Maximal repetition performance, rating of perceived exertion, and muscle fatigue during paired set training performed with different rest intervals

AbstractBackground/ObjectiveThe purpose of this study was to examine rest interval length between agonist–antagonist paired set training (PS) on maximal repetition performance, rating of perceived exertion, and neuromuscular fatigue.MethodsFourteen trained men (age, 24.2 ± 1.1 years; height, 175 ± 5.5 cm; body mass, 76.6 ± 7.0 kg) performed two experimental protocols in random order with 2 minutes (P2) or 4 minutes (P4) between agonist–antagonist PS, which consisted of a bench press set followed immediately by a seated row set with 8-repetition maximum loads, respectively. A total of three PS were performed for each rest interval protocol. The total repetitions performed and the rating of perceived exertion were recorded for each exercise set within each rest interval protocol. Electromyography signals were recorded for the posterior deltoid, biceps brachii, pectoralis major, and triceps brachii muscles during the SR exercise. The electromyography signals were then used to calculate a fatigue index for each rest interval protocol.ResultsNo significant differences were identified in the total repetitions completed between rest interval protocols for the bench press (P2 = 22.9 ± 1.3 and P4 = 22.6 ± 0.8) and seated row (P2 = 25.4 ± 1.7 and P4 = 25.1 ± 1.3). However, a significantly higher fatigue index was found for all muscles under the P2 versus the P4 protocol.ConclusionWhen performing agonist–antagonist PS, prescribing a shorter rest interval between PS may induce higher levels of fatigue, albeit with similar total repetitions versus a longer rest interval

INFLUÊNCIA DE DIFERENTES INTERVALOS DE RECUPERAÇÃO SOBRE O NÚMERO DE REPETIÇÕES MÁXIMAS NO TREINAMENTO DE FORÇA

O presente estudo tem como objetivo verificar a influência de diferentes intervalos de recuperação sobre o número de repetições máximas em dois exercícios do treinamento de força. Participaram do estudo 15 indivíduos do sexo masculino com idade de 25,44 ± 4,50 anos, estatura de 179,56 cm ± 44,02 cm, massa corporal de  81,10 ± 9,24 kg e índice de massa corporal (IMC) 25,75 kg/m² ± 2,33. Todos os avaliados realizaram cinco sessões de treinamento, sendo uma para aplicação do teste de carga para 10 repetições máximas (RM), uma para aplicação do reteste de 10 RM e mais três sessões, uma para cada intervalo (1, 3 e 5 minutos) proposto pela pesquisa, todas as sessões com intervalo de 48 horas. Definido como total de repetições completadas a última repetição máxima realizada até a falha concêntrica dentro da correta execução proposta. De acordo com os resultados houve diferença intragrupo em séries posteriores executadas nos exercícios supino reto articulado (SRA) e puxada aberta no pulley alto (PAP). Maior diferença encontrada entre os protocolos SEQA e SEQB no SRA (5,31 ± 0,83 RM e 7,84 ± 0,79 RM) e SEQD e SEQE na PAP (6,10 ± 0,61 RM e 8,11 ± 0,70 RM) e entre os protocolos SEQA e SEQC no SRA (5,33 ± 0,80 RM e 9,20 ± 0,80 RM) e SEQC e SEQF na PAP (6,10 ± 0,61 RM e 9,45 ± 0,63 RM), foi encontrado diferença entre os protocolos SEQC e SEQB no SRA, não houve diferença significativa no protocolo de intervalo entre SEQF e SEQE na PAP. Não houve diferenças nos demais protocolos em ambos os exercícios. O presente estudo apresentou diferença significativa no volume total de repetições em ambos os exercícios. Conclui-se que intervalos inferiores a 3 minutos são ineficientes para manutenção do numero de repetições com cargas máximas para 10 RM

Are the winters 2010 and 2012 archetypes exhibiting extreme opposite behavior of the North Atlantic jet stream?

The atmospheric circulation over the North Atlantic-European sector experienced exceptional but highly contrasting conditions in the recent 2010 and 2012 winters (November-March; with the year dated by the relevant January). Evidence is given for the remarkably different locations of the eddy-driven westerly jet over the North Atlantic. In the 2010 winter the maximum of the jet stream was systematically between 30ºN and 40ºN (in the ‘south jet regime’), while in the 2012 winter it was predominantly located around 55ºN (north jet regime). These jet features underline the occurrence of either weak flow (2010) or strong and persistent ridges throughout the troposphere (2012). This is confirmed by the very different occurrence of blocking systems over the North Atlantic, associated with episodes of strong cyclonic (anticyclonic) Rossby wave breaking in 2010 (2012) winters. These dynamical features underlie strong precipitation and temperature anomalies over parts of Europe, with detrimental impacts on many socioeconomic sectors. Despite the highly contrasting atmospheric states, mid and high-latitude boundary conditions do not reveal strong differences in these two winters. The two winters were associated with opposite ENSO phases, but there is no causal evidence of a remote forcing from the Pacific sea surface temperatures. Finally, the exceptionality of the two winters is demonstrated in relation to the last 140 years. It is suggested that these winters may be seen as archetypes of North Atlantic jet variability under current climate conditions

Comparison of different flexibility training methods and specific warm-up on repetition maximum volume in lower limb exercises with female jazz dancers

Introduction: Some evidences show that stretching exercises prior to a strength training session can result in decrease of performance. Therefore, the aim of this study was to compare the acute effect of different stretching protocols in the lower limbs using the sum of repetition maximum (RM) performed before a strength training session. Material and methods: The sample consisted of ten female jazz dancers (age: 24.7 ± 7.84 years), with no experience in strength training. Six visits were conducted in which participants were subjected to 10-RM test, 10-RM retest and four different warm-up protocols: specific warm-up, static stretching, proprioceptive neuromuscular facilitation and ballistic stretching. Results: The results obtained in this study showed that in the squat exercise in the Smith machine, the ballistic stretching protocol had a significantly higher volume compared to all other protocols, while the PNF had a significantly higher volume in comparison with the specific warm-up protocol and static stretching protocol (p < 0.05). However, in the leg extension, there were no significant differences in the total volume of maximum repetitions between protocols. Conclusion: Ballistic stretching was the most effective protocol to increase the levels of muscle strength in female jazz dancers

Dynamic 3D Cell Rearrangements Guided by a Fibronectin Matrix Underlie Somitogenesis

Somites are transient segments formed in a rostro-caudal progression during vertebrate development. In chick embryos, segmentation of a new pair of somites occurs every 90 minutes and involves a mesenchyme-to-epithelium transition of cells from the presomitic mesoderm. Little is known about the cellular rearrangements involved, and, although it is known that the fibronectin extracellular matrix is required, its actual role remains elusive. Using 3D and 4D imaging of somite formation we discovered that somitogenesis consists of a complex choreography of individual cell movements. Epithelialization starts medially with the formation of a transient epithelium of cuboidal cells, followed by cell elongation and reorganization into a pseudostratified epithelium of spindle-shaped epitheloid cells. Mesenchymal cells are then recruited to this medial epithelium through accretion, a phenomenon that spreads to all sides, except the lateral side of the forming somite, which epithelializes by cell elongation and intercalation. Surprisingly, an important contribution to the somite epithelium also comes from the continuous egression of mesenchymal cells from the core into the epithelium via its apical side. Inhibition of fibronectin matrix assembly first slows down the rate, and then halts somite formation, without affecting pseudopodial activity or cell body movements. Rather, cell elongation, centripetal alignment, N-cadherin polarization and egression are impaired, showing that the fibronectin matrix plays a role in polarizing and guiding the exploratory behavior of somitic cells. To our knowledge, this is the first 4D in vivo recording of a full mesenchyme-to-epithelium transition. This approach brought new insights into this event and highlighted the importance of the extracellular matrix as a guiding cue during morphogenesis

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Post-intervention Status in Patients With Refractory Myasthenia Gravis Treated With Eculizumab During REGAIN and Its Open-Label Extension

OBJECTIVE: To evaluate whether eculizumab helps patients with anti-acetylcholine receptor-positive (AChR+) refractory generalized myasthenia gravis (gMG) achieve the Myasthenia Gravis Foundation of America (MGFA) post-intervention status of minimal manifestations (MM), we assessed patients' status throughout REGAIN (Safety and Efficacy of Eculizumab in AChR+ Refractory Generalized Myasthenia Gravis) and its open-label extension. METHODS: Patients who completed the REGAIN randomized controlled trial and continued into the open-label extension were included in this tertiary endpoint analysis. Patients were assessed for the MGFA post-intervention status of improved, unchanged, worse, MM, and pharmacologic remission at defined time points during REGAIN and through week 130 of the open-label study. RESULTS: A total of 117 patients completed REGAIN and continued into the open-label study (eculizumab/eculizumab: 56; placebo/eculizumab: 61). At week 26 of REGAIN, more eculizumab-treated patients than placebo-treated patients achieved a status of improved (60.7% vs 41.7%) or MM (25.0% vs 13.3%; common OR: 2.3; 95% CI: 1.1-4.5). After 130 weeks of eculizumab treatment, 88.0% of patients achieved improved status and 57.3% of patients achieved MM status. The safety profile of eculizumab was consistent with its known profile and no new safety signals were detected. CONCLUSION: Eculizumab led to rapid and sustained achievement of MM in patients with AChR+ refractory gMG. These findings support the use of eculizumab in this previously difficult-to-treat patient population. CLINICALTRIALSGOV IDENTIFIER: REGAIN, NCT01997229; REGAIN open-label extension, NCT02301624. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, after 26 weeks of eculizumab treatment, 25.0% of adults with AChR+ refractory gMG achieved MM, compared with 13.3% who received placebo

Minimal Symptom Expression' in Patients With Acetylcholine Receptor Antibody-Positive Refractory Generalized Myasthenia Gravis Treated With Eculizumab

The efficacy and tolerability of eculizumab were assessed in REGAIN, a 26-week, phase 3, randomized, double-blind, placebo-controlled study in anti-acetylcholine receptor antibody-positive (AChR+) refractory generalized myasthenia gravis (gMG), and its open-label extension