The Second Scoop on Protein: When, What and How Much?

抗性训练后喝蛋白质奶昔是许多健身爱好者和运动员采用的流行营养策略，以提高肌肉蛋白质合bob官方app成（MPS）。bob官方体育下载

But does evidence support this practice, and if so, then what type of protein is best, how much should be ingested and when should it be consumed?

多少蛋白质？

According to the德姆Nutrition course，对健康成人的蛋白质摄入的当前推荐的每日津贴（RDA）为每千克（每磅0.36克/小时）每天（1）。这将在176磅（80 kg）人（176×0.36）中每天计算约64克蛋白质。然而，这种蛋白质RDA被认为不足以满足阻力训练或甚至耐久训练的个体的所有需求（2,3）。bob官方app随后，存在来自最可靠的健康，健身和营养组织的共识，表明运动个体在其饮食中需要更大量的蛋白质，而不是他们的久坐同行支持MPS。bob官方体育下载

A common misconception with exercisers is thatingesting more protein支持更高层次的议员,但最新的position statements from the Academy of Nutrition and Dietetics (AND), Dietitians of Canada (DC), the American College of Sports Medicine (ACSM), the National Strength and Conditioning Association (NSCA) and the International Society of Sports Nutrition (ISSN) dispute this belief. They have each provided recommended dosages for endurance and resistance-trained individuals, as well as upper thresholds for protein intake (1,4,5). The notion behind establishing an upper threshold is based upon research that fails to demonstrate increased levels of MPS when eating more protein (i.e., exceeding the daily total or suggested amount in one meal because it (a) not be fully absorbed or (b) may not be utilized for MPS by the body). Although these position statements do differ slightly between agencies, a consensus is presented below as a guideline for practitioners:

• 每千克体重（0.55-0.64克/磅/磅）2至1.4克，用于耐久训练的个体（定义为每周大于10小时的耐久性型训练）bob官方app
• 4 to 2.0 grams per kilogram of body weight (0.64 - 0.91 grams / lb.) for strength-trained individuals*.

For example, a 154-pound (70 Kg) endurance athlete would consume between 84 and 98 grams of protein (154 lbs. x 0.55 and 0.64), whereas a 220-pound (100 Kg) power athlete would consume between 140 and 200 grams of protein (220 lbs. x 0.64 and 0.91).

* A traditional dosage often used by individuals is 1 gram per pound of body weight or 2.2 grams per kilogram, a dosage that is about 10% higher than the upper threshold recommended.

However, it is also important to recognize that studies do exist that have examined higher protein intakes in experienced body builders and resistance-trained individuals who consumed high protein diets (up to 2.8 grams per kilogram or 1.27 grams per pound). These individuals continued to demonstrate MPS without any health concerns such as compromised renal function (6).

何时消耗蛋白质？

另一个讨论涉及应该在一顿饭或一个坐着内消耗的蛋白质的量。蛋白质吸收率在人们之间和蛋白质来源之间的巨大变化。虽然男性通常具有较大的胃肠道（Gi）道，因此可以吸收更多的蛋白质，而不是女性，现实情况是考虑到影响蛋白质消化和吸收率的无数的因素非常困难，包括（7）：

• Protein digestibility efficiency of foods (differs between plant and animal sources).
• 身体大小和遗传学。
• 膳食大小和组成（纤维和脂肪的存在可能阻碍蛋白质吸收）。
• Protein sources (e.g.,乳清，酪蛋白，鸡蛋）。乳清水溶性比酪蛋白更快地吸收，一种不溶性乳蛋白，其在胃中形成凝乳，延迟其胃排空和吸收小时。另一方面的鸡蛋含有六到七克蛋白质，然而，每小时，身体吸收大约3克煮熟的鸡蛋。
• Diet experience (individuals consuming higher protein intakes may adapt to digest/absorb protein more efficiently).

西蒙斯和他的同事们的研究(8)而30克rams of protein versus 90 grams on MPS in young and elderly groups. Their research demonstrated that ingestion of more than 30 grams in a single meal did not further enhance the stimulation of MPS in both populations examined. This value echoes much of the sentiment of other researchers who estimate that between 20 and 30 grams represent an ideal protein quantity that can be efficiently absorbed in one sitting (9-11). Dosages therefore, of approximately 20 grams for women and 25 to 30 grams for men in one sitting appear ideal, subsequently necessitating multiple feedings throughout the day to reach a desired total.

Regardless, what appears to be garnering much interest in MPS research is the quantity of leucine consumed (12,13). Amino acid metabolism into skeletal muscle is generally limited to six amino acids (glutamate, aspartate, asparagine, BCAAs – leucine, isoleucine and valine), but the most significant effects are tied to leucine which acts as a critical regulator of MPS (e.g., m-Tor pathway), complementing insulin’s signaling effects and the production of other amino acids in muscle development (think of leucine as the engine or switch to drive MPS). Current consensus appears to agree that a minimum dose of around 2 to 2.5 grams of leucine is needed per feeding to signal the mTOR pathways that there is adequate dietary protein present to support MPS (14).

Protein timing is critical to enhancing MPS and muscle recovery. Although it has demonstrated that pre- and post-exercise protein ingestion results in increased rates of MPS in comparison to morning- and evening-feeding (15), differences between pre-exercise and post-exercise remain less clear. Tipton and colleagues fed active individuals an amino-acid-carbohydrate beverage containing 6 grams of essential amino acids (EAA)* and 35 grams of a high-glycemic carbohydrates (EAA-CHO) 60 minutes before high-intensity resistance training (80% of 1 RM) and within 30 to 45 minutes following that same workout. The study revealed that the net MPS associated with pre-exercise protein intake was greater than protein consumed after exercise (16). However, this finding was not replicated in a study by Schoenfeld and colleagues who found no differences between pre- and post-exercise ingestion of 25 grams of protein (17). Although this study also concluded that the optimal post-exercise anabolic window for maximizing MPS is also not as small as once believed (i.e., 2-3 hours post-exercise), but rather extends for 5 to 6 hours, other studies do not support this same finding, and recommend protein intakes within the first hour post-exercise (18).

* 6 grams of EAA is equivalent to 17.5 grams of pea isolate or 12 grams of whey isolate (excludes consideration of protein absorbability where pea isolate is approximately 75% of the efficacy of whey isolates).

用于从业者的适用外带可能是在运动前一小时内消耗的剂量高达20至25克蛋白质，然后在运动后的第一个小时内再次消耗。运动后窗口中蛋白质消耗研究的共识是20克的剂量，但是使用0.25至0.3克/千克（0.11至0.14克/磅）的计量系列可以更具体地计算该量的量（1119）。例如，176磅磅（80 kg）个体的目标是蛋白质摄入20至24克蛋白质。

什么类型的蛋白质？

一篇文章回顾了起关键的不同感情n quality and the absorbability of plant- versus animal-based proteins, and between proteins within each food category. The most important outcome of protein consumed either before or immediately following exercise is rapid delivery to the muscles cells – ‘fast’ proteins deliver amino acids to the muscles more efficiently. Whereas casein can take hours to empty from the stomach, whey isolates can enter the blood within 15 to 20 minutes. Subsequently, individuals would be best served by consuming a fast protein like a whey isolate before and/or after their workout. But, because protein should also be consumed several hours later (e.g., 3-4 hours), an alternate strategy post-exercise is to consume a blend of both fast and slow proteins for the sake of convenience considering how some individuals may not have the inclination of ability to eat again several hours after their workout. Whether the inclusion of a slow protein with a fast protein (i.e., blended protein) impedes immediate MPS is largely unknown. Regardless, protein intake throughout the day should ideally follow a regimen of frequent, smaller protein dosages to sustain a more positive nitrogen balance (i.e., preserving muscle mass rather than breaking it down). Preferably, this entails a practice of ingesting quality protein every few hours (e.g., 3-4 hours) and complemented by the ingestion of a ‘slow’ protein like casein before bed to help reduce the catabolic state the body experiences during an overnight fast.

In closing, although post-exercise protein shake consumption remains a viable and effective practice, practitioners can develop and implement a few evidence-based strategies to optimize the outcomes associated with the practice of consuming additional protein.

Footnote:在运动期间，分枝链氨基酸（BCAAs）的消耗被认为减少运动后肌肉疼痛并加速恢复，尽管这项研究并非没有争议。鉴于这一争议和本文的范围，不会讨论运动过程中BCAAS的消费。

References

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3. Tarnopolsky MA, Gibala M, Jeukendrup AE, and Phillips SM (2005). Nutritional needs of elite endurance athletes. Part I: Carbohydrate and fluid requirements.European Journal of Sport Science, 5:314. 14.
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6. Poortmans JR，Dellalieux O（2000）。常规高蛋白质饮食是否对运动员的肾功能有潜在的健康风险？国际体育营养和运动新陈代谢bob官方体育下载，10（1）：28-38。
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