Acute effects of strength exercise with blood flow restriction on vascular function of young healthy males

ISSN 1677-7301 (Online) ORIGINAL ARTICLE Acute effects of strength exercise with blood flow restriction on vascular function of young healthy males Efeito agudo do exercício de força com restrição do fluxo sanguíneo sobre parâmetros antioxidantes em indivíduos jovens saudáveis Francesco Pinto Boeno1,2, Thiago Rozales Ramis1,3, Juliano Boufleur Farinha1, Leandro Silva de Lemos3, Niara da Silva Medeiros3, Jerri Luiz Ribeiro3 * Abstract Background: Strength training with blood flow restriction (STBFR) provokes similar neuromuscular adaptations to traditional strength training using low training loads. However, there is a need for better understanding of the repercussions for antioxidant parameters and vascular function. Objectives: The objective of the present study was to investigate the effects of a session of low intensity strength training with blood flow restriction, compared with high intensity and low intensity strength training without blood flow restriction, on the levels of nitric oxide products and antioxidant enzyme activity in healthy young men. Methods: Eleven young men performed three strength exercise sessions: low intensity with blood flow restriction (LIBFR), high intensity (HI), and low intensity (LI). Activity of the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) was assessed and metabolites of nitric oxide (NOx) were assayed before and after each session. Results: There were no changes to NOx plasma levels under the different exercise conditions (p > 0.05). However, SOD activity exhibited a significant reduction after the LIBFR condition (p < 0.05), while CAT activity reduced significantly after the LI condition (p < 0.05). Conclusions: The results of this study suggest that one session of low intensity strength training with blood flow restriction does not reduce bioavailability of nitric oxide or induce redox imbalance in healthy young men. Keywords: strength training; nitric oxide; oxidative stress; blood flow restriction. Resumo Contexto: O treinamento de força com restrição do fluxo sanguíneo (TFRFS) promove adaptações neuromusculares semelhantes às do treinamento de força tradicional utilizando pequenas cargas de treinamento. No entanto, sua repercussão sobre parâmetros antioxidantes e sobre a função vascular precisa ser mais bem compreendida. Objetivos: O objetivo do presente estudo foi investigar o efeito de uma sessão de exercício de força de baixa intensidade com restrição do fluxo sanguíneo, em comparação ao exercício de força de alta intensidade e de baixa intensidade sem restrição do fluxo sanguíneo, sobre os níveis de subprodutos do oxido nítrico e a atividade de enzimas antioxidantes em jovens saudáveis. Métodos: Onze indivíduos jovens realizaram três sessões de exercício de força: baixa intensidade com restrição do fluxo sanguíneo (BIRFS), alta intensidade (AI) ou baixa intensidade (BI). Foram avaliadas a atividade das enzimas antioxidantes catalase (CAT), superóxido dismutase (SOD) e dos metabólitos do óxido nítrico (NOx). Resultados: Não houve modificações nos níveis plasmáticos de NOx nas diferentes condições de exercício (p > 0,05). A atividade da SOD apresentou uma diminuição significativa na condição BIRFS (p < 0,05). A atividade da CAT diminuiu significativamente na condição BI (p < 0.05). Conclusões: A partir do presente estudo sugere-se que uma sessão de treinamento de força de baixa intensidade com restrição do fluxo sanguíneo não reduz a biodisponibilidade do óxido nítrico, bem como não induz desequilíbrio redox em indivíduos jovens saudáveis. Palavras-chave: treinamento de força; óxido nítrico; stress oxidativo; restrição do fluxo sanguíneo. Universidade Federal do Rio Grande do Sul – UFRGS, Programa de Pós-graduação em Ciências do Movimento Humano, Porto Alegre, RS, Brasil. Universidade Regional Integrada do Alto Uruguai e das Missões – URI, Departamento de Ciências da Saúde, São Luiz Gonzaga, RS, Brasil. 3 Centro Universitario Metodista – IPA, Porto Alegre, RS, Brasil. Financial support: None. Conflicts of interest: No conflicts of interest declared concerning the publication of this article. Submitted: November 05, 2017. Accepted: March 13, 2018. 1 2 The study was carried out at Centro Universitário Metodista (IPA) in collaboration with Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil. 122 J Vasc Bras. 2018 Apr.-Jun.; 17(2):122-127 https://doi.org/10.1590/1677-5449.011017 Francesco Pinto Boeno, Thiago Rozales Ramis et al. INTRODUCTION Experimental design Strength training with blood flow restriction (STBFR) can provoke significant strength and muscle hypertrophy gains using low training loads in combination with an occlusive component during exercise.1 Several studies have suggested that musculoskeletal adaptations in response to STBFR occur at intensities at 20-50% of one repetition maximum (1RM) and at a similar proportion to those observed in traditional strength training, in which loads of around 80% of 1RM are generally used.1-3 It has therefore been proposed that different molecular mechanisms are involved in the adaptations provoked by STBFR. There appears to be recruitment of motor units that are only activated at elevated work intensities, due to the low oxygen availability;1 positive signaling in the mTOR activation cascade;4 myostatin inhibition;3 and increased release of growth hormone.5 Therefore, STBFR could prove to be an important tool for health promotion in individuals with restrictions preventing high intensity exercise. However, few studies have investigated the repercussions of STBFR on prooxidant and antioxidant agents or the relationship with vascular function.2,6 Acute compromise of vascular function has been shown to be an important prognostic factor of the incidence of cardiovascular events.7 Reduced bioavailability of nitric oxide may trigger a hypertensive and prooxidant response, exponentially increasing cardiovascular risk in both healthy and diseased individuals.8 Increased production of reactive oxygen species affects vascular reactivity, accelerating the atherosclerotic process by creating an imbalance between prooxidant and antioxidant systems, leading to higher cardiovascular risk.9,10 It is therefore important to understand the behavior of variables related to vascular function in reaction to an STBFR session, since this is an alternative to traditional strength training with substantially lower intensity and volume. The objective of this study is to investigate the effects of a low intensity strength training exercise session with blood flow restriction, comparing it to high and low intensity strength exercise without blood flow restriction in terms of nitric oxide byproduct levels and antioxidant enzyme activity in healthy young men. The design is a randomized crossover study, comprising 5 days of assessments, separated by 72‑hour intervals between each. Volunteers undertook an experimental protocol consisting of 2 days (...truncated)