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cover of episode #299 ‒ Optimizing muscle protein synthesis: the crucial impact of protein quality and quantity, and the key role of resistance training | Luc van Loon, Ph.D.

#299 ‒ Optimizing muscle protein synthesis: the crucial impact of protein quality and quantity, and the key role of resistance training | Luc van Loon, Ph.D.

2024/4/22
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Peter Attia: 本期节目将讨论耐力运动中胰岛素和葡萄糖的作用，以及蛋白质在其中的作用，不同类型的蛋白质如何影响肌肉蛋白质合成速率，以及不同蛋白质类型（包括乳清蛋白和酪蛋白）的差异，以及如何通过饮食和运动来优化肌肉蛋白质合成。 Luc van Loon: 耐力运动期间的主要能量来源是碳水化合物和脂肪，蛋白质的定量贡献较小。肌肉内脂肪（IMTG）是耐力运动的重要能量来源，其储存量和周转率对运动员的表现至关重要。运动员和糖尿病患者都具有大量的肌内脂肪，但运动员会利用它，而糖尿病患者不会，这与胰岛素敏感性有关。久坐不动的生活方式会导致肌肉质量下降，这促使他开始研究蛋白质代谢。蛋白质由氨基酸组成，其中9种是必需氨基酸，其余是非必需氨基酸。氨基酸不仅是蛋白质的构成成分，也是信号分子，可以直接刺激肌肉蛋白质合成。人体每天合成约300克蛋白质，其中大部分来自体内蛋白质的循环利用。肌肉蛋白质的更新速度约为每天1%-2%，这意味着肌肉蛋白质会在50-100天内完全更新。蛋白质的消化过程包括在胃中酸化、在十二指肠中酶解以及氨基酸的吸收和运输。过量摄入的蛋白质会被转化为脂肪储存。蛋白质刺激肌肉蛋白质合成的两个主要特征是消化率和氨基酸组成（特别是亮氨酸含量）。对于健康活跃的个体，每餐摄入20克蛋白质可以最大限度地刺激肌肉蛋白质合成长达4-5小时。摄入100克蛋白质可以延长肌肉蛋白质合成的持续时间，从而获得更大的合成效果。与植物性食物相比，全食物的杂食性膳食对肌肉蛋白质合成的刺激作用更大。即使在热量限制的情况下，每周进行两次阻力训练也可以防止肌肉流失。通过体育锻炼，老年人的肌肉仍然可以对蛋白质合成做出正常的反应。摄入乳清蛋白比酪蛋白消化吸收更快，能更有效地刺激肌肉蛋白质合成，但长期来看，酪蛋白的效果会逐渐赶上。胶原蛋白补充剂是否具有额外益处尚不清楚，因为膳食中可能已经含有足够的甘氨酸和脯氨酸。摄入乳清蛋白或酪蛋白并不能增加肌肉结缔组织蛋白质的合成速率。未来研究的重点是探究人体大脑中蛋白质的代谢过程。

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Fuel selection plays a crucial role in endurance exercise. Glucose from the gut helps preserve liver glycogen, and a combination of glucose and fructose can increase carbohydrate intake. Well-trained athletes utilize fat stores, and intramuscular lipids are crucial for initial energy provision.
  • During endurance exercise, extra circulating glucose is used for oxidation, saving liver glycogen.
  • Combining glucose and fructose can increase carbohydrate intake during exercise.
  • Intramuscular lipids are important for energy provision, especially at the start of exercise.

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Luc van Loon is an internationally renowned expert in skeletal muscle metabolism. In this episode, Luc starts with an exploration of the roles of insulin and triglycerides in endurance exercise, highlighting their impact on skeletal muscle metabolism, and he offers profound insights into the significance of protein in this context. He elucidates how different protein types and forms influence muscle protein synthesis rates, exploring the nuances of protein absorption, digestibility, amino acid quality, and their implications for performance and recovery. Delving deeper, he differentiates between animal and plant protein sources, unraveling the distinctive properties of various protein types, from the differences between whey and casein to the emerging trends in collagen protein supplementation. Moreover, Luc dissects the intricate connections among physical activity, lean muscle mass, muscle protein synthesis induced by resistance training, and dietary protein.

We discuss:

  • Luc’s background and insights about fuel selection during exercise [3:30];
  • Fuel utilization during endurance exercise [9:30];
  • Fat metabolism, intramuscular lipids, and the nutritional dynamics of endurance sports [17:15];
  • The optimal window for replenishing intramuscular fat stores and glycogen post-exercise [25:15];
  • Luc’s interest in protein metabolism and exploration of amino acids' dual role as building blocks and signaling molecules in driving muscle protein synthesis [32:15];
  • How protein metabolism differs between sedentary individuals and those engaged in predominantly strength training or endurance training [38:45];
  • The basics of how proteins are digested and absorbed, and how muscle protein synthesis is measured [50:30];
  • How factors like food texture, cooking methods, and protein composition impact muscle protein synthesis, and the importance of protein distribution throughout the day [59:45];
  • Differences in whey and casein proteins, and the ability of ingested protein to stimulate muscle protein synthesis [1:03:30];
  • Dietary protein distribution and quantity for the maximization of muscle protein synthesis [1:09:00];
  • Muscle loss with age and inactivity and the importance of resistance exercise to maintain type II muscle fibers [1:17:15];
  • Differences between whey and casein proteins, and the importance of both quantity and quality of protein sources [1:28:30];
  • Optimizing muscle protein synthesis: exercise, timing of protein intake, protein quality, and more [1:37:00];
  • How to preserve muscle while trying to lose weight [1:46:00];
  • Anabolic resistance and overcoming it with physical activity [1:55:45];
  • Importance of protein intake and physical activity in hospitalized patients [2:06:30];
  • Reviewing the efficacy of collagen supplements [2:13:30];
  • Plant-based diets: how to ensure a balance of amino acids, and other considerations [2:20:30];
  • Future research: understanding protein metabolism in the brain [2:23:45]; and
  • More.

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