Whey protein supplementation, containing large amount of leucine, has been a traditional intervention to maintain net protein balance in the past decades. It has been recognized that leucine alone is able to stimulate protein synthesis by activating mTOR and its related downstream pathway without affecting protein degradation, whereas its metabolite β-hydroxy-β-methylbutyrate (HMB) is known to attenuate protein degradation when provided chronically. However, the mechanism of HMB’s benefit remains unclear. To address how HMB regulates protein synthesis and degradation signaling pathways, we compared one dose of whey protein (187.5mg/kg), HMB (400mg/kg) or leucine (1.4g/kg) by oral gavage. Blood was collected at 0, 45 and 90 min for blood glucose and plasma insulin analysis. Red and white gastrocnemius muscle was taken separately 90 min after gavage. Blood glucose was reduced by leucine at 45 and 90 min post gavage. Plasma insulin was enhanced by leucine at 45 min and then decreased at 90 min post gavage, whereas HMB decreased plasma insulin through 90 min post gavege. Western blot analysis showed that HMB phosphorylated Akt in red gastronemius, and enhanced phosphorylation of mTOR in both types of muscles. Leucine phosphorylated mTOR, p70s6k and 4E-BP1 in both red and white gastronemius. Regarding protein degradation signals, phosphorylation of FOXO3A was enhanced by HMB, but not in the other treatment groups. Whey protein had no effect on those cellular signaling. Our results indicate that both HMB and leucine may stimulate protein synthesis through the mTOR pathway in red and white gastrocnemius muscles by different degrees with leucine more effective than HMB. HMB may have a greater effect than leucine on limiting protein degradation by phosphorylating Akt and FOXO3A in red and white gastrocnemius muscles. A combination of HMB and leucine, as a new interventional strategy, is predicted to maximize protein accretion by increasing protein synthesis as well as inhibiting protein degradation. / text

The effects of supplementation of the leucine metabolite β-hydroxy-β- methylbutyrate (HMB) were examined in a resistance training study. Thirty- nine men and 36 women between the ages of 20-40 y were randomized to either a placebo (P) supplemented or HMB supplemented (3.0 g HMB/d) group in two gender cohorts. All subjects trained three times per week for 4 wk. In the HMB group, plasma creatine phosphokinase levels tended to be suppressed compared to the placebo group following the 4 wk of resistance training (HMB:174.4 ± 26.8 to 173.5 ± 17.0 U/L; P:155.0 ± 20.8 to 195.2 ± 23.5 U/L). There were no significant differences in strength gains based on prior training status or gender with HMB supplementation. The HMB group had a greater increase in upper body strength than the placebo group (HMB:7.5 ± 0.6 kg; P:5.2 ± 0.6 kg; P = 0.008). The HMB groups increased fat-free weight by 1.4 ± 0.2 kg and decreased percent fat by 1.1% ± 0.2% while the placebo groups increased fat-free weight by 0.9 ± 0.2 kg and decreased percent fat by 0.5% ± 0.2% (fat-free weight P = 0.08, percent fat P = 0.08, HMB compared to placebo). In summary, this is the first short-term study to investigate the roles of gender and training status on the effects of HMB supplementation on strength and body composition. This study showed, regardless of gender or training status, HMB may increase upper body strength and minimize muscle damage when combined with an exercise program.

Consumption of β-hydroxy β-methylbutyrate (HBM), a leucine metabolite, alters muscle composition and metabolism leading to strength and agility improvements in human athletes. To determine if HMB affects athletic performance and muscle function in horses, Thoroughbred geldings were fed a control (CON; n=5) or HMB (n=6) supplement (30 mg/kg/day) for 6 weeks prior to completing a standardized exercise test (SET). Gluteus medius (GM) muscle samples were obtained before the SET for fiber-typing and venous blood was collected before and immediately upon completion of the SET for lactate measurements. Heart rate (HR), biceps femoris (BF) and semitendinosus (ST) surface electromyograms, and fore- and hindlimb metacarpophalangeal joint angles were captured for the duration of the SET. Results demonstrate that HMB supplementation increased (P < 0.05) the percentage of type IIA muscle fibers in the GM with a corresponding decrease (P < 0.05) in type IIX fibers. The percentage of type I fibers was unaffected by diet. Supplementation with HMB did not result in any significant effects on performance, muscle function or biomechanical properties by comparison to CON. Increasing treadmill speed resulted in an increase (P < 0.05) in stride length and maximal extension angle of the fore fetlock, and a shortening (P < 0.05) of the stance phase of the gait cycle. Integrated EMG (iEMG) increased (P < 0.05) with increasing treadmill speeds for both the BF and ST, with the BF exhibiting greater iEMG values than the ST. In summary, HMB increased the percentage of type IIA fibers which did not translate into immediate, improved athletic performance / Master of Science / Muscles depend on their fibers, innervation, energy supply, and blood flow to contract. Failure to meet one or more of these requirements precludes muscle tissue from performing work, situation termed fatigue. Identification of fatigue indicators is of interest to the horse industry for a number of reasons, including horse and human safety, prevention of unnecessary expenses, and general public opinion of the sport disciplines. Diet supplementation with legal, performanceenhancing compounds is of interest to riders and horse owners alike. Molecules such as betahydroxy beta-methylbutyrate (HMB) improve muscle function, protein synthesis, and muscle tissue repair. Assessment of the athletic capacity and performance of horses by evaluating fatigue indicators favors responsible training regimes. Techniques to achieve this goal include muscle sampling, biochemical, electromyographic, and biomechanical analysis. We hypothesized that dietary supplementation of HMB would have positive effects on the athletic performance of horses. This study evaluated the effects of 45-day HMB supplementation on muscle fiber composition, muscle performance, and rates of fatigue in adult Thoroughbred horses by use of a high-speed treadmill. Muscle biopsies, blood lactate, high-speed video captures, and electromyography were analyzed. These analyses revealed that HMB supplementation increased the number of fatigue-resistant fibers in muscles but caused no substantial, immediate improvements on the athletic performance of horses.

Purpose: To examine the effects of 28 days of β-hydroxy-β-methylbutyrate free acid (HMB) and high-intensity interval training (HIIT) on maximal oxygen consumption (VO2peak), ventilatory threshold (VT), respiratory compensation point (RCP) and time to exhaustion (Tmax) in collegeaged men and women. Methods: Healthy men and women (n=34, age and VO2peak= 22.7+3.1yr and 39.3+5.0 mL. kg-1.min-1, respectively) participated in this study. All participants completed a series of tests prior and subsequent to treatment. A maximal oxygen consumption test was performed on a cycle ergometer to assess VO2peak, Tmax, VT, and RCP. The peak power output (Ppeak), power at VT (PVT) and power at RCP (PRCP) were also recorded from this test. Twenty-six subjects completed 12 HIIT (80-120% maximal workload) exercise sessions consisting of 5-6 bouts of a 2:1 minute cycling work to rest ratio protocol over a four-week period, while eight served as controls (CTL). In double-blind fashion, the HIIT groups were assigned into either a placebo (HIIT) or 3g per day of HMB (HMB-HIIT). Body composition was measured with dual energy x-ray absorptiometry (DEXA). Outcomes were assessed by ANCOVA with posttest means adjusted for pretest differences. Results: The HMB-HIIT intervention showed significant (p & lt 0.05) gains in VO2peak, VT, and PVT versus the CTL and HIIT group. Both HIIT and HMB-HIIT treatment groups demonstrated significant (p < 0.05) improvement over CTL for Ppeak, Tmax, RCP, and PRCP with no significant difference between the treatment groups. There were no significant differences observed for any measures of body composition. An independent-samples t-test confirmed that there were no significant differences between the training volumes for the HIIT and HMB-HIIT groups. Conclusion: These findings suggest that the addition of HMB supplementation may result in greater changes in VO2peak and VT than HIIT alone. Therefore, in college-aged men and women, the use of HMB supplementation may enhance the benefits of HIIT on aerobic performance measures.

Após a realização de uma sessão de treinamento (ST) é comum a ocorrência do fenômeno denominado dano muscular induzido pelo exercício (DMIE), que se caracteriza por prejuizos a estrutura da fibra muscular, com ruptura de alguns sarcômeros, desordem miofibrilar e alargamento das linhas Z. Ainda em consequência ao DMIE, surgem alguns sintomas que são utilizados como marcadores indiretos: dor muscular de início tardio (DMIT), redução na produção de força, aumento de enzimas e proteínas na corrente sanguínea e inchaço. O presente estudo examinou os efeitos da suplementação nutricional a fim de minimizar os efeitos deletérios do DMIE em 3 experimentos. No 1° estudo, 36 indivíduos inexperientes em treinamento de força (TF) foram suplementados com: placebo (PLA, n=12, 50mg·kg-1 de carboidrato); leucina (LEU) baixa dose (LBD, n=12, 50mg·kg-1 de LEU + 50mg·kg-1 de carboidrato) e LEU alta dose (LAD, n=12, 250mg·kg-1 de LEU + 50mg·kg-1 de carboidrato) por 6 dias antecedentes a sessão de treinamento (ST), e nos 3 dias seguintes. Foi observada redução significante, p<0.05, na dor muscular de início tardio (DMIT) do peitoral por palpação, e alongamento nos momentos 48h, e 72h após a ST no grupo LBD comparado ao PLA. A redução no teste de 1 repetição máxima (1RM) apresentou significância no grupo PLA em todos momentos após ST. O aumento na atividade da creatina quinase (CK) foi significante no grupo PLA comparado ao LAD em 24h, 48h e 72h após a ST, enquanto o aumento da concentração de mioglobina (Mb) foi significante no grupo PLA comparado ao grupo LBD e LAD em 24h, 48h e 72h após a ST. O 2° estudo contou com a participação de 28 indivíduos com até 6 meses de experiência em TF. Os sujeitos foram suplementados com 3g de &beta;-hidroxi-&beta;-metilbutirato (HM) por 14 dias (H14, n=07); 7 dias (H07, n=07) e placebo por 14 dias (P14) ou 7 dias (P07, n=07) antecedentes a ST, e nos 3 dias seguintes. O aumento da DMIT por palpação e alongamento foi significante no grupo P14 comparado ao H14 em 24h (apenas alongamento), 48h e 72h após ST, ainda no momento 72h o grupo P07 era superior ao H07. A redução no teste de 1RM ocorreu nos 4 grupos imediatamente após, foi mantida em 24h após a ST nos grupos H14, H07 e P07, sem diferenças entre os grupos. O aumento na concentração de Mb foi significante no grupo P14 comparado ao grupo H14. No 3° estudo, 24 indivíduos experientes em TF foram suplementados com 7g de arginina (ARG, n=12) ou placebo (PLA, n=12, 7g carboidrato) 30 minutos pré-ST. O grupo PLA apresentou aumento significante na DMIT por palpação em 24h comparado ao grupo ARG. A redução no teste de 1RM alcançou significância apenas em 24h após a ST no grupo PLA, mas sem diferença entre os grupos. Os resultados do presente estudo permitem concluir que a suplementação nutricional implementada atenuou o comportamento de alguns marcadores indiretos DMIE, com maior efeito para a DMIT e parametros bioquímicos / After performing a training session (TS) is common the occurrence of the phenomenon called muscle damage induced by exercise (DMIE), which is characterized by damage to muscle fiber structure, breaking some sarcomeres, myofibrillar disorder and extension lines Z. As a consequence of DMIE, there are some symptoms that are measured as indirect markers: delayed onset muscle soreness (DOMS), reduction in strength production, increase of enzymes and proteins in the bloodstream, and swelling. The effect of nutritional interventions to minimize deleterious responses associated with exercise-induced muscle damage (EIMD) were investigated in 3 experiments. In study 1, 36 inexperienced subjects in resistance training (RT) were supplemented for 6 days prior to the training session (TS), and in the following 3 days with: placebo (PLA, n=12, 50mg·kg-1 of carbohydrate); leucine (LEU) low dose (LLD, n=12, 250mg·kg-1 LEU + 50mg·kg-1 + carbohydrate) and LEU high dose (LHD, n=12, 250mg·kg-1 LEU + 50mg·kg-1 + carbohydrate). There was a significant reduction (p <0.05) in delayed onset muscle soreness (DOMS), of the chest by palpation and stretching at 48h, after TS in the LLD group compared to PLA. A significant reduction in the one repetition maximum (1RM) test was observed in the PLA group at all times after TS. The increase in creatine kinase (CK) activity was significant in the PLA group compared to the LHD in 24h, 48h and 72h after TS, while the increase in myoglobin concentration (Mb) was significant in the PLA group compared to the LLD and LHD group in 24h, 48h, and 72h after TS. In study 2, 28 subjects with up to 6 months of RT experience were supplemented with 3g of &beta;-hydroxy-&beta;-methylbutyrate (HM&beta;) for 14 days (H14, n=7); for 7 days (H07, n=7), and placebo for 14 days (P14, n=7) or 7 days (P07, n=7) antecedent to ST, and in the next 3 days. The increase in DOMS by palpation and stretching was significant in the P14 group compared to H14 in 24h (stretching only), 48h and 72h after TS, yet at 72h the P07 group was higher than H07. The reduction in the 1RM test occurred in the 4 groups immediately after and maintained within 24h after TS in groups H14, H07 and P07, and there was no difference between groups. The increase in Mb concentration was significant in the P14 group compared to the H14 group. In study 3, 24 resistance-trained subjects were supplemented with 7g of arginine (ARG, n=12) or placebo (PLA, n=12, 7g of carbohydrate) 30 minutes pre- TS. The PLA group presented a significant increase in DOMS by palpation in 24h compared to the ARG group, and a significant reduction in the 1RM test only in 24h after ST in the PLA group, but without a significant difference between groups. The results of the present study suggest that the responses of indirect markers associated with EIMD were attenuated by nutritional interventions, with greater effect for DOMS and biochemical parameters

Sabe-se que a cada ano cerca de dois bilhões de pessoas consomem bebidas alcoólicas, e no Brasil há uma estimativa de que aproximadamente 11,2% da população é dependente de álcool, o que representa mais de cinco milhões de pessoas. Básicamente se pode dizer que todos os órgãos são afetados pela exposição crônica e aguda, mas as miopatias alcoólicas atingem de 1/3 a 2/3 dos alcoólatras e são as das doenças musculares mais frequentes. A literatura apresenta vários suplementos nutricionais que prometem melhora na performance de atividade físicas promovendo conservação ou hipertrofia das fibras musculares, mas estudos mais profundos tem demonstrado que apenas as suplementações de creatina e &#x3B2;- hidroxi-&#x3B2;-metilbutirato (HMB) demonstraram efeitos sobre a otimização dos ganhos de força e massa muscular, Os trabalhos com HMB afirmam que esta substância diminui a degradação proteica muscular e estimula a síntese proteica, entre outras atividades. Considerando os prejuízos causados pelo álcool no tecido muscular e os benefícios produzidos pelo HMB no mesmo tecido pensou-se na realização de um trabalho associando as duas substâncias para responder as seguintes perguntas: a-) o álcool e o HMB alteram do peso dos animais, atuando individualmente e em conjunto? b-) o álcool e o HMB alteram a área das fibras musculares do EDL e do sóleo, atuando individualmente e em conjunto? c-) se as alterações ocorrerem elas são semelhantes nos músculos EDL e sóleo? Para isso foram utilizados 25 ratos (Rattus novergicus), machos, adultos (com aproximadamente 90 dias de idade (407g) divididos em 4 grupos: Grupo Controle Placebo, Grupo Experimental Álcool (25%), Grupo &#x3B2;-Hidroxi &#x3B2;-Metilbutirato (0,3g/Kg) e Grupo Álcool + &#x3B2;-Hidroxi &#x3B2;- Metilbutirato. Foram retiradas amostras dos músculos sóleo e extensor longo dos dedos e submetidas a coloração de HE. Foi realizado a morfometria de duzentas fibras de cada músculo de cada animal. Estas fibras tiveram as suas áreas calculadas. Os dados obtidos foram submetidos ao tratamento estatístico. Os dados encontrados nesta pesquisa permitiram concluir que: : a-) o álcool alterou, de maneira negativa o peso dos animais, mas o HMB não, mesmo quando atuou em conjunto com o álcool, ou seja, o HMB não conseguiu anular o efeito negativo do álcool; b-) o álcool alterou, de maneira negativa a área das fibras dos músculos EDL e sóleo, e o HMB não, mas quando ele atuou em conjunto, conseguiu anular o efeito negativo do álcool; c-) as alterações produzidas pela ação do álcool e HMB, individualmente ou em conjunto foram semelhantes nos músculos EDL e sóleo. / It is known that every year about two billion people consume alcoholic beverages, and in Brazil there is an estimate that approximately 11.2% of the population is dependent on alcohol, which is more than five million people. Basically you can say that all organs are affected by chronic and acute exposure, but alcoholic myopathy reach 1/3 to 2/3 of alcoholics, and are the most frequent muscular diseases. The literature contains several nutritional supplements that promise improvement in physical activity performance promoting conservation or hypertrophy of muscle fibers, but further study has shown that only creatine supplementation and &#x3B2;-hydroxy-&#x3B2;-methylbutyrate (HMB) have shown effects on optimization the strength gains and muscle mass, works with HMB claim that this substance decreases muscle protein degradation and stimulates protein synthesis, among other activities. Considering the damage caused by alcohol in muscle tissue and the benefits produced by the HMB in the same fabric was thought in achieving a work combining the two substances to answer the following questions: a-) alcohol and HMB alter the weight of the animals, acting individually and together? b-) alcohol and HMB alter the area of the muscle fibers of the soleus and EDL individually and jointly acting? c) if changes occur they are similar in EDL and soleus muscles? For this we used 25 rats (Rattus norvegicus), adult male (approximately 90 days old (407 g) divided in 4 groups: Control Group Placebo Experiment Group Alcohol (25%), Group &#x3B2;-hydroxy &#x3B2;-methylbutyrate (0.3g / kg), and Group Alcohol + &#x3B2;-hydroxy &#x3B2;-methylbutyrate. soleus and samples were taken long extensor muscles of the fingers and subjected to HE staining. morphometry was performed two hundred fibers of each muscle of each animal. These fibers had calculated their areas the data were subjected to statistical analysis the data found in this study showed that: a-) alcohol changed in a negative way the weight of the animals, but the HMB not even when he served in together with the alcohol, i.e., HMB could not nullify the negative effects of alcohol; b) alcohol changed in a negative way the area of the fibers of the EDL and soleus muscles, and HMB not, but when he acted together, could nullify the negative effect of alcohol; c) the changes produced by the action of alcohol and HMB, individually or together were similar in EDL and soleus muscles.

Sabe-se que a cada ano cerca de dois bilhões de pessoas consomem bebidas alcoólicas, e no Brasil há uma estimativa de que aproximadamente 11,2% da população é dependente de álcool, o que representa mais de cinco milhões de pessoas. Básicamente se pode dizer que todos os órgãos são afetados pela exposição crônica e aguda, mas as miopatias alcoólicas atingem de 1/3 a 2/3 dos alcoólatras e são as das doenças musculares mais frequentes. A literatura apresenta vários suplementos nutricionais que prometem melhora na performance de atividade físicas promovendo conservação ou hipertrofia das fibras musculares, mas estudos mais profundos tem demonstrado que apenas as suplementações de creatina e &#x3B2;- hidroxi-&#x3B2;-metilbutirato (HMB) demonstraram efeitos sobre a otimização dos ganhos de força e massa muscular, Os trabalhos com HMB afirmam que esta substância diminui a degradação proteica muscular e estimula a síntese proteica, entre outras atividades. Considerando os prejuízos causados pelo álcool no tecido muscular e os benefícios produzidos pelo HMB no mesmo tecido pensou-se na realização de um trabalho associando as duas substâncias para responder as seguintes perguntas: a-) o álcool e o HMB alteram do peso dos animais, atuando individualmente e em conjunto? b-) o álcool e o HMB alteram a área das fibras musculares do EDL e do sóleo, atuando individualmente e em conjunto? c-) se as alterações ocorrerem elas são semelhantes nos músculos EDL e sóleo? Para isso foram utilizados 25 ratos (Rattus novergicus), machos, adultos (com aproximadamente 90 dias de idade (407g) divididos em 4 grupos: Grupo Controle Placebo, Grupo Experimental Álcool (25%), Grupo &#x3B2;-Hidroxi &#x3B2;-Metilbutirato (0,3g/Kg) e Grupo Álcool + &#x3B2;-Hidroxi &#x3B2;- Metilbutirato. Foram retiradas amostras dos músculos sóleo e extensor longo dos dedos e submetidas a coloração de HE. Foi realizado a morfometria de duzentas fibras de cada músculo de cada animal. Estas fibras tiveram as suas áreas calculadas. Os dados obtidos foram submetidos ao tratamento estatístico. Os dados encontrados nesta pesquisa permitiram concluir que: : a-) o álcool alterou, de maneira negativa o peso dos animais, mas o HMB não, mesmo quando atuou em conjunto com o álcool, ou seja, o HMB não conseguiu anular o efeito negativo do álcool; b-) o álcool alterou, de maneira negativa a área das fibras dos músculos EDL e sóleo, e o HMB não, mas quando ele atuou em conjunto, conseguiu anular o efeito negativo do álcool; c-) as alterações produzidas pela ação do álcool e HMB, individualmente ou em conjunto foram semelhantes nos músculos EDL e sóleo. / It is known that every year about two billion people consume alcoholic beverages, and in Brazil there is an estimate that approximately 11.2% of the population is dependent on alcohol, which is more than five million people. Basically you can say that all organs are affected by chronic and acute exposure, but alcoholic myopathy reach 1/3 to 2/3 of alcoholics, and are the most frequent muscular diseases. The literature contains several nutritional supplements that promise improvement in physical activity performance promoting conservation or hypertrophy of muscle fibers, but further study has shown that only creatine supplementation and &#x3B2;-hydroxy-&#x3B2;-methylbutyrate (HMB) have shown effects on optimization the strength gains and muscle mass, works with HMB claim that this substance decreases muscle protein degradation and stimulates protein synthesis, among other activities. Considering the damage caused by alcohol in muscle tissue and the benefits produced by the HMB in the same fabric was thought in achieving a work combining the two substances to answer the following questions: a-) alcohol and HMB alter the weight of the animals, acting individually and together? b-) alcohol and HMB alter the area of the muscle fibers of the soleus and EDL individually and jointly acting? c) if changes occur they are similar in EDL and soleus muscles? For this we used 25 rats (Rattus norvegicus), adult male (approximately 90 days old (407 g) divided in 4 groups: Control Group Placebo Experiment Group Alcohol (25%), Group &#x3B2;-hydroxy &#x3B2;-methylbutyrate (0.3g / kg), and Group Alcohol + &#x3B2;-hydroxy &#x3B2;-methylbutyrate. soleus and samples were taken long extensor muscles of the fingers and subjected to HE staining. morphometry was performed two hundred fibers of each muscle of each animal. These fibers had calculated their areas the data were subjected to statistical analysis the data found in this study showed that: a-) alcohol changed in a negative way the weight of the animals, but the HMB not even when he served in together with the alcohol, i.e., HMB could not nullify the negative effects of alcohol; b) alcohol changed in a negative way the area of the fibers of the EDL and soleus muscles, and HMB not, but when he acted together, could nullify the negative effect of alcohol; c) the changes produced by the action of alcohol and HMB, individually or together were similar in EDL and soleus muscles.

Após a realização de uma sessão de treinamento (ST) é comum a ocorrência do fenômeno denominado dano muscular induzido pelo exercício (DMIE), que se caracteriza por prejuizos a estrutura da fibra muscular, com ruptura de alguns sarcômeros, desordem miofibrilar e alargamento das linhas Z. Ainda em consequência ao DMIE, surgem alguns sintomas que são utilizados como marcadores indiretos: dor muscular de início tardio (DMIT), redução na produção de força, aumento de enzimas e proteínas na corrente sanguínea e inchaço. O presente estudo examinou os efeitos da suplementação nutricional a fim de minimizar os efeitos deletérios do DMIE em 3 experimentos. No 1° estudo, 36 indivíduos inexperientes em treinamento de força (TF) foram suplementados com: placebo (PLA, n=12, 50mg·kg-1 de carboidrato); leucina (LEU) baixa dose (LBD, n=12, 50mg·kg-1 de LEU + 50mg·kg-1 de carboidrato) e LEU alta dose (LAD, n=12, 250mg·kg-1 de LEU + 50mg·kg-1 de carboidrato) por 6 dias antecedentes a sessão de treinamento (ST), e nos 3 dias seguintes. Foi observada redução significante, p<0.05, na dor muscular de início tardio (DMIT) do peitoral por palpação, e alongamento nos momentos 48h, e 72h após a ST no grupo LBD comparado ao PLA. A redução no teste de 1 repetição máxima (1RM) apresentou significância no grupo PLA em todos momentos após ST. O aumento na atividade da creatina quinase (CK) foi significante no grupo PLA comparado ao LAD em 24h, 48h e 72h após a ST, enquanto o aumento da concentração de mioglobina (Mb) foi significante no grupo PLA comparado ao grupo LBD e LAD em 24h, 48h e 72h após a ST. O 2° estudo contou com a participação de 28 indivíduos com até 6 meses de experiência em TF. Os sujeitos foram suplementados com 3g de &beta;-hidroxi-&beta;-metilbutirato (HM) por 14 dias (H14, n=07); 7 dias (H07, n=07) e placebo por 14 dias (P14) ou 7 dias (P07, n=07) antecedentes a ST, e nos 3 dias seguintes. O aumento da DMIT por palpação e alongamento foi significante no grupo P14 comparado ao H14 em 24h (apenas alongamento), 48h e 72h após ST, ainda no momento 72h o grupo P07 era superior ao H07. A redução no teste de 1RM ocorreu nos 4 grupos imediatamente após, foi mantida em 24h após a ST nos grupos H14, H07 e P07, sem diferenças entre os grupos. O aumento na concentração de Mb foi significante no grupo P14 comparado ao grupo H14. No 3° estudo, 24 indivíduos experientes em TF foram suplementados com 7g de arginina (ARG, n=12) ou placebo (PLA, n=12, 7g carboidrato) 30 minutos pré-ST. O grupo PLA apresentou aumento significante na DMIT por palpação em 24h comparado ao grupo ARG. A redução no teste de 1RM alcançou significância apenas em 24h após a ST no grupo PLA, mas sem diferença entre os grupos. Os resultados do presente estudo permitem concluir que a suplementação nutricional implementada atenuou o comportamento de alguns marcadores indiretos DMIE, com maior efeito para a DMIT e parametros bioquímicos / After performing a training session (TS) is common the occurrence of the phenomenon called muscle damage induced by exercise (DMIE), which is characterized by damage to muscle fiber structure, breaking some sarcomeres, myofibrillar disorder and extension lines Z. As a consequence of DMIE, there are some symptoms that are measured as indirect markers: delayed onset muscle soreness (DOMS), reduction in strength production, increase of enzymes and proteins in the bloodstream, and swelling. The effect of nutritional interventions to minimize deleterious responses associated with exercise-induced muscle damage (EIMD) were investigated in 3 experiments. In study 1, 36 inexperienced subjects in resistance training (RT) were supplemented for 6 days prior to the training session (TS), and in the following 3 days with: placebo (PLA, n=12, 50mg·kg-1 of carbohydrate); leucine (LEU) low dose (LLD, n=12, 250mg·kg-1 LEU + 50mg·kg-1 + carbohydrate) and LEU high dose (LHD, n=12, 250mg·kg-1 LEU + 50mg·kg-1 + carbohydrate). There was a significant reduction (p <0.05) in delayed onset muscle soreness (DOMS), of the chest by palpation and stretching at 48h, after TS in the LLD group compared to PLA. A significant reduction in the one repetition maximum (1RM) test was observed in the PLA group at all times after TS. The increase in creatine kinase (CK) activity was significant in the PLA group compared to the LHD in 24h, 48h and 72h after TS, while the increase in myoglobin concentration (Mb) was significant in the PLA group compared to the LLD and LHD group in 24h, 48h, and 72h after TS. In study 2, 28 subjects with up to 6 months of RT experience were supplemented with 3g of &beta;-hydroxy-&beta;-methylbutyrate (HM&beta;) for 14 days (H14, n=7); for 7 days (H07, n=7), and placebo for 14 days (P14, n=7) or 7 days (P07, n=7) antecedent to ST, and in the next 3 days. The increase in DOMS by palpation and stretching was significant in the P14 group compared to H14 in 24h (stretching only), 48h and 72h after TS, yet at 72h the P07 group was higher than H07. The reduction in the 1RM test occurred in the 4 groups immediately after and maintained within 24h after TS in groups H14, H07 and P07, and there was no difference between groups. The increase in Mb concentration was significant in the P14 group compared to the H14 group. In study 3, 24 resistance-trained subjects were supplemented with 7g of arginine (ARG, n=12) or placebo (PLA, n=12, 7g of carbohydrate) 30 minutes pre- TS. The PLA group presented a significant increase in DOMS by palpation in 24h compared to the ARG group, and a significant reduction in the 1RM test only in 24h after ST in the PLA group, but without a significant difference between groups. The results of the present study suggest that the responses of indirect markers associated with EIMD were attenuated by nutritional interventions, with greater effect for DOMS and biochemical parameters

This study investigated the effects of high intensity interval training (HIIT) and β-hydroxy-β-methylbutyric free acid (HMBFA) on the onset of neuromuscular fatigue in healthy young men and women. Thirty-seven subjects (22 men and 15 women; mean ± SD age = 22.8 ± 3.4yrs) completed an incremental cycle ergometer test (GXT) to exhaustion. During the GXT, electromyography (EMG) signals from the right vastus lateralis were recorded to determine the power output at the onset of neuromuscular fatigue (PWCFT), and peak wattage was used to assign individual training loads. After baseline testing (PRE), subjects were randomly assigned to one of three groups: control (C, n = 9), training with placebo (P, n = 14), or training with supplementation (S, n = 14). Subjects assigned to P and S completed 12 HIIT sessions over 4 weeks while subjects assigned to C were asked to maintain their normal diet and activity patterns. After 4 weeks, subjects returned for post-testing (POST). The PWCFT values (W) were determined using a DMAX method. The EMG amplitude root mean square (µVrms) values were used to generate a third-order polynomial regression (3PR) representing the increase in µVrms versus time of the GXT. The onset of fatigue (TF) was defined as the x-value (time, s) of the point on the 3PR that measured the maximal perpendicular distance from the line between the first and last data points. TF was used to estimate PWCFT according to the equation: PWCFT = PO + a · (n/N), where PO is the power output of the stage in which TF occurred, a is the increment in power output between GXT stages (25W), n is the difference (s) between TF and the beginning of the stage during which TF occurred, and N is the duration of a stage (120s). A two-way repeated measures ANOVA was used to identify group × time interaction for PWCFT. If a significant interaction occurred, one-way factorial ANOVAs were used. Fisher's least significant difference post hoc comparisons were performed between groups. If a significant main effect occurred, dependent samples t-tests with Bonferroni corrections (p = [0.05/3] = 0.017) were performed across time for each group. The two-way ANOVA resulted in a significant interaction (F = 6.69, p = 0.004). Follow-up analysis with one-way ANOVA resulted in no difference among groups at PRE (F = 0.87, p = 0.43), however a significant difference was shown for POST values (F = 5.46, p = 0.009). Post-hoc analysis among POST values showed significant differences between S and both P (p = 0.034) and C (p = 0.003). No differences (p = 0.226) were noted between P and C. Paired samples t-tests detected significant changes following HIIT for S (p < 0.001) and P (p = 0.016), but no change in C (p = 0.473). Results of this study indicate that HIIT was effective in delaying the onset of fatigue, but supplementation with HMBFA in conjunction with HIIT was more effective than HIIT alone. An increase in PWCFT represents an increase in the maximal power output an individual can sustain without eliciting fatigue. Therefore, HIIT can be used to improve performance in both endurance activities as well as intermittent sports. In addition, HMBFA supplementation is a simple method that can be used to maximize the benefits of HIIT. Acknowledgments: Metabolic Technologies, Inc. provided the supplement and funding for this study.