Analysis of Muscle Oxygenation after a Normobaric Hypoxia Tolerance Test.

The aim of this work was to analyze the influence of acute normobaric hypoxia on quadricep oxygenation. Muscle oxygen saturation (SmO2) was measured using near-infrared spectrometry (NIRS) technology during a normobaric hypoxia tolerance test (NHTT). SmO2 was measured with a Humon Hex® device. In total, 54 healthy subjects participated, 68.5 of which were males and 31.5% of which were females. They performed an NHTT with the IAltitude® simulator, breathing air with an FiO2 level of 11% (equivalent to 5050 m). The maximum duration of the NHTT was set at 10 min, stopping if it reached 83% SpO2. The initial values (PRE) were compared with those obtained at the end of the test (POST) and after 10 min of recovery. The participants were divided into two groups based on whether (G1) they completed the ten minutes or not (G2). In total, 35.1% of men and 41.2% of women completed the 10 min. In both groups, significant differences were observed in the decrease in SmO2 values (p < 0.0001) (G1: PRE = 59.5 ± 12.48%; POST = 55.95 ± 14.30%; G2: PRE = 60.06 ± 13.46%; POST = 57.2 ± 12.3%). There were no differences between groups in any of the three periods. Exposure to normobaric hypoxia produces a decrease in quadricep levels of SmO2 in both sexes, regardless of whether the test is completed. Two patterns appeared: A.-less time and more hypoxia; B. a longer duration and less hypoxia.

Influences of Intense Physical Effort on the Activity of the Autonomous Nervous System and Stress, as Measured with Photoplethysmography.

Background: The autonomic nervous system, which is composed of the sympathetic and parasympathetic nervous system, is closely related to the cardiovascular system. The temporal variation between each of the intervals between the consecutive "R" waves of an electrocardiogram is known as heart rate variability. Depending on the type of activity, both systems can be activated, and also influence the interval between "R" waves. Currently, with advancements in technology and electronic devices, photoplethysmography is used. Photoplethysmography detects changes in the intensity of reflected light that allow differentiation between systole and diastole and, therefore, determines the heart rate, its frequency and its variations. In this way, changes in the autonomic nervous system can be detected by devices such as the Max Pulse®. Objective: To determine whether the information provided by Max Pulse® on autonomic balance and stress is modified after intense physical exercise, thereby determining whether there is a relationship with body composition, and also whether there are differences with respect to gender. Materials and Methods: Fifty-three runners (38.9% female) with a mean age of 31.3 ± 8.1 years participated in the study. Two measurements (before and after intense physical effort) were performed with the Max Pulse® device. The flotoplethysmography measurement lasted 3 min, and was performed in the supine position. The exercise test was performed on a treadmill. It was initiated at a speed of 6 and 7 km/h for women and men, respectively. Subjects indicated the end of the test by making a hand gesture when unable to continue the test. Results: Autonomic nervous system activity and mental stress values decreased significantly (p < 0.05) in men and women, while autonomic nervous system balance decreased only in women. Physical stress increased (p < 0.05) in both sexes. Conclusions: Intense exercise causes changes in variables that assess autonomic nervous system balance and stress, as measured by a device based on photoplethysmography. The changes are evident in both sexes, and are not related to body composition.

Estudio de la variabilidad de la frecuencia cardiaca tras la exposición a la hipoxia normobárica / Study of heart rate variability after exposure to normobaric hypoxia

La variabilidad de la frecuencia cardiaca (VFC) es una herramienta capaz de analizar y valorar la actividad vegetativa sobre el corazón ante diversas actividades y situaciones. Consiste en medir el tiempo que trascurre entre cada dos latidos cardiacos durante un periodo de tiempo y expresarlo en función de ecuaciones matemáticas y estadísticas. Otros autores han analizado la influencia de diferentes estresores sobre la VFC. En este trabajo buscamos la acción de la hipoxia normobárica (HN) sobre la misma. La HN consiste en respirar aire empobrecido de oxígeno simulando el entrenamiento en altitud. El objetivo del estudio es determinar la influencia de la HN sobre los dominios de tiempo y frecuencia de la VFC. Sometimos a 13 sujetos sanos (deportistas recreacionales) a dos sesiones de HN. Usamos el simulador iAltitude Trainer v2.7®. La primera mediante un test de tolerancia a la hipoxia (TTH) (10 minutos, 11% O2, equivalente a 5.050 m) y, la segunda, con una exposición intermitente (HNI) (14% O2, 3.250 m) en la que se alternaron periodos de 4 minutos de hipoxia con 4 de normoxia durante 64 minutos. Para el análisis de VFC se utilizó un pulsómetro Polar H10®, la aplicación HRV-elite® y el software Kubios-Standard®. Se tomaron los datos de los 5 minutos previos y posteriores a cada sesión, comparándose estos valores mediante el test de T-student para datos pareados. Ninguna de las variables de los dominios de tiempo (RRmedio, SDNN, rMSSD, pNN50) ni de frecuencia (VLF, LF, HF, LF/HF) de la VFC mostró cambios significativos ante ninguna de las dos situaciones. La HN no provocó modificaciones en los niveles de estrés de estos sujetos, siendo bien tolerada, clínica y electrocardiográficamente. Un test de tolerancia y una sesión de exposición a hipoxia normobárica intermitente no son estímulos suficientes para provocar cambios agudos en la VFC

Heart rate variability (HRV) is a tool capable of analysing and assessing the vegetative activity of the heart in various activities and situations. It consists of measuring the time that elapses between every two heartbeats over a period of time and expressing it in terms of mathematical and statistical equations. Other authors have analysed the influence of different stressors on HRV. In this work we are looking for the action of normobaric hypoxia (NH) on HRV. NH consists of breathing oxygen-depleted air simulating altitude training. The aim of the study is to determine the influence of HN on the time and frequency domains of HRV. We subjected 13 healthy subjects (recreational athletes) to two HN sessions. We used the iAltitude Trainer v2.7® simulator. The first was a hypoxia tolerance test (HTT) (10 minutes, 11% O2, equivalent to 5050m) and the second was an intermittent exposure (HNI) (14% O2, 3250m) in which periods of 4 minutes of hypoxia alternated with 4 minutes of normoxia for 64 minutes. For HRV analysis, a Polar H10® heart rate monitor, the HRV-elite® application and the Kubios-Standard® software were used. Data were taken 5 minutes before and after each session, and these values were compared using the Student ́s t- test for paired data. None of the variables in the time (RRmean, SDNN, rMSSD, pNN50) or frequency (VLF, LF, HF, LF/HF) domains of HRV showed significant changes in either situation. HN did not cause changes in the stress levels of these subjects and was well tolerated, clinically and electrocardiographically. A tolerance test and a session of exposure to intermittent normobaric hypoxia are not sufficient stimuli to cause acute changes in HRV.(AU)

Muscle oxygenation of the quadriceps and gastrocnemius during maximal aerobic effort / Oxigenación muscular de cuádriceps y gastrocnemio durante el esfuerzo aeróbico máximo / Oxigenação muscular de quadríceps e gastrocnêmio durante o esforço aeróbico máximo

ABSTRACT Introduction: Near infrared spectroscopy (NIRS) is a non-invasive technique that is used in the assessment of tissue oxygenation and the monitoring of physical activity. Objective: To determine the influence of sexual, anthropometric and ergospirometric factors on muscle oxygenation of the quadriceps and gastrocnemius, obtained by NIRS during a stress test. Methods: Twenty healthy subjects participated in this study (10 women). Two Humon Hex® devices were placed on the dominant side of the quadriceps and gastrocnemius muscles to measure muscle oxygen saturation (SmO2). The stress test was performed on a treadmill with electrocardiographic control and measurement of oxygen consumption. SmO2 was obtained at rest and after maximum effort during the stress test. In addition, the height, weight, skinfold and waist contour were measured. Bioimpedance was used to obtain the percentages of fat mass and muscle mass, which were used to calculate the relative fat mass (RFM). Results: The SmO2 of both muscles at rest is higher in males than in females. At maximum effort, the SmO2 of the quadriceps is similar in both groups. The SmO2 of both muscles is positively related to height, body mass, percentage of mass muscle and waist contour, and negatively with percentage of mass fat, RFM and skinfold thickness. The negative correlation between fat percentage and oxygen saturation is more evident in females. It was observed that the variables that quantify maximum effort are not related to the SmO2 values, except for the correlation between HR max and SmO2 of the gastrocnemius muscle in males. Conclusion: The SmO2 of recreational athletes is influenced by the location of the device and the fat mass of the subjects. The biggest differences between the sexes are in the gastrocnemius muscle. Level of Evidence II; Diagnostic Studies - Investigating a Diagnostic Test .

RESUMEN Introducción: La espectroscopia de infrarrojo cercano (NIRS) es una técnica no invasiva usada en la evaluación de la oxigenación tisular y en la monitorización de la actividad física. Objetivos: Determinar la influencia de factores sexuales, antropométricos y ergoespirométricos sobre la oxigenación muscular de cuádriceps y del gastrocnemio, obtenidos por NIRS durante un test de esfuerzo. Métodos: Participaron en este estudio 20 individuos saludables (10 mujeres). Se colocaron dos dispositivos Humon Hex® en el lado dominante de los músculos cuádriceps y gastrocnemio para medir la saturación de oxígeno muscular (SmO2). El test de esfuerzo fue realizado en una cinta ergométrica con control electrocardiográfico y medición del consumo de oxígeno. La SmO2 fue obtenida en reposo y después de esfuerzo máximo durante el test. Además, fueron medidos altura, peso, pliegues cutáneos y contorno de la cintura. Fue usada bioimpedancia para obtener los porcentuales de masa grasa y masa muscular, que fueron usados para calcular la masa grasa relativa (MGR). Resultados: La SmO2 de ambos músculos en reposo es mayor en hombres que en mujeres. En el esfuerzo máximo la SmO2 del cuádriceps es semejante en los dos grupos. La SmO2 de ambos músculos es positivamente relacionada con altura, masa corporal, porcentual de masa muscular y contorno de la cintura y negativamente relacionada con el porcentaje de masa grasa, MGR y espesor de los pliegues cutáneos. La correlación negativa entre el porcentual de grasa y la saturación de oxígeno es más evidente en las mujeres. Se observó que variables que cuantifican el esfuerzo máximo no está relacionadas con los valores SmO2, excepto por la correlación entre FCmáx y SmO2 del músculo gastrocnemio en sexo masculino. Conclusión: La SmO2 de los atletas recreativos es influenciada por la localización del dispositivo y por la masa grasa de los individuos. Las mayores diferencias entre los sexos están en el músculo gastrocnemio. Nivel de Evidencia II; Estudios diagnósticos - Investigación de un examen para diagnóstico .

RESUMO Introdução: A espectroscopia de infravermelho próximo (NIRS) é uma técnica não invasiva usada na avaliação da oxigenação tecidual e no monitoramento da atividade física. Objetivos: Determinar a influência de fatores sexuais, antropométricos e ergoespirométricos sobre a oxigenação muscular do quadríceps e do gastrocnêmio obtidos por NIRS durante um teste de esforço. Métodos: Participaram deste estudo 20 indivíduos saudáveis (10 mulheres). Dois dispositivos Humon Hex® foram colocados no lado dominante dos músculos quadríceps e gastrocnêmio para medir a saturação de oxigênio muscular (SmO2). O teste de esforço foi realizado em uma esteira com controle eletrocardiográfico e mensuração do consumo de oxigênio. A SmO2foi obtida em repouso e depois de esforço máximo durante o teste. Além disso, foram medidos estatura, peso, dobras cutâneas e contorno da cintura. A bioimpedância foi usada para obter os percentuais de massa gorda e massa muscular, que foram usados para calcular a massa gorda relativa (MGR). Resultados: A SmO2de ambos os músculos em repouso é maior em homens do que em mulheres. No esforço máximo, a SmO2do quadríceps é semelhante nos dois os grupos. A SmO2de ambos os músculos é positivamente relacionada com estatura, massa corporal, percentual de massa muscular e contorno da cintura e negativamente relacionada com a porcentagem de massa gorda, MGR e espessura das dobras cutâneas. A correlação negativa entre o percentual de gordura e a saturação de oxigênio é mais evidente nas mulheres. Observou-se que variáveis que quantificam o esforço máximo não estão relacionadas com os valores SmO2, exceto pela correlação entre FCmáx e SmO2do músculo gastrocnêmio no sexo masculino. Conclusão: A SmO2dos atletas recreativos é influenciada pela localização do dispositivo e pela massa gorda dos indivíduos. As maiores diferenças entre os sexos estão no músculo gastrocnêmio. Nível de Evidência II; Estudos diagnósticos - Investigação de um exame para diagnóstico .

Fuerza isocinética y test de salto vertical en paracaidistas acrobáticos / Isokinetic strength and vertical jump test in acrobatic skydivers

Introducción: Las rodillas de los paracaidistas pueden sufrir lesiones durante la toma de tierra que se pueden prevenir con una adecuada fuerza muscular. Esta fuerza se puede evaluar de manera directa con dinamómetros isocinéticos y con métodos indirectos mediante el test de salto vertical. Objetivo: El objetivo del estudio fue determinar y analizar, en paracaidistas profesionales, las relaciones entre los valores fuerza isocinética máxima de cuádriceps e isquiosurales con la altura y el tiempo de vuelo en saltos verticales. Material y método: Valoramos a los catorce paracaidistas pertenecientes a la Patrulla Acrobática Paracaidista del Ejército del Aire mediante un dinamómetro isocinético (a 60º/s y 180º/s) tanto para el trabajo concéntrico como excéntrico, obteniéndose los picos máximos de fuerza y las ratios isquiosurales/cuádriceps. Evaluamos, sobre una plataforma de contacto, los siguientes saltos verticales: Squat Jump, Counter Movement Jump y Abalakov Jump. Resultados: Los resultados indican que los picos de fuerza máxima de la musculatura flexo-extensora de la rodilla son mayores en modalidad excéntrica, y en el equipo masculino. Las ratios isquiosurales/cuádriceps muestran un predominio de los primeros. Abalakov Jump es el salto donde mayor altura y tiempo de vuelo se consigue. Existe una correlación positiva entre el tiempo de vuelo de todos los saltos y la fuerza concéntrica del cuádriceps. La altura de salto por el peso corporal (Trabajo = Kg x m) se correlaciona con los picos de fuerza concéntrica y excéntrica del cuádriceps. La relación es mayor en la velocidad más alta. La fuerza excéntrica de isquiosurales no se correlaciona con la altura de vuelo, pero sí la fuerza concéntrica. Conclusiones: Podemos concluir que las rodillas de los paracaidistas presentan un predominio en la fuerza de los isquiosurales, lo que se considera positivo para la actividad que realizan ya que contribuye a mejorar la estabilidad de la rodilla y que hay altas correlaciones entre los picos de fuerza isocinético y el trabajo realizado en los saltos verticales

Introduction: Knees of the parachutists can suffer injuries during the landing that can be avoided with a correct muscular strength. This strength is posible to be evaluated of direct way with isokinetic dynanometers and indirect methods using the test of vertical jump. Objective: The aim of this study was to determine and analyze, in professional skydivers, the relationship between the values of isokinetic force of quadriceps and hamstrings with height and time of flight in vertical jumps. Material and methods: We studied the fourteen paratroopers belonging to the (patrol acrobatic jumper of the air force) using an isokinetic dynamometer (60°/s and 180°/s) both for concentric work as eccentric, obtaining the peaks maximum of strength and hamstrings/quadriceps ratios. Evaluate, on a platform of contact, the following vertical jumps: Abalakov Jump and Squat Jump, Counter Movement Jump. Results: The results indicate that the peaks of maximum strength of flexor and extensor muscles of the knee are greater in eccentric mode, and the men’s team. Hamstrings/quadriceps ratios show a predominance of the first. AJ is the jump where greater height and time of flight is achieved. There is a positive correlation between the flight time of all jumps and concentric quadriceps strength. The height of jump by body weight (Work = Kg x m) correlates with the peaks of concentric and eccentric strength of the quadriceps. The ratio is higher in the higher speed. The eccentric strength of hamstrings does not correlate with the height of flight, but the concentric strength. Conclusions: We can conclude that the knees of the skydivers have a predominance of the hamstrings what is considered positive for the activity carried out, since it helps to improve the stability of the knee and that there are high correlations between the peaks of force isokinetic and the work done in the jumps vertical