O objetivo do trabalho foi investigar o efeito da suplementação isolada de cafeína e bicarbonato de sódio sobre a contribuição dos sistemas energéticos, desempenho e reativação parassimpática após simulação de luta de taekwondo. Para tanto, a presente tese foi dividida em estudo 1, com a suplementação de cafeína e estudo 2, com a suplementação de bicarbonato de sódio. Portanto, no estudo 1, o objetivo foi investigar o efeito da suplementação de cafeína sobre a contribuição dos sistemas energéticos, desempenho e reativação parassimpática em simulação de luta de taekwondo. 10 atletas de taekwondo foram submetidos a duas sessões experimentais separadas por no mínimo de 48 horas entre elas. Nas duas visitas os atletas consumiram uma cápsula contendo cafeína (5 mg.kg-1 de massa corporal) ou placebo (celulose) uma hora antes da simulação da luta de taekwondo, composta por 3 rounds de 2 minutos com 1 minuto de intervalo entre os rounds. A ordem das sessões experimentais foi randomizada, duplo-cego e cruzada. Todas as simulações de luta foram filmadas para quantificar as ações técnico-táticas durante os rounds. Foram mensuradas a concentração de lactato, a percepção subjetiva de esforço (PSE) antes e após cada round,e a frequência cardíaca (FC) e a contribuição dos sistemas energéticos foi estimada durante a simulação de luta. Além disso, foram mensurados alguns índices da reativação parassimpática após o terceiro round. A concentração de lactato, a PSE, a FC e a contribuição dos sistemas energéticos foram comparados usando análise de variância de dois fatores (condição e tempo). Adicionalmente, os índices da reativação parassimpática foram comparados utilizando o teste t de Student entre as condições cafeína e placebo. Os principais resultados indicam que: a suplementação de cafeína aumentou a contribuição do sistema glicolítico em relação ao placebo. Porém, a cafeína não melhorou o desempenho ou alterou a PSE, a FC ou a contribuição dos sistemas oxidativo e ATP-CP quando comparados ao placebo. Adicionalmente, nenhum índice da reativação parassimpática foi afetado pela suplementação de cafeína. No estudo 2, o objetivo do estudo foi investigar o efeito da suplementação de bicarbonato de sódio sobre a contribuição dos sistemas energéticos durante a simulação de luta de taekwondo. Para tanto, foram avaliados 9 atletas de taekwondo, os quais foram submetidos a duas condições experimentais, separadas por um mínimo de 48 horas entre elas. Nas duas visitas os atletas ingeriram uma cápsula contendo 0,03 g.kg-1 da massa corporal de NaHCO3- ou placebo (carbonato de cálcio), 90 minutos antes da simulação de luta de taekwondo, composta por 3 rounds de 2 minutos com 1 minutos de intervalo entre os rounds. A ordem das sessões experimentais foi randomizada, duplo-cego e cruzada. Todas as simulações de luta foram filmadas para quantificar as ações técnico-táticas durante os rounds. Foram mensuradas a concentração de lactato, a percepção subjetiva de esforço antes e após cada round, a frequência cardíaca e a contribuição dos sistemas energéticos foram estimadas durante a simulação de luta. Além disso, foram mensurados alguns índices da reativação parassimpática após o terceiro round. A concentração de lactato, a PSE, a FC e a contribuição dos sistemas energéticos foram comparadas usando análise de variância de dois fatores (condição e tempo). Além disso, os índices da reativação parassimpática foram comparados utilizando o teste t de Student entre as condições NaHCO3 e placebo. Os principais resultados demonstraram que a suplementação de NaHCO3 aumentou a contribuição do sistema glicolítico e o tempo total de ataque em relação ao placebo. Porém, o NaHCO3 não alterou a FC, a PSE ou a contribuição dos sistemas oxidativo e ATP-CP durante a simulação de luta quando comparados ao placebo. Além disso, nenhum índice da reativação parassimpática foi afetado pela suplementação de NaHCO3 ou placebo / The aim of this study was to investigate the isolated effect of caffeine and sodium bicarbonate ingestion on performance, estimated energy system contribution and on post-exercise parasympathetic reactivation during a simulated taekwondo combat. Therefore, this thesis was divided in two studies: study 1 investigated the effect of caffeine, while study 2 investigated the effect of sodium bicarbonate. Thus, in study 1, the aim was to investigate the effect of caffeine supplementation on performance, estimated energy system contribution and on post-exercise parasympathetic reactivation during a taekwondo combat. Ten taekwondo athletes completed two experimental sessions separated by at least 48 hours. Athletes consumed a capsule containing either 5 mg?kg-1 body mass of caffeine or placebo (cellulose) one hour before the combat simulation (3 rounds of 2 min separated by 1-min passive recovery), in a double blinded, randomized, repeated-measures crossover design. All simulated combat was video recorded to quantify the time spend fighting in each round. Lactate concentration and rate of perceived exertion were measured before and after each round, while heart rate and the estimated contribution of oxidative, ATP-PCr and glycolytic systems were calculated during the combat simulation. Furthermore, parasympathetic reactivation after the combat simulation was evaluated. Lactate concentration, rate of perceived of exertion, heart rate, estimated system contributions and indices of time-motion were compared by two-way ANOVA (condition x time). All indices of parasympathetic reactivation were compared using a Student\'s t-test in both caffeine and placebo conditions. The main results showed that caffeine ingestion increased the estimated glycolytic system when compared to placebo condition. However, caffeine ingestion did not alter the rate of perceived exertion, heart rate, estimated oxidative and ATP-PCr contribution or improve the performance in relation to placebo condition. Furthermore, caffeine ingestion did not influence post-exercise parasympathetic reactivation following a taekwondo simulation when compared to placebo condition. In study 2, the main aim of the study was to investigate the effect of sodium bicarbonate ingestion on performance, estimated energy system contribution and on post-exercise parasympathetic reactivation during simulated taekwondo combat. Nine taekwondo athletes completed two experimental sessions separated by at least 48 hours. Athletes consumed 300 mg?kg-1 body mass of sodium bicarbonate or calcium bicarbonate (placebo) 90 minutes before the combat simulation (3 rounds of 2 min separated by 1-min passive recovery), in a double blinded, randomized, repeated-measures crossover design. All simulated combat was video recorded to quantify the time spent fighting in each round. Lactate concentration and rate of perceived exertion were measured before and after each round, while heart rate, estimated contribution of oxidative, ATP-PCr and glycolytic systems were calculated during the combat simulation. Furthermore, parasympathetic reactivation after the combat simulation was calculated. Lactate concentration, rate of perceived exertion, heart rate, estimated system contributions and indices of time-motion were compared by two-way ANOVA (condition x time). All indices of parasympathetic reactivation were compared using a Student\'s t-test. The main results showed that sodium bicarbonate ingestion increased the lactate concentration, estimated glycolytic contribution and total attack time when compared with placebo condition. However, sodium bicarbonate ingestion did not influence heart rate, rate of perceived exertion, estimated oxidative and ATP-PCr contribution during combat simulation compared to placebo. Furthermore, no indices of parasympathetic reactivation were different between sodium bicarbonate and placebo conditions

Mixed results, in terms of performance benefits, have been found when comparing carbohydrate (CHO) and carbohydrate-protein (CHO-P) supplementation during endurance exercise. Thus this study assessed performance from three different supplements (CHO-P, CHO, double carbohydrate [CHO-CHO]) as compared to a placebo (PLA) during a time trial (TT) run. Twelve male recreational runners (age = 32.4 ± 9.5 yrs; body mass index [BMI] = 22.7 ± 1.5 kg/m2; VO2max = 59.68 ± 7.53 mL/kg body weight; 100% white) individually completed four, 12-mile TT runs, 7-10 days apart, at about 75% of the their race pace. Dietary and physical activity consistency within the 24-hour time period prior to each run was controlled via individualized diet and activity prescriptions based off of the diet consumed and the physical activity engaged in prior to TT 1. Throughout each TT run, participants consumed a 600 mL load of one of the four aforementioned supplements. Supplement order was counterbalanced with a latin-square design. Endurance performance was measured by time to complete the 12-mile run, and time to complete the last 1.2 miles of the run, where participants were instructed to run at maximal effort, 100% race pace. A main effect of time occurred during the TTs for perceived exertion (RPE) and heart rate (HR). RPE (Borge 10-point scale) significantly increased from the mid-point of the TT to completion of the run (4.7 ± 0.7, 9.7 ± 0.9, p < 0.001); HR significantly increased from the start of the run to the start of the maximal effort, and was significantly higher at completion of the effort (84.4 ± 14.5 bpm, 166.0 ± 8.3 bpm, 178.8 ± 7.4 bpm, p < 0.001). No significant difference was found in overall time to complete the 12-mile run or maximal effort between the supplements (PLA = 88.6 ± 11.6 min, CHO = 89.1 ± 11.3 min, CHO-P = 89.1 ± 11.8 min, CHO-CHO = 89.6 ± 11.9 min; PLA = 8.3 ± 1.2 min, CHO = 8.2 ± 1.2 min, CHO-P = 8.2 ± 1.2 min, CHO-CHO = 8.4 ± 1.5 min). These findings suggest that type of supplementation (CHO, CHO-CHO, CHO-P) consumed during an endurance exercise bout has no influence on enhancing endurance performance in male recreational runners during TT runs less than 100 minutes in length.

abstract: The popularization of energy drink use as a supplement to exercise is steadily increasing, especially among young adult males. However, the effects of energy drinks on muscular performance in young adults have yet to be clearly elucidated. Eight male subjects (mean age: 23.3 &plusmn; 4.3 yrs, height: 181.0 &plusmn; 5.3 cm, fat percent 17.8 &plusmn; 5.2%, and weight 85.3 &plusmn; 12.6 kg) completed this randomized double-blinded cross over study. The purpose of this study was to determine differences in acute muscular strength and endurance and Profile of Mood States (POMS) scores between three treatments (RockStar, sugar-free RockStar, and sugar-free caffeine-free Placebo). It was hypothesized that there would be no significant differences in acute peak torque and endurance of the knee extensors and flexors or on fatigue and vigor subscores from the POMS questionnaire. Each man was tested randomly at least 1 week apart. Diet and time of day were held constant across trials. Peak torque of knee extensors and flexors at 60, 180, 240 degress/second and fatigue index and total work were calculated by performing 50 repetitions at 240 degrees/second. There were no significant differences in peak torque, fatigue index, or total work measures or in subjective measures of fatigue or vigor from the POMS between the treatments. This study indicates that RockStar energy drinks have no acute ergogenic effects in young men performing isokinetic strength or endurance testing. / Dissertation/Thesis / M.S. Exercise and Wellness 2012

Orientador: Claudio Alexandre Gobatto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-26T20:05:10Z (GMT). No. of bitstreams: 1 Beck_WladimirRafael_D.pdf: 4557264 bytes, checksum: 1a917d77f79be6706dbd45561111344e (MD5) Previous issue date: 2015 / Resumo: Sintetizada principalmente na glândula pineal de mamíferos, a melatonina é uma indoleamina responsável classicamente por sincronizar o ritmo circadiano prioritariamente por meio do ciclo geofísico terrestre de luminosidade. A identificação de diversas outras propriedades a tornou alvo recente de estudos que buscam conhecer seus efeitos sobre o exercício físico. Otimizar o uso de substratos energéticos durante o esforço, inibir inflamação e lesões teciduais exacerbadas são propriedades documentadas na literatura e consideradas como potencialmente ergogênicas, fato que compreende um capítulo controverso da atual literatura científica esportiva. Diante disso, o objetivo da tese foi determinar a capacidade ergogênica da melatonina em exercício exaustivo sob intensidade de máxima capacidade aeróbia (tlim) iniciados no nadir e acrofase da atividade espontânea (AE), identificando os efeitos dessas condições sobre a atividade da via inflamatória IKK/NF-'capa'B em músculo esquelético oxidativo, marcadores metabólicos, hematológicos e de lesão tecidual de ratos nadadores. Para isso, dois procedimentos foram originalmente padronizados: i) construção de aparato e confecção de rotina de cálculos para a determinação do ritmo circadiano da AE e ii) teste incremental (TI) para estimativa da intensidade de máxima capacidade aeróbia de ratos nadadores. Os animais foram mantidos sob condições ambientais adequadas e sob ciclo claro/escuro de 12 horas iniciando às 06:00h com luz clara (560nm; 60lux). A determinação da AE ao longo do dia foi utilizada para definição dos horários em que seriam iniciados todos os procedimentos, sendo nadir e acrofase desta variável correspondentes a 12:00 (ZT 6) e 20:00h (ZT 14), respectivamente. Ratos machos albinos da linhagem Wistar foram distribuídos aleatoriamente em grupos para aplicação do TI iniciando nestes momentos do dia, aos 90 dias de idade. Para os testes conduzidos no período noturno foi empregada luminosidade especial afim de minimizar a influência da luz na secreção fisiológica da melatonina (>600nm; <15lux). Aos 92 dias de idade os roedores receberam, via intraperitoneal, solução contendo 10 mg.kg-1 de melatonina ou solução transporte de igual volume. Após 30 minutos, os animais foram submetidos ao tlim e uma hora após o término deste esforço foram eutanasiados para coleta de amostras biológicas. Técnicas laboratoriais de Western Blotting e ELISA foram utilizadas, além de kits comerciais e técnicas bioquímicas. Melatonina aumentou significativamente a tolerância ao exercício proposto, contudo, comparações de post hoc apontaram diferença significativa apenas entre os animais cuja avaliação iniciou na acrofase, quando a melatonina endógena geralmente encontra-se elevada em ratos com hábitos noturnos. Maior inflamação e lesão tecidual foram encontradas principalmente nos animais que realizaram tlim e receberam melatonina no período de vigília. Assim, concluímos que o massivo efeito ergogênico da melatonina, que promoveu maiores períodos de contração muscular continuada, sobrepôs sua capacidade de proteção ao dano tecidual e ação anti-inflamatória. O exercício proposto na presente tese se assemelha a esportes cíclicos de longa duração (como maratonas). Entretanto, inferências diretas entre modelos devem ser cautelosas uma vez que o ser humano apresenta vigília diurna combinada a reduzidas concentrações de melatonina neste momento do dia, logo, a interpretação da ação da melatonina pode ser diferente entre espécies / Abstract: Mainly produced by mammal¿s pineal gland, melatonin is an indoleamine classically related to circadian rhythm synchronizing, primarily through geophysical light dark cycle. Many recently identified properties of melatonin has stimulated many studies about it effect on exercised organism. Optimize the use of energy substrates during exercise, inhibit exacerbated inflammation and decrease tissue damage are well documented effects. Among others, these melatonin properties has been considered as potentially ergogenic out, what comprises a controversial issue in the current sports scientific literature. The aim of this thesis was to determine the ergogenic capacity of melatonin in exhaustive exercise at maximal aerobic capacity intensity (tlim) at nadir and acrophase of spontaneous physical activity (SPA), identifying the effects of such condition on the oxidative skeletal muscle IKK/NF-'capa'B activity, metabolic, hematologic and tissue damage in swimming rats. Thus, two procedures were originally standardized: i) apparatus manufacture and mathematical calculations routine for determining the circadian rhythm of SPA in rats, and ii) the incremental test (IT) for estimative of the intensity corresponding to the maximal aerobic capacity of swimming rats. Animals were kept at light/dark cycle of 12 hours with bright lights on at 06:00h (560nm; 60lux). SPA were recorded throughout day, being nadir and acrophase of such variable corresponding to 12:00 (ZT 6) and 20:00h (ZT 14), respectively. Male Wistar albino rats were randomly splitted to incremental test (IT) performing, which begun at specifics time of day (SPA nadir or acrophase) at 90 days-old. To acrophase swimming testing were employed special illumination to avoid influences of light on physiological melatonin secretion (>600nm; <15lux). At 92 days-old a solution with or with no exogenous melatonin (10 mg.kg-1, I.P.) were administered to rats that were or not submitted to tlim 30 minutes after. Euthanasia was conducted one hour after tlim to biological material withdraw. Laboratory techniques of Western Blotting and ELISA were employed, and commercial kits and biochemical techniques. Melatonin significantly increases the tolerance to the proposed exercise, however, post hoc assumptions showed significant differences only between animals that assessments begun at SPA acrophase, when endogenous melatonin is usually higher in nocturnal rats. Significantly higher inflammatory and tissue damage markers were found to exercised animals assessed at wakefulness period (higher SA) that received exogenous melatonin, where were also found higher tlim. Thus, the massive ergogenic effect of melatonin leads to higher periods of muscle contraction, which superimposed melatonin protective effect on the tissue damage and its anti-inflammatory action. The proposed exercise resembles cyclic long duration sports, as marathons. However, direct inferences between models should be carefully conducted once the Human Being presents wakefulness period during daily hours, when melatonin is found at lower concentrations, so, the interpretation of melatonin action may differ between species. / Doutorado / Biodinamica do Movimento Humano / Doutor em Educação Física

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第22533号 / 人博第936号 / 新制||人||223(附属図書館) / 2019||人博||936(吉田南総合図書館) / 京都大学大学院人間・環境学研究科共生人間学専攻 / (主査)教授 林 達也, 教授 石原 昭彦, 教授 久代 恵介 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DGAM

Orientador: Fábio Santos Lira / Resumo: O objetivo deste estudo randomizado duplo-cego controlado por placebo foi investigar o efeito agudo da suplementação análoga de capsaicina (CAP) na corrida, em teste contra-relógio de 10-km, sobre o desempenho fisiológico e variáveis perceptivas de esforço em atletas amadores. Vinte e um participantes (idade = 29,3 ± 5,4 anos; peso = 74,2 ± 11,3 kg; altura = 176 ± 0,0 cm), completaram dois testes de 10-km na condição CAP ou placebo. Foram consumidas duas cápsulas de CAP (12 mg) ou de placebo, 45 minutos antes e imediatamente no início dos testes. Entre as condições CAP e placebo, não houve diferença significativa no desempenho dos participantes em relação às variáveis fisiológicas e perceptivas avaliadas no teste de corrida de 10-km (p> 0,05). Portanto, a suplementação de CAP não melhorou o desempenho de atletas amadores na corrida em teste contra-relógio de 10-km. / Abstract: The aim of this randomized, double-blind, placebo-controlled study was to investigate the acute effect of analog capsaicin supplementation (CAP), in a 10-km timetrial running test, on the physiological performance and perceptual responses of amateur athletes. Twenty-one participants (age = 29.3 ± 5.4 years; weight = 74.2 ± 11.3 kg; height = 176 ± 0.0 cm), completed two 10-km tests in the CAP or placebo condition. Two capsules of CAP (12 mg) or placebo were consumed 45 minutes before and immediately at the beginning of the trials. Between CAP and placebo conditions, there was no significant difference in the physiological performance or perceptual responses of the participants in the 10-km running test (p> 0.05). Therefore, CAP supplementation did not improve the performance of amateur athletes in the 10-km time-trial running test. / Mestre

Caffeine is often used in a variety of forms to enhance athletic performance; however, research regarding caffeine’s effects on strength and power in female athletes is lacking. Therefore, the purpose of this study was to analyze the acute effects of caffeine anhydrous (6 mg/kg of body mass) on jumping performance and maximal strength in female collegiate athletes. Eleven athletes (19.7 ± 0.9 yrs; 166.4 ± 10.2 cm, 67.7 ± 9.4 kg) performed two testing sessions separated by one week, and randomly received caffeine or placebo using a double-blind approach. Heart rate, blood pressure, and tympanic temperature were recorded before athletes received each condition, following 60 min of quiet sitting, and directly after performance testing. Athletes were assessed on unweighted and weighted squat jump height (SJH0, SJH20) and countermovement jump height (CMJH0, CMJH20), isometric mid-thigh pull peak force (IPF), and rate of force development from 0–200 ms (RFD200). Resting systolic blood pressure was significantly greater following caffeine administration compared to a placebo (p = 0.017). There were small, significant differences in SJH0 (p = 0.035, g = 0.35), SJH20 (p = 0.002, g = 0.49), CMJH0 (p = 0.015, g = 0.19), and CMJH20 (p < 0.001, g = 0.37) in favor of caffeine over placebo. However, there was no significant difference in IPF (p = 0.369, g = 0.12) and RFD200 (p = 0.235, g = 0.32) between conditions. Therefore, caffeine appears to enhance jumping performance, but not maximal strength in female collegiate athletes.

In an attempt to improve aerobic and anaerobic performance, athletes and fitness enthusiasts consume a variety of supplements. Because of this, energy drinks are quickly becoming more and more popular every day. Despite its highly addictive nature, caffeine, which is the main active ingredient in energy drinks, is gaining recognition as an ergogenic aid. However, due to the many factors that affects the action of caffeine, and because the research on caffeine and anaerobic performance is limited, the potential for studying energy drinks and anaerobic performance is quite large. PURPOSE: To determine if a commercially available energy drink has any ergogenic effects on lower body and upper body resistance exercise performance. METHODS: In a block randomized, double-blind, placebo-controlled, crossover study thirteen recreationally trained male and female volunteers (mean ± SD age = 22.5 ± 3.4 years) performed 4 sets of the leg press and 4 sets of the bench press exercises (at 80% of 1 RM with all sets separated by 2 minutes). Acting as their own controls, participants were tested on each dependent variable (i.e., bench press total volume, leg press total volume and total workout volume) twice, after ingesting a Venom® Energy Drink and after ingesting a placebo drink. RESULTS: Data were tested via a dependent samples t-test with p value set at < 0.05. No significant differences were found for any of the three dependent variables. DISCUSSION: The major finding of this study is that consumption of a Venom® Energy Drink does not produce an ergogenic effect by improving anaerobic exercise performance when the exercises are performed forty-five minutes following ingestion. Future studies should focus more on examining the factors behind the actions of caffeine. More specifically, the exercise performed, the training status of the participants, individual differences of the participants, and the dose of caffeine.

Abstract The Effects of a Combined Supplementation of Creatine and Sodium Bicarbonate on Repeated Sprint Performance James Jeremy Barber There is well-established research that suggests both creatine and sodium bicarbonate are effective ergogenic aids. However, only one published study has examined the combined effects of creatine and sodium bicarbonate. The primary purpose of this study was to determine if a combined supplementation of creatine monohydrate and sodium bicarbonate would further enhance the well-documented effects of creatine supplementation alone on repeated sprint performance. Thirteen healthy and fit males (Mean age = 21.15 ± 0.65 years and mean VO2 max = 66.72 ± 5.78) participated in this experimental study using a double-blinded crossover study design in which each subject was used as his own control. All subjects completed 3 conditions, followed by a 3-week washout period between each condition: 1) Placebo (Pl; 5 g maltodextrin + 0.5 g/kg maltodextrin), 2) Creatine (Cr; 5 g + 0.5 g/kg maltodextrin), and 3) Creatine plus sodium bicarbonate (Cr+Sb; 5g + 0.5 g/kg sodium bicarbonate). Each condition was a 2-day supplementation. In the morning after each supplementation, peak power, RPP, mean power, RMP, fatigue index, and perceptions of fatigue and GI distress were assessed during six 10-second repeated Wingate tests. Blood bicarbonate, pH, and lactate were measured 5 minutes before testing and immediately after the last Wingate sprint. The main findings were; 1) Cr+Sb produced 7% greater relative peak power and 4.6% greater peak power values than placebo, and 2) Cr+Sb demonstrated the greatest attenuation of decline in relative peak power over six repeated sprints. However, in contrast to our hypotheses, no benefits from either supplementation were observed for relative mean power, fatigue index, and perception of fatigue. Considering that this current study found benefits from combining creatine and sodium bicarbonate, it suggests that combining the supplements may improve repeated sprint performance. Future research on a greater sample size, a specific athletic population, various exercise modes, and comparing results with a sodium bicarbonate alone supplementation would be beneficial in determining if this combined supplementation is worthwhile.

INTRODUÇÃO: Atualmente ainda não está claro se a atividade muscular e o treinamento físico afetam a síntese de carnosina muscular (Mcar) em resposta à suplementação de beta-alanina. OBJETIVO: verificar o impacto da atividade e inatividade muscular sobre o conteúdo de carnosina muscular (Mcarn) e sobre o aumento de Mcarn em resposta à suplementação de beta-alanina e, adicionalmente, verificar seu efeito sobra a capacidade de realizar esforços de alta intensidade. METHODS: Dezesseis homens treinados com lesão medular (LM) (escala ASIA: AIS A ou AIS B) foram divididos em 2 grupos: beta-alanina (BA) (N = 11) e placebo (PL) (N = 5). Amostras de biópsias musculares foram obtidas do músculo vasto lateral inativo e do deltoide ativo, antes e após 28 dias de suplementação com beta-alanina (6.4 g.dia-1). Teste t independente foi aplicado para comparar a Mcar basal e a variação absoluta (PÓS - PRÉ) entre os músculos vasto lateral e deltoide. Um teste supramáximo de carga constante até a exaustão e um teste de Wingate de série única foram aplicados para verificar a capacidade de realizar esforços de alta intensidade. Análises por Modelo Misto foram aplicadas para comparar a Mcar, o tempo até a exaustão e os valores de potência pico intra e entre sujeitos. RESULTADOS: (média ± desvio padrão): a concentração basal de Mcar no vasto lateral foi significativamente maior que no deltoide (32,0 ± 12 vs. 20,5 ± 6,1 mmol.kg-1 de músculo seco; p = 0,02). As variações absolutas na Mcar foram significativamente maiores no grupo BA em comparação com o PL, tanto para o vasto lateral (BA: 17,6 ± 10,4 mmol.kg-1 de músculo seco; PL: 2,5 ± 2,3 mmol.kg-1 de músculo seco; p = 0,002) como para o deltoide (BA: 15,7 ± 6,8 mmol.kg-1 de músculo seco; PL: 1,4 ± 2,7 mmol.kg-1 de músculo seco; p <0,001). As variações absolutas verificadas no vasto lateral e deltoide não foram diferentes entre si (vasto lateral: 17,6 ± 10,4; deltóide: 15,7 ± 6,8 mmol.kg-1 do músculo seco; p = 0,6). Não houve efeito da suplementação sobre o tempo até exaustão e potência pico. CONCLUSÃO: a inatividade muscular crônica ocasionada por lesão medular, não afeta a Mcarn e também não interfere sobre o aumento de Mcarn em resposta à suplementação de BA. Estes resultados sugerem que a atividade muscular ou o estado de treinamento não influenciam a capacidade de síntese de Mcarn em resposta à suplementação de beta-alanina / BACKGROUND: it is currently unclear whether muscle activity and exercise training affect the ability of the skeletal muscle to synthesise carnosine in response to beta-alanine supplementation. PURPOSE: to study the impact of the extremes of muscle activity and inactivity on muscle carnosine content (Mcarn) and Mcarn loading in response to beta-alanine supplementation. METHODS: 16 trained male with spinal cord injury (SCI) (ASIA scale: AIS A or AIS B) were divided into 2 groups: beta-alanine (BA) (N = 11) and placebo (PL) (N = 5). Muscle biopsies samples were obtained from active deltoid and paralysed vastus lateralis at baseline and after 28 days of &#946;-alanine supplementation (6.4 g.day-1). Unpaired t-tests were applied to compare Mcarn at baseline and the absolute pre-post change in vastus lateralis and deltoid. Mixed model was used to compare Mcarn values within- and between-subjects. RESULTS: (mean±SD): Baseline Mcarn concentration in vastus lateralis was significantly higher than in deltoid (32.0±12 vs. 20.5±6.1 mmol.kg-1 dry muscle; p=0.02). Absolute changes in Mcarn was significantly higher in the BA group in comparison with PL for both vastus lateralis (BA: 17.6±10.4 mmol.kg-1 dry muscle; PL: 2.5±2.3 mmol.kg-1 dry muscle; p=0.002) and deltoid (BA: 15.7±6.8 mmol?kg-1 dry muscle; PL: 1.4±2.7 mmol?kg-1 dry muscle; p<0.001). Absolut changes in Mcarn following BA supplementation between inactive vastus lateralis and active deltoid was not different (vastus lateralis: 17.6±10.4; deltoid: 15.7±6.8 mmol?kg-1 dry muscle; p=0.6). CONCLUSION: chronic muscle inactivity due to paralysis in SCI does not affect Mcarn at baseline and does not affect Mcarn loading in response to BA supplementation. These results suggest that muscle activity or training status does not influence Mcarn synthesis capacity in response to beta-alanine supplementation