Effects of creatine supplementation on the performance and body composition of competitive swimmers

The effect of conjugated linoleic acids on inflammation, oxidative stress, body composition and physical performance: a comprehensive review of putative molecular mechanisms

Conjugated linoleic acids (CLAs) are polyunsaturated fatty acids primarily found in dairy products and ruminant animal products such as beef, lamb, and butter. Supplementation of CLAs has recently become popular among athletes due to the variety of health-promoting effects, including improvements in physical performance. Preclinical and some clinical studies have shown that CLAs can reduce inflammation and oxidative stress and favorably modulate body composition and physical performance; however, the results of previously published clinical trials are mixed. Here, we performed a comprehensive review of previously published clinical trials that assessed the role of CLAs in modulating inflammation, oxidative stress, body composition, and select indices of physical performance, emphasizing the molecular mechanisms governing these changes. The findings of our review demonstrate that the effect of supplementation with CLAs on inflammation and oxidative stress is controversial, but this supplement can decrease body fat mass and increase physical performance. Future well-designed randomized clinical trials are warranted to determine the effectiveness of (1) specific doses of CLAs; (2) different dosing durations of CLAs; (3) various CLA isomers, and the exact molecular mechanisms by which CLAs positively influence oxidative stress, inflammation, body composition, and physical performance.

Effects of amino acid derivatives on physical, mental, and physiological activities

Nutritional ergogenic aids have been in use for a long time to enhance exercise and sports performance. Dietary components that exhibit ergogenic activity are numerous and their consumption is common and popular among athletes. They often come under scrutiny by legal authorities for their claimed benefits and safety concerns. Amino acid derivatives are propagated as being effective aids to enhance physical and mental performance in many ways, even though studies have pointed out that individuals who are deficient are more likely to benefit from dietary supplementation of amino acid derivatives than normal humans. In this review, some of the most common and widely used amino acids derivatives in sports and athletics namely creatine, tyrosine, carnitine, HMB, and taurine have been discussed for their effects on exercise performance, mental activity as well as body strength and composition. Creatine, carnitine, HMB, and taurine are reported to delay the onset of fatigue, improve exercise performance, and body strength. HMB helps in increasing fat-free mass and reduce exercise induced muscle injury. Taurine has been found to reduce oxidative stress during exercise and also act as an antihypertensive agent. Although, studies have not been able to find any favorable effect of tyrosine administration on exercise performance, it has been proved to be very effective in fighting stress, improving mood and cognitive performance particularly in sleep-deprived subjects. While available data from published studies and findings are equivocal about the efficacy of creatine, tyrosine, and HMB, more comprehensive researches on carnitine and taurine are necessary to provide evidence for the theoretical basis of their ergogenic role in nutritional modification and supplementation.

Efeito da natacao associada a diferentes tratamentos sobre o musculo soleo de ratos: estudo histologico e morfometrico

INTRODUÇÃO: O uso de suplementos ergogênicos farmacológicos e nutricionais cresce a cada dia no ambiente esportivo. A creatina e os esteroides anabólicos são os recursos ergogênicos mais procurados ultimamente. OBJETIVO: Avaliar as alterações histológicas e morfométricas do músculo sóleo de ratos que receberam suplementos e foram submetidos a treinamento físico (TF) de natação. MÉTODOS: Foram utilizados 50 ratos, distribuidos em cinco grupos: três não submetidos à atividade física (controles) e dois que receberam treinamento de natação (treinados). Um grupo controle recebeu apenas ração (grupo controle ração), dois grupos (um controle e outro treinado) receberam diariamente 3,3 mg de creatina por grama de dieta dissolvida em água aplicada oralmente via gavagem, e os outros dois grupos (um controle e outro treinado) receberam injeção intramuscular do esteroide anabolizante decanoato de nandrolona (Deca-durabolin(r) - Organon) 5 mg/kg duas vezes por semana. Os grupos treinados foram submetidos ao TF com duração de 60 min/sessão de segunda a sexta-feira por nove semanas, e foram sacrificados no final deste período. Após o sacrifício, o músculo sóleo foi retirado, fixado em formalina (10%) tamponada e incluído em parafina. Os cortes histológicos foram corados pela técnica de hematoxilina-eosina para avaliação de hiperplasia e hipertrofia muscular. Para análise dos dados aplicou-se a análise de variância ANOVA One-Way com post hoc de Tukey-Kramer com nível de significância de 5%. RESULTADOS: Foi demonstrado que a creatina associada ao exercício provavelmente aumente o espaço intersticial no músculo esquelético sem alterar o tamanho ou número de fibras musculares, enquanto que o anabolizante aumentou o número de fibras musculares por área de músculo analisada, embora nenhuma alteração tenha sido observada na área da fibra. CONCLUSÃO: O músculo de ratos submetidos ao treinamento de natação responde diferentemente frente ao tipo de recurso ergogênico utilizado.

The effects of a high dosage of creatine and caffeine supplementation on the lean body mass composition of rats submitted to vertical jumping training

BACKGROUND

The influences of creatine and caffeine supplementation associated with power exercise on lean body mass (LBM) composition are not clear. The purpose of this research was to determine whether supplementation with high doses of creatine and caffeine, either solely or combined, affects the LBM composition of rats submitted to vertical jumping training.

METHODS

Male Wistar rats were randomly divided into 8 groups: Sedentary (S) or Exercised (E) [placebo (Pl), creatine (Cr), caffeine (Caf) or creatine plus caffeine (CrCaf)]. The supplemented groups received creatine [load: 0.430 g/kg of body weight (BW) for 7 days; and maintenance: 0.143 g/kg of BW for 35 days], caffeine (15 mg/kg of BW for 42 days) or creatine plus caffeine. The exercised groups underwent a vertical jump training regime (load: 20 - 50% of BW, 4 sets of 10 jumps interspersed with 1 min resting intervals), 5 days/wk, for 6 weeks. LBM composition was evaluated by portions of water, protein and fat in the rat carcass. Data were submitted to ANOVA followed by the Tukey post hoc test and Student's t test.

RESULTS

Exercised animals presented a lower carcass weight (10.9%; P = 0.01), as compared to sedentary animals. However, no effect of supplementation was observed on carcass weight (P > 0.05). There were no significant differences among the groups (P > 0.05) for percentage of water in the carcass. The percentage of fat in the group SCr was higher than in the groups SCaf and ECr (P < 0.05). A higher percentage of protein was observed in the groups EPl and ECaf when compared to the groups SPl and SCaf (P < 0.001). The percentage of fat in the carcass decreased (P < 0.001), while those of water and protein increased (P < 0.05) in exercised animals, compared to sedentary animals. Caffeine groups presented reduced percentage of fat when compared to creatine supplemented groups (P < 0.05).

CONCLUSIONS

High combined doses of creatine and caffeine does not affect the LBM composition of either sedentary or exercised rats, however, caffeine supplementation alone reduces the percentage of fat. Vertical jumping training increases the percentages of water and protein and reduces the fat percentage in rats.

Desempenho da potência anaeróbia em atletas de elite do mountain bike submetidos à suplementação aguda com creatina

Com o objetivo de investigar os efeitos da suplementação aguda com creatina no desempenho da potência anaeróbia de atletas de elite do mountain bike, 20 atletas em período básico do macrociclo de treinamento foram distribuídos aleatoriamente (duplo-cego) em dois grupos: placebo (PLA, n = 10) e creatina (CRE, n = 10). Foram avaliados quanto à composição corporal (pesagem hidrostática) e potência anaeróbia (teste de Wingate - TW) antes (PRÉ) e depois (PÓS) de sete dias de suplementação. A creatina ou maltodextrina foi usada em três doses diárias de 0,3g/kg de massa corporal diluídos em meio líquido adoçado. Não foram observadas diferenças significativas nas variáveis morfológicas após sete dias de suplementação (PRÉ x PÓS), e os grupos não diferiram apesar da variação percentual (Δ%) contrária (positiva para o grupo CRE e negativa para o PLA). A potência anaeróbia pico (PP) e o instante da potência pico (IPP) aumentaram e o índice de fadiga diminuiu do PRÉ para o PÓS-testes no grupo CRE, enquanto que o grupo PLA não apresentou diferenças significantes. A PP apresentou forte tendência em ser maior e o IPP foi maior no grupo CRE comparado com o PLA. Conclui-se que existem evidências de que a suplementação com creatina (0,3g/kg) em curto prazo (sete dias) pode retardar o IPP (CRE 3,0 ± 0,5/3,6 ± 0,8 Δ%= 20%) no teste de Wingate em atletas de elite do mountain bike, sugerindo que a suplementação com creatina pode melhorar o desempenho físico quanto à potência anaeróbia durante o trabalho de alta intensidade e curta duração.

Impaired estimated glomerular filtration rate associated with hypothyroidism. Does it really mean an acute renal failure?

A case of a young man with myopathy, elevated serum aminotransferase and serum creatinine levels is presented. He had a polymyositis-like-syndrome caused by hashimoto thyroiditis with hypothyroidism. Thyroid hormone replacement therapy led to improvement in both the clinical and laboratory abnormalities. With the established tests for estimating the glomerular filtration rate we cannot determine if there was really a reversible acute renal failure or not.

Efeitos da suplementação de creatina e do treinamento de potência sobre a performance e a massa corporal magra de ratos

INTRODUÇÃO: A creatina é um dos suplementos mais usados por atletas para incrementar a síntese protéica e aumentar a massa e força muscular. OBJETIVO: Investigou-se os efeitos da suplementação de creatina associada a um programa de treinamento de potência (saltos verticais) sobre a performance e a composição da massa corporal magra de ratos Wistar. MÉTODOS: Ratos Wistar adultos foram distribuídos em quatro grupos: SSC (sedentário sem creatina); SC (sedentário com creatina); ESC (exercício sem creatina) e EC (exercício com creatina). Os animais receberam água e ração ad libitum. Os grupos SC e EC ingeriam dose de creatina diariamente, adotando o procedimento de carga (0,430g/kg p.c. por 7 dias) e manutenção (0,070g/kg p.c. por 6 semanas). Os grupos EC e ESC foram submetidos a um regime progressivo de saltos verticais (5x10 saltos com 1 min de intervalo) em tanque com água, 5 dias/semana, durante 7 semanas. A performance foi avaliada pelo tempo de execução das 5 séries de 10 saltos verticais e a composição da massa corporal magra (músculos e ossos) foi avaliada pelas porções: água, proteína e gordura. RESULTADOS: A performance não foi afetada pela ingestão de creatina (p > 0,05). Os animais suplementados tiveram o percentual de proteína elevado e o de gordura reduzido (p < 0,05), independente do treinamento. Os animais exercitados exibiram maior percentual de proteína, e menor de gordura, além de menor ganho de peso corporal, comparados com os sedentários, independente da suplementação (p < 0,05). Não houve diferença para o percentual de água e consumo alimentar (p > 0,05). CONCLUSÃO: A suplementação de creatina não afetou a performance dos animais, mas alterou a massa corporal magra. A suplementação de creatina e o programa de treinamento de potência, de forma independente, elevaram o percentual de proteína dos músculos e ossos e reduziram o percentual de gordura, sem alterar o percentual de água.

Prevalence of use of performance-enhancing substances among United States adolescents

Adolescents may regard the use of performance-enhancing substances as an easy means to gain self-esteem through improved body appearance and athletic performance. The use of performance-enhancing substances by adolescents is particularly troubling because safety data are largely lacking. This poses a dilemma for the pediatrician who needs correct information, including the potential efficacy and negative health effects of such substances, to identify the patients in need of counseling and to find the best way to help adolescent patients make informed decisions to promote healthy behaviors. This article is intended to assist pediatricians by providing a summary of the current state of knowledge regarding the prevalence of use of performance-enhancing substances by United States adolescents.

Safety of creatine supplementation

The literature on creatine supplementation supporting its efficacy has grown rapidly and has included studies in both healthy volunteers and patient populations. However, the first rule in the development of therapeutic agents is safety. Creatine is well-tolerated in most individuals in short-term studies. However, isolated reports suggest creatine may be associated with various side effects affecting several organ systems including skeletal muscle, the kidney and the gastrointestinal tract. The majority of clinical studies fail to find an increased incidence of side effects with creatine supplementation. To date, studies have not found clinically significant deviations from normal values in renal, hepatic, cardiac or muscle function. Few data are available on the long-term consequences of creatine supplementation.