ABC | Volume 112, Nº1, January 2019

Original Article Shekarforoush & Naghii Cardioprotection by whole-body vibration Arq Bras Cardiol. 2019; 112(1):32-37 Figure 1 – Infarct size (IS) and area at risk (AAR) following 30-min of ischemia and 120-min of reperfusion in rats. LV: left ventricle; * p < 0.05 and ** p < 0.01 compared with the control group. Cont: control; WBV1: whole body vibration training for one week; WBV3: whole body vibration training for 3 weeks. 0.6 0.4 0.2 0 Cont WBV1 Groups WBV3 Ratio (%) AAR (% LV) IS (% AAR) * ** Table1 – Hemodynamics parameters in the experimental groups Group Baseline Ischemia Reperfusion HR MBP HR MBP HR MBP Cont 346 ± 48 113 ± 21 349 ± 51 100 ± 15 * (0.04) 361 ± 44 107 ± 17 WBV1 373 ± 41 114 ± 7 385 ± 25 97 ± 8 ** (0.001) 383 ± 26 107 ± 13 WBV3 376 ± 26 107 ± 15 372 ± 18 91 ± 7 * (0.01) 378 ± 27 108 ± 15 p-value 0.282 0.670 0.130 0.267 0.399 0.996 Note: Data presented as mean ± SD (P-value). HR: heart rate; MBP: mean arterial blood pressure. Cont: control, WBV1: whole body vibration training for one week, WBV3 = whole body vibration training for 3 weeks. * p < 0.05, ** p < 0.01 compared to baseline value. Ischemia-induced arrhythmias Table 2 represents the number of PVC, VT and VF episodes and their duration during the 30-min ischemic period. The arrhythmias occurred after approximately 5–7 min of ischemia. The number of PVC decreased non-significantly in the experimental groups (p = 0.702). Vibration produced a significant decrease in the number and duration of VT episodes compared to the control value. The mean duration of reversible VF in the WBV3 group was reduced from 32.3 ± 19.4 s in the control group to 13.7 ± 10.3 s (as a non‑significant trend). Although the longest VF episodes in the vibration groups lasted as much as 116 s, all VF episodes were self-limited. However, the longest observed non-fatal VF episode in the control group was 87 s. and 33% of the rats died due to irreversible VF (p = 0.02). The occurrence (% incidence per group) of VT during the 30-min ischemia was 100, 100 and 88% (p = 0.35) and the occurrence of VF was 75, 63 and 50% in the control, WBV1 and WBV3 groups, respectively (p = 0.58). The numbers of premature ventricular complexes (PVC), the ventricular tachycardia (VT) and ventricular fibrillation (VF) episodes and duration are shown as means ± SEM. * p < 0.05 and ** p < 0.01 compared with the control group. Cont: control; WBV1: whole body vibration training for one week; WBV3: whole body vibration training for 3 weeks. Discussion There are three main findings of the present study. First, WBV caused a significant decrease in IS following 30 min of ischemia and 120min of reperfusion. Second,WBV had a protective effect on ischemia-induced arrhythmia. Third, all VF episodes were self-limited in the vibration groups, so the vibration improved arrhythmia-related mortality. There are conflicting results regarding the effect of WBV on BP and HR. Performing dynamic exercise on a vertical vibration platform (30-35 Hz, 2 mm) for 12 weeks resulted in decreased systolic blood pressure in patients suffering from type 2 diabetes. 20 Figueroa et al.’s study showed that 6 weeks of WBV decreased systemic arterial stiffness and systolic blood pressure in young overweight/obese normotensive women. 7 Unlike these results, it was demonstrated that one session of exercise with vibration increased systolic and diastolic blood pressure and stroke volume compared with exercise with no vibration in sedentary adults. 21 In contrast, some researchers have reported that WBV had no effect on the systolic and diastolic blood pressure, which is similar to our study results. 6,8,22 These conflicting results may be explained by the different experimental conditions, including duration of the treatment and possibly the heterogeneity of the health status of participants in the different studies. 34