Inflammatory and oxidative biomarkers as determinants of functional capacity in patients with COPD assessed by 6-min walk test-derived outcomes.

INTRODUCTION: Reduction in functional capacity is a negative clinical outcome of chronic obstructive pulmonary disease (COPD). Studies have shown association between inflammatory and oxidative stress biomarkers and functional capacity. However, it is unclear whether these biomarkers are associated with outcomes of functional capacity. Therefore, the aim of this study was to evaluate whether plasma biomarkers of inflammation and oxidative stress are predictors of the 6-min walking test (6MWT)-derived outcomes. METHODS: Twenty COPD patients were assessed on three consecutive days with different clinical measures, including functional capacity, and blood sampling. Plasma concentrations of IL-6, IL-8, TNF-ɑ, IL-10 and soluble TNF-ɑ receptors (sTNFR1 and sTNFR2) were determined by immunoassays. Oxidative stress was evaluated by determining lipid peroxidation products based on the enzymatic activity of superoxide dismutase (SOD) and catalase, and total antioxidant capacity of plasma. Functional capacity was assessed considering the six-minute walking distance (6MWD) and the estimate of six-minute walking work (6MWW). The association between biomarkers (i.e. inflammation and oxidative stress) and functional exercise capacity was investigated through the Pearson's correlation coefficient. To identify the determinants of the 6MWT, multiple linear stepwise regression analyses were performed with adjustment for age, sex and GOLD classification. RESULTS: Patients were predominantly male (65%), with mean age of 64 years and moderate airflow obstruction and impaired functional capacity. There were positive correlations between SOD activity and 6MWD (r = 0.520; p = 0.02) and 6MWW (r = 0.554; p = 0.01), as well as a negative correlation between sTNF-R1 and 6MWD (r = -0.437; p = 0.05). SOD was an independent determinant of the functional capacity, explaining 23% of the variability of 6MWD (p = 0.019) and 27% of the variability of 6MWW (p = 0.011). sTNF-R1 levels were associated with 6MWD and, together with SOD explained 40% of variability in 6MWD (p = 0.005). CONCLUSION: SOD activity was an independent determinant of performance in the 6MWT, and together with sTNFR1 explained 40% of the variations in walking distance in COPD patients. SOD activity and sTNFR1 levels might be seen as potential biomarkers of the functional capacity in patients with COPD.

Cardiorespiratory responses in different types of squats and frequencies of whole body vibration in patients with chronic obstructive pulmonary disease.

This study aims to investigate the cardiorespiratory responses to different vibration frequencies to characterize the intensity of exercise, as well as to compare the effect of two types of squatting exercises (static and dynamic) on the whole body vibration (WBV) exercise in individuals with chronic obstructive pulmonary disease (COPD). Twenty-six subjects were divided and paired into healthy and COPD groups that performed static squatting associated with WBV (frequencies: 30, 35, and 40 Hz; amplitude: 2 mm) and dynamic squatting associated with WBV (frequency: 35 Hz; amplitude 2 mm) on a vertical vibration platform. Oxygen consumption (V̇o2), heart rate (HR), minute ventilation (V̇e), ratio of minute ventilation to oxygen production (V̇e/V̇o2), ratio of minute ventilation to carbon dioxide production (V̇e/V̇co2), oxygen saturation (SpO2), and rating of perceived exertion were measured. For both groups, there was a decrease in V̇e/V̇o2 and V̇e/V̇co2 ratios during static and dynamic squats, as well as an increase in other cardiorespiratory parameters, and no significant difference existed between them. There was an effect of the type of squat on the HR variation; the values in the static squat were higher than those of the dynamic squat in both groups. There was a significant difference with a reduction in SpO2 at 40 Hz frequency when compared with 30 Hz in the COPD group. The other variables behaved similarly between the frequencies. The WBV exercise, regardless of the frequencies used, represented a mild effort that promoted cardiorespiratory response in COPD, with greater responses in the static squat and no adverse effect. NEW & NOTEWORTHY This study showed that an acute session of light exercise of whole body vibration (WBV) can increase the cardiorespiratory responses in patients with chronic obstructive pulmonary disease (COPD), reaching values similar to that of the control group. The results might contribute, therefore, to the elaboration of exercise protocols with WBV for the treatment of patients with COPD during rehabilitation. Thus, future studies referring to training on the vibratory platform could use these exercise parameters and demonstrate possible long-term benefits.

Correction: Cardiorespiratory and metabolic responses and reference equation validation to predict peak oxygen uptake for the incremental shuttle waking test in adolescent boys.

[This corrects the article DOI: 10.1371/journal.pone.0206867.].

Cardiorespiratory and metabolic responses and reference equation validation to predict peak oxygen uptake for the incremental shuttle waking test in adolescent boys.

BACKGROUND: Previous studies speculated that the Incremental Shuttle Walking Test (ISWT) is a maximal test in children and adolescents, however comparison between ISWT with cardiopulmonary exercise test has not yet performed. Furthermore, there is no regression equation available in the current literature to predict oxygen peak consumption (VO2 peak) in this population. This study aimed to assesses and correlate the cardiorespiratory responses of the ISWT with the cardiopulmonary exercise (CEPT) and to develop and validate a regression equation to predict VO2 peak in healthy sedentary adolescent boys. METHODS: Forty-one participants were included in the study. In the first stage, the VO2 peak, respiratory exchange ratio (R peak), heart rate max (HR max) and percentage of predicted HR max (% predicted HR max) were evaluated in CEPT and ISWT (n = 26). Second, an equation was developed (n = 29) to predict VO2 peak. In both phases, the VO2 peak, respiratory exchange ratio R and hearth rate (HR) were evaluated. In the third stage, the validation equation was performed by another 12 participants. RESULTS: Similar results in VO2 peak (P>0.05), R peak (P>0.05) and predicted maximum HR (P>0.05) were obtained between the ISWT and CEPT. Both tests showed moderate significant correlations of VO2 peak (r = 0.44, P = 0.002) e R peak (r = -0.53, P < 0.01), as well as the agreement of these measurements by Bland-Altman analysis (VO2 peak, bias = -0.13; R peak, bias = 0.0). Distance walked was the variable that explained 42.5% (R2 = 0.425, p = 0.0001) of the variance in VO2 peak. The equation was VO2 peak (predicted) = 20.94 + (0.02 x distance walked). The results obtained by the equation were not significantly different compared to the values obtained by the gas analyzer and the Bland-Altman analysis showed agreement (bias = 1.6). CONCLUSION: The ISWT produced maximal cardiorespiratory responses comparable to the CEPT, and the developed equation showed viability for the prediction of VO2 peak in healthy sedentary adolescent boys.

Acute Effects of Whole-Body Vibration on Inflammatory Markers in People with Chronic Obstructive Pulmonary Disease: A Pilot Study.

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-α) receptors (sTNFR-1 and sTNFR-2). People with COPD had moderate disease [forced expiratory volume in the first second (FEV1) = 58.1%], as well as a worse performance in the 6MWT. The plasma cytokine profile at rest showed that participants with COPD had higher levels of IL-8 and lower levels of IL-10. After one session of WBV, we found an increased plasma IL-10 level in the COPD group, with similar levels for healthy controls. One session of WBV modified the plasma IL-10 level. No effects were found on the other investigated cytokines.

Whole body vibration training increases physical measures and quality of life without altering inflammatory-oxidative biomarkers in patients with moderate COPD.

Whole body vibration training (WBVT) has been identified as an alternative intervention to improve exercise capacity and quality of life of patients with chronic obstructive pulmonary disease (COPD). However, the effect of WBVT on inflammatory-oxidative biomarkers remains unknown. The aim of this trial was to investigate the effects of WBVT on quality of life and physical and inflammatory-oxidative parameters in patients with COPD. Twenty patients were equally divided into 1) an intervention group (IG) that performed the WBVT, and 2) a control group (CG) that did not receive any intervention. Intervention consisted in performing static squatting on a vibrating platform, in six series of 30 s, 3 days/wk, for 12 wk. Patients were evaluated for plasma levels of IL-6, IL-8, IFN-γ, soluble receptors of TNF-α; white cell count; plasma levels of oxidant and antioxidant markers; 6-min walking distance (6MWD); peak oxygen uptake (V̇o2peak); handgrip strength; quality of life; timed 5-chair sit-to-stand (5STS); and timed get-up and go test (TUG). After WBVT, patients from IG showed a significant increase in the 6MWD, V̇o2peak, and handgrip strength ( P < 0.05). Furthermore, patients from the IG reached minimal clinically important difference regarding quality of life. No significant differences were found in 5STS, TUG, inflammatory-oxidative biomarkers, and white cell count in the IG. The CG did not show significant improvement in all assessments ( P > 0.05). Taken together, our results demonstrated that the WBVT induced clinically significant benefits regarding exercise capacity, muscle strength, and quality of life in patients with COPD that were not related to inflammatory-oxidative biomarker changes. NEW & NOTEWORTHY Whole body vibration training is a new option for nonpharmacological treatment of chronic obstructive pulmonary disease (COPD). This study showed the potential of this training to improve exercise capacity, quality of life, and muscle strength in patients with COPD. Furthermore, to our knowledge this was the first study showing that vibration exercise does not modify the plasma levels of inflammatory-oxidative biomarkers, suggesting that the beneficial effects on physical measures and quality of life are independent of changes in biomarkers.

Cardiorespiratory responses and prediction of peak oxygen uptake during the shuttle walking test in healthy sedentary adult men.

BACKGROUND: The application of the Shuttle Walking Test (SWT) to assess cardiorespiratory fitness and the intensity of this test in healthy participants has rarely been studied. This study aimed to assess and correlate the cardiorespiratory responses of the SWT with the cardiopulmonary exercise testing (CEPT) and to develop a regression equation for the prediction of peak oxygen uptake (VO2 peak) in healthy sedentary adult men. METHODS: In the first stage of this study, 12 participants underwent the SWT and the CEPT on a treadmill. In the second stage, 53 participants underwent the SWT twice. In both phases, the VO2 peak, respiratory exchange ratio (R), and heart rate (HR) were evaluated. RESULTS: Similar results in VO2 peak (P>0.05), R peak (P>0.05) and predicted maximum HR (P>0.05) were obtained between the SWT and CEPT. Both tests showed strong and significant correlations of VO2 peak (r = 0.704, P = 0.01) and R peak (r = 0.737, P<0.01), as well as the agreement of these measurements by Bland-Altman analysis. Body mass index and gait speed were the variables that explained 40.6% (R2 = 0.406, P = 0.001) of the variance in VO2 peak. The results obtained by the equation were compared with the values obtained by the gas analyzer and no significant difference between them (P>0.05) was found. CONCLUSIONS: The SWT produced maximal cardiorespiratory responses comparable to the CEPT, and the developed equation showed viability for the prediction of VO2 peak in healthy sedentary men.