Beta-alanine supplementation improves isometric, but not isotonic or isokinetic strength endurance in recreationally strength-trained young men

Background: β-alanine (BA) supplementation may be ergogenic during high intensity exercise, primarily due to the buffering of hydrogen cations, although the effects of beta-alanine supplementationon strength endurance are equivocal. Aim: To determine the effects of 4 weeks of beta-alanine supplementation on skeletal muscle endurance using a battery of performance tests. Methods: This study employed a parallel group, repeated measures, randomised, double-blinded and placebo controlled design. Twenty recreationally strength-trained healthy males completed tests of isotonic strength endurance (repeated bench and leg press), along with tests of isometric and isokinetic endurance conducted using an isokinetic dynamometer. Tests were performed before and after a 4 week intervention, comprising an intake of 6.4g.day-1 10 of BA (n = 9) or placebo (maltodextrin, n = 11). Results: Time-to-exhaustion during the isometric endurance test improved by ~17% in the BA group (p 0.1) were shown for any of the performance variables in the isokinetic test (peak torque, fatigue index, total work) nor for the total number of repetitions performed in the isotonic endurance tests (leg or bench press). Conclusions: Four weeks of BA supplementation (6.4 g.day-1 15 ) improved isometric, but not isokinetic or isotonic endurance performance

Postural adjustments of scapular and global muscles as mechanisms to control the shoulder motion and posture

A falha na estabilidade escapular e no ritmo escápulo-umeral são associadas ao risco de lesão no complexo do ombro. Apesar de se saber que a estabilização ativa dos músculos escapulares é fundamental para evitar disfunções ainda pouco se sabe sobre como o controle postural no complexo do ombro ocorre e como tais mecanismos poderiam auxiliar na estabilização da articulação perante uma tarefa. Será que há ajustes posturais antecipatórios (APA) e compensatórios (APC) nos músculos escapulares (serrátil anterior, trapézio inferior e trapézio superior) em tarefas motoras que envolvem o movimento dos membros superiores? Como as ações motoras modulam a resposta postural dos músculos escapulares e globais (músculos do tronco e membros inferiores) para estabilizar e orientar o corpo? O objetivo deste estudo foi analisar a existência dos ajustes posturais antecipatórios e compensatórios nos músculos escapulares e globais em sujeitos ativos saudáveis em tarefas de membros superiores. Para tal, participaram 70 indivíduos ativos saudáveis (18 mulheres e 52 homens, 28,0±7,2 anos, 70,5±13,4 kg e 1,72±0,07 m). Foi mensurada atividade eletromiográfica do músculo focal Deltóide Anterior, músculos escapulares (Serrátil Anterior, Trapézio Superior, Trapézio Inferior) e músculos globais (Reto Abdominal, Eretor Longuíssimo, Reto Femoral, Bíceps Femoral, Gastrocnêmio, Tibial Anterior) em 4 tarefas de membros superiores (abdução no plano escapular, adução, flexão e extensão) executadas com halteres de massa 1kg e 3kg. Os resultados mostraram a existência de ajustes posturais dos músculos escapulares (p0,05); as tarefas de abdução versus flexão são semelhantes com massa 1kg (p>0,05), mas se tornam diferentes com massa 3kg (p 0.05); the abduction versus flexion tasks are similar with mass 1kg (p> 0.05), but become different with mass 3kg (p <0.001) in relation to muscular activity of the scapular and global muscles; during flexion and abduction tasks, the greatest postural adjustments were the scapular muscles (Serratus Anterior and Lower Trapezius) (p <0.001); during adduction and extension tasks, the largest of the global muscles (p <0.001); anticipatory and compensatory postural adjustments were higher in the serratus anterior and lower trapezius scapula muscles than in the anterior deltoid focal muscle (p <0.001); there were modulations in the types and levels of APA and CPA in upper limb tasks (p <0.001). In conclusion, we have an association of postural adjustments as mechanisms of stabilization and orientation of the shoulder in tasks of the upper limbs. However, the intensity and modulation of postural adjustments are affected by task and mass. We believe that the muscular activity of the scapular muscles is directly associated with the need to minimize the perturbation to the maintenance of the orietantion and stability segment (shoulder), as well as overall muscle activity is associated with maintaining stability and body orientation. These findings can be used for future studies comparing subjects with dysfunction and health and thus to understand if there is abnormal activity of the scapular muscles in the periods of anticipatory and compensatory postural adjustments and if this muscular activity contributes to dysfunction of the shoulder comple

Postural adjustments of scapular and global muscles as mechanisms to control the shoulder motion and posture

A falha na estabilidade escapular e no ritmo escápulo-umeral são associadas ao risco de lesão no complexo do ombro. Apesar de se saber que a estabilização ativa dos músculos escapulares é fundamental para evitar disfunções ainda pouco se sabe sobre como o controle postural no complexo do ombro ocorre e como tais mecanismos poderiam auxiliar na estabilização da articulação perante uma tarefa. Será que há ajustes posturais antecipatórios (APA) e compensatórios (APC) nos músculos escapulares (serrátil anterior, trapézio inferior e trapézio superior) em tarefas motoras que envolvem o movimento dos membros superiores? Como as ações motoras modulam a resposta postural dos músculos escapulares e globais (músculos do tronco e membros inferiores) para estabilizar e orientar o corpo? O objetivo deste estudo foi analisar a existência dos ajustes posturais antecipatórios e compensatórios nos músculos escapulares e globais em sujeitos ativos saudáveis em tarefas de membros superiores. Para tal, participaram 70 indivíduos ativos saudáveis (18 mulheres e 52 homens, 28,0±7,2 anos, 70,5±13,4 kg e 1,72±0,07 m). Foi mensurada atividade eletromiográfica do músculo focal Deltóide Anterior, músculos escapulares (Serrátil Anterior, Trapézio Superior, Trapézio Inferior) e músculos globais (Reto Abdominal, Eretor Longuíssimo, Reto Femoral, Bíceps Femoral, Gastrocnêmio, Tibial Anterior) em 4 tarefas de membros superiores (abdução no plano escapular, adução, flexão e extensão) executadas com halteres de massa 1kg e 3kg. Os resultados mostraram a existência de ajustes posturais dos músculos escapulares (p0,05); as tarefas de abdução versus flexão são semelhantes com massa 1kg (p>0,05), mas se tornam diferentes com massa 3kg (p 0.05); the abduction versus flexion tasks are similar with mass 1kg (p> 0.05), but become different with mass 3kg (p <0.001) in relation to muscular activity of the scapular and global muscles; during flexion and abduction tasks, the greatest postural adjustments were the scapular muscles (Serratus Anterior and Lower Trapezius) (p <0.001); during adduction and extension tasks, the largest of the global muscles (p <0.001); anticipatory and compensatory postural adjustments were higher in the serratus anterior and lower trapezius scapula muscles than in the anterior deltoid focal muscle (p <0.001); there were modulations in the types and levels of APA and CPA in upper limb tasks (p <0.001). In conclusion, we have an association of postural adjustments as mechanisms of stabilization and orientation of the shoulder in tasks of the upper limbs. However, the intensity and modulation of postural adjustments are affected by task and mass. We believe that the muscular activity of the scapular muscles is directly associated with the need to minimize the perturbation to the maintenance of the orietantion and stability segment (shoulder), as well as overall muscle activity is associated with maintaining stability and body orientation. These findings can be used for future studies comparing subjects with dysfunction and health and thus to understand if there is abnormal activity of the scapular muscles in the periods of anticipatory and compensatory postural adjustments and if this muscular activity contributes to dysfunction of the shoulder comple