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Introduction: Sleep-wake cycle disruption caused by shift work may lead to cardiovascular stress, which is observed as an alteration in the behavior of heart rate variability (HRV). In particular, HRV exhibits complex patterns over different time scales that help to understand the regulatory mechanisms of the autonomic nervous system, and changes in the fractality of HRV may be associated with pathological conditions, including cardiovascular disease, diabetes, or even psychological stress. The main purpose of this study is to evaluate the multifractal-multiscale structure of HRV during sleep in healthy shift and non-shift workers to identify conditions of cardiovascular stress that may be associated with shift work. Methods: The whole-sleep HRV signal was analyzed from female participants: eleven healthy shift workers and seven non-shift workers. The HRV signal was decomposed into intrinsic mode functions (IMFs) using the empirical mode decomposition method, and then the IMFs were analyzed using the multiscale-multifractal detrended fluctuation analysis (MMF-DFA) method. The MMF-DFA was applied to estimate the self-similarity coefficients, α(q, τ), considering moment orders (q) between -5 and +5 and scales (τ) between 8 and 2,048 s. Additionally, to describe the multifractality at each τ in a simple way, a multifractal index, MFI(τ), was computed. Results: Compared to non-shift workers, shift workers presented an increase in the scaling exponent, α(q, τ), at short scales (τ < 64 s) with q < 0 in the high-frequency component (IMF1, 0.15-0.4 Hz) and low-frequency components (IMF2-IMF3, 0.04-0.15 Hz), and with q> 0 in the very low frequencies (IMF4, < 0.04 Hz). In addition, at large scales (τ> 1,024 s), a decrease in α(q, τ) was observed in IMF3, suggesting an alteration in the multifractal dynamic. MFI(τ) showed an increase at small scales and a decrease at large scales in IMFs of shift workers. Conclusion: This study helps to recognize the multifractality of HRV during sleep, beyond simply looking at indices based on means and variances. This analysis helps to identify that shift workers show alterations in fractal properties, mainly on short scales. These findings suggest a disturbance in the autonomic nervous system induced by the cardiovascular stress of shift work.
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Abstract Background: cardiac rehabilitation is a structured program to prevent secondary cardiovascular diseases. Objective: to investigate and compare the effectiveness of home-based cardiac rehabilitation program (HBCRP) on improving cardiovascular stress indices in men and women who had experienced myocardial infarction (MI). Methods: in this randomized controlled clinical trial, 80 patients with MI were divided into two groups of intervention and control (n = 40 per group). Analyses were erformed separately in females and males in the both groups. The HBCRP included receiving routine medications along with walking for 8 weeks. The control group only received the routine care along with counseling about having adequate physical activity. Cardiovascular stress indicators including heart rate at rest (HRrest), maximum heart rate (HRmax), recovery heart rate (RHR)at 1 and 2 minutes after the exercise test (i.e. RHR1 and RHR2), systolic and diastolic blood pressures at rest (SBPR and DBPR), and rate pressure product (RPP) were measured by a researcher blinded to the intervention before and after the test. Results: the results showed significant reductions in RHR1 (p<0.001), RHR2 (p<0.01), SBPR (p<0.01), DBPR (p<0.01), and RPP (p<0.001) in both males and females in the intervention group. A significant increase was also observed in HRmax (p<0.001) in the intervention group. However, there were no significant differences in HRmax and other variables comparing per- and post-experiment values in the control group. Conclusion: our results showed that 8 weeks of HBCRP sex-independently reduced cardiovascular stress indices in both men and women with MI.
Resumen Antecedentes: la rehabilitación cardíaca es un programa estructurado para prevenir las enfermedades cardiovasculares secundarias. Objetivo: estudiar y comparar la efectividad de un programa de rehabilitación cardíaca en casa (HBCRP, por sus siglas en inglés) en la mejoría de los índices de estrés cardiovascular en hombres y mujeres que habían sufrido un infarto de miocardio (IM). Métodos: en este ensayo clínico controlado aleatorizado, 80 pacientes con IM se dividieron en dos grupos de intervención y control (n = 40 en cada grupo). Se realizaron análisis por separado en mujeres y hombres en ambos grupos. El HBCRP incluía la administración de medicamentos de rutina junto con caminatas por 8 semanas. El grupo de control solo recibió tratamiento de rutina junto con orientación acerca de la realización de actividad física adecuada. Un investigador cegado a la intervención midió los indicadores de estrés cardiovascular incluyendo frecuencia cardíaca en reposo (FCrep), frecuencia cardíaca máxima (FCmax), recuperación de la frecuencia cardíaca (RFC) 1 y 2 minutos después de la prueba de ejercicio (i.e. RFC1 y RFC2), tensión arterial sistólica y diastólica en reposo (TASR y TADR) y producto frecuencia-presión (PFP), antes y después de la prueba. Resultados: los resultados mostraron una reducción significativa en RFC1 (p<0.001), RFC2 (p<0.01), TASR (p<0.01), TADR (p<0.01), y PFP (p<0.001), tanto en hombres como en mujeres del grupo de intervención. También se observó un aumento significativo en FCmax (p<0.001) en el grupo de intervención. Sin embargo, no hubo diferencias significativas en FCmax y otros variables al comparar los valores pre- y post-experimentales en el grupo control. Conclusión: nuestros resultados mostraron que 8 semanas de HBCRP redujeron los índices de estrés cardiovascular independientemente del sexo, tanto en hombres como en mujeres con IM.
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Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Reabilitação Cardíaca , Estresse Fisiológico , Infarto do MiocárdioRESUMO
Background and Objectives: Hemodynamic stress during resistance training is often a reason why this training method is not used in cardiac patients. A lifting protocol that imposes rests between repetitions (IRRT) may provide less hemodynamic stress compared to traditional resistance training (TT). The aim of this study was to verify differences between set configurations on hemodynamic stress responses in resistance training. Materials and Methods: We compared hemodynamic (heart rate (HR), systolic blood pressure (SBP), and rate pressure product (RPP)) responses assessed with the auscultatory method in elderly (age = 75.3 ± 7.3 years) coronary male patients who were participating in a cardiac rehabilitation program allocated to either TT or IRRT with the same load (kg) and total number of repetitions (24) in the bilateral leg extension exercise. Results: IRRT resulted in significant lower values than TT for RPP at repetitions 8 (p = 0.024; G = 0.329; 95% CI: 0.061, 0.598) and 16 (p = 0.014; G = 0.483; 95% CI: 0.112, 0.854). Conclusions: IRRT appears to be a viable method of reducing the hemodynamic response (i.e., RPP) to resistance training and, thus, may contribute to the safety of cardiac rehabilitation programs. Further studies with more cardiac patients and other measurement techniques should be conducted to confirm these important findings.
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Síndrome Coronariana Aguda/complicações , Treinamento Resistido/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Feminino , Humanos , Masculino , Treinamento Resistido/métodos , Estresse Fisiológico/fisiologiaRESUMO
The potent and now longstanding evidence of the association between placentation-related disorders and cardiovascular disease should be translated into clinical practice in order to introduce a preventive approach to future obstetric and cardiovascular diseases. The purpose of this review is to integrate cardiovascular risk/disease and obstetric complications, which are linked by endothelial dysfunction, as windows of opportunity for improving women's health. Questionnaires adaptable to local practices are proposed to incorporate cardiovascular and obstetrical indexes into two stages of a woman's lifetime.
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The aim of this study was to examine the influence of physical fitness on cardiac autonomic control in passengers prior to, during and following commercial flights. Twenty-two, physically active men (36.4 ± 6.4 years) undertook assessments of physical fitness followed by recordings of 24-h heart rate (HR), heart rate variability (HRV), and blood pressure (BP) on a Control (no flight) and Experimental (flight) day. Recordings were analyzed using a two-way analysis of variance for repeated measures with relationships between variables examined via Pearson product-moment correlation coefficients. Compared to the Control day, 24-h HR was significantly greater (>7%) and HRV measures (5-39%) significantly lower on the Experimental day. During the 1-h flight, HR (24%), and BP (6%) were increased while measures of HRV (26-45%) were reduced. Absolute values of HRV during the Experimental day and relative changes in HRV measures (Control-Experimental) were significantly correlated with measures of aerobic fitness (r = 0.43 to 0.51; -0.53 to -0.52) and body composition (r = -0.63 to -0.43; 0.48-0.61). The current results demonstrated that short-term commercial flying significantly altered cardiovascular function including the reduction of parasympathetic modulations. Further, greater physical fitness and lower body fat composition were associated with greater cardiac autonomic control for passengers during flights. Enhanced physical fitness and leaner body composition may enable passengers to cope better with the cardiovascular stress and high allostatic load associated with air travel for enhanced passenger well-being.