Comparison of Omegawave Device and an Ambulatory ECG for RR Interval Measurement at rest.

The aim of this study was to validate the measurements of the beat intervals taken at rest by the Omegawave® device by comparing them to an ambulatory electrocardiogram system. For this purpose, the electrocardiogram was digitally processed, time-aligned, and scrutinized for its suitable use as gold-standard. Rest measurements were made for 10 minutes on 5 different days to 10 men and 3 women (24.8±5.05 years; 71.82±11.02 kg; 174.35±9.13 cm). RR intervals were simultaneously recorded using the Omegawave device and a Holter electrocardiogram. The processing of Holter electrocardiogram signals included the detrending of baseline noise and a high-pass filtering for emphasizing the QRS complexes and attenuating the T waves. After obtaining the RR intervals from the electrocardiogram, those from the Omegawave device were automatically aligned to them with cross-correlation digital processing techniques and compared to check whether both measurements could be considered superimposable. A Bland-Altman analysis was applied to the 5 measurements made for all subjects. The Omegawave device exhibited very strong agreement with a quality-controlled Holter electrocardiogram. Deviations not exceeding 25 ms could be expected in 95% of the cases, which is within manageable ranges both for clinical practice and for sports.

Recovery of Heart Rate Variability After Exercise Under Hot Conditions: The Effect of Relative Humidity.

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.

Off-Season Effects on Functional Performance, Body Composition, and Blood Parameters in Top-Level Professional Soccer Players.

Requena, B, García, I, Suárez-Arrones, L, Sáez de Villarreal, E, Naranjo Orellana, J, and Santalla, A. Off-season effects on functional performance, body composition, and blood parameters in top-level professional soccer players. J Strength Cond Res 31(4): 939-946, 2017-To examine the effects of a standard off-season period (OSP) on aerobic, sprint, and jumping performances, and body and blood composition in a top-level soccer team. Nineteen soccer players were measured. The OSP included to 2 weeks of no training (resting phase) and a 4-week period of moderate-training load (phase in which each player performed the vacation exercise plan). Player's functional performance (15- and 30-m sprint times [seconds], vertical jump [meter], and incremental field test Vam-Eval [kilometer per hour]), percentage of body fat (%) and blood composition (hematological and biochemical data) were measured at mid-season, end-season, and after the OSP. The percentage of body fat was nonaltered during the competitive season (10.8 ± 3.6 and 10.5 ± 3.5%) and increased significantly after the OSP (11.6 ± 3.6%, p ≤ 0.05). Similarly, the maximal aerobic speed (VVam-Eval) velocity (kilometer per hour) decreased (p ≤ 0.05) from 17.4 ± 1 and 17.3 ± 1.2 during the competitive season to 16.6 ± 0.9 after the OSP. The hematocrit and blood hemoglobin concentration increased (p ≤ 0.05) during the OSP, showing a blood hemoconcentration adaptation. However, sprint time (seconds) and jump height (meters) showed no significant changes after the OSP. Soccer players maintained their functional performance during high-intensity activities such as jumping or sprinting after the OSP proposed. By contrast, there was a decrease in aerobic performance (VVam-Eval) accompanied by a blood hemoconcentration, and an increase of body fat mass associated with a reduction of fat-free mass of the lower limbs. Our data suggest that an end-season evaluation is needed to design holiday training programs focused on regaining aerobic capacity and body composition.

Soccer Matches but Not Training Sessions Disturb Cardiac-Autonomic Regulation During National Soccer Team Training Camps.

Purpose: Heart rate variability (HRV) can be used to monitor changes in autonomic nervous system (ANS) function. Monitoring HRV via the natural log of the root-mean-square difference of successive normal RR intervals (lnRMSSD), a decrease was related to lower parasympathetic activity and a fatigued state, and an increase was related to higher parasympathetic activity and better physical conditioning. This study analyzed daily ANS function changes among professional soccer players at national team training camps during preparation for the UEFA Eurocup 2016. Method: 23 professional soccer players were distributed into two groups: First eleven (players who played more than 60 minutes per soccer match) and Reserves (the rest of the players). HRV and session training load (s-TL) were monitored. Between-group daily differences were assessed using two-way mixed repeated measures ANOVA. Results: s-TL significantly increased (p < .05) at the beginning of each camp and significantly decreased the day before the soccer match (p < .001). There was a significant time by group interaction in lnRMSSD (p = .024). Changes were found in the First eleven group from match day +1 to match day +2 (+0.523 ms, p = .003). After the soccer match, there were between-group differences (p < .05) at +24h and +72h in lnRMSSD. Conclusions: During national team training camps, ANS function was only modified 24h and 72h after playing soccer matches, in players who played a minimum of 60 minutes. This knowledge can help coaches to monitor the impact of soccer matches during training camps to detect fatigue and improve recovery.

Long-Term Combined Training in Idiopathic Pulmonary Fibrosis: A Case Study.

A supervised combined training program was applied to a sedentary 56-year-old man with idiopathic pulmonary fibrosis (IPF) along three years, until lung transplantation. It included: (a) aerobic continuous (CT) and interval training (IT), (b) high load resistance training (RT) and (c) inspiratory muscle training (IMT). IT and IMT were applied for two years, while CT and RT could be maintained until transplantation using supplemental oxygen. Maximal inspiratory pressure (MIP) kept above 180 cm H2O and forced vital capacity (FVC) remained stable until lung transplantation. Peak oxygen uptake VO2 increased during 1.5 years before its decline, staying above the poor prognosis level two years. Finally, the patient maintained his walking capacity and independence for 2 years, before the decline due to the disease. After receiving a two-lung transplant, the patient remained intubated for 12 h, left the intensive care unit after 3.5 days and was discharged after 18 days (average values: 48 h, 7-10 days and 25-35 days, respectively). These results show that systematic and supervised combined training can be safety applied in an IPF patient to maintain functionality and quality of life. In addition, we show that RT can be maintained for as long as necessary without complications.

Individual versus team heart rate variability responsiveness analyses in a national soccer team during training camps.

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-to-day 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.

Effects of detraining on breathing pattern and ventilatory efficiency in young soccer players.

BACKGROUND: This study investigated the effects of detraining on breathing pattern. The aim of this study was to evaluate the effect of a six-week detraining period on breathing patterns and ventilatory efficiency. METHODS: Fourteen young soccer players were evaluated at the end of a competitive season and after a six-week detraining period. Assessment of respiratory efficiency was based on VE/VCO2 slope changes below 70% of exercise intensity. All participants underwent twice an incremental graded exercise test up to exhaustion. RESULTS: No differences in breathing frequency and inspiratory time/total time ratio (Ti/Ttot) were found after detraining (P>0.05). Differences in tidal volume (VT), VT/Ti quotient and VE were significant (P<0.05) at between 40 to 100% of exercise intensity. The VE/VCO2 slope did not change (P>0.05) during a postdetraining maximal incremental test. CONCLUSIONS: A six-week detraining period causes changes in inspiratory flow but does not affect the inspiratory time/total respiratory cycle time ratio. The overall ventilatory efficiency of the respiratory system remains constant and is not affected by detraining.

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.

Autonomic Responses to Ultrasound-Guided Percutaneous Needle Electrolysis: Effect of Needle Puncture or Electrical Current?

OBJECTIVE: The aim of this study was to establish if the changes in sympathetic and parasympathetic activity (analyzed through heart-rate variability [HRV]) during ultrasound (US)-guided percutaneous needle electrolysis (PNE) is due to the effect of needle puncture only or of the PNE technique per se where the puncture and galvanic current are combined. METHODS: This was an experimental, case-control study that took place at the University of Seville. Subjects were 36 male footballers who were randomly allocated to three groups: a control group (CG; 12 players), for whom HRV was recorded for 10 min, both at rest and during an exhaustive US examination of the patellar tendon and adjacent structures; a first experimental group (PNE group; 12 players), for whom HRV was recorded for 10 min, both at rest and during application of US-guided PNE in the patellar tendon; and a second experimental group (needle group; 12 players), for whom HRV was recorded for 10 min, both at rest and during application of US-guided PNE without electrical current in the patellar tendon. The outcome measures were the diameters of the Poincaré plot (SD1, SD2), stress score, and sympathetic/parasympathetic ratio. RESULTS: There were no differences between groups in any baseline measurements, nor were there any significant differences between CG measurements (baseline vs. intervention). The PNE group exhibited statistically significant increases in SD1 (p = 0.01) and SD2 (p = 0.004) and statistically significant decreases in SS and S/PS ratio (p = 0.03), indicating increased parasympathetic and decreased sympathetic activity, respectively. The needle group exhibited statistically significant increases in SD2 (p = 0.02) and statistically significant decreases in SS (p = 0.02), indicating decreased sympathetic activity. CONCLUSIONS: The application of the US-guided PNE technique caused a measurable increase in parasympathetic activity (detected by HRV), which was due to the combination of needle puncture and electric current.

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.

Group-based exercise at workplace: short-term effects of neck and shoulder resistance training in video display unit workers with work-related chronic neck pain-a pilot randomized trial.

Effectiveness of exercise therapy in video display unit (VDU) workers with work-related chronic neck pain (W-RCNP) is unclear. The aim of the study was to assess the efficacy of group-based neck-shoulder resistance exercises on symptoms and muscular function in VDU workers with W-RCNP. Thirty-five employees with CNP were randomly assigned to neck-shoulder resistance exercise (NSRE) group or to conventional stretching and postural exercise (SPE) group. Participants trained 45 min, twice a week for 7 weeks. Primary outcomes were pain intensity (0-10 numeric rating scale, NRS) and pain-related disability (Vernon Neck Disability Index, NDI). Secondary outcomes were cervical active range of motion (AROM), endurance of neck flexors, strength of shoulder abductors, and health-related quality of life (SF-36). Post-treatment, pain and disability decreased 2.5 and 5 points in NSRE (p = 0.001) and 5 and 8 points in SPE (p = 0.002), with no significant differences between groups. AROM improved significantly in both groups; between-group differences were not significant. Neck flexors endurance and shoulder abductors strength improved by 59.6 and 34.2% (p = 0.001) in the NSRE group and by 27.6% (p = 0.009) and 2.3% (p = 0.002) in the SPE group; between-group differences were significant (p = 0.016 and p < 0.001, respectively). SF-36 score remained unchanged. NSRE and SPE are feasible and equally effective in reducing pain and pain-related disability as group exercises in W-RCNP. NSRE may provide some advantage in improving strength and endurance in neck muscles. Further, larger studies should confirm these findings and assess whether a better muscle function confers long-term clinical advantages.

Influence of Inspiratory Muscle Training on Ventilatory Efficiency and Cycling Performance in Normoxia and Hypoxia.

The aim of this study was to analyse the influence of inspiratory muscle training (IMT) on ventilatory efficiency, in normoxia and hypoxia, and to investigate the relationship between ventilatory efficiency and cycling performance. Sixteen sport students (23.05 ± 4.7 years; 175.11 ± 7.1 cm; 67.0 ± 19.4 kg; 46.4 ± 8.7 ml·kg-1·min-1) were randomly assigned to an inspiratory muscle training group (IMTG) and a control group (CG). The IMTG performed two training sessions/day [30 inspiratory breaths, 50% peak inspiratory pressure (Pimax), 5 days/week, 6-weeks]. Before and after the training period subjects carried out an incremental exercise test to exhaustion with gas analysis, lung function testing, and a cycling time trial test in hypoxia and normoxia. Simulated hypoxia (FiO2 = 16.45%), significantly altered the ventilatory efficiency response in all subjects (p < 0.05). Pimax increased significantly in the IMTG whereas no changes occurred in the CG (time × group, p < 0.05). Within group analyses showed that the IMTG improved ventilatory efficiency (VE/VCO2 slope; EqCO2VT2) in hypoxia (p < 0.05) and cycling time trial performance [WTTmax (W); WTTmean (W); PTF(W)] (p < 0.05) in hypoxia and normoxia. Significant correlations were not found in hypoxia nor normoxia found between ventilatory efficiency parameters (VE/VCO2 slope; LEqCO2; EqCO2VT2) and time trial performance. On the contrary the oxygen uptake efficiency slope (OUES) was highly correlated with cycling time trial performance (r = 0.89; r = 0.82; p < 0.001) under both conditions. Even though no interaction effect was found, the within group analysis may suggest that IMT reduces the negative effects of hypoxia on ventilatory efficiency. In addition, the data suggest that OUES plays an important role in submaximal cycling performance.

Ventilatory efficiency and breathing pattern in world-class cyclists: A three-year observational study.

The purpose of this three-year observational study was to analyze the ventilatory efficiency and breathing pattern in world-class professional cyclists. Twelve athletes (22.61±3.8years; 177.38±5.5cm; 68.96±5.5kg and VO2max 75.51±3.3mLkg(-1)min(-1)) were analyzed retrospectively. For each subject, respiratory and performance variables were recorded during incremental spiroergometry: oxygen uptake (VO2), carbon dioxide output (VCO2), pulmonary ventilation (VE), tidal volume (Vt), breathing frequency (fR), driving (Vt/Ti), timing (Ti/Ttot), peak power output (PPO) and maximum oxygen uptake (VO2max). Ventilatory efficiency (VE/VCO2 slope) was calculated from the beginning of exercise testing to the second ventilatory threshold (VT2). The VE/VCO2 slope was unaffected during the study period (24.63±3.07; 23.61±2:79; 24:89±2:61) with a low effect size (ES=0.04). The PPO improved significantly in the third year (365±33.74; 386.36±32.33; 415.00±24.15) (p<0.05). The breathing pattern variables, Vt/Ti and Ti/Ttot, did not change significantly over the three year period (ES=0.00; ES=0.03 respectively). These findings suggest that changes in cycling performance in world-class professional cyclists do not modify breathing variables related to the control of ventilatory efficiency.

Autonomic responses to ultrasound-guided percutaneous needle electrolysis of the patellar tendon in healthy male footballers.

BACKGROUND: Ultrasound (US)-guided percutaneous needle electrolysis (PNE) is a novel minimally invasive approach, which involves the application of a galvanic current via an acupuncture needle. As in any procedure involving needling, vagal reactions have been reported during PNE. OBJECTIVE: To examine for changes in autonomic activity during the US-guided PNE technique on healthy patellar tendons by measurement and analysis of heart rate variability (HRV). METHODS: Twenty-two male footballers were randomly allocated to: a control group (11 players), for whom HRV was recorded for 10 min, both at rest and during an exhaustive US examination of the patellar tendon and adjacent structures; and an experimental group (11 players), for whom HRV was recorded for 10 min, both at rest and during application of US-guided PNE on the patellar tendon. The following HRV parameters were assessed: mean NN interval, mean heart rate, time domain parameters (SDNN, rMSSD, pNN50), diameters of the Poincaré plot (SD1, SD2), stress score, and sympathetic/parasympathetic ratio. RESULTS: There were no differences between groups in any baseline measurements, nor were there any significant differences between control group measurements (baseline vs intervention). The experimental group exhibited statistically significant increases in SDNN/SD1 (p=0.02/p=0.03) and SD2 (p=0.03), indicating increased parasympathetic and decreased sympathetic activity, respectively. CONCLUSIONS: US-guided PNE was associated with an autonomic imbalance characterised by greater parasympathetic activity, which could potentially result in a vasovagal reaction. Care should be taken to monitor for adverse reactions during US-guided PNE and simple HRV indicators may have a role in early detection.

Atribuciones profesionales en el ejercicio para la salud de la Sociedad Española de Medicina del Deporte / Professional attributions in the exercise for the health of the Spanish Society of Sports Medicine

La práctica regular de ejercicio físico es extraordinariamente efectiva en el manejo de un número creciente de patologíascrónicas algunas de ellas con una prevalencia de magnitud pandémica, por lo que la sociedad debe asumir la incorporaciónde la actividad física como estrategia de salud para prevenir y para servir como tratamiento complementario de la enfermedad.La medicina y la fisioterapia tienen un papel primordial en el manejo del ejercicio para la salud y también, fuera de la sanidad,las titulaciones de ciencias de la actividad física y el deporte ocupan un papel muy destacado en este ámbito de trabajo.Desde la sanidad, la medicina y la fisioterapia tienen un papel primordial en el manejo del ejercicio para la salud y también,fuera de la sanidad, las titulaciones de ciencias de la actividad física y el deporte ocupan un papel muy destacado en la pro-moción y ejecución de estrategias para el fomento de la salud.Estas profesiones han venido ocupando una posición en el abordaje de este problema que, en algunas ocasiones, ha supuestopuntos de fricción respecto a su papel, responsabilidades y función. Por otra parte, existe la necesidad de resolver la cuestiónde los ámbitos competenciales de las profesiones manteniendo la voluntad de reconocer simultáneamente los crecientesespacios competenciales compartidos interprofesionalmente y los muy relevantes espacios específicos de cada profesión.Este documento parte de la necesidad de abordar la incorporación del ejercicio en la prevención y manejo de la enfermedadde una forma sólida y consistente, considerando la aportación de las profesiones implicadas desde la óptica del trabajo mul-tidisciplinar y con una colaboración no conflictiva sino cooperativa, transparente y respetuosa y, siempre, con el objetivo deservir a la sociedad de la forma más efectiva posible, definiendo de una forma clara cuáles con las atribuciones profesionalesde la medicina, de la fisioterapia y de las ciencias...(AU)

The regular practice of physical exercise is extraordinarily effective in the management of a growing number of chronic diseases,some of them with a prevalence of pandemic magnitude, for which the society must assume the incorporation of physicalactivity as a health strategy to prevent and to serve as a complementary treatment of the disease.Not only medicine and physiotherapy play a fundamental role in the management of exercise for health but also, outside ofhealth, Sports science and physical education degree is crucial in this field of work.From a health point of view, medicine and physiotherapy have a primary role in the management of exercise for health andalso, outside of health, sports science and physical education degree occupy a very prominent role in the promotion andimplementation of strategies for the promotion of health.These professions have been occupying a position in addressing this problem that, on some occasions, has led to points offriction with respect to their role, responsibilities and function. On the other hand, there is a need to resolve the question ofthe professions’ areas of competence while maintaining the will to simultaneously recognize the growing areas of competenceshared interprofessionally and the highly relevant areas specific to each profession.This document is based on the need to address the incorporation of exercise in the prevention and management of disease ina solid and consistent way, considering the contribution of the professions involved from the perspective of multidisciplinarywork and with a non-conflictual but cooperative, transparent and respectful collaboration. In addition, this collaborationshould always aim at serving society in the most effective way possible, clearly defining the professional attributions of me-dicine, physiotherapy and physical activity and sport sciences in everything related to the use of exercise as a tool for health.(AU)

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

Obesidad y ejercicio físico en adultos / Obesity and physical exercise in adults

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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.

Efectos hormonales y hematológicos en una marcha invernal de baja altitud en militares chilenos / Hormonal and hematological effects in a low-altitude winter march in chilean military

Introducción: Las exposiciones intermitentes a gran altitud tienen efectos agudos sobre algunos marcadores biológicos, como la testosterona, pero no así en baja altitud. Dado que el entrenamiento de soldados debería ir asociado a tareas militares específicas, adquiere gran importancia valorar los cambios fisiológicos que puedan producirse en determinadas circunstancias (como la altitud) pero durante la realización de actividades propias de las unidades militares. Objetivo: Identificar los cambios hematológicos y en las hormonas Testosterona Libre (TL), Testosterona Total (TT ) y Cortisol en una marcha nocturna a baja altitud en soldados de operaciones en montaña. Metodología: 32 Militares masculinos (26,3 ± 4,50 años, 75,1 ± 7,6 kg) realizaron una marcha invernal nocturna con equipo y un desnivel entre los 902 y 1648 m. Se obtuvieron muestras de sangre antes y después de la marcha y se midió TL, TT, cortisol y hemograma: hematíes (Hmt), hemoglobina (Hb), hematocrito (Htto) y volumen corpuscular medio (VCM). Resultados: Se produjo un descenso significativo de los valores de TL y TT sin cambios en el cortisol plasmático. También se observó un descenso en las cifras de Hmt, Hb, Htto y VCM. Conclusión: Una marcha invernal con equipo de combate, en baja altitud y con un desnivel de 746 m, produce un descenso significativo de los valores plasmáticos de Testosterona (libre y total) en soldados de una unidad de operaciones en montaña. No se observan cambios en los valores de cortisol. Se detecta una reducción significativa de hematíes, hemoglobina, hematocrito y VCM que podrían deberse a un efecto de hemodilución

Introduction: Intermittent exposures at high altitude have acute effects on some biological markers, such as testosterone, but not at low altitude. Since the training of soldiers should carry out specific military activities, is very important to asses physiological changes that can occur in particular circumstances (such as altitude) but during the performance of the activities of the military units. Objective: To identify the hematological changes and the hormones Free Testosterone (TL), Total Testosterone (TT ) and Cortisol during a nocturnal march at low altitude in soldiers of mountain operations. Methodology: 32 male military (26.3 ± 4.50 years, 75.1 ± 7.6 kg) performed a nocturnal winter march with equipment between 902 and 1648 m of altitude. Blood samples were obtained before and after the march, and TL, TT, cortisol and blood count were measured: red blood cells (Hmt), hemoglobin (Hb), hematocrit (Htto) and mean corpuscular volume (MCV ). Results: There was a significant decrease in TL and TT values without changes in plasmatic cortisol. A reduction in the values of Hmt, Hb, Htto and VCM has also been observed. Conclusion: A winter march with combat equipment, at low altitude and with a unevenness of 746 m, produces a significant decrease in the plasma values of Testosterone (free and total) in soldiers of mountain operations. No changes in cortisol values are observed. A significant reduction of red blood cells, hemoglobin, hematocrit and MCV is detected, which could be due to a hemodilution effect