuous exercise (marathon race) induces an increase in the proinflammatory cytokines TNF
Mechanisms by which WBV change IL-10 concentrations are still not well established; however, evidence indicates that glucocorticoids and catecholamines would be involved. These hormones stimulate the production of anti-inflammatory cytokines, such as IL-10 and IL-4 [
In the current literature, there is no consensus on the acute exercise-induced cytokine response. However, this is not very surprising because several factors are known to influence the acute response of exercise-induced cytokines, including body mass composition, age, and sex. The type, level, and time of exercise seem to influence outcomes [
Our data demonstrated (data not shown) that the WBV was performed at an intensity corresponding to about 50.9 to 53.5% of predicted heart rate (HR) max for age (220-years) in the healthy control group and 49.0 to 56.9% of the HR max in the COPD group. Thus, the exercise performed on the vibratory platform was characterized as “very light” (<2 METS) and may explain the absence of changes on these inflammatory parameters. Thus, the difference between our results and the actual literature could be partly explained by the low intensity of the exercise used in our protocol. This, in fact, is an interesting finding whereas although there was cardiorespiratory overload, the acute WBV session did not lead to an additional proinflammatory condition.
It is known that the adaptations of the various physiological systems to training result from the sum of the changes promoted by each individual exercise session. Thus, in the context of the possible benefits of vibration stimulus on inflammation parameters in COPD, it is crucial to discriminate acute and chronic vibration exercise responses [
The present study has some limitations that must be considered. The results cannot be extrapolated to other populations, since we do not know to what extent different diseases may interfere with the observed responses. The nonrandomized sample does not allow us to rule out the influence of selection bias and potential confounders. In order to avoid sample bias and study selection, groups were paired. In addition, future studies with greater samples evaluating additional inflammatory markers may allow a better understanding of WBV mechanisms in subjects with COPD.
Our data demonstrated that an acute session of WBV in people with COPD does not change levels of proinflammatory markers but was able to increase IL-10, an important anti-inflammatory marker. This trend needs to be addressed in further studies with greater samples. In addition, a better understanding of the acute effect of WBV on variables related to COPD will allow the elaboration of more effective training protocols and, consequently, this method may be an additional tool to complete rehabilitation programs.
The data described in this article will be made available at any time when requested.
The authors declare that they have no conflicts of interest.
The authors thank Centro Integrado de Pós-Graduação e Pesquisa em Saúde at the Universidade Federal dos Vales do Jequitinhonha e Mucuri and Centro Especializado em Reabilitação (CER), Diamantina, Minas Gerais, Brazil, for providing equipment and technical support for experiments. This study was supported by the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), CDS-APQ-02032-14, Brazil, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes), Brazil.