RESUMO Introdução: O treinamento intervalado de alta intensidade (HIIT) é um método muito utilizado atualmente. Objetivo: O presente estudo objetivou avaliar os efeitos do HIIT em curto prazo sobre marcadores de estresse oxidativo e dano muscular em ratos. Métodos: A amostra consistiu em ratos Wistar com 60 dias de idade, divididos em dois grupos: grupo controle (n = 8) e grupo HIIT (n = 8). O treinamento consistiu em quatorze sessões de natação de 20 segundos (com cargas equivalentes a 14% do peso corporal) com intervalos de 10 segundos entre cada sessão, realizadas por 12 dias consecutivos. Resultados: O HIIT induziu uma redução (-17,75%) das substâncias reativas ao ácido tiobarbitúrico (um marcador de estresse oxidativo) no tecido hepático (p = 0,0482). Houve também redução (-31,80%) no grupo HIIT no nível de enzima superóxido dismutase no fígado (p = 0,0375). No entanto, não houve diferenças entre os grupos com relação a catalase, glutationa peroxidase, glutationa redutase, teor total de sulfidrilas SH, hidroperóxidos ou proteínas carboniladas no tecido hepático. Nenhuma diferença significativa foi encontrada em qualquer um desses mascadores no músculo gastrocnêmio. Os marcadores de lesão muscular, creatinina quinase e lactato desidrogenase, também foram semelhantes entre os grupos no gastrocnêmio. Conclusão: Foi possível concluir que o HIIT de curta duração não causa estresse oxidativo ou dano muscular. Nível de evidência I; Estudo clínico randomizado de alta qualidade com ou sem diferença estatisticamente significante, mas com intervalos de informação estreitos.

ABSTRACT Introduction: High intensity interval training (HIIT) is a method that is widely used today. Objective: The present study aimed to evaluate the effects of HIIT on markers of oxidative stress and muscle damage in rats. Methods: The sample consisted of 60-day-old Wistar rats, divided into two groups: a control group (n=8) and an HIIT group (n=8). The training consisted of fourteen 20-second swimming sessions (loaded with weights equivalent to 14% of their body weight) with 10-second intervals between each session, performed for 12 consecutive days. Results: HIIT induced a reduction (−17.75%) in thiobarbituric acid reactive substances (an oxidative stress marker) in hepatic tissue (p=0.0482). There was also a reduction (−31.80%) in the HIIT group in the level of superoxide dismutase enzyme activity in the liver (p=0.0375). However, there were no differences between the groups in catalase, glutathione peroxidase, glutathione reductase, the total content of SH sulfhydryls, hydroperoxides, or carbonylated proteins in the hepatic tissue. No significant differences were found in any of these markers in the gastrocnemius muscle. The muscle damage markers creatinine kinase and lactate dehydrogenase were also similar between the groups in the gastrocnemius. Conclusion: The conclusion was that that short-term HIIT does not cause oxidative stress or muscle damage. Level of evidence I; High-quality randomized clinical trial with or without statistically significant difference, but with narrow confidence intervals.

RESUMEN Introducción: El entrenamiento en intervalos de alta intensidad (HIIT) es un método muy utilizado actualmente. Objetivo: El presente estudio tuvo como objetivo evaluar los efectos del HIIT en corto plazo sobre marcadores de estrés oxidativo y daño muscular en ratones. Métodos: La muestra consistió en ratones Wistar con 60 días de edad, divididos en dos grupos: grupo control (n = 8) y grupo HIIT (n = 8). El entrenamiento consistió en catorce sesiones de natación de 20 segundos (con cargas equivalentes a 14% del peso corporal) con intervalos de 10 segundos entre cada sesión, realizadas durante 12 días consecutivos. Resultados: El HIIT indujo una reducción (-17,75%) de las sustancias reactivas al ácido tiobarbitúrico (un marcador de estrés oxidativo) en el tejido hepático (p = 0,0482). También hubo reducción (~31,80%) en el grupo HIIT en el nivel de enzima superóxido dismutasa en el hígado (p=0,0375). Sin embargo, no hubo diferencias entre los grupos con relación a catalasa, glutatión peroxidasa, glutatión reductasa, tenor total de sulfhidrilos SH, hidroperóxidos o proteínas carboniladas en el tejido hepático. No fue encontrada ninguna diferencia significativa en ninguno de esos marcadores en el músculo gastrocnemio. Los marcadores de lesión muscular, creatinina quinasa y lactato deshidrogenasa también fueron similares entre los grupos en el gastrocnemio. Conclusión: Fue posible concluir que el HIIT de corta duración no causa estrés oxidativo o daño muscular. Nivel de evidencia I; Estudio clínico aleatorizado de alta calidad con o sin diferencia estadísticamente significativa, pero con intervalos de información estrechos.

Abstract Aim: The present study aimed to verify the cardiac oxidative stress biomarker responses to high-intensity interval training (HIIT) in rats. Methods: Sixteen male Wistar rats weighing 250 to 300 g were equally divided into two groups (8 animals/group): sedentary control (SC) and trained group (HIIT). The exercise protocol consisted of high-intensity swimming (14% of body weight, 20 s of activity with 10 s of pause performed 14 times) which was performed for 12 consecutive days. Results: The cardiac tissue concentrations of malondialdehyde and carbonylated proteins showed no significant changes; on the other hand, hydroperoxide levels were higher in the HIIT group than in the SC group. The activities of superoxide dismutase, catalase, and glutathione peroxidase enzymes and the levels of reduced glutathione and sulfhydryl remained unchanged. Conclusion: It is possible to conclude that short-term high-intensity interval training induces changes in the cardiac oxidative stress biomarker but with no effect on the antioxidant enzymes.

ABSTRACT Physical exercise is a known factor that can promote oxidative stress and may result in cellular damage if not neutralized by antioxidant mechanisms. This study aimed to determine if the level of hepatic oxidative stress resulting from high-intensity interval training (HIIT) is affected by the frequency pattern (consecutive vs. non-consecutive) of the training sessions. Thirty-two Wistar rats were divided equally into four groups: two control groups, (CS1) and (CS2), remained sedentary throughout the experiment, and two test groups, (CT1) and (CT2), and were submitted to HIIT for 12 consecutive and non-consecutive (12 sessions, 3 times/wk over four weeks) days, respectively. There were no significant differences in markers of oxidative damage measured in hepatic tissue (TBARS) and markers of antioxidant activity (Sulfhydryl, FRAP), as well as markers of hepatic damage (AST and ALT) and antioxidant defense (Uric Acid) measured in plasma of both HIIT groups after training compared to the control groups. The results indicate that both HIIT performed for 12 consecutive and non-consecutive sessions did not promote hepatic oxidative damage in rats.

Resumo Este estudo analisou as respostas de 24 sessões de High Intensity Interval Training (HIIT) e Contínuo Moderado (CM) sobre a lesão tecidual, estresse oxidativo e perfil glicêmico de ratos em meio líquido. Participaram 24 ratos Wistar, divididos em três grupos: sedentário (GSED), o que fez o HIIT (GHIIT) e o que executou o CM (GCM). Realizados três vezes semanais alternadamente por 8 semanas, sendo que o GHIIT executou 20 segundos de exercício por 10 de descanso. O CM foi um nado de intensidade moderada. O GHIIT aumentou a creatina quinase em relação ao GSED (GSED: 140.40 ± 35.48 U/I; GHIIT: 442.60 ± 8.35 U/I; p=0.0008, representando um aumento percentual de 215.24); a lactato desidrogenase foi aumentada no GHIIT e GCM em relação ao GSED (GSED: 112.8 ± 28.08 U/I; GHIIT: 250.9 ± 70.67 U/I, um aumento percentual de 122.42; GCM: 241.8 ± 100.70 U/I, com aumento percentual de 114.36; p=0.006), em contrapartida, o GHIIT aumentou as sulfidrilas hepáticas não oxidadas em relação ao GCM (GHIIT: 498.70 ± 214.30 nmol/ml; GCM: 270.50 ± 104.40 nmol/ml, a variação percentual foi de 84.36; p=0.03). Houve maior manutenção glicêmica no GCM (p=0.0002). Conclui-se que os protocolos de HIIT e CM, deste estudo, apontam para a uma possível lesão tecidual, em contrapartida, o HIIT desenvolve a capacidade de adaptação do sistema antioxidante hepático e o CM promove uma sustentação glicêmica maior.

Abstract This study analyzed the responses of 24 sessions of High Intensity Interval Training (HIIT) and Continuous Moderate (CM) on tissue damage, oxidative stress and glycemic profile of rats in liquid medium. Twenty-four Wistar rats participated, divided into three groups: sedentary (GSED), the one who performed the HIIT (GHIIT) and the one who performed the CM (GCM). Performed three times a week alternately for 8 weeks, and the GHIIT performed 20 seconds of exercise for 10 rest. The CM was a moderate intensity swim. GHIIT increased creatine kinase compared to GSED (GSED: 140.40 + 35.48 U / I; GHIIT: 442.60 + 8.35 U / I; p = 0.0008, representing a percentage increase of 215.24); lactate dehydrogenase was increased in GHIIT and GCM compared to GSED (GSED: 112.8 + 28.08 U / I; GHIIT: 250.9 + 70.67 U / I, a percentage increase of 122.42; GCM: 241.8 + 100.70 U / I, with a percentage increase 114.36; p = 0.006), in contrast, GHIIT increased non-oxidized liver sulfhydryls compared to GCM (GHIIT: 498.70 + 214.30 nmol / ml; GCM: 270.50 + 104.40 nmol / ml, the percentage change was 84.36; p = 0.03). There was greater glycemic maintenance in the GCM (p = 0.0002). It is concluded that the protocols of HIIT and CM, of this study, point to a possible tissue injury, in contrast, HIIT develops the adaptive capacity of the hepatic antioxidant system and the CM promotes greater glycemic support.