Does rest interval between unilateral exercise protocols influences on contralateral neuromuscular responses in untrained individuals?

INTRODUCTION: Effects on strength performance and muscle activation in the contralateral limb have been observed after training with the ipsilateral limb (IL). Cross fatigue effects in the contralateral limb (CL) can occur at intervals of up to 48 h after a training session performed with the ipsilateral limb. The objective of this study was to verify the effect of a training session in the ipsilateral limb, on the strength and activation of the muscles in the contralateral limb also submitted to the training protocol. METHODS: 10 untrained men (mean ± SD: age = 23.7 ± 4.9 years) performed unilateral knee extension with both limbs in equated protocols, in two conditions with different intervals between limbs - 20 min and 24 h. RESULTS: There were no differences in the comparison of the force produced between the pre x post interventions with the CL limb, as well as in the activation of the quadriceps during its performance. These results were similar for the two different intervals between the protocols. CONCLUSION: It was concluded that when the CL member performs the protocol after the IL, the responses in the CL depend mainly on the requirement imposed on the protocol performed by this member, without influence of the training protocol performed previously with the IL member.

Rates of Occult Invasive Disease in Patients With Biopsy-Proven Oral Cavity Squamous Cell Carcinoma in Situ.

Importance: The likelihood that an oral cavity lesion harbors occult invasive disease after biopsy demonstrating carcinoma in situ (CIS) is unknown. While de-escalated treatment strategies may be appealing in the setting of CIS, knowing whether occult invasive disease may be present and its association with survival outcomes would lead to more informed management decisions. Objective: To evaluate rate of occult invasive disease and clinical outcomes in patients with oral cavity CIS. Design, Setting, and Participants: This was a retrospective population-based cohort study using the National Cancer Database and included adults with biopsy-proven oral cavity CIS as the first diagnosis of cancer between 2004 and 2020. Data were analyzed from October 10, 2022, to June 25, 2023. Exposures: Surgical resection vs no surgery. Main Outcomes and Measures: Analyses calculated the rate of occult invasive disease identified on resection of a biopsy-proven CIS lesion. Univariate and multivariate logistic regression with odds ratios and 95% CIs were used to identify significant demographic and clinical characteristics associated with risk of occult invasion (age, year of diagnosis, sex, race and ethnicity, oral cavity subsite, and comorbidity status). Kaplan-Meier curves for overall survival (OS) were calculated for both unresected and resected cohorts (stratified by presence of occult invasive disease). Results: A total of 1856 patients with oral cavity CIS were identified, with 122 who did not undergo surgery (median [range] age, 65 [26-90] years; 48 female individuals [39.3%] and 74 male individuals [60.7%]) and 1458 who underwent surgical resection and had documented pathology (median [range] age, 62 [21-90] years; 490 female individuals [33.6%] and 968 male individuals [66.4%]). Of the 1580 patients overall, 52 (3.3%) were Black; 39 (2.5%), Hispanic; 1365 (86.4%), White; and 124 (7.8%), other, not specified. Among those who proceeded with surgery with documented pathology, 408 patients (28.0%) were found to have occult invasive disease. Higher-risk features were present in 45 patients (11.0%) for final margin positivity, 16 patients (3.9%) for lymphovascular invasion, 13 patients (3.2%) for high-grade invasive disease, and 14 patients (3.4%) for nodal involvement. For those patients with occult disease, staging according to the American Joint Committee on Cancer's AJCC Cancer Staging Manual, eighth edition, was pT1 in 341 patients (83.6%), pT2 in 41 (10.0%), and pT3 or pT4 disease in 26 (6.4%). Factors associated with greater odds of occult invasive disease at resection were female sex, Black race, and alveolar ridge, vestibule, and retromolar subsite. With median 66-month follow-up, 5-year OS was 85.9% in patients who proceeded with surgical resection vs 59.7% in patients who did not undergo surgery (difference, 26.2%; 95% CI, 19.0%-33.4%). Conclusions and Relevance: This cohort study assessed the risk of concurrent occult invasion with biopsy-proven CIS of the oral cavity, demonstrating that 28.0% had invasive disease at resection. Reassuringly, even in the setting of occult invasion, high-risk disease features were rare, and 5-year OS was nearly 80% with resection. The findings support the practice of definitive resection if feasible following biopsy demonstrating oral cavity CIS.

The effect of 10 weeks of strength training on the electromyographic response of quadriceps portions / Efeito de 10 semanas de treinamento na resposta eletromiográfica das porções do quadríceps

Abstract This study investigate the effect of 10-week strenght training on the amplitude of the electromyographic (EMG) signal of vastus medialis, vastus lateralis and rectus Femoris. Twenty three untrained volunteers performed 3-5 sets (3 sets - weeks 1 and 2; 4 series - weeks 3 and 4; 5 series weeks 5 to 10) with 6 repetitions, intensity of 50% of 1 repetition maximum (1RM), 3 min rest between sets and 6 s repetition duration at the knee extensor exercise. One group (5:1) performed concentric action of 5 s and eccentric of 1 s and the other (3:3) performed concentric of 3 s and eccentric of 3 s. The VM, VL and RF EMG (RMS) activities were recorded in each repetition of the three series at the first training session and the first three series at the last session. The protocol 5:1 led to EMG reduction in all portions, with a greater number of repetitions presenting differences at the VL and RF. VM and RF presented similar results at Group 3:3. It was verified that all the differences occurred in the second half of the series. It was also verified differences in EMG ratios just in group 3:3 and only in VM/VL and VM/RF. These results suggest that the coordination was not affected when equivalent repetitions of series were compared. It was also suggested that these results were influenced by the reduced degrees of freedom of the exercise and the training load progression adopted.

Resumo Este estudo investigou o efeito de 10 semanas de treinamento de força na resposta eletromiográfica (EMG) do vasto medial, vasto lateral e reto femoral. 23 voluntárias executaram 3 a 5 séries de 6 repetições, intensidade de 50% de 1 repetição máxima (RM), 3 minutos de pausa entre as séries e duração da repetição de 6 s no exercício extensor de joelhos. Um grupo (5:1) realizou a duração da ação concêntrica em 5 s e excêntrica em 1s e outro grupo (3:3) realizou a concêntrica em 3s e a excêntrica em 3s. A atividades EMG (RMS) destas três porções do quadríceps foram registradas em cada repetição das 3 séries da primeira sessão de treinamento e nas três primeiras séries da última sessão. Os resultados mostraram diferenças na metade final das séries, sendo que no grupo 5:1 houve redução na EMG em todas as porções e o VL e o RF mostraram redução em um número maior de repetições. No grupo 3:3 o VM e o RF apresentaram redução. Para as relações de ativação entre as porções, diferenças foram identificadas apenas no grupo 3:3 nas relações VM/VL e VM/RF em um número reduzido de repetições. Estes resultados apontam que a coordenação entre as porções sofreu poucas alterações quando comparadas as repetições equivalentes de cada série. Sugere-se que os reduzidos graus de liberdade do movimento utilizado e a progressão da carga de treinamento tenham sido os fatores que conduziram a este resultado

Focus of attention and online demonstration effects on temporal error and muscle activation / Efeitos do foco de atenção e demonstração online no erro temporal e na ativação muscular

Abstract The purpose of the present study was to examine whether there would be performance differences between external and internal focus of attention conditions and an online demonstration condition, and if these differences would be observed at a neuromuscular level through EMG analysis, in addition to traditional outcome measures. We hypothesized that under the demonstration condition participants would perform better than under external and internal focus conditions. We also hypothesized that demonstration condition would show smaller EMG activity than external and internal focus conditions. Furthermore, we hope to replicate the benefits of external focus in relation to internal focus, both in outcome and product measures. Six male participants performed a bilateral leg extension under internal focus of attention, external focus of attention and online demonstration conditions. Muscular contractions goal times were set for concentric muscle action (4 seconds) and eccentric muscle action (2 seconds). An electrogoniometer was used to record muscular activation (production measures), and temporal error was used to observe performance (outcome measures). Results showed that online demonstration condition obtained better performance than external focus condition and a reduced muscular activation. However, differences between internal focus and the other experimental conditions were not found. These findings advance in the understanding mechanisms underpining the focus of attention, such as proposed by Constrained Action Hypothesis.

Resumo O objetivo do presente estudo foi avaliar as diferenças no desempenho entre as condições de foco de atenção externo e interno e uma condição de demonstração online. Adicionalmente, se essas diferenças seriam observadas em um nível neuromuscular por meio da análise EMG, além das medidas de resultados tradicionais. Foi levantada a hipótese que sob a condição de demonstração os participantes teriam um desempenho melhor do que sob as condições de foco externo e interno. Também foi levantado a hipótese que a condição de demonstração apresentaria menor atividade EMG do que as condições de foco externo e interno. Além disso, esperava-se corrobora os benefícios do foco externo em relação ao foco interno, tanto nas medidas de resultado quanto de produto. Seis participantes do sexo masculino realizaram uma extensão de perna bilateral nas condições: foco de atenção interno, foco de atenção externo e condições de demonstração online. Os tempos de meta de contrações musculares foram definidos para ação muscular concêntrica (4 segundos) e ação muscular excêntrica (2 segundos). Um eletrogoniômetro foi usado para registrar a ativação muscular (medidas de produção) e o erro temporal foi usado para observar o desempenho (medidas de resultado). Os resultados mostraram que a condição de demonstração online obteve melhor desempenho do que a condição de foco externo e uma ativação muscular reduzida. No entanto, não foram encontradas diferenças entre o foco interno e as outras condições experimentais. Esses achados avançam no entendimento dos mecanismos que sustentam o foco de atenção, como o proposto pela Constrained Action Hypothesis.

Effect of resistance exercise with different muscle action durations on lactate response / Efeito de protocolos de treinamento com diferentes durações das ações musculares na concentração de lactato sanguíneo

ABSTRACT The aim of this study was to compare the blood lactate concentration in strength training protocols with different muscle action durations in the bench press exercise. Seventeen volunteers performed three protocols with three sets of six repetitions at 60 % of 1RM, three- minute break between sets and different muscle action durations (2-4: 2s concentric and 4s eccentric; 3-3: 3s concentric and 3s eccentric; 4-2: 4s concentric and 2s eccentric). The analysis of blood lactate concentration considered the average values ​​per set in each protocol. The ANOVA two-way of the results showed that the main effect for protocol showed no significant difference between the three protocols (F = 0,75; p = 0,48; power = 0,48; η2 = 0,17), as the interaction among the factors (F = 1,68; p = 0,13; power = 0,09; η2= 0,62). However, there was significant main effect for set (F = 320,23; p = 0,0001; power = 1,00; η2= 0,95). Therefore, resistance training protocols equated with different muscle actions durations shows no differences in blood lactate response and, regardless of the protocol, its concentration increased throughout the three sets performed.

RESUMO O objetivo deste estudo foi comparar a concentração de lactato sanguíneo em protocolos de treinamento de força com diferentes durações das ações musculares no exercício supino. Dezessete voluntários executaram três protocolos com três séries de seis repetições a 60% de 1RM, pausa de três minutos entre as séries e diferentes durações das ações musculares (2-4: 2s concêntrica e 4s excêntrica; 3-3: 3s concêntrica e 3s excêntrica; 4-2: 4s concêntrica e 2s excêntrica). A análise da concentração de lactato sanguíneo considerou os valores médios por série em cada protocolo. Os resultados da ANOVA two-way mostraram que o efeito principal protocolo não apresentou diferença significante entre os três protocolos (F = 0,75; p = 0,48; poder = 0,48; η2 = 0,17), assim como para a interação entre os fatores (F = 1,68; p = 0,13; poder = 0,09; η2 = 0,62). Porém, houve diferença significante na concentração de lactato sanguíneo para o fator série (F = 320,23; p = 0,0001; poder = 1,00; η2 = 0,95). Portanto, protocolos de treinamento de força equiparados com durações das ações musculares distintas não apresentaram diferenças na resposta do lactato sanguíneo e, independentemente do protocolo, a concentração deste substrato aumentou ao longo das três séries realizadas.