Acute performance fatigability following continuous versus intermittent cycling protocols is not proportional to total work done.

Classical training theory postulates that performance fatigability following a training session should be proportional to the total work done (TWD); however, this notion has been questioned. This study investigated indices of performance and perceived fatigability after primary sessions of high-intensity interval training (HIIT) and constant work rate (CWR) cycling, each followed by a cycling time-to-task failure (TTF) bout. On separate days, 16 participants completed an incremental cycling test, and, in a randomized order, (i) a TTF trial at 80% of peak power output (PPO), (ii) an HIIT session, and (iii) a CWR session, both of which were immediately followed by a TTF trial at 80% PPO. Central and peripheral aspects of performance fatigability were measured using interpolated twitch technique, and perceptual measures were assessed prior to and following the HIIT and CWR trials, and again following the TTF trial. Despite TWD being less following HIIT (P = 0.029), subsequent TTF trial was an average of 125 s shorter following HIIT versus CWR (P < 0.001), and this was accompanied by greater impairments in voluntary and electrically evoked forces (P < 0.001), as well as exacerbated perceptual measures (P < 0.001); however, there were no differences in any fatigue measure following the TTF trial (P ≥ 0.149). There were strong correlations between the decline in TTF and indices of peripheral (r = 0.70) and perceived fatigability (r ≥ 0.80) measured at the end of HIIT and CWR. These results underscore the dissociation between TWD and performance fatigability and highlight the importance of peripheral components of fatigability in limiting endurance performance during high-intensity cycling exercise.

Effects of 12 weeks of Tai Chi on neuromuscular responses and postural control in elderly patients with sarcopenia: a randomized controlled trial.

Objective: To explore the effect of 12 weeks of Tai Chi on neuromuscular responses and postural control in elderly patients with sarcopenia. Methods: One hundred and twenty-four elderly patients with sarcopenia from ZheJiang Hospital and surrounding communities were selected, however, 64 were later disqualified. Sixty elderly patients with sarcopenia were randomly assigned to the Tai Chi group (n = 30) and the control group (n = 30). Both groups received 45-min health education sessions once every 2 weeks for 12 weeks, and the Tai Chi group engaged in 40-min simplified eight-style Tai Chi exercise sessions 3 times per week for 12 weeks. Two assessors who had received professional training and were unaware of the intervention allocation assessed the subjects within 3 days prior to the intervention and within 3 days after completion of the intervention. They chose the unstable platform provided by the dynamic stability test module in ProKin 254 to evaluate the patient's postural control ability. Meanwhile, surface EMG was utilized to assess the neuromuscular response during this period. Results: After 12 weeks of intervention, the Tai Chi group showed a significant decrease in neuromuscular response times of the rectus femoris, semitendinosus, anterior tibialis, and gastrocnemius and overall stability index (OSI) compared to before the intervention (p < 0.05), while there was no significant difference in the control group for these indicators before and after intervention (p > 0.05). In addition, these indicators in the Tai Chi group were significantly lower than those in the control group (p < 0.05). The changes in neuromuscular response times of the rectus femoris, semitendinosus, anterior tibialis, and gastrocnemius were positively correlated with the changes in OSI (p < 0.05) in the Tai Chi group, but there were no significant correlations between changes in neuromuscular response times of the aforementioned muscles and changes in OSI in the control group (p < 0.05). Conclusion: Twelve-weeks of Tai Chi exercise can improve the neuromuscular response of the lower extremities in elderly patients with sarcopenia, shorten their neuromuscular response time when balance is endangered, enhance their dynamic posture control ability, and ultimately reduce the risk of falls.

Respostas fisiológicas do exercício concorrente associado à ETCC em idosos / Physiological responses of concurrent exercise associated with CTEE in the elderly

Introdução: As alterações ocasionadas pelo envelhecimento são diversas, principalmente nos comportamentos fisiológicos e funcionais. A neuromodulação é apresentada como uma técnica promissora nessa temática, podendo aprimorar as respostas cardiorrespiratórias e neuromusculares, proporcionando assim uma promoção da saúde. A técnica de neuromodulação utilizada foi a Estimulação Transcraniana por Corrente Contínua (ETCC) que pode ser aplicada com uma corrente elétrica em polaridades positiva (anódica) e negativa (catódica). As pesquisas com o uso da ETCC e as variáveis cardiorrespiratórias e neuromusculares na prática da atividade física, ainda são recentes e, por isso, precisam ter seus mecanismos mais bem elucidados. Desta maneira, o objetivo do estudo foi verificar o efeito da aplicação da ETCC anódica em variáveis neuromusculares e cardiorrespiratórias durante e após o exercício de força e aeróbio (concorrente), comparando com a situação placebo. Métodos: Os 12 voluntários idosos que participaram do estudo tinham 75 ± 15 anos, realizaram 4 visitas respeitando um intervalo de 2 à 7 dias entre as coletas. A primeira foi a familiarização e teste de carga de 12rm, na segunda visita foram avaliadas as medidas antropométricas e o teste de esforço máximo no ciclo ergômetro. Nas outras duas visitas os indivíduos foram submetidos a aplicação randomizada duplo-cega da ETCC anódica ou situação placebo por 20 minutos em protocolo de pesquisa com situações em repouso, teste de força na preensão manual e exercícios concorrentes. Os dados coletados foram da força de preensão manual (FPM); variáveis da variabilidade frequência cardíaca (VFC) (domínio do tempo e da frequência); frequência cardíaca (FC); pressão arterial sistólica (PAS), diastólica (PAD) e média (PAM); consumo de oxigênio (VO2) e pós exercício (EPOC); escala adaptada de borg; consumo de caloria (Kcal); trabalho total (W). Tratamento estatístico: As análises estatísticas foram por meio do teste de normalidade Shapiro-Wilk, ANOVA de Medidas Repetidas para duas entradas em todas as variáveis, com post hoc de Bonferroni quando necessário, para todas as variáveis nas duas condições (Anódica e Placebo), exceto nas variáveis do consumo de Kcal/L e do total da carga de trabalho, ambas durante o exercício aeróbio, as quais foram submetidas ao teste-t de student para amostras pareadas. Quando os dados apresentaram distribuição não paramétrica foi aplicado logarítmico neperiano. Para todos os testes foi adotado p ≤ 0,05. Resultados: Os resultados não apresentaram mudanças significativas na FPM do membro direito com p=0,30; após o exercício concorrente na PAS p=0,21, PAD p=0,59 e PAM p=0,59; média da FC após o treino concorrente p=0,35; EPOC com p=0,50; Kcal com p=0,35 e o trabalho total com p=0,35. Conclusão: Os resultados indicam que a técnica de ETCC anódica quando comparada a situação placebo, não apresentou diferenças significativas em nenhuma das variáveis analisadas

Introduction: changes caused by aging are many, especially in the physiological and functional behavior. Neuromodulation is presented as a promising technique in this theme, can improve cardiorespiratory and neuromuscular responses, thus providing a health promotion. The neuromodulation technique used was Transcranial Stimulation Direct Current (tDCS) that can be applied with an electric current of positive polarity (anode) and negative (cathode). Research on the use of tDCS and cardiorespiratory and neuromuscular variables in physical activity, are still recent and, therefore, need to have their mechanisms better elucidated. Thus, the objective of the study was to verify the application of the effect of anodal tDCS in neuromuscular and cardiorespiratory variables during and after resistance exercise and aerobic (concurrent) compared to the placebo situation. Methods: 12 elderly volunteers who participated in the study were 75 ± 15 years, made 4 visits an interval of 2 to 7 days between collections. The first was the familiarization and 12RM strength test. The second visit was evaluated anthropometric measurements and maximal exercise test on a cycle ergometer. In the other two visits, patients underwent double-blind, randomized application of anodic tDCS situation or placebo for 20 minutes in the research protocol with situations at rest, strength testing on hold manual and concurrent exercises. The collected data were the handgrip; variables of heart rate variability (HRV) (time domain and frequency); heart rate (HR); Systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean (MBP); oxygen consumption (VO2) and after exercise (EPOC); adapted Borg scale; Calorie consumption (Kcal); total work (W). Statistical analyzes: were by the normality test Shapiro-Wilk, repeated measures ANOVA for two entries in all variables, with post hoc Bonferroni when necessary, for all variables in the two conditions (anodic and Placebo) except the variables of consumption kilocalorie per liter and the total workload, both during aerobic exercise which were submitted t-test for paired samples student. When the data have non-parametric distribution was applied neperian logarithm. For all tests was adopted p ≤ 0.05. Results: The results showed no significant changes in the right member of the handgrip with p = 0.30; after the concurrent exercise SBP p = 0.21, p = 0.59 DBP and MBP p = 0.59; average HR after concurrent training p = 0.35; EPOC p = 0.50; kilocalorie per liter with p = 0.35 and the total work with p = 0.35. Conclusion: The results indicate that the anodic tDCS technique when compared to placebo situation, no significant differences in anyof the variables

The acute effects of spinal manipulation on neuromuscular function in asymptomatic individuals: A preliminary study.

OBJECTIVES: To analyse the acute effects of spinal manipulation on neuromuscular function in asymptomatic individuals. DESIGN: Randomised controlled, cross-over trial. SETTINGS: Spinal manipulation (SM) is used as therapeutic modality for various neuromuscular disorders and also in sport with asymptomatic individuals to improve range of motion and/or facilitate motor control. Experimental evidence of its effectiveness is lacking. PARTICIPANTS: 27 asymptomatic participants (15 males and 12 females) [age (mean ± standard deviation) 24 ± 3 years] were exposed to three separate treatments in random order: 1) Spinal Manipulation of the lumbar spine (MAN); 2) Stretching of the Lumbar spine (STR); 3) sham manipulation (SHA). MAIN OUTCOME MEASURES: Before (PRE), after (POST) and 15 min after (15_MIN) each treatment, the participants were asked to perform three tasks always in the same order: 1) force fluctuation task; 2) Modified Sörensen's test; 3) sit and reach. Surface EMG was recorded from Gastrocnemius medialis and Erector Spinae muscles using linear arrays during task 1 and 2. RESULTS: MAN was not shown to determine improvements superior to other treatments in the control of force output and sEMG parameters. CONCLUSIONS: Studies with larger populations are needed in order to ascertain the effectiveness of SM on neuromuscular function.