The post-exercise recovery period is associated with changes in autonomic modulation, which can promote an intercurrent-favorable environment. Caffeine has the ability to release catecholamines, but its effects after exercises is little explored. The present study aims to evaluate the acute effects of caffeine on the autonomic control and cardiorespiratory parameters after moderate intensity aerobic exercise. 32 young males (23,59 ± 3,45 years) were submitted to two protocols: Placebo and Caffeine, consisting of 15 minutes of rest, 30 minutes of exercise on a treadmill to 60% on VO2peak, followed by 60 minutes of recovery. Heart rate variability indices and cardiorespiratory parameters were determined at different times during the protocols. The RMSSD and SD1 indices recovered faster in placebo (p < 0.05). The systolic blood pressure differences were found from the 1st to the 5th minute of recovery with the caffeine protocol and from the 1st and 3rd minute with the placebo, whereas, for diastolic blood pressure, significant differences (p < 0.0001) were observed only for the caffeine protocol at the 1st and 3rd minutes of recovery. Caffeine was shown to be capable of delaying parasympathetic recovery but did not influence the behavior of the respiratory rate, oxygen saturation or frequency-domain HRV indices.

Background and objectives: As a result of ergogenic properties, caffeine has been increasingly taken prior to physical exercise, yet its effects on post-exercise recovery, considering the differences in the cardiorespiratory capacity of the individuals, has not yet been studied or fully elucidated. Optimizing the post-exercise recovery can convey advantages to physical activity practitioners. We evaluated the acute effects of caffeine on heart rate (HR) autonomic control recovery following moderate aerobic exercise in males with different cardiorespiratory capacities. Materials and Methods: We split young adult men into two groups based on their various oxygen consumption peaks (VO2 peak): (1) Higher VO2 (HO): Sixteen volunteers, peak VO2 > 42.46 mL/kg/min and (2) Low VO2 (LO): Sixteen individuals, VO2 < 42.46 mL/kg/min). The volunteers were submitted to placebo and caffeine protocols, which entailed 300 mg of caffeine or placebo (starch) in capsules, followed by 15 min of rest, 30 min of moderate exercise on a treadmill at 60% of the VO2 peak, followed by 60 min of supine recovery. Heart rate variability (HRV) indexes in the time and frequency domains were examined. Results: Effect of time for RMSSD (square root of the average of the square of the differences between normal adjacent RR intervals) and SDNN (standard deviation of all normal RR intervals recorded in a time interval) was achieved (p < 0.001). Significant adjustments were observed (rest versus recovery) at the 0 to 5th min of recovery from exercise for the LO during the placebo protocol and at the 5th at 10th min of recovery for the caffeine protocol. For the HO in both procedures we found significant alterations only at the 0 to 5th min of recovery. Conclusion: Caffeine delayed parasympathetic recovery from exercise in individuals with lower cardiorespiratory capacity.

Effects of a multidisciplinary program on autonomic modulation in overweight or obese children and adolescents J Hum Growth Dev. 2016; 26(2): 154-161 DOI: http://dx.doi.org/10.7322/jhgd.119257 AbstractPurpose: this study evaluated the effects of a multidisciplinary program on autonomic modulation in overweight or obese children and adolescents.Methods: fi fteen individuals with 10,93 ± 2,28 years were submitted to autonomic evaluation using heart rate variability before and after a program based on physical exercises for three months, three times a week, 60 minutes per session and psychological and nutritional counseling. Data was analyzed using the paired t-test or Wilcoxon test and the level of signifi cance was set at P < 0.05.Results: multidisciplinary program was able to promote benefi ts in autonomic modulation observed thought temporal (SDNN: 39,96 ± 10,33 x 49,44 ± 12,31; p = 0,019; rMSSD: 28,97 ± 11,50 x 37,26 ± 11,17; p = 0,018), spectral (LFnu: 64,49 ± 12,21 x 56,74 ± 11,18; p = 0,014; HFnu: 35,50 ± 12,21 x 43,25 ± 11,18; p = 0,014) and geometrical (SD1: 20,51 ± 8,13 x 26,36 ± 7,90; p = 0,018 SD2: 52,31 ± 13,04 x 64,58 ± 16,33; p = 0,031) indices in overweigh and obese children and adolescents. Also, after the intervention there was a reduction on resting heart rate (88,53 ± 9,24 x 83,09 ± 7,93; p = 0,023) and there were changes in the classifi cation of overweigh 26,67% x 46,66% and obesity 73,33% x 53,33%, although not signifi cant changes in body mass index.Conclusions: exercise program together with nutritional and psychological counseling is able to promote benefi ts in autonomic modulation in children and adolescents who are overweight or obese.

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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.

OBJECTIVE:A previous study suggested that the p-value of normality test applied to RR intervals is an index able to quantify Heart Rate Variability (HRV) through correlation of traditional time and frequency domain indices. We investigate the association between the p-value of normality test applied in RR intervals and symbolic analysis of HRV. METHOD: We evaluated 32 healthy women between 18 and 30 years old. RR intervals were used for HRV analysis and we performed symbolic analysis, where RR intervals are joined by symbols. Sets of three consecutive symbols (RR intervals) were grouped into four types of clusters, as follows: 1. Three equal symbols (zero variation); 2: two equal, one divergent symbol (one variation); 3. Three different symbols monotonically ascending or descending (two like variations); 4. Three different symbols, forming a peak or a trough (two unlike variations). Frequency of occurrence of each type of cluster was calculated. Normality tests were applied to all RR intervals and the p-value was calculated. We computed the correlations between the p-value of normality test and symbolic analysis of HRV. RESULTS: Correlation coefficients between the p-value of normality test from Kolmorogov-Smirnov test and the four types of clusters showed no correlation for any of them. Likewise, the correlation coefficient index between the p-value of normality test calculated from the Shapiro-Wilk test and symbolic analysis produced no significant results for any of the four types of clusters. CONCLUSION: There was no significant correlation between the p-value of normality test and HRV symbolic analysis. The physiological significance of this result is that the PNT is not related to chaotic behavior of HRV.

INTRODUCTION: We aimed to evaluate the effects of musical auditory stimulation on cardiac autonomic regulation in subjects who enjoy and who do not enjoy the music. METHOD: The study was performed in young women (18-27 years old) divided in two groups (1) volunteers who enjoyed the music and (2) volunteers who did not enjoy the music. Linear indices of heart rate variability were analyzed in the time domain. The subjects were exposed to a musical piece (Pachelbel: Canon in D Major) during 10 minutes. Heart rate variability was analyzed at rest with no music and during musical auditory stimulation. RESULTS: In the group that enjoyed the music the standard deviation of normal-to-normal R-R intervals (SDNN) was significantly reduced during exposure to musical auditory stimulation. We found no significant changes for the other linear indices. The group composed of women who did not enjoy the music did not present significant cardiac autonomic responses during exposure to musical auditory stimulation. CONCLUSION: Women who enjoyed the music presented a significant cardiac autonomic response consisting of a reduction in heart rate variability induced by the musical auditory stimulation. Those who did not enjoy the musical piece presented no such response.

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