Heart rate variability (HRV) analyses can be performed using group or individual changes. individual changes could be of potential interest during training camps for national soccer teams. the purpose of this study was to compare whether analysis of individual daily HRV could detect changes in cardiac autonomic responses during training camps for national soccer teams. During two different training camps, 34 professional soccer players were monitored daily over 9 days, using heart rate monitors. players were divided into first eleven (those who participated in the main squad) or Reserves. Daily HRV was individually analyzed using a day-today method or a baseline (days prior to first match) method, using the smallest worthwhile change and the typical error in the estimate to establish a trivial (random change) zone. Group changes were also analyzed using an AnoVA one-way repeated measures test. Players' responsiveness was classified as High-, Low-or Non-response depending on individual changes. Both analyses showed substantial daily individual changes after playing a soccer match, regardless of the group. However, group changes showed that only first eleven players had significant changes after playing a soccer match. In conclusion, individual daily HRV analyses are useful in detecting individual changes in professional soccer players. Cardiac autonomic response (CAR) can be used to monitor the cardiovascular adjustments made after exercise 1-3 , which are mediated by the autonomic nervous system 4. Professional soccer players have shown impairments in physiological and performance measures after playing soccer matches 3,5,6 , especially during congested fixture periods 7,8 , which are typical during training camps for national soccer teams 9. Therefore, monitoring post-match recovery requires tools that are sensitive to match-induced fatigue to help practitioners make decisions on a daily basis 5. However, not only do the tools or variables themselves have an impact in the analysis; so does the method of analysis employed 10. Using a simple heart rate monitor (HRM) 11 , heart rate variability (HRV) can be monitored to assess CAR during training cycles in soccer players 12-14. CAR can be studied by assessing parasympathetic and sympathetic vagal activity via time-domain variables analysis 15. LnRMSSD is a time-domain variable that reflects parasympathetic activity 2 , and more recently, the Stress Score (SS), has been proposed to reflect sympathetic activity in soccer players 16. An increase in parasympathetic activity usually reflects a positive adaptation to training 2,17 , which can typically occur after a taper period as sign of functional training adaptation and part of the super-compensation cycle 11. We have previously shown that parasympathetic activity (as measured via the natural logarithm of the root mean squared standard deviation ((LnRMSSD) did not change during typical training days at a training camp for a professional national soccer team. However, it significantly increased 48 h after playing a so...

Introduction-The aim of this study was to analyze changes in heart rate variability (HRV) during exercise in hot environments and recovery to baseline values depending on relative humidity. Methods-Ten recreational runners participated in this study. Each participant performed 2 trials consisting of 30 min of continuous running under hot and dry (HD) (38˚C and 28% relative humidity) and hot and humid (HH) conditions (38˚C and 64% relative humidity) at their common 10 km race-running rhythm. HRV and body mass were assessed pre-and post-trial; the rating of perceived exertion and HRV were assessed during the trial; and HRV measurements were repeated 2, 4, 8, and 24 h postexercise. Primary HRV outcomes were root mean square of the successive differences, high frequency power, stress score, and sympathetic/parasympathetic ratio. One-way analysis of variance testing was used to analyze differences. Results-No significant difference in body mass occurred across the different conditions or distances covered (P>0.05). Rating of perceived exertion presented the highest correlation values with stress score (r=0.729 for HD; r=0.568 for HH) and sympathetic/parasympathetic ratio (r=0.621 for HD; r=0.519 for HH) during exercise. HRV recovered to baseline values more quickly after exercising under dry conditions (4 h) than under humid conditions (between 8 and 24 h). Conclusions-Stress score and sympathetic/parasympathetic ratio seem to be the best HRV predictors of internal load. Although there are no differences in HRV during recovery at the same time points in both conditions, the recovery is slower after exercise in HH than in HD.

El objetivo de este estudio fue describir una metodología de seguimiento en una atleta que combina el Ultra Trail Running (UTR) y el Ironman durante 16 semanas, mediante variabilidad de la frecuencia cardiaca (VFC). La carga de entrenamiento (CE) diaria se programó y se cuantificó el sumatorio semanal. Se registraron los intervalos RR (ms) en reposo cada mañana durante 5 minutos y a partir de ellos se midió la RMSSD (raíz cuadrada de la media de las diferencias de la suma de los cuadrados entre intervalos RR adyacentes) como medida de la actividad parasimpática y el índice de estrés (SS) como actividad simpática. Los registros diarios de VFC matutinos parecen ser una forma útil para monitorizar el estado de equilibrio simpático-parasimpático en deportistas antes de abordar las sesiones de entrenamiento. Esta monitorización serviría para detectar precozmente estados de fatiga y para poder monitorizar la planificación de las cargas.

El objetivo del presente estudio fue evaluar el efecto de un entrenamiento intenso en atletas de resistencia sobre el comportamiento de las colinesterasas (ChE) tras condiciones de fatiga y su relación con otros marcadores de carga interna. Participaron 18 atletas de sexo masculino especialistas en pruebas de resistencia. Se evaluó las ChE y dos índices de variabilidad de la frecuencia cardiaca en tres momentos diferentes, previo al protocolo (BASAL), 15 minutos posterior al protocolo (FINAL) y 24 horas después del entrenamiento (24H). Un ANOVA de una vía con post-hoc de Tukey HSD se utilizó para comparar las medias. Se encontraron cambios significativos en las variables analizadas (p < .001) con tamaños de efecto muy grandes (d > 0.9) en los diferentes momentos y correlaciones moderadas entre variables (p < .001). El comportamiento de las ChE muestra un cambio significativo (p < .001) posterior al ejercicio y una relación con otros indicadores de carga interna. Nuestros resultados indican que las ChE tienen relación con la fatiga en el caso de los deportistas estudiados, pudiendo ser una medida para determinar la carga de entrenamiento.