OBJECTIVES: Physical activity (PA) may reduce cardiovascular risk and preserve functional capacity of people living with human immunodeficiency virus (HIV). However, only limited research objectively measured PA in patients with low socioeconomic status (SES) in low-income countries, particularly in South America and sub-Saharan Africa. This study compared the PA assessed by accelerometers in women of low SES living with HIV under common antiretroviral therapy (cART) from two major cities in Brazil (Rio de Janeiro, n=33; 40.1±6.1 years) and Mozambique (Maputo, n=50; 38.8±8.7 years). METHODS: Eligible women wore triaxial accelerometers during seven consecutive days, to estimate their habitual PA and daily energy expenditure. RESULTS: The proportion of participants with overweight/obesity was greater in Rio than Maputo (57% vs. 30%; p=0.021), as well as those classified as sedentary based on steps/day (45% vs. 22%; p=0.02). Sedentary time was prevalent (Median±IQD: Rio-1236±142 vs. Maputo-1192±135 min/day; p=0.15). Time spent in PA was short, but Brazilians exhibited lower amount of light (111±56 vs. 145±51 min/day; p<0.001) and moderate-to-vigorous PA (88±3 vs. 64±36 min/day; p=0.001) vs. Mozambicans. The proportion of patients performing 60 min/day of moderate-to-vigorous PA were 58% (Rio) and 82% (Maputo), respectively. Despite of this, estimated daily energy expenditure was equivalent in both groups (1976±579 vs. 1933±492 kcal; p=0.731). CONCLUSIONS: Women with low SES living with HIV in Maputo were more active vs. patients from Rio de Janeiro. Albeit sedentary behavior was prevalent, the proportion of patients complying with the minimum recommended PA for health was higher than values usually reported in developed countries.

Abstract AIM To compare the amount of cardioprotection induced by a single exercise session with those achieved after an 8-week aerobic exercise training following ischemia reperfusion injury in rats. METHODS Twenty-five male Wistar rats (250-300g) were assigned into a group submitted to physical training (TR; n=12) or a single maximal exercise session (EXE; n=13). Following sedentarism or physical training (8 weeks, 5 sessions/wk, 1h/session at 70% of maximal speed) both groups performed a maximal exercise test. Then, groups were submitted to ischemia reperfusion injury (30 min/1h) through an isolated heart protocol, in which left ventricle developed pressure was measured. RESULTS The TR group presented greater maximal oxygen consumption compared to the EXE group (77.25±20.41 vs 41.32±25.86 ml/Kg/min; P=0.003). Regarding left ventricle developed pressure, no differences were detected between groups at baseline (TR: 89.78±24.40 vs EXE: 81.37±31.84 mmHg; P=0.48). However, after reperfusion, the TR group presented superior intraventricular pressure than EXE group (37.94±18.34 vs 21.59±13.67 mmHg; P=0.03). CONCLUSION Eight-week aerobic training induced greater cardioprotection against ischemia reperfusion injury in rats compared to a single exercise session, due to an increased cardiac function. This suggests that exercise-induced cardioprotection is a multifactorial process that may involve different mediators according to the exercise duration.

Fundamento:O infarto agudo do miocárdio é a principal causa de mortalidade e de morbidade na população mundial. Por outro lado, pesquisas já demonstraram que o exercício físico, além de reduzir os fatores de risco cardiovascular, também é capaz de promover cardioproteção contra lesões por isquemia e reperfusão, por meio de um efeito direto no miocárdio. No entanto, o mecanismo específico envolvido no pré-condicionamento cardíaco induzido pelo exercício ainda é alvo de discussão.Objetivo:Realizar uma revisão sistemática acerca dos estudos que se debruçaram sobre os mecanismos pelos quais o exercício físico aeróbio promove cardioproteção direta contra lesões por isquemia e reperfusão.Métodos:Foi realizada uma pesquisa nas seguintes bases de dados: MEDLINE, LILACS e SciELO. Os dados foram extraídos de forma padronizada, por dois investigadores independentes, responsáveis pela avaliação da qualidade metodológica dos manuscritos.Resultados:A busca inicial resultou em 78 estudos, dos quais, após revisão dos resumos, 30 foram excluídos. Os 48 manuscritos restantes foram lidos na íntegra e, destes, 20 foram excluídos, restando 28 estudos incluídos nesta revisão sistemática.Conclusão:Com base nos estudos selecionados, os seguintes mecanismos estão potencialmente envolvidos na resposta cardioprotetora do exercício: aumento na produção de proteínas de choque térmico; envolvimento da via do óxido nítrico; aumento na capacidade antioxidativa cardíaca; melhora na função dos canais de potássio dependentes de ATP; e ativação do sistema de opióides. Apesar de todo o investimento já realizado, ainda é necessário mais investimento em trabalhos futuros, para obtenção de conclusão mais consistente.

Background:Acute myocardial infarction is the leading cause of morbidity and mortality worldwide. Furthermore, research has shown that exercise, in addition to reducing cardiovascular risk factors, can also protect the heart against injury due to ischemia and reperfusion through a direct effect on the myocardium. However, the specific mechanism involved in exerciseinduced cardiac preconditioning is still under debate.Objective:To perform a systematic review of the studies that have addressed the mechanisms by which aerobic exercise promotes direct cardioprotection against ischemia and reperfusion injury.Methods:A search was conducted using MEDLINE, Literatura Latino-Americana e do Caribe de Informação em Ciências da Saúde, and Scientific Electronic Library Online databases. Data were extracted in a standardized manner by two independent researchers, who were responsible for assessing the methodological quality of the studies.Results:The search retrieved 78 studies; after evaluating the abstracts, 30 studies were excluded. The manuscripts of the remaining 48 studies were completely read and, of these, 20 were excluded. Finally, 28 studies were included in this systematic review.Conclusion:On the basis of the selected studies, the following are potentially involved in the cardioprotective response to exercise: increased heat shock protein production, nitric oxide pathway involvement, increased cardiac antioxidant capacity, improvement in ATP-dependent potassium channel function, and opioid system activation. Despite all the previous investigations, further research is still necessary to obtain more consistent conclusions.

Fundamento: O treinamento aeróbio intervalado produz maior benefício na função cardiovascular comparado ao treinamento aeróbio contínuo. Objetivo: O presente estudo teve como objetivo analisar os efeitos de ambas as modalidades nas respostas hemodinâmicas de ratos sadios. Métodos: Ratos machos foram distribuídos aleatoriamente em três grupos: exercício contínuo (EC, n = 10); exercício intervalado (EI, n = 10); e controle (C, n = 10). A sessão do grupo EC consistiu em 30 min à intensidade de 50% da velocidade máxima (Vel Máx). O grupo EI realizou 30 min, incluindo três períodos de 4 min a 60% da Vel Máx intercalados com 4 min de recuperação a 40% da Vel Máx. Frequência Cardíaca (FC), Pressão Arterial (PA) e Duplo Produto (DP) foram medidos antes, durante e após o exercício. Resultados: Os grupos EC e EI apresentaram aumento da PA sistólica e DP durante o exercício em comparação ao repouso. Após o término do exercício, o grupo EC mostrou menor resposta da PA sistólica e do DP em relação ao repouso, enquanto o grupo EI apresentou menor PA sistólica e PA média. No entanto, somente no grupo EI a FC e o DP apresentaram menor resposta na recuperação. Conclusão: Uma sessão de exercício intervalado em ratos sadios induziu respostas hemodinâmicas similares durante o exercício às obtidas em exercício contínuo. Na recuperação, o exercício intervalado promoveu maiores reduções no esforço cardíaco do que em sessões contínuas de exercício.

Background: Aerobic interval exercise training has greater benefits on cardiovascular function as compared with aerobic continuous exercise training. Objective: The present study aimed at analyzing the effects of both exercise modalities on acute and subacute hemodynamic responses of healthy rats. Methods: Thirty male rats were randomly assigned into three groups as follows: continuous exercise (CE, n = 10); interval exercise (IE, n = 10); and control (C, n = 10). Both IE and CE groups performed a 30-minute exercise session. The IE group session consisted of three successive 4-minute periods at 60% of maximal velocity (Max Vel), with 4-minute recovery intervals at 40% of Max Vel. The CE group ran continuously at 50% of Max Vel. Heart rate (HR), blood pressure(BP), and rate pressure product (RPP) were measured before, during and after the exercise session. Results: The CE and IE groups showed an increase in systolic BP and RPP during exercise as compared with the baseline values. After the end of exercise, the CE group showed a lower response of systolic BP and RPP as compared with the baseline values, while the IE group showed lower systolic BP and mean BP values. However, only the IE group had a lower response of HR and RPP during recovery. Conclusion: In healthy rats, one interval exercise session, as compared with continuous exercise, induced similar hemodynamic responses during exercise. However, during recovery, the interval exercise caused greater reductions in cardiac workload than the continuous exercise.