Relação entre variáveis antropométricas e de aptidão física em crianças e adolescentes estratificados por sexo / Relationship between anthropometric and physical fitness variables in children and adolescents stratified by sex / Relación entre variables antropométricas y de aptitud física en niños y adolescentes estratificados por sexo

A aptidão física (ApF) pode estar associada à saúde, ao desempenho esportivo e refere-se a capacidade de apresentar um determinado desempenho motor quando submetido a situações que envolvam esforços físicos. O objetivo deste estudo foi relacionar as variáveis antropométricas e de aptidão física em crianças e adolescentes da cidade de Pelotas/RS, estratificados por sexo. Foram avaliados 1720 escolares da rede municipal de Pelotas/RS, sendo 896 crianças (idade = 9,91 ± 1,21 anos) e 824 adolescentes (idade = 13,11 ± 1,04 anos), através de uma bateria de avaliações das medidas antropométricas (estatura [EST], massa corporal [MC], envergadura [ENV], índice de massa corporal [IMC]) e de testes físicos (flexibilidade [FLEX], potência de membros superiores [PMS], potência de membros inferiores [PMI], velocidade com troca de direção [VTD], velocidade linear [VL], resistência muscular localizada [RML] e capacidade cardiorrespiratória [CC]). O estudo de caráter de diagnóstico com cunho observacional utilizou o teste de correlação através do r de Pearson e classificou-as como muito fraca (0-0,19), fraca (0,2-0,39), moderada (0,4-0,69), forte (0,7-0,89) e muito forte (0,9-1). Destacou-se que no sexo feminino houve correlação moderada com IMC e PMS, as variáveis antropométricas EST, ENV e MC apresentaram pelo menos uma correlação com as variáveis de ApF, enquanto que estas variáveis demonstraram correlações moderadas entre PMS, VL e VTD. Já no sexo masculino foi observada correlação moderada entre IMC e CC, além de correlações fracas e moderadas entre EST, ENV e MC com pelo menos uma das variáveis de ApF, enquanto as variáveis de ApF demonstraram correlações moderadas entre PMI, VL e VTD. Portanto, ressalta-se a importância do diagnóstico destas variáveis para controle dos fatores de risco à saúde bem como para identificar potenciais relacionados ao desempenho esportivo.

Physical fitness (PhF) can be associated with health, sports performance and refers to the ability to present a certain motor performance when submitted to situations involving physical efforts. The aim of this study was to relate anthropometric and physical fitness variables in children and adolescents from the city of Pelotas/RS, stratified by sex. A total of 1720 schoolchildren from the municipal schools of Pelotas/RS were evaluated, 896 children (age = 9.91 ± 1.21 years) and 824 adolescents (age = 13.11 ± 1.04 years), through a battery of the anthropometric measurements (height [HT], body mass [BM], wingspan [WP], body mass index [BMI]) and physical tests (flexibility [FLEX], upper limb power [ULP], lower limb power [LLP], change of direction speed [CODS], linear speed [LS], localized muscular endurance [LME] and cardiorespiratory capacity [CC]). The study of a diagnostic character with an observational nature used the correlation test through Pearson's r and classified them as very small (0-0.19), small (0.2- 0.39), moderate (0.4- 0.69), large (0.7-0.89) and very large (0.9-1). It was highlighted that in females there was moderate correlation with BMI and ULP, the anthropometric variables HT, WP and BM showed at least one correlation with the PhF variables, while these variables showed moderate correlations between ULP, LS and CODS. In males, a moderate correlation was observed between BMI and CC, in addition to small and moderate correlations between HT, WP and BM with at least one of the PhF variables, while the PhF variables showed moderate correlations between LLP, LS and CODS. Therefore, it emphasizes the importance of diagnosing these variables to control health risk factors as well as to identify potentials related to sports performance.

La aptitud física (AF) puede estar asociada a la salud, al rendimiento deportivo y se refiere a la capacidad de presentar un determinado desempeño motor cuando sometido a situaciones que impliquen esfuerzos físicos. El objetivo de este estudio fue relacionar variables antropométricas y de aptitud física en niños y adolescentes de la ciudad de Pelotas/RS, estratificados por sexo. Fueron evaluados 1720 escolares de las escuelas municipales de Pelotas/RS, 896 niños (edad = 9,91 ± 1,21 años) y 824 adolescentes (edad = 13,11 ± 1. 04 años), a través de una batería de medidas antropométricas (altura [HT], masa corporal [BM], envergadura [WP], índice de masa corporal [IMC]) y pruebas físicas (flexibilidad [FLEX], potencia de miembros superiores [ULP], potencia de miembros inferiores [LLP], velocidad de cambio de dirección [CODS], velocidad lineal [LS], resistencia muscular localizada [LME] y capacidad cardiorrespiratoria [CC]). El estudio, de carácter diagnóstico y observacional, utilizó la prueba de correlación mediante la r de Pearson y las clasificó en muy pequeñas (0-0,19), pequeñas (0,2-0,39), moderadas (0,4- 0,69), grandes (0,7-0,89) y muy grandes (0,9-1). Se destacó que en las hembras hubo una correlación moderada con el IMC y el ULP, las variables antropométricas HT, WP y BM mostraron al menos una correlación con las variables PhF, mientras que estas variables mostraron correlaciones moderadas entre ULP, LS y CODS. En los varones, se observó una correlación moderada entre IMC y CC, además de correlaciones pequeñas y moderadas entre HT, WP y BM con al menos una de las variables PhF, mientras que las variables PhF mostraron correlaciones moderadas entre LLP, LS y CODS. Por lo tanto, se destaca la importancia del diagnóstico de estas variables para controlar los factores de riesgo para la salud, así como para identificar potenciales relacionados con el rendimiento deportivo.

Physiological Demands of Basic Fire Management Tasks in Members of the Canadian Armed Forces: A Pilot Study.

INTRODUCTION: Members of the Canadian Armed Forces (CAF) are required to meet the minimum standards of the Fitness for Operational Requirements of CAF Employment (FORCE) job-based simulation test (JBST) and must possess the capacity to perform other common essential tasks. One of those tasks is to perform basic fire management tasks during fire emergencies to mitigate damage and reduce the risk of injuries and/or death until professional firefighters arrive at the scene. To date however, the physiological demands of common firefighting tasks have mostly been performed on professional firefighters, thus rendering the transferability of the demands to the general military population unclear. This pilot study aimed to quantify, for the first time, the physiological demands of basic fire management tasks in the military, to determine if they are reflected in the FORCE JBST minimum standard. We hypothesized that the physiological demands of basic fire management tasks within the CAF are below the physiological demands of the FORCE JBST minimum standard, and as such, be lower than the demands of professional firefighting. MATERIALS AND METHODS: To achieve this, 21 CAF members (8 females; 13 males; mean [SD] age: 33 [10] years; height: 174.5 [10.5] cm; weight: 85.4 [22.1] kg, estimated maximal oxygen uptake [$\dot V$O2peak]: 44.4 (7.4) mL kg-1 min-1) participated in a realistic, but physically demanding, JBST developed by CAF professional firefighting subject matter experts. The actions included lifting, carrying, and manipulating a 13-kg powder fire extinguisher and connecting, coupling, and dragging a 38-mm fire hose over 30 m. The rate of oxygen uptake ($\dot V$O2), heart rate, and percentage of heart rate reserve were measured continuously during two task simulation trials, which were interspersed by a recovery period. Rating of perceived exertion (6-no exertion; 20-maximal exertion) was measured upon completion of both task simulations. Peak $\dot V$O2 ($\dot V$O2peak) was estimated based on the results of the FORCE JBST. RESULTS: The mean (SD) duration of both task simulation trials was 3:39 (0:19) min:s, whereas the rest period in between both trials was 62 (19) minutes. The mean O2 was 21.1 (4.7) mL kg-1 min-1 across trials, which represented 52.1 (12.2) %$\dot V$O2peak and ∼81% of the FORCE JBST. This was paralleled by a mean heart rate of 136 (18) beats min-1, mean percentage of heart rate reserve of 61.2 (10.8), and mean rating of perceived exertion of 11 ± 2. Other physical components of the JBST consisted of lifting, carrying, and manipulating a 13-kg load for ∼59 seconds, which represents 65% of the load of the FORCE JBST. The external resistance of the fire hose drag portion increased up to 316 N, translating to a total of 6205 N over 30 m, which represents 96% of the drag force measured during the FORCE JBST. CONCLUSIONS: Our findings demonstrate that the physiological demands of basic fire management tasks in the CAF are of moderate intensity, which are reflected in the CAF physical fitness standard. As such, CAF members who achieve the minimum standard on the FORCE JBST are deemed capable of physically performing basic fire management tasks during fire emergencies.

Respuesta fisiológica al test de lanzadera en pacientes candidatos a cirugía bariátrica / Physiologic response to the incremental shuttle walk test in candidates to undergo bariatric surgery / Resposta fisiológica ao teste incremental de caminhada em candidatos a cirurgia bariátrica

Objetivos: la valoración de la tolerancia al ejercicio es clave para prescribir ejercicio en candidatos a cirugía bariátrica. El test de lanzadera (TL) se ha propuesto para este objetivo. Sin embargo, la evidencia que describe el rendimiento y respuesta fisiológica asociados a esta prueba en dicha población es escasa. El objetivo de este estudio fue describir la respuesta fisiológica a la realización del TL en candidatos a cirugía bariátrica. Métodos: este estudio transversal incluyó a 56 participantes. Se midieron factores antropométricos como la edad, peso, estatura y circunferencia de cintura, así como el nivel de actividad física espontáneo. Se valoró el rendimiento en el TL en metros, la respuesta fisiológica asociada en términos de frecuencia cardiaca de reserva (FCR) utilizada, presión arterial sistólica y diastólica, oximetría de pulso, sensación subjetiva al esfuerzo (SSE) y de fatiga de extremidades inferiores, antes y después del TL. Resultados: todos los participantes completaron la prueba sin complicaciones. Caminaron una mediana de 465 metros, equivalente al 61% de la distancia esperada. Utilizaron un 56% de la FCR, mientras que la SSE y fatiga de extremidades inferiores alcanzó valores 7/10 y 6/10 respectivamente. Fueron observadas asociaciones significativas entre el rendimiento en el TL vs factores antropométricos e indicadores de respuesta fisiológica. Conclusión: el TL es una prueba segura para valorar la tolerancia al esfuerzo en candidatos a cirugía bariátrica, la cual induce respuestas fisiológicas asociadas a intensidades moderadas. Se sugiere incluir esta prueba para la valoración de la condición física de estos sujetos.

Objective: Exercise tolerance measurement is key for exercise prescription in bariatric surgery candidates. Thus, the incremental shuttle walking test (ISWT) has been proposed as a useful tool for this purpose. However, reports describing the performance, and related physiological response, in candidates to bariatric surgery are scarce. Therefore, the aim of this study was to describe the physiological response of bariatric surgery candidates to the ISWT. Methods: This cross-sectional study included 56 participants. Anthropometric factors such as age, weight, height, and waist circumference were measured, as well as their spontaneous physical activity levels. Their ISWT performance was recorded, as well as the percentage of heart rate reserve used during the test, systolic and diastolic pressure, pulse oximetry, perceived exertion scale, and lower extremities fatigue, both before and after the ISWT. Results: All participants completed the test without complications. They walked a median of 465 meters, 61% of the expected distance. Heart rate reserve utilization reached 56%, while the perceived exertion rate and lower extremities fatigue reached 7/10 and 6/10, respectively. Moreover, significant associations between the ISWT performance vs anthropometric factors and physiological response outcomes were found. Conclusion: The ISWT is a safe and useful tool to assess exercise tolerance in bariatric surgery candidates, which induces physiological responses associated to moderate effort intensities. We suggest including the ISWT when assessing the physical performance of bariatric surgery candidates.

Objetivo: A medida da tolerância ao exercício é fundamental para a prescrição do exercício em candidatos à cirurgia bariátrica. Assim, o teste incremental de caminhada em vaivém (ISWT) tem sido proposto como uma ferramenta útil para este fim. No entanto, são escassos os relatos que descrevem o desempenho e a resposta fisiológica relacionada em candidatos à cirurgia bariátrica. Portanto, o objetivo deste estudo foi describir a resposta fisiológica do ISWT em candidatos à cirurgia bariátrica. Métodos: Este estudo transversal incluiu 56 participantes. Fatores antropométricos como idade, peso, altura, circunferência da cintura foram medidos, assim como os níveis de atividade física espontânea. O desempenho do ISWT foi registrado, assim como a porcentagem de reserva de frequência cardíaca utilizada durante o teste, pressão sistólica e diastólica, oximetria de pulso, escala de esforço percebido e fadiga de membros inferiores, tanto antes quanto após o ISWT. Resultados: Todos os participantes completaram o teste sem intercorrências. Eles caminharam uma mediana de 465 metros, o equivalente a 61% da distância esperada. A utilização de reserva de frequência cardíaca atingiu 56%, enquanto a taxa de esforço percebido e fadiga de membros inferiores atingiram 7/10 e 6/10, respectivamente. Além disso, foram encontradas associações significativas entre o desempenho do ISWT versus fatores antropométricos e os resultados da resposta fisiológica. Conclusão: O ISWT é uma ferramenta segura e útil para avaliar a tolerância ao exercício em candidatos à cirurgia bariátrica, que induz respostas fisiológicas associadas a intensidades moderadas de esforço. Sugerimos incluir o ISWT para avaliar o desempenho físico dos candidatos à cirurgia bariátrica.

Percepción del esfuerzo y niveles objetivos de intensidad en clases de Educación Física de escolares de primaria según sexo y estado nutricional: Estudio piloto / Perception of Effort and Objective Levels of Intensity in Physical Education Classes of Primary Schoolchildren According to Gender and Nutritional Status: A Pilot Study

Resumen El presente estudio aborda el análisis del esfuerzo percibido y tiempo en actividades de intensidad moderada y vigorosa en clases de Educación Física, considerando las diferencias según sexo y el estado nutricional de la persona estudiante. Participaron 95 estudiantes de 5° y 6° año de primaria de escuelas de la ciudad de Coyhaique, Chile. Se utilizó la escala EPInfant para la evaluación del esfuerzo percibido y acelerómetros Actigraph GT3X+ para determinar el tiempo en intensidad moderada y vigorosa. En el esfuerzo percibido no se encontraron diferencias significativas según sexo (p=0,144), pero sí según estado nutricional, siendo los estudiantes con obesidad quienes indican una percepción de esfuerzo mayor que el estudiantado de peso normal (p=0,022). En actividades moderadas y vigorosas dentro de la clase de Educación Física, los niños presentan significativamente más minutos en comparación a las niñas (p=0,017); mientras que los escolares normopeso presentarían levemente mayor tiempo en este nivel de intensidad, sin que esta diferencia sea estadísticamente significativa (p=0,622). El esfuerzo realizado en las clases de Educación Física ha sido percibido como más exigente por los escolares con obesidad, y para esto se deben comprender las dificultades físicas y motrices que este grupo presenta. Asimismo, las niñas han participado un menor tiempo en intensidades moderadas y vigorosas, por lo que es pertinente buscar estrategias que permitan aumentar el tiempo de su participación.

Abstract This study focuses on the analysis of perceived effort and time of moderate and vigorous activities in physical education classes, considering differences based on gender and the nutritional status of schoolchildren. A total of 95 children in 5th and 6th grade of primary school in the city of Coyhaique, Chile, participated in the study. The EPInfant scale was used to assess the perceived effort, and Actigraph GT3X+ accelerometers were used to determine the time of moderate and vigorous activity. No significant differences were found in the perceived effort by gender (p=0.144); instead, by nutritional status, obese students indicated a higher perceived effort than students with a normal weight (p=0.220). Regarding moderate and vigorous activities in Physical Education class, the boys were significantly more active than the girls (p=0.017). In contrast, normal-weight children were slightly more active at this intensity level, but this difference was not statistically significant (p=0.622). The effort in Physical Education classes has been perceived as more demanding by the obese students; for this reason, it is important to understand the physical and motor difficulties that this group presents. Likewise, girls have participated for a shorter time in moderate and vigorous intensities, being pertinent to look for didactic strategies to increase the time of their participation.

Resumo O presente estudo aborda a análise do esforço e do tempo percebido em atividades de intensidade moderada e vigorosa nas aulas de educação física, considerando as diferenças de acordo com o sexo e o estado nutricional de cada estudante. Participaram do estudo noventa e cinco alunos do 5º e 6º ano do ensino fundamental de escolas da cidade de Coyhaique, no Chile. A escala EPInfant foi utilizada para avaliar o esforço percebido e os acelerômetros Actigraph GT3X+ para determinar o tempo em intensidade moderada e vigorosa. Não foram encontradas diferenças significativas na percepção de esforço segundo o sexo (p=0,144), mas foram encontradas diferenças significativas segundo o estado nutricional, com estudantes obesos indicando uma percepção de maior esforço do que estudantes de peso normal (p=0,022). Nas atividades moderadas e vigorosas nas aulas de Educação Física, os meninos apresentam significativamente mais minutos que as meninas (p=0,017), enquanto os estudantes de peso normal apresentaram um pouco mais de tempo nesse nível de intensidade, embora essa diferença não tenha sido estatisticamente significativa (p=0,622). O esforço feito nas aulas de educação física foi percebido como mais exigente por estudantes obesos, e para isso é necessário compreender as dificuldades físicas e motoras que este grupo apresenta. Da mesma forma, as meninas têm participado por um tempo mais curto em intensidades moderadas e vigorosas, por isso é pertinente procurar estratégias para aumentar o tempo da sua participação.

Cardiorespiratory Parameters Comparison Between Incremental Protocols Performed in Aquatic and Land Environments by Healthy Individuals: A Systematic Review and Meta-Analysis.

BACKGROUND: Physical properties of water cause physiological changes in the immersed human body compared with the land environment. Understanding the magnitude of cardiorespiratory alterations might ensure adequate intensity control during aquatic exercise programs. OBJECTIVE: We aimed to compare the oxygen uptake (VO2), heart rate (HR), and rating of perceived exertion (RPE) parameters during aquatic and land incremental tests. METHODS: Four databases (PubMed, LILACS, EMBASE, and SPORTDiscus) were searched in September 2020. Eligibility criteria included studies in a crossover design comparing aquatic and land incremental tests for healthy individuals with at least one of the following parameters: VO2 (maximal, VO2max; anaerobic threshold, VO2AT), HR (HRmax; HRAT), and RPE (RPEmax; RPEAT). The random-effects meta-analysis included mean difference and 95% confidence interval for VO2 and HR or standardized mean difference for RPE. The Joanna Briggs Institute Critical Appraisal tool was adapted to assess methodological quality. RESULTS: Twenty-eight studies were eligible and included in the meta-analysis. Aquatic protocols showed lower values compared with land for VO2max (- 7.07 mL.kg-1.min-1; - 8.43 to - 5.70; n = 502), VO2AT (- 6.19 mL.kg-1.min-1; - 7.66 to - 4.73; n = 145), HRmax (- 11.71 bpm; - 13.84 to - 9.58; n = 503), and HRAT (- 15.29 bpm; - 19.05 to - 11.53; n = 145). RPEmax (0.01; - 0.16 to 0.18; n = 299) and RPEAT (- 0.67; - 1.35 to 0.02; n = 55) values were similar between aquatic and land protocols. CONCLUSIONS: Our study reinforces the specificity of the environment during incremental tests for prescribing exercises based on physiological parameters as VO2 and HR parameters presented lower values in aquatic protocols than land protocols. Conversely, RPE seems an interchangeable measure of exercise intensity, with similar values during the protocols in both environments. Substantial levels of heterogeneity were present for the VO2max and HRmax meta-analyses, and as such, results should be interpreted with attention. PROTOCOL REGISTRATION: This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020212508).

Assessment of a Treadmill Speed Incline Conversion Chart: A Validation Study.

PURPOSE: To investigate the validity of a treadmill speed incline conversion chart using physiological and subjective measures. METHODS: Two groups of experienced runners (SLOW and FAST: divided based on their easy run pace) ran 6 speed incline combinations for 5 minutes each. Stages were equivalent according to the HillRunner.com chart, and stage order was randomized. Due to limitations of the chart, SLOW (n = 11) ran at inclines up to 4%, while FAST (n = 22) ran at inclines up 10%. Oxygen consumption (VO2), respiratory exchange ratio, heart rate, blood lactate, overall rating of perceived exertion (RPE), and leg RPE were measured for each stage. VO2 was compared against the VO2 predicted by the American College of Sports Medicine (ACSM) equation (ACSM VO2). Repeated-measures analysis of variance was used to detect differences between stages and inclines, and Hedges g was used as a measure of effect size. RESULTS: Pooled results (0%-4%, N = 33) showed no incline effect on VO2, respiratory exchange ratio, heart rate, blood lactate, or RPE (P > .05; ηp2=.198), validating the chart at these inclines. At or above 6%, meaningful and significant increases occur in VO2 (g > 0.9, P < .05), with increases in heart rate, blood lactate, and leg RPE at higher inclines. ACSM VO2 underestimated oxygen consumption at all inclines up to 8% (P < .05) but not at 10% (45.9 [4.0] vs 46.7 [2.4] mL·kg-1·min-1; P = .186). CONCLUSION: The HillRunner.com chart is only valid at or below 4%. At higher inclines, supposedly equivalent stages result in increased exercise intensity. ACSM VO2 underestimates VO2 in trained runners at inclines up to 8%.

Effect of Divergent Solar Radiation Exposure With Outdoor Versus Indoor Training in the Heat: Implications for Performance.

ABSTRACT: O'Connor, FK, Doering, TM, Minett, GM, Reaburn, PR, Bartlett, JD and Coffey, VG. Effect of divergent solar radiation exposure with outdoor versus indoor training in the heat: implications for performance. J Strength Cond Res 36(6): 1622-1628, 2022-The aim of this study was to determine physiological and perceptual responses and performance outcomes when completing high-intensity exercise in outdoor and indoor hot environments with contrasting solar radiation exposure. Seven cyclists and 9 Australian Football League (AFL) players undertook cycling trials in hot conditions (≥30 °C) outdoors and indoors. Cyclists completed 5 × 4 minutes intervals (∼80% peak power output [PPO]) with 2 minutes recovery (∼40% PPO) before a 20-km self-paced ride. Australian Football League players completed a standardized 20 minutes warm-up (∼65% mean 4-minute power output) then 5 × 2 minutes maximal effort intervals. Heart rate (HR), PO, ratings of perceived exertion (RPE), thermal comfort (TC), and thermal sensation (TS) were recorded. Core (Tc) and skin temperature (Tsk) were monitored in cyclists alone. In both studies, ambient temperature, relative humidity, and solar radiation were monitored outdoors and matched for ambient temperature and relative humidity indoors, generating different wet bulb globe temperature (WBGT) for cyclists, but the similar WBGT for AFL players through higher relative humidity indoors. The statistical significance was set at p ≤ 0.05. Cyclists' HR (p = 0.05), Tc (p = 0.03), and Tsk (p = 0.03) were higher outdoors with variable effects for increased RPE, TS, and TC (d = 0.2-1.3). Power output during intervals was not different between trials, but there were small-moderate improvements in cyclists' PO and 20-km time indoors (d = 0.3-0.6). There was a small effect (d = 0.2) for AFL players' mean PO to increase outdoors for interval 4 alone (p = 0.04); however, overall there were small-moderate effects for lower RPE and TS indoors (d = 0.2-0.5). Indoor training in hot conditions without solar radiation may promote modest reductions in physiological strain and improve performance capacity in well-trained athletes.

Bi-exponential modelling of [Formula: see text] reconstitution kinetics in trained cyclists.

PURPOSE: The aim of this study was to investigate the individual [Formula: see text] reconstitution kinetics of trained cyclists following repeated bouts of incremental ramp exercise, and to determine an optimal mathematical model to describe [Formula: see text] reconstitution. METHODS: Ten trained cyclists (age 41 ± 10 years; mass 73.4 ± 9.9 kg; [Formula: see text] 58.6 ± 7.1 mL kg min-1) completed three incremental ramps (20 W min-1) to the limit of tolerance with varying recovery durations (15-360 s) on 5-9 occasions. [Formula: see text] reconstitution was measured following the first and second recovery periods against which mono-exponential and bi-exponential models were compared with adjusted R2 and bias-corrected Akaike information criterion (AICc). RESULTS: A bi-exponential model outperformed the mono-exponential model of [Formula: see text] reconstitution (AICc 30.2 versus 72.2), fitting group mean data well (adjR2 = 0.999) for the first recovery when optimised with parameters of fast component (FC) amplitude = 50.67%; slow component (SC) amplitude = 49.33%; time constant (τ)FC = 21.5 s; τSC = 388 s. Following the second recovery, W' reconstitution reduced by 9.1 ± 7.3%, at 180 s and 8.2 ± 9.8% at 240 s resulting in an increase in the modelled τSC to 716 s with τFC unchanged. Individual bi-exponential models also fit well (adjR2 = 0.978 ± 0.017) with large individual parameter variations (FC amplitude 47.7 ± 17.8%; first recovery: (τ)FC = 22.0 ± 11.8 s; (τ)SC = 377 ± 100 s; second recovery: (τ)FC = 16.3.0 ± 6.6 s; (τ)SC = 549 ± 226 s). CONCLUSIONS: W' reconstitution kinetics were best described by a bi-exponential model consisting of distinct fast and slow phases. The amplitudes of the FC and SC remained unchanged with repeated bouts, with a slowing of W' reconstitution confined to an increase in the time constant of the slow component.

Estimated energy expenditure and training intensity in young female artistic gymnasts

Abstract Aim: This study determined the energy expenditure and effort intensity of athletes during women's artistic gymnastics training sessions. Methods: Ten gymnasts (age 10.9 ± 1.7 years) performed a test to estimate the maximum rate of oxygen uptake (VO2max), during which the maximum heart rate (HRmax) was also obtained. The heart rate (HR) of these gymnasts was recorded during five training sessions and then used to estimate the exercise intensity and energy expenditure. Results: Mean duration of training sessions was 4.08 ± 0.42 h, with mean HR corresponding to 137 ± 8 bpm or 69.0 ± 3.5% of HRmax. Gymnasts spent less training time at 90-100% HRmax compared to the other HR ranges (p < 0.05). Time spent at 60-70% and 70-80% was higher compared to 80-90% HRmax (p = 0.012 and p = 0.001, respectively). The training impulse was 239.2 ± 35.4 AU. Estimated energy expenditure was 768.3 ± 168.5 kcal, metabolic rate was 3.1 ± 0.6 kcal/min, and the metabolic equivalent of task (MET) corresponded to 6.1 ± 0.6. Conclusion: Young gymnasts performed prolonged and moderate-intensity training sessions that generated high energetic demands. This information is beneficial to gymnasts since the coaching team can use the data to control the training load and prescribe a proper diet.

Aerobic training-mediated DNA hypermethylation of Agtr1a and Mas1 genes ameliorate mesenteric arterial function in spontaneously hypertensive rats.

BACKGROUND: The imbalance of vasoconstrictor and vasodilator axes of the renin-angiotensin system (RAS) is observed in hypertension. Exercise regulates RAS level and improves vascular function. This study focused on the contribution of RAS axes in vascular function of mesenteric arteries and exercise-induced DNA methylation of the Agtr1a (AT1aR) and Mas1 (MasR) genes in hypertension. METHODS: Spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats were randomized into exercise or sedentary group. Levels of plasma RAS components, vascular tone, and DNA methylation markers were measured. RESULTS: Blood pressure of SHR was markedly reduced after 12 weeks of aerobic exercise. RAS peptides in plasma were all increased with an imbalanced upregulation of Ang II and Ang-(1-7) in SHR, exercise revised the level of RAS and increased Ang-(1-7)/Ang II. The vasoconstriction response induced by Ang II was mainly via type 1 receptors (AT1R), while this contraction was inhibited by Mas receptor (MasR). mRNA and protein of AT1R and MasR were both upregulated in SHR, whereas exercise significantly suppressed this imbalanced increase and increased MasR/AT1R ratio. Exercise hypermethylated Agtr1a and Mas1 genes, associating with increased DNMT1 and DNMT3b and SAM/SAH. CONCLUSIONS: Aerobic exercise ameliorates vascular function via hypermethylation of the Agtr1a and Mas1 genes and restores the vasoconstrictor and vasodilator axes balance.

Gas exchange threshold to guide exercise training intensity of older individuals during cardiac rehabilitation.

ABSTRACT: The gas exchange threshold (GET), which is determined during incremental exercise (Inc-Ex) testing, is often considered a safe training intensity for cardiac rehabilitation. However, there are only a limited number of reports on the actual implementation of this method. We assessed the applicability of GET-guided exercise using a constant load exercise (CL-Ex) protocol.We recruited 20 healthy older individuals (healthy, age: 69.4 ±â€Š6.8 years) and 10 patients with cardiovascular diseases or risk factors (patient, age: 73.0 ±â€Š8.8 years). On day 1, we determined the GET during symptomatic maximal Inc-Ex. On day 2, CL-Ex at work rate (watt: W) where the GET manifested during Inc-Ex (therefore, not corrected for the known oxygen response delay) was maintained for 20 minute. Arterialized blood lactate (BLa) levels were also determined.Oxygen uptake reached a steady state in all participants, with a mean respiratory exchange ratio of < 1.0. The mean BLa at the GET during Inc-Ex was 1.51 ±â€Š.29 mmol·l-1 in the healthy group and 1.78 ±â€Š.42 mmol·L-1 in the patient group, which was about .5 mmol·L-1 above the resting level. During CL-Ex, BLa increased significantly over the value at the GET (Inc-Ex). However, it reached a steady-state level of 2.65 ±â€Š1.56 (healthy) and 2.53 ±â€Š0.95 (patient) mmol·L-1. The %peak oxygen uptake, %peak heart rate, and %heart rate reserve during CL-Ex were 58.8 ±â€Š11.5, 71.8 ±â€Š10.3, and 44.9 ±â€Š17.4, respectively. All participants could complete CL-Ex with mean perceived exertion ratings (Borg/20) of 11.8 ±â€Š1.3 (healthy) and 12.2 ±â€Š1.3 (patient). These heart rate-related indices and exertion ratings were all within the recommended international guidelines for cardiac rehabilitation.CL-Ex at the GET appears to be the optimal exercise intensity for cardiac rehabilitation.

Effect of Lactobacillus fermentum HFY03 on the Antifatigue and Antioxidation Ability of Running Exhausted Mice.

Yak yogurt is mainly produced in Qinghai-Tibet Plateau. It is a kind of naturally fermented dairy product. It contains abundant microorganisms. Lactobacillus fermentum (LF) HFY03 is a lactic acid bacteria derived from it. Our main research content is to study the influence of LF-HFY03 on the antifatigue and antioxidation ability of running exhausted mice. We gave different doses of LF-HFY03 to mice by gavage for 4 weeks. We selected vitamin C as the positive control group, mainly to study the relationship between antioxidant capacity and fatigue resistance and LF-HFY03 in mice with running exhaustion. The results showed that LF-HFY03 and vitamin C could significantly improve the running time of mice. And with the increase in LF-HFY03 concentration, the exhaustion time of mice was also extended. LF-HFY03 can reduce the content of urea nitrogen and lactic acid and also can increase the content of free fatty acids and liver glycogen. The levels of alanine aminotransferase, serum creatine kinase, and aspartate aminotransferase in mice decreased gradually as the antioxidant peptide level of walnut albumin increased. LF-HFY03 can reduce malondialdehyde (MDA) levels in a quantification-dependent manner and can also increase catalase (CAT) and superoxide dismutase (SOD) levels. LF-HFY03 can also increase the expressions of CAT mRNA, Cu/Zn-SOD, and Mn-SOD in the liver of mice. At the same time, LF-HFY03 can also increase the expression of protein of threonine transporter 1 (AST1)/alanine/cysteine/serine, mRNA, nNOS, and eNOS. At the same time, the solution could reduce the expression of TNF-α, syncytin-1, and inducible nitric oxide synthase (iNOS). The results showed that LF-HFY03 has a high development and application prospect as an antifatigue probiotic nutritional supplement.

Oestrogen engages brain MC4R signalling to drive physical activity in female mice.

Oestrogen depletion in rodents and humans leads to inactivity, fat accumulation and diabetes1,2, underscoring the conserved metabolic benefits of oestrogen that inevitably decrease with age. In rodents, the preovulatory surge in 17ß-oestradiol (E2) temporarily increases energy expenditure to coordinate increased physical activity with peak sexual receptivity. Here we report that a subset of oestrogen-sensitive neurons in the ventrolateral ventromedial hypothalamic nucleus (VMHvl)3-7 projects to arousal centres in the hippocampus and hindbrain, and enables oestrogen to rebalance energy allocation in female mice. Surges in E2 increase melanocortin-4 receptor (MC4R) signalling in these VMHvl neurons by directly recruiting oestrogen receptor-α (ERα) to the Mc4r gene. Sedentary behaviour and obesity in oestrogen-depleted female mice were reversed after chemogenetic stimulation of VMHvl neurons expressing both MC4R and ERα. Similarly, a long-term increase in physical activity is observed after CRISPR-mediated activation of this node. These data extend the effect of MC4R signalling - the most common cause of monogenic human obesity8 - beyond the regulation of food intake and rationalize reported sex differences in melanocortin signalling, including greater disease severity of MC4R insufficiency in women9. This hormone-dependent node illuminates the power of oestrogen during the reproductive cycle in motivating behaviour and maintaining an active lifestyle in women.

Mitochondria-targeted antioxidant supplementation improves 8 km time trial performance in middle-aged trained male cyclists.

BACKGROUND: Exercise increases skeletal muscle reactive oxygen species (ROS) production, which may contribute to the onset of muscular fatigue and impair athletic performance. Mitochondria-targeted antioxidants such as MitoQ, which contains a ubiquinone moiety and is targeted to mitochondria through the addition of a lipophilic triphenylphosphonium cation, are becoming popular amongst active individuals as they are designed to accumulate within mitochondria and may provide targeted protection against exercise-induced oxidative stress. However, the effect of MitoQ supplementation on cycling performance is currently unknown. Here, we investigate whether MitoQ supplementation can improve cycling performance measured as time to complete an 8 km time trial. METHOD: In a randomized, double-blind, placebo-controlled crossover study, 19 middle-aged (age: 44 ± 4 years) recreationally trained (VO2peak: 58.5 ± 6.2 ml·kg- 1·min- 1, distance cycled per week during 6 months prior to study enrollment: 158.3 ± 58.4 km) male cyclists completed 45 min cycling at 70% VO2peak followed by an 8 km time trial after 28 days of supplementation with MitoQ (20 mg·day- 1) and a placebo. Free F2-isoprostanes were measured in plasma samples collected at rest, after 45 min cycling at 70% VO2peak and after completion of the time trial. Respiratory gases and measures of rating of perceived exertion (RPE) were also collected. RESULTS: Mean completion time for the time trial was 1.3% faster with MitoQ (12.91 ± 0.94 min) compared to placebo (13.09 ± 0.95 min, p = 0.04, 95% CI [0.05, 2.64], d = 0.2). There was no difference in RPE during the time trial between conditions (p = 0.82) despite there being a 4.4% increase in average power output during the time trial following MitoQ supplementation compared to placebo (placebo; 270 ± 51 W, MitoQ; 280 ± 53 W, p = 0.04, 95% CI [0.49, 8.22], d = 0.2). Plasma F2-isoprostanes were lower on completion of the time trial following MitoQ supplementation (35.89 ± 13.6 pg·ml- 1) compared to placebo (44.7 ± 16.9 pg·ml- 1 p = 0.03). CONCLUSION: These data suggest that MitoQ supplementation may be an effective nutritional strategy to attenuate exercise-induced increases in oxidative damage to lipids and improve cycling performance.

Acute effect of high-definition and conventional tDCS on exercise performance and psychophysiological responses in endurance athletes: a randomized controlled trial.

Transcranial direct current stimulation (tDCS) has been used aiming to boost exercise performance and inconsistent findings have been reported. One possible explanation is related to the limitations of the so-called "conventional" tDCS, which uses large rectangular electrodes, resulting in a diffuse electric field. A new tDCS technique called high-definition tDCS (HD-tDCS) has been recently developed. HD-tDCS uses small ring electrodes and produces improved focality and greater magnitude of its aftereffects. This study tested whether HD-tDCS would improve exercise performance to a greater extent than conventional tDCS. Twelve endurance athletes (29.4 ± 7.3 years; 60.15 ± 5.09 ml kg-1 min-1) were enrolled in this single-center, randomized, crossover, and sham-controlled trial. To test reliability, participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion. Next, they randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. TTE, heart rate (HR), associative thoughts, peripheral (lower limbs), and whole-body ratings of perceived exertion (RPE) were recorded every minute. Outcome measures were reliable. There was no difference in TTE between HD-tDCS (853.1 ± 288.6 s), simulated conventional (827.8 ± 278.7 s), sham (794.3 ± 271.2 s), or control conditions (TTE1 = 751.1 ± 261.6 s or TTE2 = 770.8 ± 250.6 s) [F(1.95; 21.4) = 1.537; P = 0.24; η2p = 0.123]. There was no effect on peripheral or whole-body RPE and associative thoughts (P > 0.05). No serious adverse effect was reported. A single session of neither HD-tDCS nor conventional tDCS changed exercise performance and psychophysiological responses in athletes, suggesting that a ceiling effect may exist.

Chronic Exercise Protects against the Progression of Renal Cyst Growth and Dysfunction in Rats with Polycystic Kidney Disease.

INTRODUCTION: Polycystic kidney disease (PKD) is a genetic disorder characterized by the progressive enlargement of renal epithelial cysts and renal dysfunction. Previous studies have reported the beneficial effects of chronic exercise on chronic kidney disease. However, the effects of chronic exercise have not been fully examined in PKD patients or models. The effects of chronic exercise on the progression of PKD were investigated in a polycystic kidney (PCK) rat model. METHODS: Six-week-old male PCK rats were divided into a sedentary group and an exercise group. The exercise group underwent forced treadmill exercise for 12 wk (28 m·min-1, 60 min·d-1, 5 d·wk-1). After 12 wk, renal function and histology were examined, and signaling cascades of PKD progression, including arginine vasopressin (AVP), were investigated. RESULTS: Chronic exercise reduced the excretion of urinary protein, liver-type fatty acid-binding protein, plasma creatinine, urea nitrogen, and increased plasma irisin and urinary AVP excretion. Chronic exercise also slowed renal cyst growth, glomerular damage, and interstitial fibrosis and led to reduced Ki-67 expression. Chronic exercise had no effect on cAMP content but decreased the renal expression of B-Raf and reduced the phosphorylation of extracellular signal-regulated kinase (ERK), mammalian target of rapamycin (mTOR), and S6. CONCLUSION: Chronic exercise slows renal cyst growth and damage in PCK rats, despite increasing AVP, with the downregulation of the cAMP/B-Raf/ERK and mTOR/S6 pathways in the kidney of PCK rats.

Exertional rhabdomyolysis in newly enrolled cadets of a military academy.

INTRODUCTION/AIMS: Exertional rhabdomyolysis (ER) often occurs during prolonged intense exercise in hot environments, posing a threat to the health of military personnel. In this study we aimed to investigate possible risk factors for ER and provide further empirical data for prevention and clinical treatment strategies. METHODS: A retrospective investigation of 116 concurrent ER cases was conducted. Conditional logistic regression analyses were performed to assess the association between each potential risk (or protective) factor and ER. The clinical characteristics of the 71 hospitalized patients were analyzed descriptively. RESULTS: After screening, the following variables significantly increased the risk of ER: shorter length of service (recruits; odds ratios [OR], 7.49; 95% confidence interval [CI], 2.58-21.75); higher body mass index (BMI; OR, 1.14, 95% CI, 1.03-1.26); lack of physical exercise in the last half year (less than once per month; OR, 3.20; 95% CI, 1.08-9.44); and previous heat injury (OR, 2.94; 95% CI, 1.26-6.89). Frequent fruit consumption (OR, 0.57; 95% CI, 0.33-0.99), active hydration habit (OR, 0.37; 95% CI, 0.20-0.67), water replenishment of more than 2 L on the training day (OR, 0.15; 95% CI, 0.05-0.45), and water replenishment of at least 500 mL within 1 hour before training (OR, 0.33; 95% CI, 0.12-0.88) significantly decreased the risk of ER. Of the 71 hospitalized patients, 41 (57.7%) were diagnosed with hypokalemia on admission. DISCUSSION: In military training, emphasis should be placed on incremental adaptation training before more intense training, and close attention should be given to overweight and previously sedentary recruits. Fluid replenishment before exercise, increased fruit intake, and proper potassium supplementation may help prevent ER.

Effects of Including Sprints in LIT Sessions during a 14-d Camp on Muscle Biology and Performance Measures in Elite Cyclists.

PURPOSE: This study investigated the effects of including sprints within low-intensity training (LIT) sessions during a 14-d training camp focusing on LIT, followed by 10-d recovery (Rec), on performance and performance-related measures in elite cyclists. METHODS: During the camp, a sprint training group (SPR; n = 9) included 12 × 30-s maximal sprints during five LIT sessions, whereas a control group (CON; n = 9) performed distance-matched LIT only. Training load was equally increased in both groups by 48% ± 27% during the training camp and subsequently decreased by -56% ± 23% during the recovery period compared with habitual training. Performance tests were conducted before the training camp (Pre) and after Rec. Muscle biopsies, hematological measures, and stress/recovery questionnaires were collected Pre and after the camp (Post). RESULTS: Thirty-second sprint (SPR vs CON: 4% ± 4%, P < 0.01) and 5-min mean power (SPR vs CON: 4% ± 8%, P = 0.04) changed differently between groups. In muscle, Na+-K+ ß1 protein content changed differently between groups, decreasing in CON compared with SPR (-8% ± 14%, P = 0.04), whereas other proteins showed similar changes. SPR and CON displayed similar increases in red blood cell volume (SPR: 2.6% ± 4.7%, P = 0.07; CON: 3.9% ± 4.5%, P = 0.02) and V˙O2 at 4 mmol·L-1 [BLa-] (SPR: 2.5% ± 3.3%, P = 0.03; CON: 2.2% ± 3.0%, P = 0.04). No changes were seen for V˙O2max, Wmax, hematological measures, muscle enzyme activity, and stress/recovery measures. CONCLUSIONS: Inclusion of 30-s sprints within LIT sessions during a high-volume training camp affected competition-relevant performance measures and Na+-K+ ß1 protein content differently from LIT only, without affecting sport-specific stress/recovery or any other physiological measure in elite cyclists.

Variability in Submaximal Self-Paced Exercise Bouts of Different Intensity and Duration.

PURPOSE: Rating of perceived exertion (RPE) as a training-intensity prescription has been extensively used by athletes and coaches. However, individual variability in the physiological response to exercise prescribed using RPE has not been investigated. METHODS: Twenty well-trained competitive cyclists (male = 18, female = 2, maximum oxygen consumption = 55.07 [11.06] mL·kg-1·min-1) completed 3 exercise trials each consisting of 9 randomized self-paced exercise bouts of either 1, 4, or 8 minutes at RPEs of 9, 13, and 17. Within-athlete variability (WAV) and between-athletes variability (BAV) in power and physiological responses were calculated using the coefficient of variation. Total variability was calculated as the ratio of WAV to BAV. RESULTS: Increased RPEs were associated with higher power, heart rate, work, volume of expired oxygen (VO2), volume of expired carbon dioxide (VCO2), minute ventilation (VE), deoxyhemoglobin (ΔHHb) (P < .001), and lower tissue saturation index (ΔTSI%) and ΔO2Hb (oxyhaemoglobin; P < .001). At an RPE of 9, shorter durations resulted in lower VO2 (P < .05) and decreased ΔTSI%, and the ΔHHb increased as the duration increased (P < .05). At an RPE of 13, shorter durations resulted in lower VO2, VE, and percentage of maximum oxygen consumption (P < .001), as well as higher power, heart rate, ΔHHb (P < .001), and ΔTSI% (P < .05). At an RPE of 17, power (P < .001) and ΔTSI% (P < .05) increased as duration decreased. As intensity and duration increased, WAV and BAV in power, work, heart rate, VO2, VCO2, and VE decreased, and WAV and BAV in near-infrared spectroscopy increased. CONCLUSIONS: Self-paced intensity prescriptions of high effort and long duration result in the greatest consistency on both a within- and between-athletes basis.