Background: Cardiovascular complications are the major cause of death in diabetic patients. Diabetic rats by streptozotocin (STZ) administration present many alterations similar to those occurring in humans like diabetic cardiomyopathy and neuropathy, impairing the cardiovascular autonomic control. Aerobic exercise training improves these alterations, however evidence about the effects of resistance exercise on these parameters are scarce.
Objective: To evaluate the effects of low-intensity resistance training in baroreflex sensitivity (BRS), in autonomic control and cardiac function in STZ diabetic rats.
Methods: Male Wistar rats (3 months of age) were divided into sedentary control group (SC, n = 8), sedentary diabetic (SD, n = 8), trained diabetic (TD, n = 8) and trained control (TC, n = 8). Trained groups underwent low-intensity resistance training (40-50% maximal voluntary contraction) for 10 weeks. All animals were instrumentalized with femoral artery and vein cannulas. Blood pressure (BP) and heart rate (HR) signals, baroreflex sensitivity (BRS) and autonomic tonus were evaluated, as well as cardiac function by echocardiography.
Statistical analysis: Data were compared by two-way ANOVA followed by Student Newmann Keuls post hoc test. Significance level was p<0.05.
Results: Diabetic rats showed lower systolic BP and HR, impairment of BRS and autonomic function and systolic and diastolic dysfunction in comparison with controls. Resistance training did not change glycemia, however it attenuated the resting hypotension (SD: 105±4 vs. TD: 117±4 mmHg) and bradycardia (SD: 283±4 vs. TD: 16±13 bpm), improved the reflex bradycardia (SD: -0.57±0.08 vs. TD: -1.75±0.1 bpm/mmHg) and the reflex tachycardia to BP changes (SD: 1.08±0.2 vs.TD: 3.10±0.15 bpm/mmHg), the vagal tonus (SD: 13±3 vs. TD: 43±4 bpm), as well as the ejection fraction (SD: 68±2 vs. TD: 75±3 %) of diabetic rats.
Conclusion: Low-intensity resistance training attenuated the hemodynamic impairment, improved BRS, autonomic control and systolic function in STZ diabetic rats without modifying the hyperglycemia. These data suggest that resistance exercise training induced-cardiovascular improvement can be independent of changes in glycemic control in a model of type 1 diabetes.