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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.

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BACKGROUND: The aim of this study was to explore the effects of non-invasive positive pressure ventilation (NIPPV) associated with high-intensity exercise on heart rate (HR) and oxygen uptake (V̇O2) recovery kinetics in in patients with coexistence of chronic obstructive pulmonary disease (COPD) and heart failure (HF). METHODS: This is a randomized, double blinded, sham-controlled study involving 14 HF-COPD patients, who underwent a lung function test and Doppler echocardiography. On two different days, patients performed incremental cardiopulmonary exercise testing (CPET) and two constant-work rate tests (80% of CPET peak) receiving Sham or NIPPV (bilevel mode - Astral 150) in a random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin and deoxyhemoglobin were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, Netherland). RESULTS: The kinetic variables of both V̇O2 and HR during the high-intensity constant workload protocol were significantly faster in the NIPPV protocol compared to Sham ventilation (P < 0.05). Also, there was a marked improvement in oxygenation and lower deoxygenation of both peripheral and respiratory musculature in TLim during NIPPV when contrasted with Sham ventilation. CONCLUSIONS: NIPPV applied during high-intensity dynamic exercise can effectively improve exercise tolerance, accelerate HR and V̇O2 kinetics, improve respiratory and peripheral muscle oxygenation in COPD-HF patients. These beneficial results from the effects of NIPPV may provide evidence and a basis for high-intensity physical training for these patients in cardiopulmonary rehabilitation programs.

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RESUMEN Introducción: Las enfermedades cardiovasculares son un problema de salud y una de las principales causas de muerte a nivel mundial. Presentan alta morbilidad y mortalidad en mujeres de entre 40 y 59 años, período que coincide con la menopausia natural. Objetivo: Caracterizar el riesgo cardiovascular en pacientes femeninas sanas. Métodos: Se realizó un estudio descriptivo, en 96 mujeres sanas. Fueron estudiadas variables epidemiológicas, clínicas, la valoración nutricional, circunferencia abdominal, estudios de laboratorio (triacilglicéridos, glucemia y colesterol total) y se realizó estratificación del riesgo cardiovascular. Se realizó un análisis de frecuencias y se empleó el test de ji cuadrado de Pearson para las comparaciones. Resultados: El grupo más representativo fue de 20 a 29 años de edad, los factores de riesgo con mayor incidencia fueron, la circunferencia abdominal por encima de 88 cm, IMC superior a 25 kg/m2, colesterol elevado e hipertrigliceridemia con asociación estadísticamente significativa (p< 0,000), predominaron las mujeres sin factores de riesgo en menores de 40 años, el bajo riesgo cardiovascular en todas las edades; el moderado y alto fue más significativo entre 40 y 49, y entre 50 y 59 años de edad (p< 0,000). Conclusiones: Predomina el bajo riesgo cardiovascular en mujeres menores de 40 años sin asociación de factores de riesgo; en las mayores de 40 predomina el moderado, con asociaciones entre factores de riesgo. El aumento del IMC, el colesterol elevado, la hipertrigliceridemia y la circunferencia abdominal mayor de 88 cm, fueron los factores de riesgo más importantes y estuvieron relacionados con la edad. Palabras clave: factores de riesgo; enfermedad cardiovascular; fisiología cardiovascular; identidad de género. ABSTRACT Introduction: Cardiovascular diseases are a health problem and one of the main causes of death worldwide. They present high morbidity and mortality in women between the ages of 40 and 59, a period that coincides with natural menopause. Objective: To characterize cardiovascular risk in healthy female patients. Methods: A descriptive study was carried out in 96 healthy women. Epidemiological and clinical variables, nutritional assessment, abdominal circumference, laboratory studies (triacylglycerides, glycemia and total cholesterol) were studied, and cardiovascular risk stratification was performed. A frequency analysis was performed and Pearson's chi-square test was used for comparisons. Results: The most representative group was 20 to 29 years old, the risk factors with the highest incidence were abdominal circumference above 88 cm, body mass index above 25 kg/m2, high cholesterol and hypertriglyceridemia with association statistically significant (p< 0.000), women without risk factors prevailed in those under 40 years of age, low cardiovascular risk in all ages; moderate and high was more significant between 40 and 49, and between 50 and 59 years of age (p< 0.000). Conclusions: Low cardiovascular risk predominates in women under 40 years of age without association of risk factors; in those over 40 the moderate predominates, with associations between risk factors. Increased BMI, high cholesterol, hypertriglyceridemia, and abdominal circumference greater than 88 cm were the most important risk factors and were related to age.

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Abstract Aim: Cardiovascular physiology learned by exercise science students is often quickly forgotten. We tested whether a state rotation model would help students to recall key principles of Cardiovascular Physiology (CV). Methods: Seventy-one undergraduate students enrolled in the Exercise Physiology Course at the School of Physical Education and Sport, University of São Paulo, participated in the study. The students were randomly assigned into one of 4 stations, dedicated to recalling the concepts of the heart as a pump (e.g. preload, post-load, and contractility; station 1) and hemodynamics (e.g. serial and parallel conductance; station 2) by using the educational tool. Heart rate (HR) control by sympathetic nervous system activation (station 3) and HR control by vagal activation (station 4) were assessed by quantifying HR response to the Stroop color and word test and during face immersion in cold water, respectively. To evaluate the efficacy of the intervention, we used a Socrative app to launch eight multiple-choice questions before (PRE) and after (POST) the student's station rotation. The questions were related to the basic principles of exercise physiology and its consequences on the cardiovascular system. Results: The 4-station average score (% of corrected answers) achieved after the station rotation was higher than the score achieved before (71.21%, SD 14.50 vs. 31.07%, SD 18.04; for POST and PRE, respectively p < 0.005). Considering specific stations, the lowest score of corrected answers before the rotation was observed at station 2- hemodynamics when compared with station 1-heart as a pump and station 3/4 - autonomic control (18.9%, SD 0.9 vs. 46.5, SD 24.1 and 34.8, SD 2.1 for hemodynamics, heart as a pump and autonomic control, respectively). Interestingly, after the rotation, there was a significant increase in corrected scores for all stations (33.9, SD 9.8; 80.5, SD 4.6 and 90.2, SD 2.3, for hemodynamics, heart as a pump, and autonomic control, respectively). Conclusion: Our results suggest that the use of the educational tool was effective to recall CV principles that are essential to a better understanding of the CV responses to exercise and applying the concepts in exercise testing and prescription for different populations.

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INTRODUCTION AND OBJECTIVES: Studies assessing the effects of caffeine (CAF) on the cardiovascular system have demonstrated that CAF can delay cardiac recovery following exercise. This study intended to assess the impact of CAF intake before physical exercise on heart rate variability (HRV) and cardiovascular parameters. METHODS: This is a prospective, crossover, controlled clinical trial conducted at the University of Pernambuco, Petrolina, PE, Brazil. The experimental protocol was split into three stages with a minimum of 48 hours between them. Exercises intensity was standardized based on the one repetition maximum test (1RM), obtaining the load of each volunteer for the intensity of 75% of 1RM. In the second and third phases, the control protocols were applied and 300 mg caffeine was given 45 minutes before training. HRV indices were determined at the subsequent times: 0 to 5 minutes of rest (before) and during 30 minutes of recovery (Rec) (after exercise), divided into six intervals, each of 5 minutes. RESULTS: The final sample involved 30 volunteers. CAF delayed HRV recovery after resistance exercise. In general, CAF impaired recovery of HRV after resistance exercise. Significant changes were observed in the RMSSD, SDNN, TINN, SD1, low frequency and high frequency indices between the control and CAF group. CONCLUSION: CAF protocol delayed parasympathetic regulation of heart rhythm following exercise, slowing recovery of HR, blood pressure and HRV indices after exercise.

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BACKGROUND: There is a spectrum of possibilities for analyzing muscle O2 resaturation parameters for measurement of reactive hyperemia in microvasculature. However, there is no consensus with respect to the responsiveness of these O2 resaturation parameters for assessing reactive hyperemia. OBJECTIVES: This study investigates the responsiveness of the most utilized muscle O2 resaturation parameters to assess reactive hyperemia in the microvasculature of a clinical group known to exhibit impairments of tissue O2 saturation (StO2). METHODS: Twenty-three healthy young adults, twenty-nine healthy older adults, and thirty-five older adults at risk of cardiovascular disease (CVD) were recruited. Near-infrared spectroscopy (NIRS) was used to assess StO2 after a 5-min arterial occlusion challenge and the following parameters were analyzed: StO2slope_10s, StO2slope_30s, and StO2slope_until_baseline (upslope of StO2 over 10s and 30s and until StO2 reaches the baseline value); time to StO2baseline and time to StO2max (time taken for StO2 to reach baseline and peak values, respectively); ∆StO2reperfusion (the difference between minimum and maximum StO2 values); total area under the curve (StO2AUCt); and AUC above the baseline value (StO2AUC_above_base). RESULTS: Only StO2slope_10s was significantly slower in older adults at risk for CVD compared to healthy young individuals (p < 0.001) and to healthy older adults (p < 0.001). Conversely, time to StO2max was significantly longer in healthy young individuals than in older adult at CVD risk. CONCLUSIONS: Our findings suggest that StO2slope_10s may be a measure of reactive hyperemia, which provides clinical insight into microvascular function assessment.

CONTEXTO: Existe um espectro de possibilidades na análise dos parâmetros de ressaturação de O2 muscular como uma medida de hiperemia reativa na microvasculatura. No entanto, não há consenso com relação à responsividade desses parâmetros de ressaturação de O2 para avaliação de hiperemia reativa. OBJETIVOS: Este estudo investigou a capacidade de resposta dos parâmetros de ressaturação muscular de O2 mais utilizados para avaliar a hiperemia reativa na microvasculatura de um grupo clínico conhecido por apresentar comprometimento da saturação de O2 (StO2). MÉTODOS: Foram recrutados 23 jovens saudáveis, 29 idosos saudáveis e 35 idosos com risco para doença cardiovascular. A espectroscopia no infravermelho próximo foi usada para avaliar a StO2 após um teste de oclusão arterial de 5 minutos, no qual os seguintes parâmetros foram analisados: StO2slope_10s, StO2slope_30s e StO2slope_until_baseline (inclinação da StO2 em 10 s, 30 s e até StO2 atingir valores basais); tempo para StO2baseline e tempo para StO2máx (o tempo necessário para StO2 atingir os valores da linha de base e o máximo, respectivamente); ∆StO2reperfusão (a diferença entre o valor de StO2mínimo e StO2máximo); área total sob a curva (StO2AUCt); e área sob a curva acima do valor da linha de base (StO2AUC_above_base). RESULTADOS: Apenas StO2slope_10s foi significativamente mais lento em idosos em risco de doença cardiovascular comparados com indivíduos jovens saudáveis (p < 0,001) e idosos saudáveis (p < 0,001). Por outro lado, o tempo para StO2max foi significativamente maior em indivíduos jovens saudáveis do que em idosos em risco de doença cardiovascular. CONCLUSÕES: Nossos achados sugerem que StO2slope_10s pode ser uma medida de hiperemia reativa, que fornece informações clínicas sobre a avaliação da função microvascular.

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Abnormalities in the muscle metaboreflex concur to exercise intolerance and greater cardiovascular risk. Exercise training benefits neurocardiovascular function at rest and during exercise, but its role in favoring muscle metaboreflex in health and disease remains controversial. While some authors demonstrated that exercise training enhanced the sensitization of muscle metabolically afferents and improved neurocardiovascular responses to muscle metaboreflex activation, others reported unaltered responses. This narrative review aimed to: (a) highlight the current evidence on the effects of exercise training upon cardiovascular and autonomic responses to muscle metaboreflex activation; (b) analyze the role of training components and indicate potential mechanisms of metaboreflex adaptations; and (c) address key methodological features for future research. Though limited, accumulated evidence suggests that muscle metaboreflex adaptations depend on the individual clinical status, exercise modality, and training duration. In healthy populations, most trials negated the hypothesis of metaboreflex improvement due to chronic exercise, irrespective of the training duration. Favorable changes in patients with impaired metaboreflex, particularly chronic heart failure, mostly resulted from long-term interventions (> 16 weeks) including aerobic exercise of moderate to high intensity, performed in isolation or within multimodal training. Potential mechanisms of metaboreflex improvements include enhanced sensitivity of channels and receptors, greater antioxidant capacity, lower metabolite accumulation, increased functional sympatholysis, and muscle perfusion. Future research should investigate: (1) the dose-response relationship of training components within different exercise modalities to elicit improvements in individuals showing intact or impaired muscle metaboreflex; and (2) potential and specific underlying mechanisms of metaboreflex improvements in individuals with different medical conditions.

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Our study aimed to explore the influence of bariatric surgery (BS) on heart rate (HR) variability (HRV) through a systematic review. Manuscripts were selected based on electronic searches of the MEDLINE, EMBASE, and CINAHL databases from the inception of each database up to year 2020, and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Searching of these studies was systematized using the Population Intervention Comparison Outcome Study Design strategy. We selected randomized and nonrandomized controlled trials and cohorts from prospective studies that reported the influence of BS on HRV. We assessed the quality rating using the Black and Downs questionnaire. Following the screening and eligibility stages, 14 studies were included in the review. All studies agreed that BS promotes an increase in parasympathetic HR control and HRV and a decrease in HR. Yet the literature does not provide evidence that these outcomes are directly caused by the surgical procedure. There is limited evidence to support that patients with type 2 diabetes have greater improvement in HRV as an interim measure, to individuals without. The decrease in insulin resistance was correlated with the increase in HRV in some studies, but, other studies are unsupportive of this outcome. Improvements in 2 metabolic parameters (e.g., leptin, N-terminal pro B-type natriuretic peptide) were connected with superior increases in HRV. This review demonstrated that BS promotes an increase in HRV, indicating improved autonomic control of HR.

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Resistance training (RT) with blood flow restriction (BFR) appears to accelerate muscle hypertrophy and strength gains in older populations. However, the training-related effects of RT with BFR upon blood pressure (BP) and cardiac autonomic modulation in the elderly remains unclear. The objective of this study is to compare the chronic effects of low-intensity RT performed with soft BFR (BFR) vs. high-intensity (HI) and low-intensity RT (CON) without BFR on BP and heart rate variability (HRV) indices in older adults. Thirty-two physically inactive participants (72 ± 7 yrs) performed RT for upper and lower limbs (50-min sessions, 3 times/week) for 12 weeks, being assigned into three groups: a) BFR; 30% of 1 repetition maximum (RM) with BFR corresponding to 50% of arterial occlusion pressure; b) HI; 70% of 1RM without BFR; c) CON; 30% of 1 RM without BFR. Resting BP and HRV were assessed at rest in the supine position, before and after exercise interventions. Systolic BP (Δ = -7.9 ± 8.0 mmHg; p = 0.002; effect size = 0.62), diastolic BP (Δ = trace length by the duration of the test 5.0 ± 6.0 mmHg; p = 0.007; effect size = 0.67) and mean arterial pressure (Δ = -6.3 ± 6.5 mmHg; p = 0.003/effect size = 0.77) reduced after BFR, remaining unaltered in HI and CON. HRV indices of sympathetic and vagal modulation did not change in all groups (p ≥ 0.07 for all comparisons). 12-wk RT with low intensity and relatively soft BFR substantially reduced BP at rest in older adults vs. traditional RT performed with either low or high intensity. Those reductions were not parallel to changes in autonomic modulation.

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OBJECTIVE: the complexity of heart-rate variability (HRV) in amyotrophic lateral sclerosis (ALS) patients with different pulmonary capacities was evaluated. METHODS: We set these according to their pulmonary capacity, and specifically forced vital capacity (FVC). We split the groups according to FVC (FVC > 50% (n = 29) and FVC < 50% (n = 28)). In ALS, the presence of an FVC below 50% is indicative of noninvasive ventilation with two pressure levels and with the absence of other respiratory symptoms. As the number of subjects per group was different, we applied the unbalanced one-way analysis of variance (uANOVA1) test after three tests of normality, and effect size by Cohen's d to assess parameter significance. RESULTS: with regard to chaotic global analysis, CFP4 (p < 0.001; d = 0.91), CFP5 (p = 0.0022; d = 0.85), and CFP6 (p = 0.0009; d = 0.92) were enlarged. All entropies significantly increased. Shannon (p = 0.0005; d = 0.98), Renyi (p = 0.0002; d = 1.02), Tsallis (p = 0.0004; d = 0.99), approximate (p = 0.0005; d = 0.97), and sample (p < 0.0001; d = 1.22). Detrended fluctuation analysis (DFA) (p = 0.0358) and Higuchi fractal dimension (HFD) (p = 0.15) were statistically inconsequential between the two groups. CONCLUSIONS: HRV complexity in ALS subjects with different pulmonary capacities increased via chaotic global analysis, especially CFP5 and 3 out of 5 entropies.

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Objective: This study aimed to verify the effect of resistance training performed with single (SET1) or three sets (SET3) on muscle strength and resting blood pressure (BP) of individuals with hypertension. BP was also assessed during knee extension exercise with submaximal load before and after training. Methods: Thirty-eight patients with hypertension were randomly assigned to a control group (CON: n = 12; 55.6 ± 3.2 years; 65.3 ± 9.3 kg; 163.5 ± 8.6 cm), SET1 group (n = 14; 58.1 ± 2.0 years; 65.4 ± 8.7 kg; 162.4 ± 11.1 cm) or SET3 group (n = 12; 57.9 ± 2.4 years; 66.3 ± 11.4 kg; 161.6 ± 7.5 cm). The training was conducted for 12 weeks (3 d.w-1; 4 exercises; 12-15 repetitions; moderate intensity). Results: No differences were found in pre-training values for BP and strength between groups. After training, SET3 showed lower values than CON for resting systolic (121.3 ± 8.0 vs 129.3 ± 10.3 mmHg; P = .01) and diastolic BP (73.5 ± 6.0 vs 79.5 ± 7.4 mmHg; P = .02). Muscle strength in bench-press and knee extension exercises increased in SET1 (48.1 ± 6.3 and 71.3 ± 12.2 kg, respectively) and SET3 (50.2 ± 7.8 and 75.2 ± 9.6 kg, respectively) in relation to CON (39.3 ± 5.1 and 62.4 ± 9.9 kg) (P < .01). BP during knee extension (70% of one maximal repetition) did not differ between groups either before or after training. Conclusion: Resistance training with a single set could be interesting when there is a need to increase muscle strength without necessarily reducing resting BP. On the other hand, the performance of three sets increased muscle strength and reduced BP at rest in individuals with hypertension.

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AIM: To evaluate the effect of non-invasive positive pressure ventilation (NIPPV) on (1) metabolic, ventilatory, and hemodynamic responses; and (2) cerebral (Cox), respiratory, and peripheral oxygenation when compared with SHAM ventilation during the high-intensity exercise in patients with coexisting chronic obstructive pulmonary disease (COPD) and heart failure (HF). METHODS AND RESULTS: On separate days, patients performed incremental cardiopulmonary exercise testing and two constant-work rate tests receiving NIPPV or controlled ventilation (SHAM) (the bilevel mode-Astral 150) in random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin (OxyHb+Mb) and deoxyhemoglobin (DeoxyHb+Mb) were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, The Netherlands). NIPPV associated with high-intensity exercise caused a significant increase in exercise tolerance, peak oxygen consumption ( V · O 2 in mlO2·kg-1·min-1), minute ventilation peak ( V · E in ml/min), peak peripheral oxygen saturation (SpO2, %), and lactate/tlim (mmol/s) when compared with SHAM ventilation. In cerebral, respiratory, and peripheral muscles, NIPPV resulted in a lower drop in OxyHb+Mb (p < 0.05) and an improved deoxygenation response DeoxyHb+Mb (p < 0.05) from the half of the test (60% of Tlim) when compared with SHAM ventilation. CONCLUSION: Non-invasive positive pressure ventilation during constant work-rate exercise led to providing the respiratory muscle unloading with greater oxygen supply to the peripheral muscles, reducing muscle fatigue, and sustaining longer exercise time in patients with COPD-HF.

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Abstract Background There is a spectrum of possibilities for analyzing muscle O2 resaturation parameters for measurement of reactive hyperemia in microvasculature. However, there is no consensus with respect to the responsiveness of these O2 resaturation parameters for assessing reactive hyperemia. Objectives This study investigates the responsiveness of the most utilized muscle O2 resaturation parameters to assess reactive hyperemia in the microvasculature of a clinical group known to exhibit impairments of tissue O2 saturation (StO2). Methods Twenty-three healthy young adults, twenty-nine healthy older adults, and thirty-five older adults at risk of cardiovascular disease (CVD) were recruited. Near-infrared spectroscopy (NIRS) was used to assess StO2 after a 5-min arterial occlusion challenge and the following parameters were analyzed: StO2slope_10s, StO2slope_30s, and StO2slope_until_baseline (upslope of StO2 over 10s and 30s and until StO2 reaches the baseline value); time to StO2baseline and time to StO2max (time taken for StO2 to reach baseline and peak values, respectively); ∆StO2reperfusion (the difference between minimum and maximum StO2 values); total area under the curve (StO2AUCt); and AUC above the baseline value (StO2AUC_above_base). Results Only StO2slope_10s was significantly slower in older adults at risk for CVD compared to healthy young individuals (p < 0.001) and to healthy older adults (p < 0.001). Conversely, time to StO2max was significantly longer in healthy young individuals than in older adult at CVD risk. Conclusions Our findings suggest that StO2slope_10s may be a measure of reactive hyperemia, which provides clinical insight into microvascular function assessment.

Resumo Contexto Existe um espectro de possibilidades na análise dos parâmetros de ressaturação de O2 muscular como uma medida de hiperemia reativa na microvasculatura. No entanto, não há consenso com relação à responsividade desses parâmetros de ressaturação de O2 para avaliação de hiperemia reativa. Objetivos Este estudo investigou a capacidade de resposta dos parâmetros de ressaturação muscular de O2 mais utilizados para avaliar a hiperemia reativa na microvasculatura de um grupo clínico conhecido por apresentar comprometimento da saturação de O2 (StO2). Métodos Foram recrutados 23 jovens saudáveis, 29 idosos saudáveis e 35 idosos com risco para doença cardiovascular. A espectroscopia no infravermelho próximo foi usada para avaliar a StO2 após um teste de oclusão arterial de 5 minutos, no qual os seguintes parâmetros foram analisados: StO2slope_10s, StO2slope_30s e StO2slope_until_baseline (inclinação da StO2 em 10 s, 30 s e até StO2 atingir valores basais); tempo para StO2baseline e tempo para StO2máx (o tempo necessário para StO2 atingir os valores da linha de base e o máximo, respectivamente); ∆StO2reperfusão (a diferença entre o valor de StO2mínimo e StO2máximo); área total sob a curva (StO2AUCt); e área sob a curva acima do valor da linha de base (StO2AUC_above_base). Resultados Apenas StO2slope_10s foi significativamente mais lento em idosos em risco de doença cardiovascular comparados com indivíduos jovens saudáveis (p < 0,001) e idosos saudáveis (p < 0,001). Por outro lado, o tempo para StO2max foi significativamente maior em indivíduos jovens saudáveis do que em idosos em risco de doença cardiovascular. Conclusões Nossos achados sugerem que StO2slope_10s pode ser uma medida de hiperemia reativa, que fornece informações clínicas sobre a avaliação da função microvascular.

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ABSTRACT Bradycardia in athletes can range from moderate to severe, and the factors that contribute to slow heart rate are complex. Studies investigating the mechanisms associated with this condition are controversial, and may be linked to the form of exercise practiced. A systematic literature review was conducted to discuss bradycardia mechanisms in athletes who practice different forms of sport. The databases consulted were Pubmed (MEDLINE), Clinical Trials, Cochrane, Scopus, Web of Science, SciELO, Sport Discus and PEDro. The search included English language articles published up to January 2019, that evaluated athletes who practiced different forms of sport. One hundred and ninety-three articles were found, ten of which met the inclusion criteria, with 1549 male and female athletes who practiced diverse forms of sport. Resting heart rate and cardiac structure were studied in association with the form of sport practiced, through heart rate variability, electrocardiogram, echocardiogram and pharmacological blockade. The studies suggest that a slow resting heart rate cannot be explained by increased vagal modulation alone, but also includes changes in cardiac structure. According to the studies, different sports seem to produce different cardiac responses, and the bradycardia found in athletes can be explained by non-autonomic and autonomic mechanisms, depending on the type of effort or the form of sport practiced. However, the mechanism underlying the slow heart rate in each form of sport is still unclear. Level of evidence II; Prognostic studies - Investigating the effect of a patient characteristic on the outcome of disease.

RESUMO A bradicardia em atletas pode variar de moderada a grave, e os fatores que contribuem para a redução da frequência cardíaca são complexos. Estudos que investigam os mecanismos associados à bradicardia são controversos e, possivelmente, ligados ao tipo de exercício. Realizou-se uma pesquisa bibliográfica sistemática para discutir os mecanismos de bradicardia em atletas de diferentes modalidades esportivas. As bases de dados consultadas foram Pubmed (MEDLINE), Clinical Trials, Cochrane, Scopus, Web of Science, SciELO, Sport Discus e PEDro. Foram incluídos artigos em inglês, que avaliaram atletas de diferentes modalidades esportivas, publicados até janeiro de 2019. Cento e noventa e três artigos foram encontrados e dez preencheram os critérios de inclusão, perfazendo 1.549 homens e mulheres atletas de diversas modalidades esportivas. A frequência cardíaca em repouso e a estrutura cardíaca foram estudadas em associação com a modalidade esportiva, por variabilidade da frequência cardíaca, eletrocardiograma, ecocardiograma e bloqueio farmacológico. Os estudos sugerem que a redução da frequência cardíaca em repouso não é explicada apenas pelo aumento da modulação vagal, mas também por alterações da estrutura cardíaca. De acordo com os estudos, diferentes esportes parecem produzir diferentes respostas cardíacas e a bradicardia encontrada em atletas pode ser explicada por mecanismos não autonômicos e autonômicos. Este achado parece depender do tipo de esforço ou modalidade esportiva praticada. No entanto, o mecanismo envolvido na redução da frequência cardíaca em cada modalidade esportiva ainda não está claro. Nível de evidência II; Estudos prognósticos - Investigação do efeito de característica de um paciente sobre o desfecho da doença.

RESUMEN La bradicardia en atletas puede variar de moderada a grave, y los factores que contribuyen para la reducción de la frecuencia cardíaca son complejos. Los estudios que investigan los mecanismos asociados a la bradicardia son controvertidos y, posiblemente, vinculados al tipo de ejercicio. Se realizó una investigación bibliográfica sistemática para discutir los mecanismos de bradicardia en atletas de diferentes modalidades deportivas. Las bases de datos consultadas fueron Pubmed (MEDLINE), Clinical Trials, Cochrane, Scopus, Web of Science, SciELO, Sport Discus y PEDro. Se incluyeron artículos en inglés, que evaluaron a atletas de diferentes modalidades deportivas, publicados hasta enero de 2019. Se encontraron ciento noventa y tres artículos y diez cumplieron con los criterios de inclusión, totalizando 1549 hombres y mujeres atletas de diversas modalidades deportivas. La frecuencia cardíaca en reposo y la estructura cardíaca fueron estudiadas en asociación con la modalidad deportiva, por variabilidad de la frecuencia cardíaca, electrocardiograma, ecocardiograma y bloqueo farmacológico. Los estudios sugieren que la reducción de la frecuencia cardíaca en reposo no es explicada sólo por el aumento de la modulación vagal, sino también por alteraciones de la estructura cardíaca. De acuerdo con los estudios, los diferentes deportes parecen producir diferentes respuestas cardíacas y la bradicardia encontrada en atletas puede explicarse por mecanismos no autonómicos y autonómicos. Este hallazgo parece depender del tipo de esfuerzo o modalidad deportiva practicada. Sin embargo, el mecanismo involucrado en la reducción de la frecuencia cardíaca en cada modalidad deportiva aún no está claro. Nivel de evidencia II; Estudios pronósticos - investigación del efecto de característica de un paciente sobre el desenlace de la enfermedad.

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Impaired cardiovascular and autonomic function during treatment and during recovery from leukemia has been indicated. In this context, heart rate variability (HRV) is a non-invasive measure that describes the oscillations of the intervals between consecutive heart beats (RR intervals), influenced by the autonomic nervous system. We intend to review literature showing HRV changes in leukemia subjects. The articles selected in the current review were attained up to March 2018, and the search was limited to articles in English language, published in peer-reviewed journals, with both adult and child age samples. The articles were investigated in the five electronic databases: PubMed, Physiotherapy Evidence Database (PEDro), Cochrane Clinical Trials, Scientific Electronic Library Online (SciELO), and Excerpta Medica dataBASE (EMBASE). Towards the end of the research, 9 studies were included. Subjects undergoing treatment for leukemia have reduced HRV, signifying decreased vagal control of heart rate. The subjects that undertook leukemia treatment and their survivors experienced a reduction in HRV with subsequent recovery, but the recovery time is ill defined. HRV is reduced in leukemia subjects who progress to neuropathy secondary to chemotherapy, accompanied by cardiac dysfunction. We advocate the use of HRV to evaluate autonomic function and decide the treatment to prevent autonomic impairment in leukemia subjects.

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Evaluating different doses of caffeine (CAF) on heart rate (HR) variability (HRV) during and following exercise in order to assess its impact on autonomic control. We intended to evaluate the influence of CAF as a supplement before exercise on HRV through a systematic review. Manuscripts were selected based on electronic searches of MEDLINE, EMBASE and CINAHL databases from 2010 to 2019 and followed the protocol Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA). Blind randomized designs and controlled trials that reported the influence of CAF on HRV during exercise and during recovery from exercise, with strength of evidence assessed using the GRADE system; the search for the studies was organized using the PICOS strategy. A total of 1797 articles were recognized, following the screening and eligibility stages, 9 studies continued to the final sample. Six studies reported that the combination of CAF supplementation with physical exercise exhibited higher HR when compared to the placebo group during post-exercise recovery; additionally, prolonged activation of sympathetic cardiac control and delayed parasympathetic reactivation following exercise was observed. However, three studies demonstrated no CAF influence when using similar doses. This review observed equivocal results in HR and HRV recovery following exercise with the presence of CAF consumption. These findings cannot confirm the cardiac autonomic changes observed where entirely due to the influence of CAF, and further studies should be performed to better understand this relationship.KEY TEACHING POINTSCAF increased HR during exercise and throughout the recovery period.CAF prolonged post exercise sympathetic activity.CAF delayed vagal reactivation.Deviations in HRV and HR are dependent on the combination of three main factors: CAF dosage, type of exercise, and cardiorespiratory fitness.

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Stress induced by driving has been revealed to increase the chances of cardiovascular complications and is involved or related to traffic accidents. In order to develop strategies to avoid health problems during driving we aimed to evaluate the acute effects of auditory stimulation with music on heart rate variability (HRV) during driving in congested urban traffic. This is a prospective cross-sectional randomized controlled pilot study conducted with five healthy women. Subjects were evaluated on two different random days, whose order of execution was established through a randomization process. In the music protocol the volunteers were exposed to music for the entire 20 min of traffic while in the control protocol the subjects performed the same procedures but were not exposed to any music. We noted that all Higuchi fractal dimension parameters except Kmax 10, Kmax 130 and Kmax 140 were reduced between pre-driving in the control protocol vs. driving in the control protocol. The same changes were noted between pre-driving in the music protocol vs. driving in the control protocol. In conclusion, musical auditory stimulation improved nonlinear HRV changes induced by driving.

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INTRODUCTION: The literature concerning the effects of cardiac rehabilitation (CR) on field tests results is inconsistent. PURPOSE: To perform a systematic review with meta-analysis on field tests results after programs of CR. METHODS: Studies published in PubMed and Web of Science databases until May 2016 were analyzed. The standard difference in means correct by bias (Hedges' g) was used as effect size (g) to measure que amount of modifications in performance of field tests after CR period. Potential differences between subgroups were analyzed by Q-test based on ANOVA. RESULTS: Fifteen studies published between 1996 e 2016 were included in the review, 932 patients and age ranged 54,4 - 75,3 years old. Fourteen studies used the six-minutes walking test to evaluate the exercise capacity and one study used the Shuttle Walk Test. The random Hedges's g was 0.617 (P<0.001), representing a drop of 20% in the performance of field test after CR. The meta-regression showed significantly association (P=0.01) to aerobic exercise duration, i.e., for each 1-min increase in aerobic exercise duration, there is a 0.02 increase in effect size for performance in the field test. CONCLUSION: Field tests can detect physical modification after CR, and the large duration of aerobic exercise during CR was associated with a better result.

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Abstract Introduction: The maximal heart rate (HRmax) is considered the highest value of HR achieved during a physical effort close to exhaustion. Objective: To evaluate the applicability of the predictive HRmax equations during exercise tests in child and adolescent athletes through a systematic review. Methods: It is a systematic review, through Scopus, Pubmed, Lilacs, Scielo and PEDro. The included studies compared the measured and estimated HRmax predictive equations during exercise tests in child and adolescent athletes. The following search strategy was used: "Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise capacity OR Heart rate OR Heart rate OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations". Results: From a total of 1,664 articles, only 4 were included. All compared the measured HRmax values with those estimated by the "220 - age" equation; 3 used the formula "208 - (0.7 x age)", and only 1 used the "223 - (1.44 x age)" equation. Although all of them stated that the "220 - age" equation overestimates HRmax, the formula "208 - (0.7 x age") underestimated (2 articles) and overestimated (1 study) the measured results, while the equation "213 - (1.44 x age) was also not adequate. Conclusion: The use of predictive HRmax equations for child and adolescent athletes does not seem to be recommended. The use of cohort points for these estimates is carefully recommended.

Resumo Introdução: A frequência cardíaca máxima (FCmáx) é denominada o maior valor de FC alcançada durante um esforço físico intenso. Objetivo: Avaliar a aplicabilidade das equações preditivas de FCmáx durante testes de exercício em crianças e adolescentes atletas. Métodos: Trata-se de uma revisão sistemática, através do Scopus, Pubmed, Lilacs, Scielo e PEDro. Foram incluídos estudos que compararam a FCmáx medida e a estimada por equações preditivas durante testes de exercício em crianças e adolescentes atletas. Utilizou-se a seguinte estratégia de busca: "Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise tolerance OR Exercise capacity AND Heart rate OR Heart rates OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations". Resultados: De um total de 1664 artigos, apenas 4 foram incluídos. Todos os estudos compararam os valores medidos de FCmáx com os estimados pela equação "220 - idade", 3 utilizaram a fórmula "208 - (0,7 x idade)" e apenas 1 a equação "223 - (1,44 x idade)". Embora todos demonstraram que a equação "220 - idade" superestima a FCmáx, a fórmula "208 - (0,7 x idade") subestimou (2 artigos) e superestimou (1 estudo) os resultados medidos, enquanto a equação "213 - (1,44 x idade) também não foi adequada. Conclusão: O uso de equações preditivas de FCmáx em crianças e adolescentes atletas não parece indicado. Recomenda-se cuidadosamente a utilização de pontos de coorte para essas estimativas.

Resumen Introducción: La frecuencia cardiaca máxima (FCmáx) se denomina el mayor valor de FC alcanzado durante un esfuerzo físico cercano al agotamiento. Objetivo: Evaluar la aplicabilidad de las ecuaciones predictivas de FCmáx durante las pruebas de ejercicio en niños y adolescentes atletas. Métodos: Se trata de una revisión sistemática, a través del Scopus, Pubmed, Lilacs, Scielo y PEDro. Se incluyeron estudios que compararon la FCmáx medida y la estimada por ecuaciones predictivas durante pruebas de ejercicio en niños y adolescentes atletas. Se utilizó la siguiente estrategia de búsqueda: "Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise tolerance OR Exercise capacity AND Heart rate OR Heart rates OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations". Resultados: De un total de 1664 artículos, sólo 4 fueron incluidos. Todos los estudios compararon los valores medidos de FCmáx con los estimados por la ecuación "220 - edad", 3 utilizaron la fórmula "208 - (0,7 x edad)" y sólo 1 la ecuación "223 - (1,44 x edad". Aunque todos demostraron que la ecuación "220 - edad" sobreestima la FCmáx, la fórmula "208 - (0,7 x edad") subestimó (2 artículos) y sobreestimó (1 estudio) los resultados medidos, mientras que la ecuación "213 - (1,44 x edad) tampoco fue adecuada. Conclusión: El uso de ecuaciones predictivas de FCmáx en niños y adolescentes atletas no parece indicado. Se recomienda cuidadosamente el uso de puntos de cohorte para estas estimaciones.

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