DSpace Coleção:

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

2026-09-30T18:44:14Z

Título: Respostas neuromusculares, termorregulatórias e oxidativas ao treinamento de força tradicional e excêntrico em atletas de powerlifting paralímpico Autor(es): 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

2026-09-30T17:25:51Z

Título: Efeito antinociceptivo e mecanismos de ação da corrente interferencial na antinocicepção em modelo experimental de inflamação articular Autor(es): 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.

Avaliação dos perfis comportamentais e inflamatórios em modelos murinos de obesidade: influência do sexo e do tempo de exposição

2026-09-30T17:11:34Z

Título: Avaliação dos perfis comportamentais e inflamatórios em modelos murinos de obesidade: influência do sexo e do tempo de exposição Autor(es): Freitas, Camila Evelyn Perete de Abstract: Advances in the study of the Developmental Origins of Health and Disease (DOHaD) suggest that insults occurring during early developmental stages can trigger significant physiological changes in adulthood, rendering the individual more susceptible to developing conditions such as obesity. In this context, "neonatal overnutrition" is a known factor associated with various metabolic and inflammatory alterations similar to those observed in obesity. It is also known that the persistence of obesity-related inflammatory changes negatively affects neural metabolism and synaptic transmission, leading to behavioral alterations. Thus, this study compared the effects of obesity induced by different murine models on metabolism and behavioral responses in both sexes. Male and female Swiss mice were assigned to control (CTRL) groups or to obesity-induction groups using either litter reduction (SL) or a high-fat diet (HFD). Body mass was monitored weekly after weaning. This monitoring lasted 10 weeks for both experimental groups, extending to 21 weeks for a subgroup of SL animals. Following an acclimatization period, a battery of three behavioral tests (defensive, social interaction, and cognitive) was conducted, followed by an analysis of locomotor activity in an open-field test. To evaluate the influence of time on the progression of the inflammatory response in LR animals, cytokine concentrations and the expression of genes associated with macrophage polarization were analyzed in various tissues at two different time points. Results showed a progressive increase in body mass and adiposity in both models at the 10-week and 21-week marks, with higher food intake observed only in male LR mice. Regarding behavior, female SL mice and both male and female HFD mice exhibited reduced active defense responses. Alterations in social affiliation and social memory were found, and age-dependent cognitive deficits were observed in SL animals of both sexes. Regarding inflammation, male RN mice exhibited an early inflammatory profile—characterized by increased TNF-α concentrations in adipose tissue and the liver, as well as the expression of genes associated with M1 macrophage polarization in the liver—as early as 10 weeks of age. In contrast, female SL mice displayed a delayed and limited inflammatory profile, with increased IL-1β levels observed only in the spleen. These results establish a significant sexual dimorphism by demonstrating that, in both models, obesity manifested as distinct metabolic and behavioral phenotypes in males and females. Furthermore, in SL animals, the progression over time played a significant role in the development of the metabolic and behavioral outcomes observed in both sexes.

Impacto da cafeína sobre indicadores neuromusculares, estresse oxidativo e dano muscular no powerlifting paralímpico

2026-08-05T17:22:46Z

Título: Impacto da cafeína sobre indicadores neuromusculares, estresse oxidativo e dano muscular no powerlifting paralímpico Autor(es): Menezes, Jainara Lima Abstract: Introduction: Resistance exercise improves performance but generates fatigue and muscle damage. Caffeine (CA) supplementation is used to mitigate these effects; however, neuromuscular parameters, muscle damage, and oxidative stress still need to be clarified, especially in paralympic powerlifting. Objective: To evaluate the effects of CA supplementation on strength performance (static and dynamic), oxidative stress, and muscle damage in paralympic powerlifting. Methods: This study investigated the acute effects of CA supplementation (9 mg/kg) on indicators of static strength (Rate of Force Development (RFD), Impulse, Peak torque, maximum isometric strength, peak strength at 1 second, and force variability) and dynamic strength (Mean Propulsive Velocity (MPV), Maximum Velocity (Vmax), and Power were evaluated at 45% of 1RM before, after, 24h, and 48h of a training session, and also at 80% of 1RM, performing 5x5). Markers of oxidative stress and enzymatic antioxidant activity (TBARS/MDA, total antioxidant capacity, sulfhydryl groups, and uric acid) and markers of muscle damage (thermography, CK (creatine kinase), LDH (lactate dehydrogenase), and creatinine) were assessed in 14 male Paralympic powerlifting athletes. The protocol included two conditions (CA and PLA (placebo)), 5x5 at 80% of 1RM in the bench press. Results: Regarding static strength, CA significantly increased RFD, impulse, peak torque, and maximum isometric strength, while improving peak strength at 1 second and reducing variability, suggesting enhanced motor unit recruitment. Regarding dynamic strength, no significant differences were observed at 45% of 1RM. However, at 80% of 1RM, the CA group demonstrated significant improvement compared to the PLA group during Set 1 and Set 5. Nonetheless, CA also led to an increase in oxidative stress, as evidenced by elevated TBARS levels, reduced antioxidant capacity, decreased sulfhydryl groups, and higher uric acid concentrations post-exercise. Thermography showed an increase in all evaluated muscles with CA compared to the PLA condition. For CK, LDH, and creatinine, there were no significant differences. Conclusion: CA demonstrates promising ergogenic properties, contributing to increased muscle strength and allowing athletes to maintain training intensity even with higher loads. Furthermore, it does not appear to increase muscle damage, suggesting a safe usage profile in this regard. However, while it acutely improves neuromuscular performance, CA does not reduce—and may even exacerbate—exercise-induced oxidative stress, indicating that its use in strength sports should be approached with caution.