Mathematical model of COVID-19 intervention scenarios for São Paulo-Brazil.

With COVID-19 surging across the world, understanding the effectiveness of intervention strategies on transmission dynamics is of primary global health importance. Here, we develop and analyze an epidemiological compartmental model using multi-objective genetic algorithm design optimization to compare scenarios related to strategy type, the extent of social distancing, time window, and personal protection levels on the transmission dynamics of COVID-19 in São Paulo, Brazil. The results indicate that the optimal strategy for São Paulo is to reduce social distancing over time with a stepping-down reduction in the magnitude of social distancing every 80-days. Our results also indicate that the ability to reduce social distancing depends on a 5-10% increase in the current percentage of people strictly following protective guidelines, highlighting the importance of protective behavior in controlling the pandemic. Our framework can be extended to model transmission dynamics for other countries, regions, states, cities, and organizations.

Effects of Transcranial Direct Current Stimulation With Caffeine Intake on Muscular Strength and Perceived Exertion.

Lattari, E, Vieira, LAF, Oliveira, BRR, Unal, G, Bikson, M, de Mello Pedreiro, RC, Marques Neto, SR, Machado, S, and Maranhão-Neto, GA. Effects of transcranial direct current stimulation with caffeine intake on muscular strength and perceived exertion. J Strength Cond Res 33(5): 1237-1243, 2019-The aim of this study was to investigate the acute effects of transcranial direct current stimulation (tDCS) associated with caffeine intake on muscular strength and ratings of perceived exertion (RPE). Fifteen healthy young males recreationally trained (age: 25.3 ± 3.2 years, body mass: 78.0 ± 6.9 kg, height: 174.1 ± 6.1 cm) were recruited. The experimental conditions started with the administration of caffeine (Caff) or placebo (Pla) 1 hour before starting the anodal tDCS (a-tDCS or sham). There was an intake of 5 mg·kg of Caff or 5 mg·kg of Pla. After the intake, a-tDCS or sham was applied in the left dorsolateral prefrontal cortex with intensity of 2 mA and 20 minutes of duration. The experimental conditions were defined as Sham + Pla, a-tDCS + Pla, Sham + Caff, and a-tDCS + Caff. After the conditions, muscular strength and RPE were verified. Muscular strength was determined by volume load performed in bench press exercise. Muscular strength in Sham + Pla condition was lower compared with all others conditions (p < 0.05). The RPE in the Sham + Pla was greater compared with a-tDCS + Caff (p < 0.05). Muscular strength was greater in all experimental conditions, and a-tDCS + Caff had lower RPE compared with placebo. When very little gains in muscle strength are expected, both caffeine and tDCS were effective in increasing muscle strength. Besides, the improvement in RPE of the caffeine associated with a-tDCS could prove advantageous in participants experienced in strength training. In fact, coaches and applied sport scientists quantitating the intensity of training based on RPE.

Prediction of cardiorespiratory fitness in the brazilian population aged 20 to 59 years: a non-exercise model approach with self-reported variables / Estimativa da aptidão cardiorrespiratória da população brasileira de 20 a 59 anos: abordagem por meio de modelo sem exercício com variáveis auto-relatadas

ABSTRACT Unlike other more common health-related variables, cardiorespiratory fitness (CRF) is not frequently measured in the general population. This omission characterizes a loss of relevant information. Thus, the objectives of the present study were: a) to characterize the CRF of the Brazilian population aged 20 to 59 years and to develop normative values using a non-exercise equation for predicting maximal oxygen uptake (VO2max), and b) to verify the association between lower levels of CRF and the prevalence of chronic diseases. A total of 32,531 individuals from the National Health Survey (NHS-IBGE-2013) composed the sample. Only self-reported variables were included in the equation of Wier et al. (2006): sex, age, physical activity level, and body mass index. The mean predicted VO2max was 44.6, 39.3, 34.8 and 30.6 ml/kg/min for men, and 34.5, 29.6, 25.4 and 21.1 ml/kg/min for women aged 20-29, 30-39, 40-49 and 50-59 years, respectively. The 20th and 80th percentiles were established as the extremes (very low and very high CRF). Participants with low fitness had a 33% higher chance of cardiovascular disease, an 89% higher chance of diabetes mellitus, and a 67% higher chance of hypertension, regardless of sex, age and presence of obesity, which seem to corroborate the quality of the equation.

RESUMO Diferentemente de outras variáveis mais comuns relacionadas à saúde, a aptidão cardiorrespiratória (ACR) não é medida constantemente na população em geral. Sua omissão caracteriza numa perda de informação relevante. Com isso os objetivos do presente estudo foram: a) caracterizar a ACR da população brasileira de 20 a 59 anos, desenvolvendo valores normativos através de uma equação para estimar o consumo máximo de oxigênio (VO2Máx) sem a realização de exercícios; e b) verificar a associação de menores níveis de ACR com a prevalência de doenças crônicas. Ao todo, 32.531 indivíduos compuseram a amostra oriunda da Pesquisa Nacional de Saúde (PNS-IBGE-2013). Apenas variáveis auto-relatadas foram incluídas a partir da equação de Wier et al. (2006): sexo, idade, nível de atividade física e Índice de Massa Corporal. A média de VO2Máx foi estimada como 44,6; 39,3; 34,8 e 30,6 ml/kg/min (homens) e 34,5; 29,6; 25,4 e 21,1 ml/kg/min (mulheres) com idades 20-29; 30-39; 40-49 e 50-59. Os valores de percentil 20 e 80 foram estabelecidos como os extremos de muito baixa e muito alta ACR. A baixa aptidão demonstrou significativamente 33% maiores chances de prevalência de doença cardiovascular, 89% de diabetes mellitus e 67% de hipertensão arterial independentemente de sexo, idade, e presença de obesidade, o que parece corroborar a qualidade da equação utilizada.

Diagnostic validity of screening questionnaire american college of sports medicine/american heart association / Validade diagnóstica do questionário de triagem do american college of sports medicine/american heart association

ABSTRACT The prevention of cardiovascular events is one of the main objectives of a preexercise screening questionnaire. The aim of this study was to evaluate the diagnostic validity of ACSM/AHA questionnaire (AAPQ), through the Sensitivity (Se), Specificity (Sp) and AUC (area under the curve). The study included 69 subjects (40-81 years). Comparisons between sex and age categories were performed. There was no significant difference. However, the variation in positive responses seemed to increase in percentage terms, especially after 60 years (from 78.6% to 100%). The AAPQ Se values were high (88.2%) suggesting that the majority of individuals in whom the instrument was positive showed some contraindication. However, the Sp value was only 13.5%, indicating that the questionnaire was not able to identify those with no contra indication to start an exercise program. Thus, the instrument would have a low diagnostic capacity (AUC = 0.51). The results suggest that the questionnaire presents a low capacity to identify individuals suitable for inclusion in an exercise program.

RESUMO A prevenção de eventos cardiovasculares é um dos principais objetivos de um questionário de triagem para a prática de exercícios. O objetivo do estudo foi verificar a validade diagnóstica do questionário do ACSM/AHA (AAPQ), através da sensibilidade (SE) e especificidade (ES), e AUC (área sob a curva). Participaram do estudo 69 indivíduos (40 a 81 anos). Comparações entre sexo e categorias de idade foram realizadas. Não foi verificada diferença significativa. Contudo, a variação nas respostas positivas pareceu aumentar percentualmente, principalmente a partir dos 60 anos (de 78,6% a 100%). Os valores de SE do AAPQ foram altos (88,2%), sugerindo que grande parte dos indivíduos em que o resultado do instrumento foi positivo apresentava alguma contraindicação. Contudo, o valor da ES foi de apenas 13,5%, indicando que o questionário não foi capaz de identificar aqueles indivíduos sem contraindicação ao início de um programa de exercícios. Com isso, o instrumento teria uma baixa capacidade diagnóstica (AUC=0,51). Os resultados sugerem que o questionário apresenta baixa capacidade em identificar indivíduos aptos a iniciar um programa de exercícios.

Marcadores antropométricos de adiposidade e hipertensão arterial em academias de ginástica: um estudo exploratório / Anthropometric markers of adiposity and hypertension in Fitness Clubs: an exploratory study

Introdução: Há uma falta de conhecimento sobre o perfil de saúde das pessoas que frequentam as academias de ginástica. Objetivo: Investigar a prevalência de hipertensão arterial (HA) e sua associação com Índice de Massa Corporal (IMC) e Circunferência da Cintura (CC) em frequentadores de academias no município do Rio de Janeiro. Métodos: A amostra foi constituída de 2836 mulheres e 1707 homens com idades entre 19 e 64 anos. A HA foi diagnosticada como pressão arterial ≥140/90 mm Hg. Todas as medidas antropométricas seguiram as diretrizes preconizadas pela International Society for the Advancement of Kinanthropometry. Resultados: As prevalências de HA (10,9%), sobrepeso (30,3%) e obesidade (11,5%), foram significativamente maiores nos homens e associados com a idade, e a prevalência de CC elevada (56,6%) foi significativamente maior em mulheres e se associou com a idade (p<0,001). Apesar da prevalência de HA ter sido relativamente baixa, tanto o IMC quanto o CC mostraram-se marcadores associados a HA. Conclusão: Profissionais que trabalham em academias de ginástica devem ter conhecimento sobre a importância desses indicadores e principalmente sobre a sua relação com a HA.

Introduction: There is a lack of knowledge about the health profile of the people who attend fitness clubs. Objective: The aim of the present study was to investigate the prevalence of Hypertension and its association with anthropometric markers such as Body Mass Index (BMI) and Waist Circumference (WC) in Fitness Clubs of Rio de Janeiro City. Methods: The sample was composed of 2836 women and 1707 men (age range 19-64 years). The hypertension was diagnosed as ≥140/90 mm Hg. All anthropometric measures followed the guidelines recommended by the International Society for the Advancement of Kinanthropometry. Results: The prevalence of hypertension (10.9%), overweight (30.3%) and obesity (11.5%) were significantly higher in men and associated with age and the prevalence of high WC (56.6%) was significantly higher in women and associated with age (p<0.001). Despite the relatively low hypertension prevalence, the BMI and WC were associated the hypertension. Conclusion: Fitness clubs professionals should be aware of the importance of these markers and their relation with the hypertension.

Effects of transcranial direct current stimulation on time limit and ratings of perceived exertion in physically active women.

The limiting factors of maximum performance in humans have been extensively investigated. The aim of this study was to verify the acute effects of transcranial direct current stimulation on time limit (i.e., the time by which an individual is able to sustain a certain intensity of effort) at 100% of peak power (tlim@100%PP) and ratings of perceived exertion (RPE). Eleven moderately active women underwent an anthropometric evaluation and a maximal incremental test in the cycle ergometer, in order to obtain peak power (PP). At the two subsequent visits, which were separated by 48-72h, participants were randomly assigned to two experimental conditions: anodal stimulation (a-tDCS) and sham. In the a-tDCS condition, the stimulus was applied in the left dorsolateral prefrontal cortex (DLPFC), with intensity of 2mA for 20min. In the sham condition, the equipment was switched off after 30s of stimulation. Immediately after the conditions, participants performed the tlim@100%PP. Immediately after the tlim@100%PP test, the RPE scale was applied. The results demonstrated that the tlim@100%PP was higher in a-tDCS condition compared to sham condition (p=0.005). No difference was found between the conditions (a-tDCS vs sham) for the RPE (p=0.52). The anodal stimulus increased the tolerance to the exercise performed in the cycloergometer with maximum load, having some ergogenic effect in exercises of cyclic characteristics.

Prediction of cardiorespiratory fitness from self-reported data in elderly / Predição da aptidão cardiorrespiratória através de dados auto-relatados em idosos

Abstract Cardiorespiratory fitness (CRF) is associated with several health outcomes. Some non-exercise equations are available for CRF estimation. However, little is known about the validation of these equations among elderly. The aim of this study was to exam the validity of non-exercise equations with self-reported information in elderly. Participants (n= 93) aged 60 to 91 years measured CRF using maximal cardiopulmonary exercise test. Five non-exercise equations were selected. Data included in the equations (age, sex, weight, height, body mass index, physical activity and smoking) were self-reported. Coefficient of determination (R2) of linear regressions with laboratory-measured VO2 peak ranged from 0.04 to 0.64. The Bland-Altman plots showed higher agreement between achieved and predicted CRF obtained by Jackson and colleagues, and Wier and colleagues equations. On the other hand, the other equations showed lower agreement and overestimation. Our findings provide evidences that two non-exercise equations, previously developed, could be used on the prediction of CRF among elderly.

Resumo A aptidão cardiorrespiratória (ACR) está associada a vários desfechos de saúde. Algumas equações sem exercício estão disponíveis para estimar a ACR. No entanto, pouco se sabe sobre a validação dessas equações entre os idosos. Objetivo: O estudo foi desenvolvido com o objetivo de examinar a validade de equações sem exercício com informações auto-relatadas em idosos. Métodos: Os participantes (n = 93) com idades entre 60 e 91 anos foram submetidos ao teste de exercício cardiopulmonar máximo para avaliar a ACR. Cinco equações sem exercício foram selecionadas. Os dados incluídos nas equações (idade, sexo, peso, altura, índice de massa corporal, atividade física e tabagismo) foram auto-relatados. Resultados: O coeficiente de determinação (R2) das regressões lineares com o VO2 pico, medido em laboratório, variou de 0,04 a 0,64. Os gráficos de Bland-Altman mostraram maior concordância entre a ACR obtida e prevista por Jackson e colaboradores, e equações de Wier e colaboradores. Por outro lado, as demais equações mostraram menor concordância e superestimação. Conclusões: Nossos resultados fornecem evidências de que duas equações sem exercício, previamente desenvolvidas, poderiam ser usadas na estimação da ACR em idosos.

Normalizing handgrip strength in older adults: An allometric approach.

PURPOSE: Handgrip strength is an important variable to assess as part of any health intervention among older adults. Although the use of allometric normalization is the appropriate approach for removing the body size effect in handgrip performance, the best body size variable for this normalization is still unclear. Therefore, the aim of the present study was to compare the use of three body size variables (body mass, fat-free mass and body height) in allometric normalization for Handgrip strength among older adults. METHODS: Data from individuals admitted to the Elderly Care Center of the Open University of the Third Age were used, the sample consisting of 263 individuals (140 women), aged between 60-87. RESULTS: The results provided allometric exponents for normalization of HGS in each body size variable (body mass: 0.31; fat-free mass: 0.11; body height: 0.46). The correlations between normalized HGS and body size variables were significant (p<0.05) when HGS were normalized by body mass or fat-free mass. On the contrary, no significant correlations were found when HGS were normalized by body height. CONCLUSIONS: Body height seems to be the best body size variable for performing allometric normalization of HGS among older adults.

Acute cardiovascular responses to strength exercise for biceps and quadriceps muscles in middle-aged women / Respostas cardiovasculares agudas de exercício de força para os músculos bíceps e quadríceps em mulheres de meia idade

OBJECTIVE: Strength Training is increasingly popular and is studied for its efficacy in increasing muscular power and endurance. It has been claimed that cardiovascular responses are related to the muscle mass involved during execution, but some studies do not confirm these findings. We analyzed the behavior of heart rate, systolic/diastolic blood pressure, and double product in middle-aged women while performing exercises for two muscle groups with different volumes: elbow flexors (small mass) and knee extensors (large mass). METHOD: The study sample comprised eight women physically active for at least 6 months. The experimental procedure was performed in 3 sessions. In the first session, the characterization of the sample and a 10 repetition maximum (10RM) test were conducted. In the second, participants performed a warm up and then (depending on randomization), either the elbow flexion or the knee extension exercises in 3 series of 10 repeats. In the third session, participants performed the alternate exercise, folllowing the same procedures. Systolic and diastolic pressures and heart rate were measured 5 minutes before warm up and at the end of each series. RESULTS: No difference was observed in the acute cardiovascular responses for exercises involving the two different muscle mass volumes in normotensive women above age 45 years. CONCLUSION: The cardiovascular response is not affected by the exercised muscular mass in this specific population. Further studies should examine these variables in different conditions such as weather, climate and other populations.

OBJETIVO: O treinamento de força é cada vez mais popular e é estudado pela sua eficácia no aumento da potência muscular e resistência. Alega-se que as respostas cardiovasculares estão relacionadas com a massa muscular envolvida durante o exercício, mas alguns estudos não confirmam esses achados. Analisamos o comportamento da freqüência cardíaca, pressão arterial sistólica/diastólica e duplo produto em mulheres de meia-idade durante a execução de exercícios para dois grupos musculares com diferentes volumes: flexores do cotovelo (massa pequena) e extensores do joelho (massa grande). MÉTODO: A amostra foi constituída por oito mulheres fisicamente ativas por pelo menos 6 meses. O procedimento experimental foi realizado em 3 sessões. Na primeira, a caracterização da amostra e um teste de 10 repetições máximas (10RM) foram realizados. Na segunda, as participantes realizaram um aquecimento e, em seguida, (dependendo da randomização), a flexão do cotovelo ou a extensão do joelho em 3 séries de 10 repetições. Na terceira sessão, os participantes realizaram o exercício alternado, respeitando os mesmos procedimentos. As pressões sistólica e diastólica e a frequência cardíaca foram verificadas 5 minutos antes do aquecimento e ao final de cada série. RESULTADOS: Não foi observada diferença nas respostas cardiovasculares agudas de exercícios envolvendo os dois volumes diferentes de massa muscular em mulheres normotensas acima de 45 anos de idade. CONCLUSÃO: A resposta cardiovascular não é afetada pela massa muscular exercida nessa população específica. Novos estudos devem analisar essas variáveis em diferentes condições, tais como tempo, clima e outras populações.

Perímetro abdominal: evidências para a predição da gordura corporal subcutânea em meninos escolares / Abdominal girth: evidence for the prediction of subcutaneous body fat in student boys

Introdução: O diagnóstico de sobrepeso e obesidade pode ser realizado pela antropometria, por facilidade de execução e baixo custo. Considerando a preocupação com a característica de distribuição de gordura, novas estratégias poderiam ser desenvolvidas para a avaliação da composição corporal partindo de medidas antropométricas. Objetivos: Verificar a correlação do Perímetro Abdominal (PAB) e Perímetro da Cintura (PC) em separado, com o somatório de duas dobras cutâneas (DC), triciptal e subescapular; e incluir o perímetro com os maiores valores de correlação em uma equação de regressão para estimativa do somatório de DC. Métodos: Amostra composta por 1.729 meninos (9 e 14 anos), a avaliação da morfologia corporal foi realizada por medidas antropométricas simples e compostas. Foi utilizada uma correlação de Spearman para determinar a associação entre os PAB e PC com as DC. Foi feita uma análise de regressão linear múltipla com o PAB e idade para estimar o somatório de DC. Resultados: A seguinte equação foi gerada: Somatório de DC = 1,16397 (PAB) ­ 1,414922 (Idade) ­ 36,33021 (R=0,83). O valor da área sob a curva ROC (AUC) foi de 83% para identificar corretamente indivíduos abaixo ou acima do percentil 85 do somatório de DC. Conclusões: O PAB em conjunto com a idade, se torna um bom preditor da gordura corporal, caracterizada como o somatório de DC, em crianças e adolescentes do sexo masculino.

Introduction: The diagnosis of overweight and obesity can be accomplished by anthropometry, for ease of implementation and low cost. Considering the concern for the distribution of fat, new strategies could be developed for the diagnosis of body composition from anthropometric measurements. Objectives: To investigate the association of the abdominal girth (AG) and waist girth (WG) separately, with the sum of two skinfolds (SF), triceps and subscapular; and include the girth with higher correlation levels in a regression equation to estimate the SF sum. Methods: A sample of 1,729 boys (9 and 14), the evaluation of body composition was composed by simple and compound anthropometric measurements. The Spearman correlation was used to determine the association between AG and WG with the sum of SF. A multiple linear regression was applied including AG and age to estimate the sum of SF. Results: The following equation was generated: Sum of SF = 1.16397 (AG) - 1.414922 (age) - 36.33021 (R = 0.83). The area under the ROC curve (AUC) was 83% for correctly identifying individuals below or above the 85th percentile of the SF sum. Conclusions: AG, together with age, becomes a good predictor of body fat, characterized as the sum of two SF in children and adolescent males.