Comprehensive cardiac evaluation to maximal exercise in a contemporary population of prepubertal children.

BACKGROUND: Heart rate (HR) is a biomarker used to measure physiological function, health status and cardiovascular autonomic function. The purpose of this study was to determine sex- and age-specific reference values for cardiac autonomic function at rest, during maximal exercise and the recovery phase in prepubertal children. METHODS: Five hundred and twelve healthy children 7-11 years of age performed a Léger test. A heart RR-interval monitor recorded the heart data and a specific software analysed the cardiac autonomic response through HR and HR variability (HRV). It analysed HR before the test (resting HR, RHR), during the test (HRpeak) and HR recovery (HRR) in the first minute (HRR1) and the fifth minute (HRR5). The values are mean ± SD. RESULTS: Collectively, 91.2% of girls and 92.3% of boys were within the recommended ranges regarding RHR. The average HRpeak was 199 ± 10.83 b.p.m. and 96.8% of girls and 95.3% of boys were within the minimum threshold value recommended (180 b.p.m.). Boys showed lower values of RHR than girls (p < 0.001) and larger values of HRR 1 and HRR5 (p < 0.001). CONCLUSIONS: This study comprehensively provides a reference set of data for the most important HR variables that can be obtained during exercise testing in prepubertal children regarding age and sex and in a field setting. IMPACT: This is the first study to provide reference values of autonomic cardiac function at rest, during maximal exercise and during the recovery period in prepubertal children aged 7-11 years. Despite the early age of participants, cardiorespiratory fitness, RHR and HRR are different according to sex. Aerobic performance and HRpeak have a negative correlation with body mass index and cardiometabolic risk.

Sex Differences in the Glycemic Response to Structured Exercise Interventions in Adults with Type II Diabetes Mellitus: A Systematic Review.

Despite physiological sex differences in the prevalence, pathogenesis, and responses to pharmacologic therapies of glucose metabolism in type 2 diabetes mellitus (T2DM) and the current evidence regarding the benefits of physical activity in people with T2DM, there is still a lack of information about the response to physical activity in T2DM depending on the sex. Thus, the aim of the present systematic review was to analyze the physiological sex differences response to physical activity programs in adults with T2DM. A systematic review following PRISMA guidelines was performed up to 4th January 2022 in PubMed, SportDiscus and Web of Science databases. The research protocol of this systematic review was registered in PROSPERO (CRD42020189020). The PEDro scale and Cochrane risk of bias tools were used to analyze the quality and risk of bias of the studies included. Glycaemic (blood glucose, HbA1c, AUC glycemia, metabolic clearance rate, QUICKI) insulin (HOMA-IR, insulin levels, C-peptide) and cardiovascular parameters (VO2max, body fat mass, waist circumference, cardiovascular index) were registered. 6 studies met the inclusion criteria. Physical activity showed improvements in the glycaemic and insulin profiles and cardiovascular risk parameters for both men and women, but no relevant and significant differences between sex were found. No significant differences between males and females with regard to the effects elicited by physical activity on glycaemic biomarkers and cardiorespiratory fitness in individuals with T2DM were found. These results seem to lead towards the same physical activity prescription in men and women.

Cardiac Evaluation of Exercise Testing in a Contemporary Population of Preschool Children: A New Approach Providing Reference Values.

The objective of this study was to evaluate cardiac autonomic function at rest, during maximal exercise, and in post-exercise recovery, to determine sex-specific and age-specific differences in resting heart rate (RHR), linear and spectral parameters of Heart Rate Variability (HRV), HRpeak, and heart rate recovery (HRR) after one and five minutes, in preschool children. This study involved a cohort of 167 healthy children (79 girls) aged 3 to 6 years that were selected from several schools in southern Spain. A 10 × 20 m test was conducted, and the cardiovascular response was recorded. No significant differences were found in all variables between the sexes. However, a significant reduction in RHR and an increase in HRR were found from age 4 to age 6. HRV parameters at rest were higher in older children. No associations between 10 × 20 m performance, weight status, and cardiac parameters were found. Simple linear regression analysis revealed that heart rate reserve (HRr), HRR5min, RMSSD, and HF were the variables that showed association with all HR parameters. There was also a significant correlation between HRr and HRR5min. In conclusion, cardiovascular autonomic function during rest, exercise, and recovery in Spanish preschool children was not influenced by sex, although older children showed greater cardiovascular modulation. Cardiorespiratory fitness status was not associated with HR response.

Full Band Spectra Analysis of Gait Acceleration Signals for Peripheral Arterial Disease Patients.

Peripheral arterial disease (PAD) is an artherosclerotic occlusive disorder of distal arteries, which can give rise to the intermittent claudication (IC) phenomenon, i.e., limb pain and necessity to stop. PAD patients with IC have altered their gait, increasing the fall risk. Several gait analysis works have studied acceleration signals (from sensors) to characterize the gait. One common technique is spectral analysis. However, this approach mainly uses dominant frequency (fd ) to characterize gait patterns, and in a narrow spectral band, disregarding the full spectra information. We propose to use a full band spectral analysis (up to 15 Hz) and the fundamental frequency (f0) in order to completely characterize gait for both control subjects and PAD patients. Acceleration gait signals were recorded using an acquisition equipment consisting of four wireless sensor nodes located at ankle and hip height on both sides. Subjects had to walk, free-fashion, up to 10 min. The analysis of the periodicity of the gait acceleration signals, showed that f0 is statistically higher (p < 0.05) in control subjects (0.9743 ± 0.0716) than in PAD patients (0.8748 ± 0.0438). Moreover, the spectral envelope showed that, in controls, the power spectral density distribution is higher than in PAD patients, and that the power concentration is hither around the fd . In conclusion, full spectra analysis allowed to better characterize gait in PAD patients than classical spectral analysis. It allowed to better discriminate PAD patients and control subjects, and it also showed promising results to assess severity of PAD.

Two new indexes for the assessment of autonomic balance in elite soccer players.

PURPOSE: The application of Poincaré-plot analysis to heart-rate variability (HRV) is a common method for the assessment of autonomic balance. However, results obtained from the indexes provided by this analysis tend to be difficult to interpret. In this study the authors aimed to prove the usefulness of 2 new indexes: the stress score (SS) and the sympathetic:parasympathetic ratio (S:PS ratio). METHODS: 25 professional Spanish soccer players from same team underwent 330 resting measurements of HRV. All subjects experienced 10 min of HRV monitoring through an R-R-interval recorder. The following parameters were calculated: (1) Poincaré-plot indexes: SD1 (transverse axis), which is proportional to parasympathetic activity; SD2 (longitudinal axis), which is inversely proportional to sympathetic activity; and the SD1:SD2 ratio; (2) time-domain parameters: standard deviation of R-R intervals (SDNN), root-mean-square differences of successive heartbeat intervals (rMSSD), and percentage of successive R-R-interval pairs differing in more than 50 ms in the entire recording divided by the total number of R-R intervals (pNN50); and (3) the proposed 2 new indexes: the SS and the S:PS ratio. RESULTS: The study found a high negative correlation between the SS and SDNN (R2=.94). The S:PS ratio correlated inversely to rMSSD (R2=.95), SDNN (R2=.94), and pNN50 (R2=.74). The S:PS ratio showed a strong correlation with SD1 (R2=.95) and SS (r=.87, R2=.88). CONCLUSIONS: The application of the SS as sympathetic-activity index and the S:PS ratio as a representation of autonomic balance (SS:SD1) provides a better understanding of the Poincaré-plot method in HRV.

Heart rate variability is lower in patients with intermittent claudication: a preliminary study / La variabilidad de la frecuencia cardiaca es menor en pacientes con claudicación intermitente: un estudio preliminar

Introduction: Peripheral arterial disease is a chronic disorder affecting blood flow to lower limbs and many patients can develop intermittent claudication (IC). They suffer a blood flow decrease to lower limbs, making impossible to walk short distances without feeling pain or stopping the gait. Heart Rate Variability (HRV) is a non-invasive tool based on the calculation of time variations along consecutive heartbeats. It is reasonable to think that, since HRV assess the autonomic balance through the cardiovascular system, it could be useful in the assessment of patients with IC. Objectives: The aim of this study was to assess if there are differences in resting HRV between patients with IC and age matched controls, both with linear and non-linear analysis, and its possible relation with the gait capacity. Methods: 14 control male subjects (60±5 years) and 14 male IC patients (64±6 years) underwent 10 minutes of HRV analysis. The study calculated Time Domain variables, Poincaré Plot analysis and nonlinear parameters (Entropy and slopes of Detrend Fluctuation Analysis). Results: The main finding of this study is the presence of a clear sympathetic predominance at rest in the IC patients and a significant correlation between the parasympathetic rest tone and the distance covered in the 6MWT when all subjects are included. Conclusions: HRV seems to be an accurate method to detect the sympathetic misbalance present in patients with IC but as a nonspecific finding that could be present in other cardiovascular pathologies. Complex structure of the heartbeat signal is not affected by IC

Introducción: La enfermedad arterial periférica es un trastorno crónico que afecta al flujo sanguíneo de los miembros inferiores y muchos pacientes desarrollan claudicación intermitente (CI), sufriendo una reducción del flujo sanguíneo que les hace imposible caminar cortas distancias sin sufrir dolor o tener que detenerse. La variabilidad de la frecuencia cardiaca (VFC) es una herramienta no invasiva basada en el cálculo de las variaciones de tiempo entre latidos sucesivos. Es razonable pensar que, puesto que la VFC evalúa el balance autonómico a través del sistema cardiovascular, podría ser útil en la valoración de pacientes con CI. Objetivos: Evaluar si hay diferencias en la VFC de reposo entre pacientes con CI y controles de la misma edad (tanto con análisis lineal como no lineal) y su posible relación con la capacidad de marcha. Métodos: Se realiza un análisis de VFC de 10 min a 14 controles (60±5 años) y 14 pacientes con CI (64±6 años). Se calcularon variables del dominio de tiempo, gráfico de Poincaré y parámetros no lineales. Todos los sujetos realizaron a continuación un test de 6 min. Resultados: El principal hallazgo de este estudio es la presencia de un claro predominio simpático en reposo en los pacientes con CI y una correlación significativa entre el tono parasimpático de reposo y la distancia recorrida en el test de 6 min. Conclusiones: La VFC parece ser un método adecuado para detectar la disfunción simpática presente en pacientes con CI pero como un hallazgo inespecífico que puede estar presente en otras patologías vasculares. La estructura compleja de la señal cardiaca no se ve afectada en la CI

Heart rate variability and phantom pain in male amputees: application of linear and nonlinear methods.

Phantom-limb pain (PLP) is a phenomenon that may appear among people with amputation. Some studies reveal that 70% of people with amputation experience PLP years postamputation. There is a lack of scientific evidence about the cause of PLP. It has been hypothesized that the autonomic nervous system (ANS) could be involved in the mechanism that triggers PLP, but this hypothesis remains unclear. The aim of this study was to correlate ANS function, through heart rate variability (HRV) analysis, with PLP in adult males with amputation. The study population comprised 35 subjects, with 27 reporting PLP often or always. The rest of the subjects did not report any PLP. In order to calculate linear and nonlinear parameters of HRV, all subjects underwent 10 min of resting heart rate monitoring. The study did not find correlations between HRV parameters and PLP. Most of the subjects showed decreased values in linear parameters of HRV while nonlinear values were normal. HRV is not implicated in PLP. Linear and nonlinear methods for HRV analysis might reflect different physiological phenomena; while linear values place people with amputation at cardiovascular risk, nonlinear values indicate normality.

Estudio comparativo de las de los perfiles semanales de creatin kinasa, urea y variabilidad de la FC en remeros de élite españoles / Week-long profile of creatine kinase, urea and heart rate variability in elite spanish rowers. A comparative study

Aunque ha sido demostrado que la fatiga deportiva puede ser detectada mediante parámetros bioquímicos como la Creatín Kinasa (CK) y la Urea, las últimas tendencias en el estudio del sobreentrenamiento deportivo apuestan por el rol del Sistema Nervioso Autónomo (SNA) como indicador de estados de sobrecarga. El análisis de la Variabilidad de la Frecuencia Cardíaca (VFC), se ha convertido en el método más empleado para determinar la implicación del SNA en estados de sobreentrenamiento, estados de fatiga y asimilación de cargas de trabajo. En un intento de comparar ambas metodologías, el objetivo de esta investigación fue examinar la relación entre parámetros de VFC y perfiles de CK y Urea (P-CK/U). En este estudio participaron 11 remeros del equipo nacional sub 23 masculino español, los cuales fueron sometidos durante 5 días consecutivos en periodo competitivo a un análisis basado en mediciones de P-CK/U y VFC durante la fase de sueño. No se hallaron correlaciones significativas entre P-CK/U y parámetros de VFC; sin embargo los parámetros de VFC correlacionaron entre sí. Aun así, el perfil de CK y los parámetros de VFC mostraron una clara relación cualitativa. La Urea se mantuvo estable durante todo el estudio mientras la CK y los parámetros de VFC oscilaron. Las correlaciones encontradas entre parámetros de VFC apuntan que en futuros estudios no sería necesario utilizarlos todos. La relación cualitativa encontrada entre parámetros de VFC y el perfil de CK sugiere que la actividad parasimpática puede aumentar al mismo tiempo que lo hacen las cargas de trabajo si dichas cargas de trabajo son recuperadas por el deportista (AU)

It is known that exercise fatigue can be detected through biochemical markers as Creatine Kinase (CK) and Urea; but recently, several studies have demonstrated that the Autonomic Nervous System (ANS) behaviour could be also an important indicator of overtraining and fatigue. Heart Rate Variability (HRV) analysis, has currently become the main tool for the assessment of ANS implication in overtraining syndrome, fatigue and training load quantification. In order to compare both methods, the aim of the study was to examine the relationship between HRV parameters and CK and Urea profiles (CK/U-P).The study comprised 11 Under 23 male rowers of the Spanish National Team, which underwent during 5 consecutive days in competitive season, an analysis of CK/U-P and sleeping HRV during the night. The present research did not find significant correlations between CK/U-P and HRV parameters; but did find correlations among HRV parameters. The study also showed a clear qualitative association between CK profile and HRV parameters. Urea profile was steady during the whole study but HRV parameters and CK profile oscillated. The correlations among HRV parameters suggest that for future studies the calculation of all HRV domains could not be necessary. The qualitative correlation between HRV parameters and CK profile might indicate that higher training loads may be related to higher parasympathetic activity if the athletes recover after the training (AU)