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.

Purpose: The aim of the study was to evaluate the cardiac autonomic modulation after 9 months of martial arts practice in healthy children and adolescents. Method: The study included 59 children and adolescents who were divided into 3 groups: judo, Muay Thai, and control. Heart rate variability was measured by a heart rate monitor, model Polar RS800CX. The intervention occurred twice a week on nonconsecutive days, lasting 60 minutes each session. A 1-way analysis of variance was used to compare participants at baseline. The comparisons between groups at baseline and after the intervention were carried out by a 2-way analysis of variance for repeated measures. Results: After 9 months of intervention, significant increases were observed for root mean square successive differences, with higher values post compared with baseline (19.5%; P = .04). For SD1, an interaction effect was observed, with increased posttraining values compared with baseline (24.1%; P = .04) for the judo group. Qualitative analysis of the Poincaré plot showed greater dispersion of RR intervals, mainly beat to beat, after the judo intervention compared with the baseline. The Muay Thai and control groups presented no improvement. Conclusion: After 9 months of intervention, there were increases in cardiac autonomic modulation of children and adolescents participating in judo training. The practice of martial arts, such as judo, can be encouraged from an early age to improve cardiovascular system functioning, possibly providing protection against cardiovascular problems.

OBJECTIVE:To gather current information about the effects of type 1 diabetes mellitus on children's cardiac autonomic behavior.DATA SOURCES: The search of articles was conducted on PubMed, Ibecs, Medline, Cochrane, Lilacs, SciELO and PEDro databases using the MeSH terms: "autonomic nervous system", "diabetes mellitus", "child", "type 1 diabetes mellitus", "sympathetic nervous system" and "parasympathetic nervous system", and their respective versions in Portuguese (DeCS). Articles published from January 2003 to February 2013 that enrolled children with 9-12 years old with type 1 diabetes mellitus were included in the review.DATA SYNTHESIS: The electronic search resulted in four articles that approached the heart rate variability in children with type 1 diabetes mellitus, showing that, in general, these children present decreased global heart rate variability and vagal activity. The practice of physical activity promoted benefits for these individuals.CONCLUSIONS: Children with type 1 diabetes mellitus present changes on autonomic modulation, indicating the need for early attention to avoid future complications in this group.

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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.

A systematic review was undertaken to investigate the involvement of hydration in heart rate (HR), HR variability (HRV) and diastolic (DBP) and systolic (SBP) blood pressure in response to exercise. Data synthesis: The EMBASE, MEDLINE, Cochrane Library, CINAHL, LILACS and Web of Science databases were searched. In total, 977 studies were recognized, but only 36 were included after final screening (33 studies in meta-analysis). This study includes randomized controlled trials (RCTs) and non-RCTs with subjects > 18 years old. The hydration group consumed water or isotonic drinks, while the control group did not ingest liquids. For the hydration protocol (before, during and after exercise), the HR values during the exercise were lower compared to the controls (−6.20 bpm, 95%CI: −8.69; −3.71). In the subgroup analysis, “water ingested before and during exercise” showed lower increases in HR during exercise (−6.20, 95%CI: 11.70 to −0.71), as did “water was ingested only during exercise” (−6.12, 95%CI: −9.35 to −2.89). Water intake during exercise only revealed a trend of avoiding greater increases in HR during exercise (−4,60, 95%CI: −9.41 to 0.22), although these values were not significantly different (p = 0.06) from those of the control. “Isotonic intake during exercise” showed lower HRs than the control (−7.23 bpm, 95% CI: −11.68 to −2.79). The HRV values following the exercise were higher in the hydration protocol (SMD = 0.48, 95%CI: 0.30 to 0.67). The values of the SBP were higher than those of the controls (2.25 mmHg, 95%CI: 0.08 to 4.42). Conclusions: Hydration-attenuated exercise-induced increases in HR during exercise, improved autonomic recovery via the acceleration of cardiac vagal modulation in response to exercise and caused a modest increase in SBP values, but did not exert effects on DBP following exercise.