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The effects of leucine metabolites on performance, body composition and biochemical markers of muscle damage and inflammation
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Os metabolitos da leucina (LM) β-hidroxi-β-metilbutirato (cálcico, HMB-Ca e livre, HMB-FA) e ácido hidroxiisocapróico (α-HICA) têm sido propostos na melhoria do desempenho (potência e força muscular), composição corporal (espessuras musculares, massa isenta de gordura [FFM], massa gorda [FM], conteúdo mineral ósseo [BMC]) e modulação hormonal induzida pelo exercício (testosterona, cortisol, factor de crescimento semelhante à insulina [IGF-1] e hormona do crescimento [GH], inflamação (factor de necrose tumoral α [TNF-α], interleucina 6 [IL-6] e proteína C-reactiva de alta sensibilidade [hsCRP]) e marcadores de dano muscular (creatina cinase [CK]), em indivíduos jovens, saudáveis e com experiência no treino da força. Adicionalmente, alguns LM também foram propostos na melhoria da mobilidade e composição corporal de populações idosas e/ou em contextos clínicos. A presente dissertação é composta por quatro estudos, conduzidos de forma a fornecer mais evidência em relação aos efeitos destes compostos em homens jovens, treinados e num indivíduo diabético tipo 1. Três estudos foram conduzidos em 40 jovens treinados, comparando directamente estes LM com um placebo, durante 8 semanas de treino da força supervisionado, em relação a alterações na espessura muscular, composição corporal, hormonas, inflamação e dano muscular. Um estudo de caso foi realizado num diabético tipo 1 para avaliar os efeitos do α-HICA na composição corporal, força e parâmetros hematológicos, durante 120 dias, na ausência de exercício. Nenhum LM resultou em quaisquer efeitos ergogénicos, no que diz respeito a qualquer variável estudada, em homens treinados, durante as 8 semanas do protocolo de treino da força, enquanto no estudo de caso, foi detectado um aumento na FFM do tronco. Pequenos incrementos em relação à força de preensão manual e à densidade mineral óssea também foram observados neste estudo de caso, embora de significado clínico desconhecido. Suplementar com metabolitos da leucina não é uma estratégia eficaz para melhorar a força muscular ou a composição corporal em homens jovens treinados. São necessários mais estudos em relação ao α-HICA, em populações clínicas, que comparem de forma directa os diversos metabolitos da leucina.
Leucine metabolites β-hydroxy-β-methylbutyrate (calcium, HMB-Ca and free acid, HMB-FA) and α-hydroxyisocaproic acid (α-HICA) have been proposed to enhance performance (muscle power and strength), body composition (muscle thickness, fat-free mass [FFM], fat mass [FM] and bone mineral content [BMC]) and to modulate training-induced hormonal (testosterone, cortisol, insulin-like growth factor-1 [IGF-1] and growth hormone [GH]), inflammatory (tumor necrosis factor α [TNF-α], interleukine 6 [IL6] and high-sensitivity C-reactive protein [hsCRP]) and muscle damage responses (creatine kinase [CK]), in healthy young resistance trained individuals. Additionally, some leucine metabolites have also been proposed to improve functionality and body composition in elderly populations and/or under clinical settings. The present dissertation is comprised of four research studies conducted to further elucidate the effects of these compounds in both young resistance trained men and an older type 1 diabetic individual. Three studies were conducted in 40 young resistance trained men, directly comparing these leucine metabolites with placebo, over 8 weeks of a supervised resistance exercise training, regarding changes in muscle thickness, body composition, several hormones, inflammation and proxy markers of muscle damage. One clinical case study was also conducted in a type 1 diabetic patient to assess the effects of α-HICA on body composition, isometric strength and full hematologic measures, over 120 days without any exercise. No leucine metabolite resulted in any ergogenic effects on any outcome variable in young resistance-trained men, during the 8 weeks of the resistance training, while in the clinical case study a body mass increase was detected due to an increase in trunk FFM. Small increases regarding handgrip strength and bone mineral density were also noted in this clinical case study, albeit of unknown clinical significance. Leucine metabolites are not an effective strategy to improve muscle strength or body composition in young resistance-trained men. More research is warranted regarding α-HICA in diseased populations, particularly to compare different leucine metabolites.
Leucine metabolites β-hydroxy-β-methylbutyrate (calcium, HMB-Ca and free acid, HMB-FA) and α-hydroxyisocaproic acid (α-HICA) have been proposed to enhance performance (muscle power and strength), body composition (muscle thickness, fat-free mass [FFM], fat mass [FM] and bone mineral content [BMC]) and to modulate training-induced hormonal (testosterone, cortisol, insulin-like growth factor-1 [IGF-1] and growth hormone [GH]), inflammatory (tumor necrosis factor α [TNF-α], interleukine 6 [IL6] and high-sensitivity C-reactive protein [hsCRP]) and muscle damage responses (creatine kinase [CK]), in healthy young resistance trained individuals. Additionally, some leucine metabolites have also been proposed to improve functionality and body composition in elderly populations and/or under clinical settings. The present dissertation is comprised of four research studies conducted to further elucidate the effects of these compounds in both young resistance trained men and an older type 1 diabetic individual. Three studies were conducted in 40 young resistance trained men, directly comparing these leucine metabolites with placebo, over 8 weeks of a supervised resistance exercise training, regarding changes in muscle thickness, body composition, several hormones, inflammation and proxy markers of muscle damage. One clinical case study was also conducted in a type 1 diabetic patient to assess the effects of α-HICA on body composition, isometric strength and full hematologic measures, over 120 days without any exercise. No leucine metabolite resulted in any ergogenic effects on any outcome variable in young resistance-trained men, during the 8 weeks of the resistance training, while in the clinical case study a body mass increase was detected due to an increase in trunk FFM. Small increases regarding handgrip strength and bone mineral density were also noted in this clinical case study, albeit of unknown clinical significance. Leucine metabolites are not an effective strategy to improve muscle strength or body composition in young resistance-trained men. More research is warranted regarding α-HICA in diseased populations, particularly to compare different leucine metabolites.
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Acido hidroxiisocapróico β-hidroxi-β-metilbutirato livre β-hidroxi-β-metilbutirato cálcico Composição corporal Desempenho Composição corporal Desempenho β-hydroxy-β-methylbutyrate free acid β-hydroxy-β-methylbutyrate calcium α-hydroxyisocaproic acid Body composition Performance