Department of Physical Education and Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, V94 T9PX Limerick, Ireland.
Carnegie School of Sport, Leeds Beckett University, Leeds LS6 3QS, UK.
Nutrients. 2020 Jul 12;12(7):2067. doi: 10.3390/nu12072067.
We investigated the effects of ingesting a leucine-enriched essential amino acid (EAA) gel alone or combined with resistance exercise (RE) versus RE alone (control) on plasma aminoacidemia and intramyocellular anabolic signaling in healthy younger (28 ± 4 years) and older (71 ± 3 years) adults. Blood samples were obtained throughout the three trials, while muscle biopsies were collected in the postabsorptive state and 2 h following RE, following the consumption of two 50 mL EAA gels (40% leucine, 15 g total EAA), and following RE with EAA (combination (COM)). Protein content and the phosphorylation status of key anabolic signaling proteins were determined via immunoblotting. Irrespective of age, during EAA and COM peak leucinemia (younger: 454 ± 32 µM and 537 ± 111 µM; older: 417 ± 99 µM and 553 ± 136 µM) occurred 60-120 min post-ingestion (younger: 66 ± 6 min and 120 ± 60 min; older: 90 ± 13 min and 78 ± 12 min). In the pooled sample, the area under the curve for plasma leucine and the sum of branched-chain amino acids was significantly greater in EAA and COM compared with RE. For intramyocellular signaling, significant main effects were found for condition (mTOR (Ser2481), rpS6 (Ser235/236)) and age (S6K1 (Thr421/Ser424), 4E-BP1 (Thr37/46)) in age group analyses. The phosphorylation of rpS6 was of similar magnitude (8-fold) in pooled and age group data 2 h following COM. Our findings suggest that a gel-based, leucine-enriched EAA supplement is associated with aminoacidemia and a muscle anabolic signaling response, thus representing an effective means of stimulating muscle protein anabolism in younger and older adults following EAA and COM.
我们研究了单独摄入富含亮氨酸的必需氨基酸（EAA）凝胶或与阻力运动（RE）联合摄入（RE）与单独摄入 RE（对照）对健康年轻（28 ± 4 岁）和老年（71 ± 3 岁）成年人的血浆氨基酸血症和肌内合成代谢信号的影响。在三个试验中都采集了血液样本，而在吸收后状态和 RE 后 2 小时采集了肌肉活检，分别在摄入两个 50 毫升 EAA 凝胶（40%亮氨酸，15 克总 EAA）和摄入 EAA 后进行了 RE（联合（COM））。通过免疫印迹法测定蛋白质含量和关键合成代谢信号蛋白的磷酸化状态。无论年龄大小，在 EAA 和 COM 亮氨酸峰值时（年轻组：454 ± 32 µM 和 537 ± 111 µM；老年组：417 ± 99 µM 和 553 ± 136 µM），摄入后 60-120 分钟（年轻组：66 ± 6 分钟和 120 ± 60 分钟；老年组：90 ± 13 分钟和 78 ± 12 分钟）发生。在合并样本中，与 RE 相比，EAA 和 COM 的血浆亮氨酸和支链氨基酸总和的曲线下面积明显更大。对于肌内信号，在年龄组分析中，条件（mTOR（Ser2481），rpS6（Ser235/236））和年龄（S6K1（Thr421/Ser424），4E-BP1（Thr37/46））均有显著的主效应。在 COM 后 2 小时，rpS6 的磷酸化在合并和年龄组数据中具有相似的幅度（~8 倍）。我们的研究结果表明，基于凝胶的富含亮氨酸的 EAA 补充剂与氨基酸血症和肌肉合成代谢信号反应相关，因此是刺激年轻和老年成年人 EAA 和 COM 后肌肉蛋白质合成代谢的有效手段。
