Variabilidad de la frecuencia cardíaca como indicador de carga interna en mujeres no deportistas: estudio piloto / Heart rate variability as an indicator of internal load in non-athlete women: pilot study

La variabilidad de la frecuencia cardiaca (VFC) es una herramienta no invasiva que permite evaluar la modulación simpática y parasimpática y se ha propuesto como un método válido para valorar la respuesta individual a una carga de trabajo y, por tanto, la carga de entrenamiento. El objetivo es utilizar la RMSSD-Slope (La pendiente de la raíz cuadrada de la media de las diferencias de la suma de los cuadrados entre intervalos RR adyacentes) para analizar la recuperación tras dos intensidades diferentes en tapiz rodante en mujeres no deportistas, como medida de carga interna (CI) y su posible relación con la carga externa (CE).Participaron 9 mujeres sanas, físicamente activas. Se realizaron dos test, separados entre sí por 48-72 h. El primero fue una prueba máxima en tapiz rodante, en el que se determinó la velocidad aeróbica máxima (VAM). En la segunda sesión, se realizó una prueba al 80% de la VAM. En cada una de las sesiones se hizo un seguimiento la escala de Borg y de la VFC (reposo, ejercicio y recuperación) para su posterior análisis con la RMSSD-Slope.El valor de la RMSSD-Slope en la prueba del 80% de intensidad fue de 0,97 (±0,78), y en la Prueba Máxima fue 0,84 (±0,36). Ambas pruebas presentan una R2 con la escala de Borg (0,62 y 0,62) respectivamente. En el caso de la R2 entre la CE y la RMSSD-Slope fue de 0,04 y 0,14 respectivamente. La pendiente de recuperación de la RMSSD es una buena herramienta de valoración de CI en mujeres físicamente activas pero no deportistas

Heart rate variability (HRV ) is a non-invasive tool capable to evaluate the sympathetic and parasympathetic modulation and it has been proposed as a valid method to assess the individual response to a workload and, therefore, the training load. The objective is to use the RMSSD-Slope (square root of the mean of the differences of the sum of the squares between adjacent RR intervals) to analyze the recovery after two different treadmill intensities in non-athletic women, as an internal training load (ITL) measure and its possible relation with the external training load (ETL) 9 healthy, physically active women participated in the study. Two tests were performed, separated from each other for 48-72h. The first was a maximum treadmill test, in which the maximal aerobic speed (MAS) was determined. In the second session, an 80% test of the MAS was carried out. In each of the sessions, Borg scale and HRV was monitored (rest, exercise and recovery) for further analysis with the RMSSD-Slope. The RMSSD-Slope value in the 80% intensity test was 0.97 (± 0.78), and in the Maximum Test it was 0.84 (± 0.36). Both tests show an R2 with Borg scale of 0.62 and 0.62 respectively. In the case of the R2 between the ETL and the RMSSD-Slope it was 0.04 and 0.14 respectively. The recovery slope of the RMSSD is a good ITL assessment tool in physically active women but not athletes

Basal and post-exercise heart rate variability correlates with training load in endurance athletes / La variabilidad de la frecuencia cardíaca basal y posterior al ejercicio correlaciona con la carga de entrenamiento en atletas de resistencia / A variabilidade da frequência cardíaca basai e pós-exercício está correlacionada com a carga de treinamento em atletas de resistência

OBJECTIVE: Heart rate variability has been proposed as a valid method to examine the individual response to training load in endurance athletes. Thanks to this tool, the relationship between basal and post-exercise Heart rate variability measurements can be analyzed during a microcycle (one week) using straight values or their coefficients of variation. METHOD: Ten amateur endurance athletes (n = 5 men, n = 5 women) were monitored during a 7-day microcycle that included three road-cycling sessions, two running sessions and two trail-running sessions. The RR series were measured for 5 minutes upon wake up and after training, in a seating position, using a chest strap. RESULTS: Basal and post-exercise Heart rate variability measurements showed high correlation when weekly mean values were used, very similar to when coefficients of variation values were used. In women, the root mean square of successive differences (RMSSD) was: r= 0.73; RMSSD coefficients of variation (RMSSDcv) was: r= 0.66; natural logarithm (Ln) RMSSD: r= 0.68; LnRMSSDcv: r= 0.79; and in men it RMSSD was: r= 0.78; RMSSDcv: r= -0.62; LnRMSSD: r= 0.75; LnRMSSDcv: r= -0.73). CONCLUSION: the relationship between these two measurements could be useful to program the training loads of the following microcycle

OBJETIVO: La variabilidad de la frecuencia cardíaca se ha propuesto como un método válido para examinar la respuesta individual a la carga de entrenamiento en atletas de resistencia. El objetivo de este estudio fue analizar la relación entre las mediciones basales y post ejercicio durante un microciclo (una semana) utilizando valores directos o sus coeficientes de variación. MÉTODO: Se monitorizó a diez atletas aficionados de resistencia durante un microciclo de 7 días, que incluyó tres sesiones de ciclismo de ruta, dos sesiones de carrera y dos sesiones de trail running. Las series RR se midieron durante 5 minutos al despertar y después del entrenamiento, en posición sentado, utilizando una banda torácica. RESULTADOS: Las mediciones de variabilidad de la frecuencia cardíaca basales y post ejercicio mostraron una alta correlación cuando se usaron valores medios semanales, como cuando se usaron valores de los coeficientes de variación. En mujeres, la raíz cuadrada de la media de las diferencias de la suma de los cuadrados entre intervalos RR adyacentes (RMSSD) fue: r = 0.73; el coeficiente de variación (cv) de la RMSSD fue RMSSDcv: r = 0.66; el logaritmo natural (Ln) de la RMSSD (LnRMSSD) fue: r = 0.68; LnRMSSDcv: r = 0.79; y en los hombres fueron RMSSD: r = 0.78; RMSSDcv: r = -0.62; LnRMSSD: r = 0.75; LnRMSSDcv: r = -0.73. CONCLUSIONES: La relación entre estas dos mediciones podría ser útil para el programa de entrenamiento del microciclo posterior

OBJETIVO: A variação da frequência cardíaca tem sido utilizada como método de análise de respostas individuais a carga de treino em atletas de endurance. Graças a esta ferramenta, a relação entre a variação da frequência cardíaca basal e pós-exercício pode ser analisada durante um microciclo (uma semana) usando valores diretos ou seus coeficientes de variação. MÉTODO: Dez atletas de endurance amadores (n = 5 homens, n = 5 mulheres) foram monitorados durante microciclos de 7 dias que incluíram 3 sessões de ciclismo em estrada, duas sessões de corrida e duas sessões de corrida em trilha. As series de RR foram medidas durante 5 minutos depois de acordar e depois do exercício, em posição sentada, com recurso a cardiofrenquencímetros toráxicos. RESULTADOS: Os resultados mostram uma correlação alta entre as medidas de variação de frequência cardíaca basal e pós-exercício quando utilizados valores médios semanais, muito semelhantes aos resultados quando utilizados coeficientes de variação. Nas mulheres, a raiz quadrada media das diferenças sucessivas (RMSSD) foi: r= 0.73; coeficientes de variação RMSSD, (RMSSDcv) foi: r= 0.66; logaritmo natural (Ln) RMSSD: r = 0.68; LnRMSSDcv: r= 0.79; e nos homens, raiz quadrada media das diferenças sucessivas r= 0.78; RMSSDcv: r= -0.62; LnRMSSD: r= 0.75; LnRMSSDcv: r= -0.73). CONCLUSÃO: a relação entre estas duas medidas poderia ser útil para prescrição de cargas de treino dos microciclos seguintes

Heart rate variability to assess the effect of sleep deprivation in mountain troops of the chilean army: a pilot study / Variabilidad de la frecuencia cardíaca para evaluar el efecto de la privación del sueño en tropas de montaña del ejército chileno: un estudio piloto

BACKGROUND: Our objective was to identify the effect of sleep deprivation on a stress test simulating a military march, via changes in heart rate variability (HRV) in special mountain troops. Eight subjects from special mountain troops carried out a simulated march test on a treadmill. The incremental march test had 7 stages of 3 minute duration at a constant velocity of 5 km/h and slopes of 1, 3, 5, 7, 8, 9 and 10 %. To assess the HRV, two heartbeat records were taken over 5 minutes in dorsal decubitus position before and after the march test; the first session took place without sleep deprivation, and the following day with sleep deprivation. RESULTS: The main finding of this study is that the physiological stress imposed by the simulated treadmill march is the same with and without sleep deprivation. There were no significant differences between pre and post HRV data in any of the situations, but effect size was moderate or large (d=0.2 was considered as the Smallest Worthwhile Change). indicating a highly relevant response. However, after comparing with and without sleep deprivation tests no changes were found (non-significant and non-relevant). CONCLUSIONS: The stress test performed, did not present differences in physical and physiological responses while being deprived of sleep over 24 hours. A simple test is proposed to evaluate the effect of sleep deprivation as a stressor agent. A treadmill test at a constant speed with increasing slopes would be performed and repeated the following day after 24 hours of sleep deprivation

INTRODUCCIÓN: Nuestro objetivo fue identificar el efecto de la falta de sueño en una prueba de esfuerzo que simula una marcha militar, a través de cambios en la variabilidad de la frecuencia cardiaca (VFC) en tropas especiales de montaña. Ocho sujetos de tropas especiales de montaña realizaron una prueba de marcha simulada en una cinta de correr. La prueba de marcha incremental tuvo 7 etapas de 3 minutos de duración a una velocidad constante de 5 km/h y pendientes de 1, 3, 5, 7, 8, 9 y 10%. Para evaluar la VFC, se tomaron los registros de latidos latido del corazón durante 5 minutos en posición de decúbito dorsal antes y después de la prueba de marcha; la primera sesión tuvo lugar sin privación de sueño y al día siguiente con privación de sueño. RESULTADOS: El principal hallazgo de este estudio es que el estrés fisiológico impuesto por la marcha simulada de la cinta rodante es el mismo con y sin privación del sueño. No hubo diferencias significativas entre los datos de VFC anteriores y posteriores en ninguna de las situaciones, pero el tamaño del efecto fue moderado o grande (d = 0.2 se consideró como umbral de cambio pequeño). Indica una respuesta altamente relevante. Sin embargo, después de comparar con y sin las pruebas de privación de sueño, no se encontraron cambios (no significativos y no relevantes). CONCLUSIONES: La prueba de esfuerzo realizada no presentó diferencias en las respuestas físicas y fisiológicas al estar privada de sueño durante 24 horas. Se propone una prueba simple para evaluar el efecto de la falta de sueño como agente estresante. Se realizaría una prueba de la cinta rodante a una velocidad constante con pendientes crecientes y se repetiría al día siguiente después de 24 horas de falta de sueño

Cambios hormonales en soldados aclimatados durante una marcha en gran altitud con esquí de montaña / Hormonal changes in acclimatized soldiers during a march at a high altitude with mountain skis

Background: The aim of the present study is to identify the physiological impact of acute exposure to high altitudes on special acclimatized troops of the Chilean Army. Twenty-nine soldiers carried out a nocturnal winter march on mountain skis at an initial altitude of 2,800 m and up to 3,640 m. Two separate blood measurements were taken. The first one was taken the day before the march (Pre-sample) and the second one just after returning to the base camp (Post-sample). All subjects had been acclimatized prior to the study. For hypothesis comparison purposes, the normality of the distribution was tested using the Shapiro-Wilk test. To determine if there were significant differences between the Pre and Post tests, a paired-samples Student t-test was applied for the variables with a normal distribution, and the Wilcoxon test was applied for the variables without a normal distribution. In all cases, a level of significance of 95% (p<0.05) was taken into consideration. Results: Exposure of acclimatized troops to altitudes of 2,800 m to 3,640 m has an impact on the endocrine parameters and on the reduction of cortisol (p<0.01), total testosterone (p<0.0001), free testosterone (p<0.0001) and the free testosterone-cortisol ratio (p<0.01). Likewise, an increase in total leukocytes (p<0.0001), neutrophils (p<0.0001), monocytes (p<0.0001) and basophils (p<0.001), as well as a decrease of eosinophils (p<0.0001) and lymphocytes (p<0.01), was observed. No hematological changes were detected. Conclusions: Endocrine changes were observed during high-altitude winter marches on mountain skis carried out by accli-matized Special Operation Troops, resulting in decreased cortisol and free and total testosterone levels. A stress condition due to the high altitudes also affected the anabolic/catabolic environment, which manifested as a significant decrease in the free testosterone/cortisol ratio. No hematological changes were identified. Marked changes were observed in some white cell series

Introducción: El objetivo del presente estudio es identificar el impacto fisiológico (con especial atención a los parámetros endocrinos y hematológicos) de la exposición aguda a gran altitud (GA) en tropas especiales aclimatadas del Ejército de Chile. Veintinueve soldados llevaron a cabo una marcha nocturna con esquí de montaña invernal a una GA de 2.800 m. hasta 3.640 m. Se tomaron dos muestras de sangre. La primera muestra fue tomada el día antes de la marcha (Pretest) y la segunda muestra justo después al regresar al campamento base Post test (a los 2.800 m). Todos los sujetos se encontraban aclimatados antes del estudio. Para cada análisis se testeo la normalidad de las distribuciones empleando el test de Shapiro-Wilk. Se calculó el promedio y la desviación estándar para cada medición. Para determinar si existían diferencias significativas entre el pre y post test se aplicó la prueba de t-Student pareada para las variables con distribución normal y el test de Wilcoxon para las variables que no tenían distribución normal. En todos los casos se consideró un nivel de confianza de 95% (valor p < 0,05). Resultados: La exposición de las tropas aclimatadas a GA tiene un impacto en los parámetros endocrinos y en la reducción de cortisol (p <0,01), testosterona total (p <0,0001), testosterona libre (p <0,0001) y el ratio testosterona libre-cortisol (p <0.01). Asimismo, se observaron un aumento de leucocitos (p <0,0001), neutrófilos (p <0,0001), monocitos (p <0,0001) y basófilos (p <0,001), así como una decrease de eosinófilos (p <0,0001) y linfocitos (p < 0.01). No se observaron cambios en la serie roja. Conclusiones: La marcha invernal nocturna con esquí de montaña en GA para tropas de operaciones especiales aclimatadas presento cambios endocrinos con disminución del cortisol, testosterona libre y total. Una condición de estrés por la marcha en GA también afectó al ambiente anabólico/catabólico, lo que se ve reflejado en una disminución significativa en el cociente testosterona libre/cortisol. No se observaron cambios hematológicos. Se observaron cambios significativos en algunas células de la serie blanca

Impact of Hypothermic Stress During Special Operations Training of Chilean Military Forces.

Introduction: The Chilean Army considers processes that can optimize physical capacities for responding to the impact of situations and given stressors. The study of the effect of hypothermia as a stressor agent (HSA) and its relationship with cardiovascular, hematological, anthropometric, endocrine, and immunological parameters has not been fully addressed experimentally in military populations. Objective: To identify the endocrine, hematological, cardiovascular, and immunological changes caused by HSA and to associate these variables with body composition and physical fitness in the military special operation courses of the Chilean Army. Materials and Methods: Forty-two male subjects were exposed to remain in cold water (10.6 °C) in the context of regular military operations training, the longest time of exposure was determined by individual volitional limits. The measurements were taken in pre-hypothermia conditions, then 2 d later under acute hypothermia condition, and finally during the course period of lesser physical and psychological stressors where the baseline measurements were taken. The statistical analysis consisted of testing normality of the distribution through the Shapiro-Wilk test, assessing the equality of variances through the Levene test, and variance analysis by applying the ANOVA test (analysis of variance). The Bonferroni test was used for multiple comparison correction and the Pearson test for correlations between two variables. The level of significance was of p < 0.05. Results: The main finding of this study is that HSA has a significant impact at the cardiovascular level and produces an increment in the cell population of the immune and hematologic systems. Significant hormonal changes were observed: ACTH (r = 0.50, p < 0.002), cortisol (r = 0.32, p < 0.03), free testosterone (r = 0.13, p < 0.002), total testosterone r = 0.31, p < 0.002), and anthropometrics (r = -0.51, p < 0.05). However, there is no significant correlation between physical fitness and HAS. Conclusions: All subjects experienced hypothermia stress elicited by immersion in cold water. This was evidenced by the decrease in core temperature as well as cardiovascular, endocrine, anthropometric, and immunological changes. Individual differences exist between subjects and their resistance to hypothermia in cold water. These differences are not explained by the physical fitness profile but rather respond to a greater body adiposity index and minor changes in the adrenocorticotropic hormone and cortisol hormone. An acute hypothermia stress condition also affects the anabolic/catabolic environment. Finally, HSA produces an increase in the cell population of the immune system. The authors believe that this study allows to standardize HSA exposure times during regular military operations training by identifying the physiological impacts under this extreme environment. At present, the availability of intra-abdominal temperature measurement apparatus with capsule thermometers raises the interest of corroborating the findings of the current study through the use of such measuring devices. Likewise, an interesting line of research for the future would be to compare the HSA against a psychological evaluation with the purpose of identifying the stress management mechanisms among subjects of these characteristics and include heart rate variability measurements as an indicator of sympathetic stress.