Ventilatory Pattern Influences Tolerance to Normobaric Hypoxia in Healthy Adults.

INTRODUCTION: Tolerance to breathing in conditions with a decreased oxygen ratio is subject-specific. A normobaric hypoxia tolerance test (NHTT) is performed to assess the ability of each individual, as this may be influenced by genetic or personal factors such as age or gender. The aim of this study is to test the influence of deep breathing on hypoxia tolerance time. MATERIAL AND METHODS: A total of 45 subjects (21 parachutists and 24 students) performed two NHTTs at 5050 m altitude (iAltitude). Arterial (SatO2) and muscle (SmO2) oxygen saturation were monitored with the Humon Hex® device. The first NHTT was performed with free breathing, without any instructions; and the second NHTT was performed with wide, slow, diaphragmatic breathing. The NHTT was terminated at the end of 10 min or when a value of less than 83% was obtained. RESULTS: The first NHTT was completed by 38.1% of parachutist and 33.3% of students while the second NHTT was completed by 85.7% and 75%, respectively. In the second NHTT, both parachutists and students had a significantly (p = 0.001) longer duration compared to the first NHTT. SmO2 and SatO2 values also increased significantly (p < 0.001) in both groups (p < 0.05). CONCLUSION: Performing controlled diaphragmatic breathing is successful in increasing hypoxia tolerance time and/or SatO2 values.

The Effect of Normobaric Hypoxia in Middle- and/or Long-Distance Runners: Systematic Review.

BACKGROUND: The use of normobaric hypoxia can bring benefits to sports performance because it improves haematological parameters and/or physical activity tests. Our objective was to conduct a systematic review so as to analyse the methods used in hypoxia and to detect its effects on middle- and/or long-distance runners. METHODS: Research was conducted using five electronic databases (PubMed, SportDiscus, Cochrane Library, Scopus and PEDro) until December 2021. The methodological quality of the included studies was assessed using the PEDro scale. RESULTS: Having analysed 158 studies, 12 were chosen for the qualitative and quantitative synthesis. A significant improvement on time until exhaustion was detected, and oxygen saturation decreased after the intervention. There were no significant changes in the 3000-metre time trial or in the haematocrit percentage. The changes in percentage of reticulocytes, heart rate, maximal heart rate, lactate concentration and erythropoietin were heterogeneous between the different research studies. CONCLUSION: short exposure (less than 3 h to normobaric hypoxia significantly increases the time to exhaustion). However, longer exposure times are necessary to increase haemoglobin. Altitude and exposure time are highly heterogeneous in the included studies.

Validity and Absolute Reliability of the Cobb Angle in Idiopathic Scoliosis with TraumaMeter Software.

The Cobb angle value is a critical parameter for evaluating adolescent idiopathic scoliosis (AIS) patients. This study aimed to evaluate a software's validity and absolute reliability to determine the Cobb angle in AIS digital X-rays, with two different degrees of experienced observers. Four experts and four novice evaluators measured 35 scoliotic curves with the software on three separate occasions, one month apart. The observers re-measured the same radiographic studies on three separate occasions three months later but on conventional X-ray films. The differences between the mean bias errors (MBE) within the experience groups were statistically significant between the experts (software) and novices (manual) (p < 0.001) and between the novices (software) and novices (manual) (p = 0.005). When measured with the software, the intra-group error in the expert group was MBE = 1.71 ± 0.61° and the intraclass correlation coefficient (ICC (2,1)) = 0.986, and in the novice group, MBE = 1.9 ± 0.67° and ICC (2,1) = 0.97. There was almost a perfect concordance among the two measurement methods, ICC (2,1) = 0.998 and minimum detectable change (MCD95) < 0.4°. Control of the intrinsic error sources enabled obtaining inter- and intra-observer MDC95 < 0.5° in the two experience groups and with the two measurement methods. The computer-aided software TraumaMeter increases the validity and reliability of Cobb angle measurements concerning manual measurement.

Validity and reliability of a computer-assisted system method to measure axial vertebral rotation.

Background: Axial vertebral rotation and Cobb's angle are essential parameters for analysing adolescent idiopathic scoliosis. This study's scope evaluates the validity and absolute reliability of application software based on a new mathematical equation to determine the axial vertebral rotation in digital X-rays according to Raimondi's method in evaluators with different degrees of experience. Methods: Twelve independent evaluators with different experience levels measured 33 scoliotic curves in 21 X-rays with the software on three separate occasions, separated one month. Using the same methodology, the observers re-measured the same radiographic studies three months later but on X-ray films and in a conventional way. Results: Both methods show good validity and reliability, and the intraclass correlation coefficients are almost perfect. According to our results, the software increases 1.7 times the validity and 1.9 times the absolute reliability of axial vertebral rotation on digital X-rays according to Raimondi's method, compared to the conventional manual measurement. Conclusions: The intra-group and inter-group agreement of the measurements with the software shows equal or minor variations than with the manual method, among the different measurement sessions and in the three experience groups. There is almost perfect agreement between the two measurement methods, so the equation and the software may be helpful to increase the accuracy in the axial vertebral rotation assessment.

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 .

Sex differences in the effort indicators during cardiopulmonary resuscitation manoeuvres on manikins.

The aims of this study were to examine sex differences in college students while they performed cardiopulmonary resuscitation (CPR) on a manikin for 20 min in (a) objective and subjective effort indicators and (b) to analyse the influence of potential confounders (age, BMI and cardiorespiratory fitness) on these sex differences. Sixty-three participants were recruited. Participants performed 20 min of CPR on a manikin. During the CPR trial, percentages of maximal heart rate levels were higher in women than in men (P<0.05) and perceived exertion increased significantly in both sexes over time (P=0.05); furthermore, at the last two time points analysed, women scored higher than men (P<0.05). However, these sex differences disappeared when controlling for age, BMI and cardiorespiratory fitness. In conclusion, indicators of exertion during CPR are higher in women than in men, but these sex differences are because of BMI and differences in physical fitness conditions.