Contingent Negative Variation in the Evaluation of Neurocognitive Disorders Due to Possible Alzheimer's Disease.

The usefulness of Contingent Negative Variation (CNV) potential as a biomarker of neurocognitive disorders due to possible Alzheimer's disease, is based on its possible physiological correlates. However, its application in the diagnostic evaluation of these disorders is still incipient. The aim of this study is to characterize the patterns of cognitive processing of information in the domain of nonspecific global attention, by recording potential CNV in a group of patients with neurocognitive disorders due to possible Alzheimer's disease. An experimental study of cases and controls was carried out. The sample included 39 patients classified according to DSM-5 with a neurocognitive disorder subtype possibly due Alzheimer's disease, and a Control Group of 53 subjects with normal cognitive functions. CNV potential was registered using standard protocol. The analysis of variance obtained significant differences in mean values and confidence intervals of total CNV amplitude between the three study groups. The late CNV segment amplitudes makes it possible to discriminate between the level of mild and major dysfunction in the group of patients. The CNV total amplitudes of potential allows for effective discrimination between normal cognitive functioning and neurocognitive disorders due to possible Alzheimer's disease.

The Relationship between Paresthesia and the Presence of Cardiac Dysautonomia in Patients with Post-COVID-19 Syndrome: A Preliminary Observational Study.

INTRODUCTION: Post-Coronavirus disease 2019 (Post-COVID-19) syndrome has neurological symptoms related to the dysfunction of the autonomous nerve system. However, a pathogenic relationship between post-COVID-19 syndrome and dysautonomia still remains to be demonstrated. Establishing a pathogenic relationship between paresthesia and the presence of cardiac dysautonomia in patients with post-COVID-19 syndrome is the objective of this study. PARTICIPANTS AND METHODS: This observational study was carried out in the neurophysiology service wing of the Juan Bruno Zayas Hospital, Santiago de Cuba, in Cuba. The patients were recruited through a post-COVID-19 clinic at the same hospital. A variability study of cardiac frequency and a test of autonomic cardiovascular reflexes was carried out, which is composed of deep breathing, orthostatism, and the Valsalva maneuver. RESULTS: The variability parameters of the cardiac frequency, the expiration-inspiration ratio between deep breaths, and the Valsalva Index showed no statistically significant differences between healthy participants and those with post-COVID-19 syndrome. During the Valsalva maneuver, there was a greater cardiac frequency response in participants with post-COVID-19 syndrome than in healthy subjects. The difference in supine and standing blood pressure was significantly minor in patients with post-COVID-19 syndrome. The logarithm of high frequency (log HF) increased significantly in patients with paresthesia when compared to patients without paresthesia. CONCLUSIONS: In the autonomic function tests, no signs of dysautonomia were found in patients with post-COVID-19 syndrome. The presence of paresthesias is associated with differences in cardiac vagal activity, which may suggest that damage to peripheral sensory nerve fibers could be associated with an affectation to autonomic fibres.

Autonomic and Vascular Responses during Reactive Hyperemia in Healthy Individuals and Patients with Sickle Cell Anemia.

Background and Objectives: To compare autonomic and vascular responses during reactive hyperemia (RH) between healthy individuals and patients with sickle cell anemia (SCA). Materials and Methods: Eighteen healthy subjects and 24 SCA patients were subjected to arterial occlusion for 3 min at the lower right limb level. The pulse rate variability (PRV) and pulse wave amplitude were measured through photoplethysmography using the Angiodin® PD 3000 device, which was placed on the first finger of the lower right limb 2 min before (Basal) and 2 min after the occlusion. Pulse peak intervals were analyzed using time-frequency (wavelet transform) methods for high-frequency (HF: 0.15-0.4) and low-frequency (LF: 0.04-0.15) bands, and the LF/HF ratio was calculated. Results: The pulse wave amplitude was higher in healthy subjects compared to SCA patients, at both baseline and post-occlusion (p < 0.05). Time-frequency analysis showed that the LF/HF peak in response to the post-occlusion RH test was reached earlier in healthy subjects compared to SCA patients. Conclusions: Vasodilatory function, as measured by PPG, was lower in SCA patients compared to healthy subjects. Moreover, a cardiovascular autonomic imbalance was present in SCA patients with high sympathetic and low parasympathetic activity in the basal state and a poor response of the sympathetic nervous system to RH. Early cardiovascular sympathetic activation (10 s) and vasodilatory function in response to RH were impaired in SCA patients.

Discriminant Model for Insulin Resistance in Type 2 Diabetic Patients.

Introduction: Patients with type 2 diabetes mellitus tend to have insulin resistance, a condition that is evaluated using expensive methods that are not easily accessible in routine clinical practice. Objective: To determine the anthropometric, clinical, and metabolic parameters that allow for the discrimination of type 2 diabetic patients who have insulin resistance from those who do not. Methods: A cross-sectional analytical observational study was carried out in 92 type 2 diabetic patients. A discriminant analysis was applied using the SPSS statistical package to establish the characteristics that differentiate type 2 diabetic patients with insulin resistance from those without it. Results: Most of the variables analyzed in this study have a statistically significant association with the HOMA-IR. However, only HDL-c, LDL-c, glycemia, BMI, and tobacco exposure time allow for the discrimination of type 2 diabetic patients who have insulin resistance from those who do not, considering the interaction between them. According to the absolute value of the structure matrix, the variable that contributes most to the discriminant model is HDL-c (-0.69). Conclusions: The association between HDL-c, LDL-c, glycemia, BMI, and tobacco exposure time allows for the discrimination of type 2 diabetic patients who have insulin resistance from those who do not. This constitutes a simple model that can be used in routine clinical practice.

Reactive Hyperemia and Cardiovascular Autonomic Neuropathy in Type 2 Diabetic Patients: A Systematic Review of Randomized and Nonrandomized Clinical Trials.

Objective: This work aimed to determine the relationship between the autonomic nervous system and reactive hyperemia (RH) in type 2 diabetes patients with and without cardiovascular autonomic neuropathy (CAN). Methodology: A systematic review of randomized and nonrandomized clinical studies characterizing reactive hyperemia and autonomic activity in type 2 diabetes patients with and without CAN was performed. Results: Five articles showed differences in RH between healthy subjects and diabetic patients with and/or without neuropathy, while one study did not show such differences between healthy subjects and diabetic patients, but patients with diabetic ulcers had lower RH index values compared to healthy controls. Another study found no significant difference in blood flow after a muscle strain that induced reactive hyperemia between normal subjects and non-smoking diabetic patients. Four studies measured reactive hyperemia using peripheral arterial tonometry (PAT); only two found a significantly lower endothelial-function-derived measure of PAT in diabetic patients than in those without CAN. Four studies measured reactive hyperemia using flow-mediated dilation (FMD), but no significant differences were reported between diabetic patients with and without CAN. Two studies measured RH using laser Doppler techniques; one of them found significant differences in the blood flow of calf skin after stretching between diabetic non-smokers and smokers. The diabetic smokers had neurogenic activity at baseline that was significantly lower than that of the normal subjects. The greatest evidence revealed that the differences in RH between diabetic patients with and without CAN may depend on both the method used to measure hyperemia and that applied for the ANS examination as well as the type of autonomic deficit present in the patients. Conclusions: In diabetic patients, there is a deterioration in the vasodilator response to the reactive hyperemia maneuver compared to healthy subjects, which depends in part on endothelial and autonomic dysfunction. Blood flow alterations in diabetic patients during RH are mainly mediated by sympathetic dysfunction. The greatest evidence suggests a relationship between ANS and RH; however, there are no significant differences in RH between diabetic patients with and without CAN, as measured using FMD. When the flow of the microvascular territory is measured, the differences between diabetics with and without CAN become evident. Therefore, RH measured using PAT may reflect diabetic neuropathic changes with greater sensitivity compared to FMD.

Temporal inequality of RR intervals like a new psychophysiological indicator of mental stress / Desigualdad temporal de los intervalos RR como nuevo indicador psicofisiológico de estrés mental / Desigualdade temporal de intervalos RR como um novo indicador psicofisiológico de estresse mental

Introduction: Gini coefficient (Gini index or Gini ratio) is a parameter that is normally used in economy to measure the income distribution in a country or in the whole wide world, but it can be used to measure any kind of distribution. In the present study it is exposed an innovative proposal of application of the Gini coefficient to Heart Rate Variability (HRV) like a psychophysiological indicator of mental stress. Purpose: To assess the application of the Gini coefficient as a psychophysiological indicator of mental stress. Methods: The involved participants are 13 healthy individuals (age 19 ± 1.5 years). Heart rate was continuously recorded at rest (5 minutes) and during a mental stress (5 minutes). Linear and nonlinear methods of heart rate variability were assessed, and 2 new indicators (Sequential and Non-Sequential Gini) were calculated and proposed to measure HRV differences between states. Results: When comparing rest and mental stress conditions, a sensible decrease of the traditional indicators of the HRV was founded (p<0.05), an increase of the heart rate (p=0.004) and of the Sequential Gini (p=0.004) and Non-Sequential Gini (p=0.04). Conclusions: The results suggest that temporary inequality of the RR intervals analyzed from the Gini coefficient could be an adequate indicator of sympathetic activity present during the mental stress, with great potentialities with the objective to assess the consequences of psychosomatic affections and anxiety disorders.

Introducción: El coeficiente de Gini o índice de Gini es un parámetro que normalmente se usa en economía para medir la distribución del ingreso en un país o en todo el mundo, pero puede usarse para medir cualquier tipo de distribución. En el presente estudio se expone una propuesta innovadora de aplicación del coeficiente de Gini a la Variabilidad de la Frecuencia Cardíaca (VFC) como indicador psicofisiológico del estrés mental. Objetivo: Evaluar la aplicación del coeficiente de Gini como indicador psicofisiológico de estrés mental. Métodos: Los participantes involucrados son 13 individuos sanos (edad 19 ± 1,5 años). La frecuencia cardíaca se registró continuamente en reposo (5 minutos) y durante un estrés mental (5 minutos). Se evaluaron métodos lineales y no lineales de variabilidad de la frecuencia cardíaca, y se calcularon y propusieron 2 nuevos indicadores (Gini secuencial y no secuencial) para medir las diferencias de VFC entre estados. Resultados: Al comparar las condiciones de reposo y estrés mental, se encontró una sensible disminución de los indicadores tradicionales de la VFC (p<0,05), un aumento de la frecuencia cardiaca (p=0,004) y del Gini Secuencial (p=0,004) y Gini no secuencial (p=0,04). Conclusiones: Los resultados sugieren que la desigualdad temporal de los intervalos RR analizados a partir del coeficiente de Gini podría ser un indicador adecuado de la actividad simpática presente durante el estrés mental, con grandes potencialidades en la evaluación las consecuencias de afecciones psicosomáticas y trastornos de ansiedad.

Introdução: O coeficiente de Gini ou índice de Gini é um parâmetro normalmente usado em economia para medir a distribuição de renda em um país ou no mundo, mas pode ser usado para medir qualquer tipo de distribuição. No presente estudo, apresenta-se uma proposta inovadora de aplicação do coeficiente de Gini à Variabilidade da Frequência Cardíaca (VFC) como indicador psicofisiológico de estresse mental.Objetivo: Avaliar a aplicação do coeficiente de Gini como indicador psicofisiológico de estresse mental.Métodos: Os participantes envolvidos são 13 indivíduos saudáveis ​​(idade 19 ± 1,5 anos). A frequência cardíaca foi registrada continuamente em repouso (5 minutos) e durante o estresse mental (5 minutos). Métodos lineares e não lineares de variabilidade da frequência cardíaca foram avaliados e 2 novos indicadores (gini sequencial e não sequencial) foram calculados e propostos para medir as diferenças na VFC entre os estados.Resultados: Ao comparar as condições de repouso e estresse mental, foi encontrada diminuição significativa nos indicadores tradicionais da VFC (p<0,05), aumento da frequência cardíaca (p=0,004) e do Gini Sequencial (p= 0,004) e não - Gini sequencial (p=0,04).Conclusões: Os resultados sugerem que a desigualdade temporal dos intervalos RR analisados ​​a partir do coeficiente de Gini pode ser um indicador adequado da atividade simpática presente durante o estresse mental, com grande potencial na avaliação das consequências de condições psicossomáticas e transtornos de ansiedade.

Early cardiovascular sympathetic reflex activation is independent of occlusion time during reactive hyperemia / La activación temprana del reflejo simpático cardiovascular es independiente del tiempo de oclusión durante la hiperemia reactiva / A ativação precoce do reflexo simpático cardiovascular é independente do tempo de oclusão durante a hiperemia reativa

Purpose: The aim of the present study was to investigate the role of occlusion time in dynamic changes of autonomic activation during reactive hyperemia. Methods: Healthy subjects (n = 30) in the age range of 18­25 years participated in this study. Vascular reactivity was assessed by measuring the dynamic changes in finger pulse volume amplitude (PVA) and  pulse transit time relative to the RR intervals in the test (occluded arm) and control arm (contralateral non-occluded arm) during 1, 3 and 5 minute of occlusion using two separate Photoplethysmographic sensors. Heart Rate Variability was computed from a simultaneously acquired ECG signal to monitor the dynamic changes in cardiac autonomic nervous activity. Time-varying analysis of all signals were shown every 1 second in average response graphs. Results: Time-varying analysis of vascular and autonomic response during reactive hyperemia demonstrated the presence of a characteristic response pattern with an increase in the Sympathetic index and a decrease in Parasympathetic index at 8 to 10 seconds, an increase in heart rate at 20 seconds and a progressive increase in PVA during the first 60 seconds after occlusion regardless of the time spent in the procedure. Moreover, a decrease in pulse transits time relative to RR intervals,  followed by an increase regardless of the occlusion time was evidenced.  Conclusions: Early cardiovascular sympathetic activation is independent of occlusion time during reactive hyperemia, which suggests this is a vascular autonomic reflex response involved in the generation of the physiological phenomenon of reactive hyperemia.

Objetivo: El objetivo del presente estudio fue investigar el papel del tiempo de oclusión en los cambios dinámicos de la activación autónoma durante la hiperemia reactiva.Métodos: Participaron en este estudio sujetos sanos (n = 30) en el rango de edad de 18 a 25 años. La reactividad vascular se evaluó midiendo los cambios dinámicos en la amplitud del volumen del pulso del dedo (PVA) y el tiempo de tránsito del pulso en relación con los intervalos RR en la prueba (brazo ocluido) y el brazo de control (brazo contralateral no ocluido) durante 1, 3 y 5 minutos. de oclusión utilizando dos sensores fotopletismográficos separados. La variabilidad de la frecuencia cardíaca se calculó a partir de una señal de ECG adquirida simultáneamente para controlar los cambios dinámicos en la actividad nerviosa autónoma cardíaca. El análisis variable en el tiempo de todas las señales se mostró cada segundo en gráficos de respuesta promedio.Resultados: El análisis variable en el tiempo de la respuesta vascular y autonómica durante la hiperemia reactiva demostró la presencia de un patrón de respuesta característico con un aumento en el índice simpático y una disminución en el índice parasimpático a los 8 a 10 segundos, un aumento en la frecuencia cardíaca a los 20 segundos y un aumento progresivo de PVA durante los primeros 60 segundos después de la oclusión independientemente del tiempo transcurrido en el procedimiento. Además, se evidenció una disminución en el tiempo de tránsitos del pulso en relación con los intervalos RR, seguido de un aumento independientemente del tiempo de oclusión.Conclusiones: La activación simpática cardiovascular temprana es independiente del tiempo de oclusión durante la hiperemia reactiva, lo que sugiere que se trata de una respuesta refleja autonómica vascular involucrada en la generación del fenómeno fisiológico de hiperemia reactiva.

Objetivo: O objetivo do presente estudo foi investigar o papel do tempo de oclusão nas mudanças dinâmicas da ativação autonômica durante a hiperemia reativa.Métodos: Participaram deste estudo indivíduos saudáveis ​​(n = 30) na faixa etária de 18 a 25 anos. A reatividade vascular foi avaliada medindo as mudanças dinâmicas na amplitude do volume do pulso do dedo (PVA) e tempo de trânsito do pulso em relação aos intervalos RR no teste (braço ocluído) e braço controle (braço não ocluído contralateral) durante 1, 3 e 5 minutos de oclusão usando dois sensores fotopletismográficos separados. A variabilidade da frequência cardíaca foi calculada a partir de um sinal de ECG adquirido simultaneamente para monitorar as mudanças dinâmicas na atividade nervosa autonômica cardíaca. A análise variável no tempo de todos os sinais foi mostrada a cada 1 segundo em gráficos de resposta média.Resultados: A análise variável no tempo da resposta vascular e autonômica durante a hiperemia reativa demonstrou a presença de um padrão de resposta característico com um aumento no índice simpático e uma diminuição no índice parassimpático em 8 a 10 segundos, um aumento na frequência cardíaca em 20 segundos e aumento progressivo do PVA durante os primeiros 60 segundos após a oclusão, independentemente do tempo despendido no procedimento. Além disso, foi evidenciada uma diminuição no tempo de trânsito de pulso em relação aos intervalos RR, seguida de um aumento independente do tempo de oclusão.Conclusões: A ativação simpática cardiovascular precoce independe do tempo de oclusão durante a hiperemia reativa, o que sugere que se trata de uma resposta reflexa autonômica vascular envolvida na geração do fenômeno fisiológico de hiperemia reativa.

Dynamics of cardiac autonomic regulation during isometric sustained weight test in hypertensive patients

Background: The Sustained Weight Test (SWT) is an isometric exercise test that has great practical value for carrying out massive studies on hypertension, however, is insufficient knowledge of the dynamics of cardiac autonomic regulation during this test. The aim of this study was to determine variations in the dynamics of cardiac autonomic regulation and in hemodynamic response during SWT in hypertensive subjects. Methods: A quasi-experimental study was conducted on 15 hypertensive patients of both sexes, paired with 30 normotensive individuals, measuring arterial blood pressure, entropy sample and the Heart Rate Variability (HRV) in time-frequency with the Continuous Wavelet Transform Morlet-type (CWT  morlet) through the electrocardiographic signal of the polygraph AD Instruments in the functional states of Rest and SWT. Results: A significant increase in heart rate and blood pressure was found, as well as a decrease in sample entropy in the functional states of normotensive and hypertensive patients. In hypertensive patients, an early response pattern increased with multiple fluctuations during SWT in the time-frequency analysis of HRV with the CWT morlet. Conclusions: SWT produces an increase in blood pressure, which is more frequent and evident in hypertensive subjects. Cardiac autonomic regulation during SWT increases the sympathetic and decreases the parasympathetic components, manifesting itself in hypertensive patients with a pattern of imbalance in the regulation of both sympathetic and parasympathetic response.

Influence of the emotional alterations in the arterial stiffness index and cardiovascular risk of pre-hypertensive patients

Purpose: To determine the influence of emotional alterations in the arterial stiffness index and cardiovascular risk of pre-hypertensive patients.Methods: A cross-sectional study was carried out in 48 pre-hypertensive patients. Emotional alterations, global cardiovascular risk and arterial stiffness index were evaluated. The PPG technique was used to record the arterial pulse wave in the first finger of the lower right limb, using the ANGIODIN® digital plethysmograph.Results: Pre-hypertensive patients with emotional alterations had major Weight, Body Mass Index, systolic blood pressure, diastolic blood pressure and arterial stiffness index with respect to patients who did not find emotional alterations. In pre-hypertensive patients, 58.3% presented a positive Cornell test, 39.6% of them female, and 18.8% male. There was a significant relationship (p<0.001) between the presence of emotional disturbances and moderate cardiovascular risk.Conclusions: Emotional alterations in pre-hypertensive patients is associated with an increase in arterial stiffness and an increased global cardiovascular risk.

Respuesta autonómica cardiovascular al estrés mental inducido por la prueba de cálculo aritmético / Autonomic cardiovascular response to mental stress induced by the arithmetic computation test

Introducción: El estrés mental agudo, así como los estados de ansiedad inducidos para influenciar la reactividad psicofisiológica en jóvenes sanos, aportan cambios en los patrones nerviosos que pueden ser medidos mediante la variabilidad de la frecuencia cardiaca. Objetivo: Determinar las diferencias en los parámetros lineales del balance autonómico cardiovascular en individuos jóvenes en estado basal y durante la prueba de cálculo aritmético. Métodos: Se realizó un estudio cuasi-experimental, sin grupo control de tipo antes y después, en el Laboratorio de Ciencias Básicas Biomédicas de la Universidad de Ciencias Médicas de Santiago de Cuba. Población y muestra de 10 sujetos. Se registró el trazado electrocardiográfico (5 min) durante el reposo y luego durante la prueba de cálculo aritmético. Resultados: Existieron diferencias significativas entre ambos estados en las variables frecuencia cardiaca (p = 0,005); mínima (p = 0,007); máxima (p = 0,005); intervalo RR (p = 0,005); stress index (p = 0,028); índice simpático (p = 0,005); bajas frecuencias (p = 0,005); relación LF/HF (p = 0,005); RMSSD (p = 0,007); NN50 (p = 0,008); pNN50 (p = 0,005); índice parasimpático (p = 0,005) y altas frecuencias (p = 0,005). El estrés mental provocó una disminución parasimpática y un predominio simpático uniforme en todos los sujetos participantes en el estudio. Conclusiones: Durante el estrés mental inducido por la prueba de cálculo aritmético la dinámica lineal de la respuesta autonómica cardiovascular experimenta un aumento en la actividad simpática y una disminución del tono parasimpático, traduciendo una respuesta adaptativa en la regulación de la función cardiovascular por el sistema nervioso autónomo(AU)

Introduction: Acute mental stress and states of anxiety induced to influence psychophysiological reactivity in healthy young people, result in changes in nervous patterns which may be measured in terms of heart rate variability. Objective: Determine the differences in linear parameters for autonomic cardiovascular balance in young individuals at baseline and during the arithmetic computation test. Methods: A non-observational quasi-experimental before-after study without a control group was conducted at the Basic Biomedical Sciences Laboratory of the University of Medical Sciences of Santiago de Cuba. The study population and sample was 10 subjects. The electrocardiographic tracing (5 min) was recorded at rest and then during the arithmetic computation test. Results: Significant differences were found between the two states as to the variables heart rate (p = 0.005), minimum (p = 0.007), maximum (p = 0.005), RR interval (p = 0.005), stress index (p = 0.028), sympathetic index (p = 0.005), low frequencies (p = 0.005), LF/HF ratio (p = 0.005), RMSSD (p = 0.007), NN50 (p = 0.008), pNN50 (p = 0.005), parasympathetic index (p = 0.005) and high frequencies (p = 0.005). Mental stress caused a parasympathetic reduction and uniform sympathetic predominance in all the subjects participating in the study. Conclusions: During the mental stress induced by the arithmetic computation test, the linear dynamic of the autonomic cardiovascular response experiences an increase in sympathetic activity and a reduction in parasympathetic tone, displaying an adaptive response in cardiovascular function regulation by the autonomous nervous system(AU)

Diferencias en los parámetros lineales del balance autonómico basal entre estudiantes de medicina y atletas juveniles de béisbol / Differences in linear parameters of the basal autonomic balance between medical students and young baseball players

RESUMEN Introducción: La modulación autonómica cardiovascular puede ser considerada como una herramienta útil en la determinación del estado fisiológico de la interacción entre los sistemas nervioso autónomo y cardiovascular. Objetivo: Determinar las diferencias en los parámetros lineales del balance autonómico basal entre estudiantes de medicina y atletas juveniles de béisbol. Método: Se realizó un estudio analítico de tipo transversal en el Laboratorio de Ciencias Básicas Biomédicas de la Facultad Nº. 1 de la Universidad de Ciencias Médicas de Santiago de Cuba. Universo y muestra de 36 individuos (Grupo 1: 18 atletas juveniles de béisbol de alto rendimiento, Grupo 2: 18 estudiantes de medicina). Los datos fueron recolectados mediante de polígrafo PowerLab de 8 canales, y fueron procesados usando el software Kubios® versión 3.0.4 Premium. Resultados: Existieron diferencias significativas en los valores de pNN50 (p=0,009), índice de estrés (stress index [p=0,044]), y en los índices parasimpático (p=0,005) y simpático (p=0,001) entre estudiantes y atletas. La capacidad discriminatoria del índice parasimpático para asociarse con la mejor forma física de los atletas fue buena (área bajo la curva 0,784). El punto de corte óptimo por encima del cual el índice parasimpático se asocia al grupo de los atletas, quedó establecido en 0,57. Conclusiones: El índice parasimpático se asoció con el grupo de atletas, lo que evidencia el predominio vagal en la modulación de la actividad cardíaca en los sujetos de este grupo.

ABSTRACT Introduction: Cardiovascular autonomic modulation can be considered a useful tool in determining the physiological state of the interaction between the autonomic nervous system and the cardiovascular system. Objective: To determine the differences in linear parameters of the basal autonomic balance between medical students and young baseball players. Method: A cross-sectional analytical study was carried out in the Biomedical Basic Sciences Laboratory, Faculty No.1, of the Universidad de Ciencias Médicas in Santiago de Cuba. The population and sample consisted of 36 individuals (Group 1: 18 high-performance young baseball athletes, Group 2: 18 medical students). Data was collected using an 8-channel PowerLab polygraph and it was processed using the Kubios® Software version 3.0.4 Premium. Results: There were significant differences in the values between students and athletes: pNN50 (p=0.009), stress index (p=0.044) and in parasympathetic (p=0.005) and sympathetic (p=0.001) indexes. The discriminatory ability of the parasympathetic index to be associated with the best physical fitness of the athletes was good (area under the curve 0.784). The optimum cut-off point above which the parasympathetic index is associated with the group of athletes was set at 0.57. Conclusions: The parasympathetic index was associated with the group of athletes, showing the vagal predominance in the modulation of cardiac activity in the individuals belonging to this group.

Modifications of the non-linear parameters of the heart rate variability related to the systematic practice of physical exercise

Introduction: In recent years, the relationship between the systematic practice of physical exercise, cardiovascular dynamics and the functioning of the autonomic nervous system has been recognized. Objective: To determine the modifications that non-linear parameters undergo in the autonomic cardiovascular regulation of the heart rate variability with the systematic practice of physical exercise. Methods: A retrospective cohort analytical study was conducted from February 2016 to August 2018. Population and sample: 36 individuals (Group 1: 18 high- performance baseball athletes; Group 2: 18 medical students). The data were collected in the Biomedical Basic Sciences Laboratory at Medical school 1, University of Santiago de Cuba, through the 8-channel PowerLab polygraph, and stored using the Kubios Software version 3.0.4 Premium. Results: Statistically significant differences between means were found in heart rate values (p = 0.000); SD1 (p = 0.025); SD2/SD1 ratio (p = 0.007); sample entropy (p = 0.011); short-term fluctuations α 1 (p = 0.019); mean line length (p = 0.016); max line length (p = 0.001); recurrence rate (p = 0.034); determinism (p = 0.010) and Shannon entropy (p = 0.015). The parameters of SD1 (C = 0.906) and sample entropy (C = 0.712) were significantly associated with a heart rate ≤ 70 beats per minute. Conclusions: With the systematic practice of physical exercise, the non-linear parameters of the autonomic cardiovascular regulation of the heart rate variability undergoes modifications that respond to a better adaptability of the autonomic nervous system, and to a greater capacity to regulate cardiovascular function(AU)

Respuesta autonómica cardiovascular durante la prueba isométrica cubana del peso sostenido / Cardiovascular autonomic response during the Cuban dynamic weight-bearing test

RESUMEN Introducción: La prueba del peso sostenido (PPS) es un ejercicio isométrico cubano, similar a la de handgrip, de mucha utilidad para inducir modificaciones hemodinámicas que permiten identificar la hiperreactividad cardiovascular en poblaciones de riesgo. Sin embargo, los cambios en la respuesta autonómica cardiovascular durante la PPS no se encuentran totalmente dilucidados. Objetivo: Determinar la respuesta autonómica cardiovascular durante la prueba isométrica cubana del peso sostenido. Método: Estudio cuasi-experimental (crossover) con 16 sujetos sanos, donde se evaluaron la presión arterial y la variabilidad de la frecuencia cardíaca, 5 minutos antes (reposo) y durante la PPS (2 minutos de maniobra y 3 minutos de recuperación), a través del análisis frecuencial (Fourier) y en tiempo-frecuencia (wavelet) de las bandas de altas (HF: 0,15-0,4 Hz) y bajas frecuencias (LF: 0,04-0,15 Hz), así como el análisis temporal y no-lineal (entropía de Shannon) de la serie de intervalos RR. Resultados: Aunque no existieron diferencias significativas (p>0,05) en los indicadores temporales (SDNN, RMSSD, pNN50), ni en los frecuenciales (LF, HF, LF/HF), se encontraron incrementos (p<0,05) de la presión arterial y una disminución significativa (p<0,05) de la complejidad (entropía) en la PPS con respecto al reposo, asociados con un pico en la LF y la relación LF/HF alrededor de los 2 minutos reflejados con los métodos en tiempo-frecuencia. Conclusiones: Existió un incremento dinámico en la respuesta simpática cardiovascular durante la PPS que se asocian a una disminución de la complejidad de este proceso fisiológico, lo que no es evidente con los métodos lineales tradicionales de la variabilidad de la frecuencia cardíaca.

ABSTRACT Introduction: The dynamic weight-bearing test (WBT) is a Cuban isometric exercise, similar to the hand grip test, which is very useful to induce hemodynamic modifications to identify cardiovascular hyperreactivity in at-risk populations. However, changes in the cardiovascular autonomic response during weight-bearing test are poorly understood. Objective: To determine the cardiovascular autonomic response during the Cuban dynamic WBT. Method: Quasi-experimental crossover trial with 16 healthy subjects; blood pressure and heart rate variability were assessed, 5 minutes before (rest) and during the WBT (2 minutes for maneuver and 3 minutes for recovery), through the frequency (Fourier) and time-frequency (Wavelet) analysis of high-frequency (HF: 0.15-0.4 Hz) and low-frequency (LF: 0.04-0.15 Hz) bands, as well as temporal and non-linear analysis (Shannon entropy) of the RR interval series. Results: Although temporal indicators (SDNN, RMSSD, pNN50) showed no significant differences (p>0.05) nor the frequencies (LF, HF, LF/HF); we found an increase (p<0.05) in blood pressure and a significant decrease (p<0.05) in complexity (entropy) in the WBT with respect to rest, associated with an HF peak and LF/HF ratio at nearly 2 minutes reflected with the time-frequency methods. Conclusions: There was a dynamic increase in the cardiovascular sympathetic response during the WBT associated with a decrease in the complexity of this physiological process, which is not evident with the traditional linear methods of heart rate variability.