Un año de seguimiento con variabilidad de la frecuencia cardiaca en trail runners / One-year follow-up with heart rate variability in trail runners

Este estudio tuvo como objetivo analizar las medidas de variabilidad de la frecuencia cardíaca (VFC) para proporcionar valores de referencia en atletas de Ultra-Trail Running (UTR). Dieciséis UTR chilenos fueron monitoreados con registros basales al despertar de 5 minutos durante un año de seguimiento, tiempo en el cual, mantuvieron sus actividades habituales de entrenamiento, competición y descanso. Como variable para evaluar la actividad parasimpática la RMSSD (raíz cuadrada de la media de las diferencias de la suma de los cuadrados entre intervalos RR adyacentes) fue analizada. Además, se calculó el Stress Score (SS) como indicador de la actividad simpática. Los datos aportados proporcionan valores de referencia de VFC para UTR a través de una distribución de percentiles, que pueden ser particularmente útiles cuando la VFC se utiliza para el control de las cargas de entrenamiento en atletas de UTR. (AU)

This study aimed to analyze measures of heart rate variability (HRV) to provide reference values in Ultra-Trail Running (UTR) athletes. Sixteen Chilean UTR were monitored with 5-minute baseline wake-up records during a one-year follow-up during which they maintained their usual training, competition and rest activities. As a variable to evaluate parasympathetic activity the RMSSD (square root of the mean value of the sum of the squared differences of all successive RR intervals) was analyzed. In addition, the Stress Score (SS) was calculated as an indicator of sympathetic activity. The data provided are reference baseline HRV values for UTR through a percentile distribution, which can be particularly useful when HRV is used to control training loads in UTR athletes. (AU)

Comportamiento de las colinesterasas tras condiciones de fatiga en corredores de fondo / Behaviour of cholinesterases after fatigue conditions in endurance runners

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. (AU)

The objective of the present study was to evaluate the effect of intense training in endurance athletes on the behaviour of cholinesterases (ChE) after fatigue conditions and its relationships with other internal load markers. 18 male athletes specializing in endurance events participated. ChEs and two index of heart rate variability were evaluated at three different moments, before the study protocol (BASAL), 15 minutes after (FINAL) and the day after finishing the training (24H). A one-way ANOVA with post-hoc Tukey HSD was used to compare means. Significant differences were found in the variables analysed (p < .001), with very large effect sizes (d > 0.9) between BASAL, FINAL and 24H and moderate correlations between ChE and LnRMSSD and SS (p < .001). The behaviour of the ChEs showed a significant change (p < .001) after exercise and relationship with other internal training load indicators. Our results indicate that ChEs are related with fatigue in the studied athletes and may be a measure for training load determination. (AU)

Non-linear heart rate dynamics during and after three controlled exercise intensities in healthy men.

We aimed to analyse the complexity and fractal nature of heartbeat during constant exercise, at three different intensities, and recovery.Fourteen healthy men underwent 4 separate sessions. The first session was an incremental treadmill test to determine ventilatory thresholds (VT1 and VT2) and maximal aerobic speed (MAS). Each subject ran at VT1 and VT2 speeds and MAS (second, third and fourth day). The duration of VT1 and VT2 loads were selected in such a way that the product intensity-duration (training load) was the same. Sample Entropy (SampEn) and slope of Detrended Fluctuation Analysis (DFA α1) were measured during the whole session.DFA α1 declines with exercise, being less in the VT1 trial than in the other two.SampEn shows no significant change during exercise. The three tests induce the same decline in SampEn, but at the highest intensity (MAS) tends to decline during the exercise itself, whereas at lower intensities (VT1, VT2) the decline is delayed (10 min of recovery). Subsequently, SampEn at VT1 gradually recovers, whereas at VT2 and MAS it remains stable during recovery.In conclusion, exercise produces a loss of heartbeat complexity, but not fractal nature, during recovery and it depends on intensity.

Carga de entrenamiento y VFC en una atleta femenina: estudio de caso / Training Load and HRV in a Female Athlete: A Case Study

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

The purpose of this study was to describe a follow-up methodology in a female athlete who combines Ultra Trail Running (UTR) and Ironman during 16 weeks, using Heart Rate Variability (HRV). The daily training load (TL) was previously programmed and the weekly summation was recorded. The RR (ms) intervals at rest were recorded every morning for 5 minutes. The RMSSD (root mean square of the successive differences between adjacent RR intervals) was measured as an index of the parasympathetic activity and the stress score (SS) as a measure of sympathetic activity. Daily HRV morning records appear to be a useful way to monitor sympathetic-parasympathetic balance in athletes before tackling training sessions. This monitoring would serve to detect early fatigue states and to be able to monitor the planning of the loads

Jump percentile: a proposal for evaluation of high level sportsmen.

AIM: The goal of this study was to determine reference values of explosive strength for Spanish professional athletes using a force platform. Reference values are displayed as a sports-independent percentile distribution. METHODS: A total of 323 elite male athletes (age: 20.38 ± 4.65 years, body mass: 75.04 ± 14.30 kg, height: 178.62 ± 14.18 cm) from different disciplines performed the following test: squat jump (SJ), countermovement jump (CMJ), Abalakov test (AB), drop jump (DJ) and repeated jumps (RJ). We calculated: relative peak power, relative peak force, maximal height, symmetry index, explosive index of strength, relative effective impulse, duration of jump, elastic capacity, eccentric time, action of arm, jump number, average height, intensity and fatigue index of force. RESULTS: Significant differences were found among sports disciplines (P<0.05) in relative peak power, maximal height and relative effective impulse during the SJ, CMJ and AB tests. No significant differences were found among disciplines in DJ variables. In RJ, the main variable characterizing the disciplines analyzed was average height, which showed a significant negative association with athletics, soccer, volleyball and gymnastics. CONCLUSION: The results obtained suggest that a percentile table may be useful in assessing explosive strength in athletes, regardless of there being any reference values available for their sports discipline.

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.

Revisión sobre la lesión de la musculatura isquiotibial en el deporte: factores de riesgo y estrategias para su prevención / Review on the hamstring muscle injury in sport: risk factors and prevention strategies

La lesión aguda de la musculatura isquiotibial es una de las más frecuentes en el ámbito deportivo, presentando una alta incidencia e, incluso, una elevada tasa de recurrencia. Ambos fenómenos se han relacionado a menudo con la ineficacia de las estrategias utilizadas para prevenir la aparición de esta lesión, ya que éstas no tienen en consideración, en muchas de las ocasiones, el carácter multifacético de la lesión. Además, la evidencia científica sobre los factores de riesgo asociados a la lesión isquiotibial es limitada aún, lo que dificulta el desarrollo de estrategias de prevención apropiadas. En base a lo expuesto, los objetivos de esta revisión son: analizar los factores de riesgo asociados a esta lesión y, de acuerdo a estos, describir las estrategias utilizadas para prevenir dichas lesiones(AU)

Acute hamstrings injury is one of the most common in sport, presenting a high incidence and even a high recurrence rate. Both are often associated with the ineffectiveness of the strategies used to prevent the occurrence of this injury, because they do not take into cosideration, in many instances, the multifaceted nature of the injury. In addition, scientific evidence about the risk factors associated with hamstring injury is still low, limiting the development of appropriate prevention strategies. Based on the above, the aims of this review are: analyze the risk factors associated with this injury and, according to them, describe the strategies used to prevent injuries(AU)

Analysis of heart rate variability at rest and during aerobic exercise: a study in healthy people and cardiac patients.

OBJECTIVE: To analyse HRV at rest in healthy people and in patients with acute myocardial infarction (AMI) and how it changes during aerobic exercise. METHODS: The heartbeat signal was recorded beat to beat for 15 minutes at rest and 15 minutes while pedalling in 10 healthy and active men (H group) and 10 cardiac patients (C group). The statistical parameters in the time domain were calculated as well as the spectral analysis applying the Fast Fourier Transform (FFT) and Poincare's graphic analysis (PGA). RESULTS: At rest, H group have an average SDRR (standard deviation of RR intervals) of 71.24 msec, a pRR50 (percentage of differences higher than 50 msec in RR intervals) of 9.97% and a PGA called "comet-type". The C group have a SDRR of 36.69 msec, a pRR50 of 1.69%, and a PGA "torpedo-type". These data show a low or moderate risk for healthy people and a high risk for patients. The FFT analysis lies in the very-low-frequency (VLF) zone in both groups. During exercise, H group shows a significant decrease in all parameters; the PGA turns to "torpedo-type" and the FFT remains in the VLF zone. However, C group is characterised by the maintenance of pRR50, no change in PGA and a second peak in FFT in the high-frequency zone. CONCLUSION: The HRV at rest and during aerobic exercise follows a different pattern in healthy people and in patients and it provides further information about performance during exercise.

Use of beta2 agonists in sport: are the present criteria right?

BACKGROUND: The regulations for doping control prohibit the use of beta2 agonist bronchodilators (salbutamol, salmeterol, formoterol, and terbutaline) unless the subject follows the procedure known as abbreviated therapeutic use exemption (ATUE). OBJECTIVE: To highlight how the interest in discovering possible cheats may result in damage to athletes who really need bronchodilator treatment. METHODS: Thirty one high level athletes (18 men and 13 women) with a previous diagnosis of asthma were examined in our laboratory in order to obtain an ATUE for beta2 agonists. All the subjects underwent spirometry at rest. If the results were normal, the subjects underwent an effort test and, if negative, a methacholine test inhaling progressive doses of methacholine until a fall of 20% in forced expiratory volume in one second (FEV1) was achieved. The international anti-doping regulations require that the fall in FEV1 occurs with a concentration of methacholine (PC20) lower than 2 mg/ml (4 mg/ml for Torino 2006). In clinical practice, a test is positive if the response occurs with a PC20 lower than 8 mg/ml. RESULTS: Only one subject met the criterion for the bronchodilation test at rest. The remaining 30 athletes underwent an effort test, which was positive in nine of them. In 21 cases (13 men and 8 women) the effort test was negative so a methacholine test was carried out. Seven (33%) were negative for ATUE with a PC20 higher than 8 mg/ml, seven (33%) were positive for ATUE with a PC20 less than 2 mg/ml, in four (19%) the PC20 was 2-4 mg/ml, and in three (14%) it was 4-8 mg/ml. CONCLUSIONS: Strict vigilance of fair play should be pursued, but excessive control can lead to situations of inequality for asthmatic athletes such that a third of athletes cannot be treated with beta2 agonists. Therefore under current regulations, asthmatic athletes are often denied the most effective therapeutic option.