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Respostas neuromusculares, termorregulatórias e oxidativas ao treinamento de força tradicional e excêntrico em atletas de powerlifting paralímpico

2026-09-03T00:00:00Z

Title: Respostas neuromusculares, termorregulatórias e oxidativas ao treinamento de força tradicional e excêntrico em atletas de powerlifting paralímpico Authors: Leite Júnior, Joilson Alves de Souza Abstract: Introduction: Powerlifting is a maximal strength sport characterized by the execution of three multi-joint movements: the squat, bench press, and deadlift, requiring high levels of neuromuscular control and mechanical efficiency. In the Paralympic context, due to the functional characteristics of eligible athletes, only the bench press is performed in competition, with specific adaptations implemented to ensure safety, technical standardization, and competitive equity. Objectives: To investigate the acute and subacute effects of traditional and eccentric strength training on neuromuscular, mechanical, thermoregulatory, and oxidative indicators in Paralympic powerlifting athletes, as well as to compare these responses with those of conventional athletes. Methods: This thesis consisted of three experimental studies involving trained male Paralympic powerlifting athletes. Neuromuscular indicators were assessed, including maximum isometric force (MIF), rate of force development (RFD), time to maximum isometric force (TMIF), and muscle activation measured by surface electromyography (sEMG) of the pectoralis major (sternocostal and clavicular portions), anterior deltoid, and triceps brachii (long head). Mechanical variables included peak velocity (Vmax), mean propulsive velocity (MPV), and power output (POT), while thermoregulatory responses were evaluated באמצעות skin temperature (Tsk). Oxidative stress was assessed using biomarkers such as thiobarbituric acid reactive substances (TBARS) and sulfhydryl groups (SH). Measurements were performed at baseline, immediately post-exercise, and at 24 and 48 hours following traditional and eccentric training sessions, using protocols based on relative loads (%1RM). Results: The findings demonstrated that eccentric training elicited more pronounced physiological responses, characterized by increased skin temperature, greater elevations in oxidative stress markers, and enhanced neuromuscular adaptations at specific time points, although it was also associated with greater fatigue and prolonged recovery. In contrast, traditional training produced more stable responses, with faster recovery of performance indicators. Conclusion: Eccentric training appears to be an effective strategy for promoting relevant neuromuscular and physiological adaptations in Paralympic powerlifting athletes, although it requires careful management of fatigue and recovery. Conversely, traditional training represents a more stable approach, particularly suitable for maintenance phases and competitive preparation. A strategic combination of both methods may optimize athletic performance while respecting the physiological and functional specificities of Paralympic athletes, reinforcing the need for individualized training prescription.

Efeito antinociceptivo e mecanismos de ação da corrente interferencial na antinocicepção em modelo experimental de inflamação articular

2019-02-20T00:00:00Z

Title: Efeito antinociceptivo e mecanismos de ação da corrente interferencial na antinocicepção em modelo experimental de inflamação articular Authors: Reis, Kamilla Mayara Lucas da Cruz Abstract: Introduction: Interferential current (IC) has been currently used for different clinical conditions, mainly for the purpose of analgesia. However, little is known about the mechanism of neurobiological action of this current. The objective of this study was to investigate the effect of IC on sensory and motor intensity in the hypernociception caused after induction of joint inflammation and if, systemically, the cholinergic, monoaminergic and nitric oxide receptors are involved in the mechanism of antinociceptive action of this current. Material and methods: A total of 96 Wistar rats were divided into experimental series (Control, Motor and Sensory) and pharmacological block series (Control, CI + Saline, CI + DMSO, CI + Reserpine, CI + CI + Atropine, CI + Haloperidol, CI + L-NNA, CI + ODQ, CI + Glibenclamide). Electrical stimulation was applied 24 hours after the induction of inflammation and in the reserpine group with 48h due to its mechanism of action. Behavioral tests for sensitivity and motor performance were performed before induction, 24 hours after induction of inflammation and after IC application. Pharmacological blockade was achieved by intraperitoneal injection applied prior to treatment according to the time of action and dose of each drug. Values of p <0.05 were considered significant. Results: In the behavioral series, there was an increase in the cutaneous sensory threshold (p = 0.03) in the group treated with motor intensity, and an increase in the thermal latency in the groups treated with sensory and motor intensities (p <0.009), the motor group presented greater effect size in the mechanical sensitivity (d = 1.42). In contrast, high intensity promoted a decrease in motor performance (p = 0.03) compared to pre-treatment. In the series that evaluated the possible mechanisms of action in the reserpine series, it was identified that amine depletion prevented the increase of the cutaneous sensory threshold in the IC + Reserpine group differently from the IC + Saline group in which there was antinociception (p = 0.01). Of the monoamines investigated, there was an impediment in the effect of the current on the sensory threshold in the CI + Yohimbine and CI + Atropine groups, since there was no difference between the pre and post treatment groups differently from CI + Salina, CI + Prazosin and CI + Haloperidol (p < 05). Inhibition of nitric oxide synthase (NOS) in the CI + L-NNA group prevented IC-promoted antinociception and in the intracellular cascade of this pathway both guanylate cyclase and dependent K-channels were found of ATP also participate in their antihyperalgesic mechanism because they do not increase the mechanical threshold after IC treatment. All groups treated with IC plus vehicle or antagonists had a reduction of the distance covered (p <0.03) less control and CI + yohimbine groups. Conclusion: Based on the present study, we can conclude that the interferential current in motor intensity is more effective for the reduction of antinociception and that this effect involves mechanisms of action of the alpha-2 receptors, muscarinic cholinergic and is related to the nitric oxide pathway.

Caracterização clínica, comportamental, sensorial e eletrofisiológica de crianças e adolescentes com dor reumatológica crônica: estudo transversal comparativo

2026-08-03T00:00:00Z

Title: Caracterização clínica, comportamental, sensorial e eletrofisiológica de crianças e adolescentes com dor reumatológica crônica: estudo transversal comparativo Authors: Silva, Tauane Grasiela dos Santos Abstract: Rheumatic conditions comprise a diverse group of diseases that predominantly affect the joints, but also muscles, bones, connective tissues, and internal organs, arising from immune-mediated, inflammatory, infectious, or degenerative mechanisms, characterized by a prolonged, painful, and function-limiting course, and which also affect children and adolescents. Among pediatric rheumatic conditions, juvenile idiopathic arthritis (JIA), of inflammatory and autoimmune nature, and juvenile fibromyalgia syndrome (JFS), of non-inflammatory nature and associated with central sensitization mechanisms, potentially involving cognitive, autonomic, and sensory dysfunction, stand out. In this context, electroencephalography (EEG) stands out as a tool for objectively characterizing the neurological processes underlying pediatric chronic pain. However, studies detailing the physiological mechanisms involved in JFS and JIA remain scarce. Objective: To characterize the clinical, behavioral, sensory, and electrophysiological profile of children and adolescents with chronic rheumatic pain resulting from juvenile fibromyalgia syndrome or juvenile idiopathic arthritis, compared with a healthy control group matched by sex and age range. Materials and Methods: This was an analytical, observational, cross-sectional study including children and adolescents of both sexes, aged 7 to 18 years, allocated into two groups: a pain group (JFS and JIA) and a control group. The groups were assessed using socioeconomic questionnaires, pain intensity (11-point numerical rating scale), mechanical detection threshold (esthesiometry), electrophysiological profile (electroencephalogram), and cognitive profile (auditory P300 event-related potential). Results: The sample consisted of 54 participants, 27 in the pain group and 27 in the control group, stratified into children and adolescents (24 children and 30 adolescents). A mean diagnostic delay of 21.3 months was observed in children and 50.7 months in adolescents. Children in the pain group showed generalized mechanical hypersensitivity to light touch at a site distant from the affected joint (p=0.004; d=−1.297), and adolescents in the pain group showed greater pain sensitivity to mechanical pressure (p=0.013 and p=0.045) and greater self-reported pain intensity (p=0.001) compared with controls. No intergroup EEG differences were identified under the resting-state condition. During the P300 paradigm, adolescents in the pain group showed greater relative amplitude in the theta band and lower relative amplitude in the beta3 band in the right anterior and posterior regions compared with controls (p<0.05; d ranging from 0.94 to 1.41), a finding significant under the uncorrected primary criterion adopted in this exploratory study; in a Benjamini-Hochberg sensitivity analysis restricted to relative-amplitude variables and applied per age subgroup within each experimental condition (m=24), right posterior theta power remained significant (q=0.015). In children, a differentiated pattern of right posterior relative amplitude was observed during exposure to educational and recreational screen conditions. The topographic pain contrast between diagnoses was statistically significant for back pain, leg pain, and headache, all more frequent in JFS (FDR-adjusted p<0.01). Conclusion: In response to the overall objective, the electrophysiological profile of children and adolescents with JFS and JIA, compared with healthy controls, was characterized by the absence of EEG differences at rest and by specific alterations under active cognitive and sensory demand. Children and adolescents with JFS and JIA present measurable sensory alterations and specific electrophysiological changes during conditions of active cognitive and sensory demand, though not generalized to the resting state, consistent with early stages of central sensitization and pain-related cognitive interference. These findings reinforce the relevance of early diagnosis as a possible therapeutic window and point to the need for longitudinal studies investigating the progression of these alterations throughout development.

Sensibilidade β-adrenérgica e variabilidade alterada da frequência cardíaca no hipotireoidismo: uma abordagem mecanicista

2026-08-21T00:00:00Z

Title: Sensibilidade β-adrenérgica e variabilidade alterada da frequência cardíaca no hipotireoidismo: uma abordagem mecanicista Authors: Rocha, Camila Souza Gama Abstract: Hypothyroidism is one of the most prevalent endocrine disorders worldwide, affecting more than 10% of adults, and is associated with structural and functional alterations of the cardiovascular system. Although its chronotropic and hemodynamic effects are well described, the mechanisms integrating autonomic modulation and β-adrenergic sensitivity in the genesis of cardiac electrical alterations are poorly understood. This study aimed to investigate changes in cardiac electrical function resulting from autonomic modulation associated with hypothyroidism in a murine model. Methods: Male Swiss mice were used (n = 6–7 per group; 5–6 weeks old; 25–30 g). Hypothyroidism was induced with methimazole (0.1% in drinking water) for 21 days, while the control group received water only. Cardiac function was assessed by in vivo electrocardiography on days 0, 11, and 21, determining heart rate, electrical conduction, and heart rate variability in the time and frequency domains. β-adrenergic sensitivity was analyzed through intraperitoneal administration of isoproterenol, dobutamine, and salbutamol, with electrocardiographic monitoring before and 3 minutes after administration. Adenylyl cyclase activity was assessed in isolated hearts perfused using a Langendorff system, before and after stimulation with forskolin. The expression of β₁ and β₂ receptors, protein kinase A (PKA), and phospholamban (PLB) was determined by Western blot. Results: Hypothyroid animals showed a significant reduction in heart rate, prolongation of the PR interval, and an increase in corrected QT. Heart rate variability revealed an increase in the Very Low Frequency (VLF) component, an increase in the Root mean square of successive differences (RMSSD), and a reduction in the Standard deviation of NN intervals (SDNN), characterizing autonomic imbalance with vagal predominance and decreased overall adaptability. Hypothyroid hearts showed a significant reduction in β₁-receptor expression and PKA substrate phosphorylation, as well as an increase in β₂-receptor expression. These results indicate that hypothyroidism reduces canonical β₁-adrenergic/PKA signaling while increasing β₂-adrenergic receptor expression. The chronotropic response to isoproterenol and dobutamine was attenuated, accompanied by reduced PKA substrate phosphorylation, indicating decreased cardiac β₁-adrenergic responsiveness. In contrast, the response to salbutamol was increased, with no changes in PKA substrate phosphorylation or PLB expression/phosphorylation, suggesting that β₁-adrenergic signaling is selectively impaired in hypothyroidism, with a possible reorganization toward the β₂-adrenergic signaling pathway. Forskolin stimulation restored the heart rate response without altering the p-PLB/PLB ratio, which remained unchanged, indicating preservation of the intracellular steps downstream of β-adrenergic receptor activation. Conclusion: Hypothyroidism induces marked remodeling of cardiac adrenergic signaling, with a greater contribution of alternative pathways associated with the β₂ adrenergic receptor. These findings demonstrate that thyroid hormone deficiency leads to reorganization of cardiac adrenergic signaling, contributing to bradycardia, reduced chronotropic adaptability, and decreased complexity of autonomic control in hypothyroidism.