Objective: To evaluate autonomic modulation in individuals with COPD, compared with healthy controls, via recurrence plots (RPs) and linear heart rate variability (HRV) indices. Methods: We analyzed data on 74 volunteers, who were divided into two groups: COPD (n = 43) and control (n = 31). For calculation of HRV indices, heart rate was measured beat-by-beat during 30 min of supine rest using a heart-rate meter. We analyzed linear indices in the time and frequency domains, as well as indices derived from the RPs. Results: In comparison with the control group, the COPD group showed significant increases in the indices derived from the RPs, as well as significant reductions in the linear indices in the time and frequency domains. No significant differences were observed in the linear indices in the frequency domains expressed in normalized units or in the low frequency/high frequency ratio. Conclusions: Individuals with COPD show a reduction in both sympathetic and parasympathetic activity, associated with decreased complexity of autonomic nervous system function, as identified by RPs, which provide important complementary information in the detection of autonomic changes in this population.

The aim of this study was to compare heart rate variability (HRV) recovery after 2 sessions of high-intensity intermittent exercise at different volumes (1.25 km [HIIE_1.25] and 2.5 km [HIIE_2.5]). 13 participants determined their maximal aerobic speed (MAS) and completed 2 HIIE (1:1 at 100% MAS) trials. The heart rate was recorded before and after each session. HRV indicators were calculated according to time (RMSSD and SDNN) and frequency (LF, HF and LF/HF ratio) domains. SDNN and RMSSD presented effect of test (F=20.97; p<0.01 and F=21.00; p<0.01, respectively) and moment (F=6.76; p<0.01 and F=12.30; p<0.01, respectively), without interaction. Even though we did not find an interaction effect for any HRV variables, the HIIE_2.5 presented a delay of only 5 min in HRV recovery, when compared to HIIE_1.25. However, the effects of the test (SDNN, RMSSD, LF-log, and HF-log) indicate higher autonomic stress during the entire recovery period. These findings may indicate that exercise volume interferes with HRV recovery. If so, physically active subjects may choose a lower volume exercise (i. e., HIIE_1.25) in order to promote similar physical fitness adaptations with lower loading on autonomic modulation.

Background: The use of autonomic modulation as a predictor of cardiovascular risk in women with breast cancer is important. Objective: To evaluate the cardiac autonomic modulation of postmenopausal women using aromatase inhibitors for breast cancer treatment, as well as its relation with the following biochemical variables. Methods: Postmenopausal women who did not have breast cancer (n = 33) and postmenopausal women with breast cancer (n = 15). For evaluation of the autonomic modulation the heart rate was recorded beat-to-beat for 30 minutes and the series of RR intervals obtained were used to calculate the following heart rate variability indices: Mean RR ms, SDNN (standard deviation of all normal RR intervals, expressed in milliseconds) ms, Mean HR, RMSSD (square root of the mean of the squared differences between adjacent normal RR interval) ms, NN50 (number of pairs of successive NNs that differ by more than 50 ms) count, pNN50% (proportion of NN50 divided by total number of NNs), RRtri (RR triangular), TINN (triangular interpolation of NN interval) ms, SD1 ms, SD2 ms, LF ms(2), HF ms(2), LH/HF ms(2). The values of biochemical variables (fasting glycemia, triglycerides, HDL-cholesterol, and C-reactive protein) were analyzed by blood sample. Results: Lower values of heart rate variability indices were observed in postmenopausal women with breast cancer in relation to postmenopausal women who did not have breast cancer: Mean RR (p = 0.03); SDNN (p = 0.03); RMSSD (p = 0.03); NN50 count (p = 0.03); pNN50 % (p = 0.03); RRtri (p = 0.02); SD1 (p = 0.01); SD2 (p = 0.02); LF ms(2) (p = 0.01); HF ms(2) (p = 0.03).There was an inversely proportional correlation between the indices SDNN, SD2, and HFms(2) with triglycerides (SDNN p = 0.04; SD2 p = 0.04; HF ms(2) p = 0.04). No statistically significant correlations were found between heart rate variability indices and others variables. Statistical significance was set at 5% for all analyses. Conclusion: Women with breast cancer present reduced autonomic modulation and in these women of heart rate variability indices are inversely correlated with triglyceride values.

This study evaluated the capacity of cardiac risk stratification protocols on simple complications that occur during activities of a cardiovascular rehabilitation program. Observational longitudinal cohort study. Outpatient clinic of cardiovascular rehabilitation. Patients diagnosed with cardiovascular disease and/or risk factors. Not applicable. The relationship between the cardiac risk classes of seven risk stratification protocols and the occurrence of simple complications (such angina, abnormal changes in blood pressure, arrhythmias, fatigue, muscle pain, pallor) was assessed using the chi-square test, and when statistical significance was observed, sensitivity, specificity and accuracy were determined. About 76 patients were analyzed. The American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) protocol showed a statistically significant relationship between simple complications and cardiac risk classes (P-value = 0.046), however the results of sensitivity (0.53), specificity (0.52), and accuracy (0.53) were not significant. The other protocols analyzed were not significant: American College of Sports Medicine (P-value = 0.801), Brazilian Society of Cardiology (P-value = 0.734), American Heart Association (P-value = 0.957), Pashkow (P-value = 0.790), Society French Cardiology (P-value = 0.314), and Spanish Society of Cardiology (P-value = 0.078). The AACVPR protocol showed a significant relationship between the risk classes and the occurrence of simple complications, however, the low values obtained for sensitivity, specificity and accuracy show that it is not useful for this purpose. NCT03446742.

Keywords Autonomic nervous system; heart rate; blood pressure; metabolic syndrome; syndrome x; exercise