Abstract The aim of the present study was to investigate the effects of β-hydroxy-β-methylbutyrate (HMB) supplementation in association with concurrent training on morphological soleus muscle of rats. Wistar male rats were divided randomly into four groups: Control (C), Supplemented (S), Training (T) and Training + Supplemented (TS). Groups S and TS received 76mg/kg/day of HMB and the training groups (T and TS) were inserted into concurrent training program 3 times/week for 8 weeks. HMB had positive effects either on body composition of the animals or in type II muscle fibers. The concurrent exercise training was able in reducing the total fat mass as well as in increasing the diameter of muscle fibers. Our findings shows that HMB had an anti-catabolic effect with reference to the parameters of volume, weight and morphology of the soleus muscle, and there was a positive interaction between HMB supplementation and concurrent exercise training.

The objective of the present study was to analyze the effects of 14 weeks of resistance training on muscle tissue in Wistar rats. 20 male Wistar rats were used in the study; 10 allocated to the untrained group (Group 1) and 10 to the trained (Group 2). The physical training (PT) program consisted of four sets of ten water jumps, three times a week for 14 weeks. A progressive increase in load was applied from the14nd to the 42nd day. Following this, the animals were euthanized with an overdose of potassium chlorate (100 mg/kg) applied intraperitoneally. The ventral portion of the gastrocnemius muscle was removed for histological processing. The muscles were frozen in liquid nitrogen and cut into thicknesses of 5 µm using a rotative microtome. The sections were stained with hematoxylin-eosin for general analysis of the structure of muscles and analysis of the area of muscle fibers. The reaction with NADH-TR was utilized for differentiation between fast twitch (FT) and slow twitch (ST) fibers. The sections subjected to staining and histochemical reactions were observed in normal and polarized light and photomicrographed using a microscope (Zeiss®). The measurement of muscle fibers was performed using AxioVision software (Zeiss®). Statistical analysis was performed using the Student t test for analysis of the samples average. An average area of 5061.29 µm2 for Group 1 versus 5768.93 µm2 for Group 2 was observed. It can be concluded that 14 weeks of training with water jumps was effective in increasing muscle area. An increase in transverse area section (TAS) of ST and FT was also verified in the trained group.

El objetivo fue investigar los efectos de 14 semanas de entrenamiento de resistencia sobre el tejido muscular de ratas Wistar. Fueron utilizadas 20 ratas, 10 en el grupo sin entrenamiento (Grupo 1) y 10 con entrenamiento (Grupo 2). El programa de entrenamiento físico estaba compuesto de cuatro series con 10 saltos acuáticos, tres veces en la semana, durante 14 semanas. Un aumento progresivo de la carga fue aplicado desde el día 14 al día 42. Los animales fueron eutanasiados con clorhidrato de potasio (100 mg/kg) intraperitoneal. La parte ventral del músculo gastrocnemio fue removida para el análisis histológico. La musculatura fue congelada en nitrógeno líquido y cortada con 5 µm de espesor con micrótomo rotatorio. La coloración fue H-E para el análisis del músculo y área en las fibras musculares. La reacción com NADH-TR fue utilizada para la comparación entre las fibras rápidas (FR) y fibras lentas (FL). Las reacciones histoquímicass se observaron bajo microscópio de luz (Zeiss®) y sobre las microfotografias obtenidas se realizaron las mediciones con el programa Axio Vision (Zeiss®). El análisis estadístico se realizó con la prueba t de student para comparación de medias. Se observó una media de 5061,29 µm2 en el Grupo 1 y 5768,93 µm2 en Grupo 2. Es posible concluir que 14 semanas de programa de entrenamiento físico con 10 saltos acuáticos son capaces de aumentar el área del músculo. Un aumento del área transversal de las FR y FL fue observado en el grupo 2.

O objetivo do presente estudo foi analisar as alterações morfológicas do músculo gastrocnêmio medial (GM) de ratos Wistar submetidos a oito semanas de treinamento concorrente (TC). Foram utilizados quinze ratos Wistar machos, separados em três grupos com cinco animais: linha de base (LB), controle (C) e treinados (T). O TC consistiu na realização de um treinamento de resistência aeróbia em natação (TRA) e um treinamento de força (TF) na mesma sessão, três vezes por semana, durante oito semanas. Foi observado um aumento de 4,4 % na comparação entre as médias da área da secção transversa do GM dos animais dos grupos T (4905,5 ± 77,1µm²) e C (4699,9 ± 78,3µm²). Conclui-se que o treinamento concorrente foi eficaz em promover hipertrofia no GM de ratos Wistar.

The aim of this study was to analyze the morphophysiological changes of medial gastrocnemius muscle (GM) of Wistar rats underwent to eight weeks of concurrent training (TC). We used fifteen male Wistar rats divided into three groups with five animals each: baseline (LB), control (C) and trained (T). The TC consisted of aerobic endurance training in swimming (TRA) and a forced training (TF) in the same session, three times per week, for eight weeks. There was an increase of 4.4% in the comparison between average cross section area of the GM in animals of groups T (4905,5 ± 77,1µm²) and C (4699,9 ± 78,3 µm²). It is concluded that concurrent training was effective in causing hypertrophy in GM of rats.

El objetivo de este estudio fue analisar los cambios morfofisiológicos del músculo gaastrocnemio medial (GM) de ratones Wistar sometidos a ocho semanas de entrenamiento concurrente (TC). Se utilizó quince ratones Wistar divididos en tres grupos com cinco animales: línea de base (LB), control (C) y entrenado (T). El TC consistió en un entrenamiento de resistencia aerobia en natación (TRA) y en un entrenamiento de fuerza (TF) en la misma sesión, tres veces por semana, durante ocho semanas. Hubo um aumento de 4,4% en la comparación promedio entre el area de la sección transversal de los grupos de animales T (4905,5 ± 77,1 µm²) y C (4699,9 ± 78,3 µm²). Se concluye que el entrenamiento concurrente fue eficaz en la causa de la hipertrofia en el GM de ratones Wistar.