Effects of different methods of antagonist muscles pre-activation on knee extensors neuromuscular responses / Efeitos da ordem de pré-ativação dos músculos antagonistas nas respostas neuromusculares dos extensores do joelho

BACKGROUND: Pre-activation of antagonistic muscles is used in different modalities of exercise and neuromuscular rehabilitation protocols, but its effectiveness is still controversial. OBJECTIVE: To verify the impact of two different methods of pre-activation of knee antagonist muscles in the neuromuscular performance and electromyographic activity of knee extensors. METHODS: Fifteen healthy men (23.9±4.2 years of age, 1.78±0.08 meters and 81.4±10.7 kg) performed, on different days, two protocols of isokinetic muscle contraction with 4 sets of 10 repetitions at 60°.s-1 and 1 minute between sets: (1) Reciprocal Contraction (RC): reciprocal concentric exercise of agonist/antagonist muscles (knee flexion [KF] immediately followed by knee extension [KE]) and (2) Superset (SS): alternated concentric exercise of agonist/antagonist muscles (KF set followed by a set of KE). A repeated measures ANOVA with least-significant difference post-hoc test was used to detect differences between protocols. RESULTS: There were no significant differences between protocols (p>0.05) for peak torque (PT) and total work (Tw). On the SS protocol there was a significant decrease in Tw on the last two sets (p<0.05) while for RC the decrease occurred only in the last set. There were no significant differences of root mean square (RMS) between protocols, but the activation pattern was more uniform during the RC protocol. CONCLUSION: The results indicated that the peak torque was not influenced by the different pre-activation methods. However, the RC protocol appears to better maintain the total work training volume.

CONTEXTUALIZAÇÃO: A pré-ativação de músculos antagonistas é utilizada em diferentes modalidades de exercício e em diferentes protocolos de reabilitação neuromuscular, porém suas respostas ainda são controversas. OBJETIVO: Verificar o impacto de duas diferentes estratégias de pré-ativação de músculos antagonistas no desempenho neuromuscular e na atividade eletromiográfica dos extensores do joelho. MÉTODOS: Quinze homens sadios (23,9±4,2 anos; 1,78±0,08 m e 81,4±10,7 kg) realizaram, em dias distintos, dois protocolos de ações musculares isocinéticas com quatro séries de dez repetições a 60°.s-1 e intervalo de 1 minuto entre séries: 1) contração recíproca (CR): exercício concêntrico recíproco de antagonistas/agonistas (uma repetição de flexão do joelho [FJ] imediatamente seguida por uma de extensão do joelho [EJ]) e 2) supersérie (SS): exercício concêntrico alternado dos antagonistas/agonistas (dez repetições de FJ seguidas por dez de EJ). Utilizou-se a ANOVA para medidas repetidas com teste post-hoc LSD (Least-significant diference) para verificar a diferença entre protocolos. RESULTADOS: Não houve diferença significante (p>0,05) entre protocolos para o pico de torque (PT) e trabalho total (Tt). Em relação ao Tt, o protocolo SS apresentou quedas significantes nas duas últimas séries (p<0,05) enquanto, no CR, a queda ocorreu apenas na última série de exercício. Não houve diferenças no Root Mean Square (RMS) entre protocolos, mas o padrão de ativação foi mais uniforme durante o CR. CONCLUSÃO: Os resultados indicaram que a queda na força muscular não é influenciada pelas diferentes formas de pré-ativação da musculatura antagonista, no entanto parece que a utilização de CR permite uma melhor manutenção do volume de treinamento.

Origin and distribution of the femoral nerve in fetuses of zebu-crossed bovines

In this study the femoral nerve origin and distribution was assessed through the dissection of 30 fetuses of zebu-crossed bovines, 20 males and 10 females. These animals samples fixation in 10% formaldehyde aqueous medium occurred either by subcutaneous, intra-muscle, and intra-cavity injections in different sites, or by immersion of the mentioned pieces in vessels containing the same medium. The femoral nerve originated from the forth (L4), fifth (L5), and sixth (L6) spinal lumbar ventral branches in 14 animals (46.7%), from L4 and L5 in 13 samples (43.3%), and L5 and L6 in three cases (10%). In the course of its way, on both antimeres the mentioned nerve was branched to the greater psoas (100%), iliac (100%), pectinal (56.7%), femoral quadriceps (100%), muscles, and gave off saphena nerve, which gave branches for the pectinal (43.3%) and sartorius (100%) muscles and continued distally along the saphena artery to spread on the medial face of the knee and leg medial articulation skin. Statistically, there was no significant difference between the muscle branch frequencies given by the femoral nerve to the right and left antimeres. The obtained results related to the femoral nerve origin and distribution in fetuses of zebu-crossed bovines generally presented common characteristics with the ruminant corresponding data found in the literature, and this information is important as the basis for clinical or surgical approaches involving the studied structures.

Peripheral nerve connections influence the appearance of neurosecretary material in neural sheath of ventral ganglion of the fly Sarcophaga bullata: an immunocytochemical study.

This study examined the role of the brain and peripheral connections with the target organs in the appearance of neurosecretary material within the dorsal neural sheath of the ventral ganglion of the fly S. bullata. Specifically, the accumulation of the neuropeptide FMRFamide (the neurosecretary material) was examined by immunocytochemistry. Immunoreactions were performed on: (1) a normal intact ventral ganglion, (2) an isolated ventral ganglion that was cultured in vivo, and (3) a ventral ganglion that was isolated by transection from the brain, but retained its peripheral nerve connections. The results demonstrate that (a) the neurons of the ganglia survive and exhibit FMRFamide immune reaction independent of their peripheral connections, and (b) the accumulation of neuropeptide in the dorsal neural sheath is controlled by intact peripheral nerve connections with the ganglion. It is suggested that in the absence of their peripheral connections, the axons of FMRFamide immunoreactive neurons fail to invade the neural sheath resulting in the accumulation of neurosecretary material.