ABSTRACT
Resumo Sindemia é o termo utilizado para designar como interações biológicas e sociais influenciam no comportamento de uma determinada doença. A retomada das atividades escolares presenciais em meio à sindemia de covid-19 suscita controvérsias. Os defensores alegam que o retorno presencial mitigaria vulnerabilidades sociais, sanitárias e educacionais, enquanto os críticos afirmam que tal decisão contribuiria para a disseminação do vírus. O presente estudo analisa a dinâmica das internações e mortes por covid-19 entre estudantes da educação básica mediante a retomada das atividades escolares presenciais no município de São Paulo. Ademais, procura desvelar se a incidência de infecção por Sars-Cov-2 entre profissionais da educação teria relação com a qualidade socioterritorial que circunscreve as unidades de ensino básico (UE). As análises foram realizadas utilizando base de dados de instituições públicas paulistas. A retomada das atividades presenciais coincidiu com o aumento de internações e óbitos por covid-19 entre estudantes. O pico ocorreu 15 dias após o início das aulas. As UE inseridas em territórios com menores índices de desenvolvimento humano (IDH) registraram as maiores taxas de infecção por Sars-Cov-2. Retomar as aulas presenciais sem diminuir os riscos de contaminação parece ameaçar principalmente os indivíduos de territórios vulneráveis.
Abstract The term syndemic has been used to designate how biological and social interactions influence the behavior of a particular disease. The resumption of face-to-face school activities amidst the covid-19 syndemic sparks considerable controversy: while supporters claim that returning to school would mitigate social, health, and educational vulnerabilities, critics say that such a decision would help to spread the virus. In this scenario, this study analyzes the dynamics of hospital admissions and deaths related to covid-19 among elementary students in terms of the resumption of face-to-face school activities in the city of São Paulo, Brazil. Moreover, it also investigates the association between the incidence of covid-19 among education professionals and the socio-spacial properties in which the based education units (UEs) are located. The analyses were conducted with data from the public institutions of São Paulo. The results indicate that in-person activities resumption coincided with an increase in admissions and deaths from covid-19 among students, peaking 15 days after the beginning of the classes. UEs located in territories with lower human development indices registered the highest SARS-Cov-2 infection rates. Thus, resuming in-person classes without mitigating contamination risks poses a threat for the population, especially for those from vulnerable territories.
Subject(s)
Humans , Male , Female , Child , Adolescent , Socioeconomic Factors , Students , Education , Syndemic , COVID-19ABSTRACT
The aim of this study was to develop predictive equations for minute ventilation based on heart rate, and to test the precision of the equations in two forms of endurance exercise. Eighteen men (age 27.8 ± 5.4 years old, maximal oxygen uptake 45.4 ± 8.3 ml·kg-1·min-1) performed a maximal progressive cycle test in which minute ventilation and heart rate were continually measured and further used to establish the proposed equations with quadratic and exponential adjustments. In the second and third laboratory visits, sixteen participants completed two cycling bouts, one high-intensity interval exercise and one low-intensity continuous exercise. The minute ventilation and heart rate were measured in both exercises and the validity of the equations tested. The Bland-Altman analysis showed agreement between the minute ventilation and estimated equations for interval and continuous exercise. There was no difference between the minute ventilation obtained from both equations and the minute ventilation directly measured during the interval exercise. However, the quadratic equation underestimated the minute ventilation during continuous exercise (p < 0.05). While both equations seem to be suitable to estimate minute ventilation during high-intensity interval exercise, the exponential equation is recommended for low-intensity continuous exercise.
Subject(s)
Exercise/physiology , Heart Rate/physiology , Respiratory Function Tests/methods , Adult , Humans , Male , Models, Theoretical , Respiration , Sports Medicine , Young AdultABSTRACT
Os objetivos do estudo foram verificar se a potência mecânica estimada pela capacidade de trabalho físico, no limiar da frequência cardíaca (CTFLFC), correspondia à carga de trabalho equivalente ao máximo estado estável da frequência cardíaca (MEEFC) e analisar a influência da duração do exercício sobre o cálculo da CTFLFC. Sete sujeitos foram submetidos a um teste máximo e cinco testes em carga constante relativas ao segundo limiar metabólico (Lim2). A frequência cardíaca (FC) e a variabilidade da FC (VFC) foram estimadas por regressão linear e plotagem de Poincaré, respectivamente. Verificou-se diferença significativa entre a CTFLFC e o MEEFC, independente da intensidade empregada. Além disso, intensidades superiores a 50% do Lim2 não apresentaram estabilização da FC. No entanto, isso foi independente de controle autonômico cardiovascular, pois não havia diferença para SD1 ou SD1/SD2 em função da duração da tarefa. Em síntese, a CTFLFC não representa o MEEFC para adultos jovens fisicamente ativos. Adicionalmente, a ausência de estabilização da FC parece ser independente de mecanismos neurais.
The objectives of this study were to determine whether the power output measured by physical working capacity at threshold heart rate (PWCTHR) was equivalent to power output at the maximal steady state of heart rate (MSSHR), and to analyze the influence of exercise duration on the calculation of PWCTHR. Seven subjects were submitted to a maximal progressive test and five bouts at constant power relative to the second metabolic threshold (Lim2). Heart rate (HR) and HR variability were estimated by linear regression and Poincaré plotting, respectively. There was a significant difference between PWCTHR and MSSHR, irrespective of the intensity used. Additionally, intensities higher than 50% of Lim2 did not result in HR stabilization. However, the latter finding did not depend on cardiovascular autonomic control since there was no difference in SD1 or SD1/SD2 as a function of duration of the effort. Thus, PWCTHR does not represent MSSHR in physically active young adults. Furthermore, the lack of HR stabilization seems to be independent of neural mechanisms.
ABSTRACT
A proposta desse estudo foi descrever o comportamento cinético da freqüência cardíaca (FC) e como avariabilidade da FC (VFC) associa-se a esse fenômeno. Sete voluntários foram submetidos a um protocolode testes em cicloergômetro, para determinação da capacidade aeróbia (Lan) e da potência aeróbiamáxima. Em cinco visitas subseqüentes, os indivíduos desempenhavam 30 minutos de exercício físicoem carga constante, correspondendo a 25, 50, 75, 100 e 125% do Lan. As respostas cinéticas on eoff cardíacas (FCON e FCOFF) foram analisadas por funções exponenciais. Utilizou-se a análise espectralpara descrever VFC. Para comparação dos coeficientes estimados pelas funções exponenciais, utilizouseANOVA com medidas repetidas, seguido pelo teste pos-hoc de Bonferroni. Adotou-se um nível designificância de 5% para todas as análises. A manifestação da fase cardiodinâmica foi observada nossegundos iniciais do esforço. O componente lento foi evidente para FCON em intensidades superiores aoLan75. O drift cardíaco também foi observado para intensidades a partir do Lan75. Inversamente, aFCOFF apresentou um comportamento monoexponencial, mesmo em elevados níveis de esforço. Houvediferença entre amplitude da FCOFF (Aoff) no Lan75, no Lan100, constante de tempo da FCOFF (Toff) noLan100 e no Lan125 comparado aos mesmos índices no Lan25 e Lan50. A atividade vagal diminuiu emfunção do exercício, mas elevou-se novamente após a interrupção do mesmo, enquanto a contribuiçãosimpática não apresentou associação com o esforço. A assimetria entre FCON e FCOFF refletem diferençasnas respostas hemodinâmicas e neurais envolvidas no controle cardíaco.
The aim of this study was to describe the heart rate kinetics (FC) and how the heart rate variability (VFC) wasassociated with this phenomenon. Seven subjects were submitted to a cycling protocol to determine theanaerobic threshold (Lan) and the maximal aerobic power. In five subsequent tests, the subjects performedthirty minutes of a steady state exercise, corresponding to 25, 50, 75, 100 e 125% of the anaerobic threshold,respectively. The cardiac kinetic responses on and off (FCON e FCOFF) were analyzed using exponential functions.The spectral analysis was used to describe the VFC. The parameters calculated with the exponential functionwere compared using an one - way repeated measures ANOVA, with pos hoc Bonferroni test. All the statisticalprocedures were considered significant at p < 0.05. The cardiodynamic phase was observed during the firstseconds of the effort for all the subjects. The slow component was observed in the FCON at the intensity abovethe Lan75. The cardiac drift was observed at an intensity of Lan75. Inversely, the FCOFF demonstrated a firstexponential function, independently of the level of the effort. There was a significant difference betweenamplitude of the FCOFF at Lan75, Lan100 and time constants of the FCOFF at Lan100 and Lan125 when comparedto the same indices at Lan25 and Lan50. The parasympathetic activity reduced in the beginning of theexercise, but increased after completion, while the sympathetic contribution did not demonstrate anyassociation with the effort. The asymmetry between FCON and FCOFF indicates differences between hemodynamicsand neural responses associated with the cardiac control.