走下神坛的体育运动产品（奇文共欣赏，疑义相与析）

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　　今天早上刷微博，发现“跑步指南”转发了一篇微博，原文是“功能饮料让人快速补充体力？运动鞋能让人跑得更快？研究人员在《英国医学杂志》发表报告对号称能提升运动表现的104个运动产品广告进行了分析，包括葛兰素史克生产的著名功能饮料葡萄适，运动鞋品牌耐克和彪马等，结果约一半没有任何科研数据，或许还会带来负作用。”
　　乍一看很吓人，打开BMJ原文一看，部分说得对，验证了孔明先生的一句话：“偏信则暗，旁听则明”。因为BMJ为专业医学杂志，可能对大多数人而言有一定困难，所以，从今日起，我开始翻译此篇文献，以飧各位跑友，绝对不太监！同时，由于本人英语水平有限，难免有翻译不到位情况发生，只能争取与各位“奇文共欣赏，疑义相与析”。
      原文见附件。

结论：

1、The colour of urine accurately reflects hydration
尿色是机体精确的水指标？

General public—Evidence is lacking to suggest that urine colour is a useful, safe, or accurate marker of hydration

运动群众：尿色是有效、安全、精确的补水指标的说法缺乏依据

Professional athletes—Limited evidence to show that first morning urine colour can be reliably used to assess dehydration and rehydration

专业运动员：有限的证据显示，晨尿颜色是可靠的反应肌体缺水/水过多的指标。

　　
2、You should drink before you feel thirsty
你必须在感到口渴前补水？

General public—Drinking ahead of thirst may worsen performance in endurance exercise and carries a rare but serious risk of hyponatraemia. The body’s internal mechanism for staying hydrated is cheaper, easier, and seems to be the best way to optimize performance.

运动群众：在耐力训练中补水可能对锻炼有负面影响，并可能引起罕见但严重的低钠血症。通过人体自身对缺水的感知机制来补水是便宜、容易的，似乎是提高训练质量的最好方法。

Professional athletes—Elite endurance athletes perform best when they drink to thirst; some studies suggest exercise induced dehydration can improve performance.

专业运动员：顶级耐力运动员在口渴时喝水，一些研究显示，适度失水有助于提升运动水平。

　　序

　　BMJ 2012;345:e4848 doi: 10.1136/bmj.e4848 (Published 18 July 2012)

　　Mythbusting sports and exercise products
　　走下神坛的体育运动产品

　　There is no doubt that sport and exercise are beneficial for health and wellbeing. Yet, one might be fooled into thinking it is more important to heed correct nutrition and hydration advice than to actually exercise. In our analysis of the evidence of sports products there were six claims that were so pertinent in terms of performance that we wanted to answer them with evidence. To find the evidence we searched PubMed Clinical Queries using systematic reviews and randomised controlled trial filters.

　　毋庸置疑，体育锻炼有助于健康，然而，人们往往过分关注正确的营养和水分的补充，而忽略了运动本身。我们选取传统意义上与运动表现相关的六个方面，对运动产品进行分析，并根据循证医学证据给出结果，在分析中，我们通过PubMed搜索相关文献，包括综述和随机对照试验（RCT）。

　　In terms of hydration we wanted to know if the colour of urine accurately reflects hydration and whether you should hydrate before exercise or just when you feel thirsty? For nutrition, we wanted to know whether carbohydrate-protein combinations and branched chain amino acids improve performance or recovery after exercise. Finally, we wanted to determine the benefits of caffeine ingestion and analyse whether wearing compression garments helps improve overall performance?

　　我们对于补水的研究，旨在确认尿液的颜色是否真实的反映了机体水合情况，探讨我们应在运动前补水或仅需在感到口渴时补水。我们对于补水的研究，旨在确认糖-蛋白复合物和支链氨基酸是否对运动表现或运动后恢复有所稗益。最后，我们试图证实咖啡因对人体的影响，以及压缩衣是否能提高运动能力。

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专题1
The colour of urine accurately reflects hydration
尿色是机体精确的水指标

The qualitative measure of urine colour is viewed as a simple way to assess hydration status. Athletes are advised to “observe urine output over the course of a day and notice changes in urine flow and colour. Output volume and frequency should be consistent and the colour should be getting lighter towards the end of the day, aiming for the last outputs of the day being close to clear.” But recommendations from the American College of Sports Medicine state that urine colour is often subjective and might be confounded. Many companies also provide a “urine colour chart” allowing athletes to quantify their level of hydration.

尿液颜色的定性检测被认为是检测水合状态的简易方法。运动员们被建议“观察全天尿液情况，尤其是尿量和尿色的变化。尿量、尿频在一天中不应有太大的波动，尿色应在晚上变清，临睡前的排尿最好几近清澈。”但美国运动医学会认为尿液颜色的判断常常是主观的，且容易混淆标准。许多公司制造出“尿液比色卡”，以便让运动员对水合状态进行定量测定。

Science behind the claim

Antidiuretic hormone is secreted by the posterior pituitary gland as a result of dehydration, resulting in increased water absorption in the collecting ducts of the kidneys. This decreases urine output and concentrates the solutes (including urea, uric acid, creatinine), leading to a darker colour of urine. After fluid ingestion less water needs to be reabsorbed to maintain homeostasis so larger quantities of pale urine are produced.

缺水时，脑垂体后叶分泌抗利尿激素，促进肾脏集合管对水的吸收。此时，尿量减少，尿液浓缩（包括尿素、尿酸、肌酐等），导致尿色变深。补水后，维持稳态所需重吸收的水分随之减少，故大量浅色的尿液产生。

What the evidence says

We found eight low quality studies published with no systematic reviews. As there is no objective measure of hydration, all of these studies compared urine colour to surrogate markers: none directly investigated the correlation between urine colour and performance or the correlation between urine colour and thirst.

我们找到8篇质量较差的原创性研究报道，由于缺乏对水合作用的客观测量方法，所有的报道将尿液颜色和替代标志物作对比：没有一篇报道直接分析尿液颜色和运动表现的联系，亦无一项研究直接分析尿液颜色和口渴之间的联系。

The results are divided. Three studies recommend urine colour as a tool to roughly estimate hydration status, albeit when accurate results are not required or other assessment tools are not available, while three conclude urine colour is too inaccurate to be useful. Two further studies suggest urine colour can be useful but only in specific situations (such as first morning void) or in combination with other measures of hydration such as body mass.

8项研究的结果不尽相同。3项研究证实尿液颜色是一项粗略估计水合状态的工具，尤其适用于不需要精确结果时或缺乏其他检测工具时，但有3项研究认为，尿液颜色因不够精确而对水合状态的评估毫无作用。另有2篇文献认为尿液颜色判定的方法仅在特定的情况下（如晨尿）或结合其他测量方法（如体重）时有效。

The three studies that support the use of urine colour include several caveats: vitamins and medicines interfere with the results by making urine darker, variations in diet and dietary supplements affect accuracy, and, if large volumes of hypotonic drink are consumed following exercise, copious volumes of dilute urine will be produced before normal hydration is achieved. Despite this, no study has looked at the correlation of urine colour with hydration when different fluids are used for rehydration.

三项研究支持使用尿液颜色作为补水指标，但有如下说明：维生素和药物摄入可能会导致尿色加深，节食状态和减肥药物影响准确性，此外，如果运动后摄入大量低渗饮料，大量低渗尿液将在正常水合平衡达到前排出。即便如此，尽管采用了不同的补水制剂，没有一项研究发现尿液颜色与补水之间的联系。

None of the eight studies looked at the correlation between urine colour and overhydration. This important oversight makes it difficult to recommend urine colour as a safe hydration assessment tool: attempts to produce pale or straw coloured urine may go too far, potentially leading to overhydration and hyponatraemia. Many of the studies recommend a stopping point, often using the 8-point scale to assess urine colour described by Armstrong and colleagues. but this seems to be based on speculation rather than research.

没有一项研究报道尿液颜色与体内水分过多之间的关系。此方面研究的缺失使尿液颜色难以成为安全的水合状态测量指标：当尿色变清时也许补水过量，也许低钠血症已发生。许多研究提出“停止补水点”的概念，使用Armstrong报道的8点尿液颜色测量方法，但此方法仅是经验猜测，而无相应临床研究支持。

Finally, one study showed that 66 people were less reliable at distinguishing their urine colour than trained investigators. However, all eight trials used trained investigators to interpret urine colour but they were unblinded to the results of other measurements of hydration status. This alone seriously undermines the use of urine colour for assessing hydration. In the practical sports setting it is likely to be misleading.

最后，一项由66名受试者参与的研究显示，相较于专业检测人员，受试者无法正确区别尿液颜色。所有8项研究均使用专业检测人员检测尿液颜色，但这些人同时知晓其他水合指标（可靠的临床实验应该是“blinded”的，即观察者、记录者仅知晓所观察、记录的治疗），这严重削弱了尿液颜色对水合状态评估的应用，在实际运动中可能产生误导。

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专题2

You should drink before you feel thirsty

你必须在感到口渴前补水

The website for sports drink Gatorade says Your brain may know a lot, but it doesn’t know when your body is thirsty. You need to drink during exercise before you feel thirsty in order to get enough fluids in your body to maintain your performance level” (wardmulroy.com/gatorade/DOCS/4/content(13).html). Powerade advises customers that
“To avoid dehydration … you should drink before, during, and after sport” and that, “You may be able to train your gut to tolerate more fluid if you build your fluid intake gradually” "www.powerade.com.au/Sports-Hydration/Using-Powerade-for-Training-and-Competition.html).

运动饮料厂商佳得乐的网站宣称，“你的大脑也许知道很多，但它不知道你的身体何时口渴。在锻炼时，你在感到口渴前就需要补水以保持运动状态”。可口可乐旗下的Powerade忠告顾客“为了不出现缺水的状况……你必须在运动前、运动时、运动后补水”，“你可以通过训练逐步提高肠道对的水摄入的耐受性。”

Science behind the claim

When the body loses fluid due to sweat, the extracellular concentration of sodium rises leading to a subsequent increase in osmotic pressure and intracellular dehydration. Osmoreceptors in the hypothalamus detect dehydration and signal other parts of the brain to stimulate the sensation of thirst. In extreme conditions such as malnutrition or when children are left in hot cars failure to react to thirst sensations by consuming fluid can have fatal consequences.

当身体由于出汗而失水时，细胞外钠浓度上升，引起细胞外（胞外）渗透压升高，细胞脱水。位于下丘脑的渗透压感受器检测到脱水，接收到大脑其他部分传导的信号，刺激产生口渴感。在某些极端状态下（如营养不良者或在炎热汽车中的儿童）人体无法对脱水产生渴觉，可能发生致死的情况。

Drinking too much leads to other potential problems. If the body takes in more water than the kidneys can excrete, body solutes become diluted. Hyponatraemia occurs when the sodium concentration in the blood drops below 136 mmol/L. The effects of hyponatraemia range from mild (asymptomatic) to fatal.

摄水过量可导致其他潜在的问题。低钠血症在血钠浓度低于136mmol/L时发生，其导致的后果轻者无临床症状，重者死亡。

What the evidence says

One systematic review of the effects of glycerol induced hyperhydration on fluid retention and endurance performance in long cycling time trials found performance was maintained provided loss of body water is kept between 1.8% and 3.2% of body weight (roughly 1.5 L of sweat for a 60 kg human).

有一项研究聚焦于长距离自行车计时绕圈赛中甘油诱导的水肿，通过对水肿引起的液体潴留 和耐力变化进行综述，发现当失水量在体重的1.8%~3.2%（大约相当于60公斤体重的人出汗1.5升）时，运动能力不受影响。

A more recent systematic review of the effects of exercise induced dehydration on performance in long cycling time trials suggested that drinking according to thirst sensations (as opposed to drinking more or less frequently) was associated with better sports outcomes. One of the studies in the review found that exercise induced dehydration of up to 2.3% of body weight significantly improved performance. The explanation for how exercise induced dehydration might improve performance is straightforward: you carry less weight, and you don’t have to interrupt your exercise.

一项较新的综述发现，在自行车计时绕圈赛中，根据渴感补水能获得更好的成绩（相对于频繁喝水或更少喝水）。这篇综述所引用的一篇文献发现，由运动引起的失水量占体重达2.3%时，能显著提高运动表现，出现这个现象的原因十分简单：你的负重减轻了，而且你不用因补水而频繁中断你的运动。

Although we could not find a report in the medical literature of dehydration being a direct cause of death in marathon runners, we did find overhydration was responsible for several deaths. By following advice to “drink before thirst,” many athletes are drinking too much, which does not help performance and puts them at risk. A recent study of 88 participants in the London marathon found that 11 (12.5%) developed asymptomatic hyponatraemia.

尽管我们未能找到相关文献报导失水是马拉松运动员的直接死因，但我们发现水分过多是数起死亡病例的元凶。遵循着“口渴前补水”的建议，许多运动员摄入了过多的水分，这不仅不利于他们运动成绩的提高，反而将他们置于险地。近期，一项基于88名伦敦马拉松参加者的研究发现，11名（12.5%）参加者出现无临床症状的低钠血症。

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专题3

Energy drinks with caffeine and other compounds improve sports performance

含咖啡因和其他成分的能量饮料有助于提高运动成绩

Drinks manufacturers claim that “Stimulants such as caffeine, guarana and taurine with energising fast and slow release carbohydrates produces a scientifically proven range designed to enhance your overall performance (www.maxifuel.com/maxifuelranges/focus). Red Bull says “In extensive studies it has been repeatedly proven that Red Bull increases performance”(www.redbull.co.uk/cs/Satellite/e ... ink/001243026254412).

饮料厂商Maxifuel声称“咖啡因、瓜拉纳、牛磺酸等兴奋剂可快速补充体力，缓慢释放碳水化合物，从而在科学证实的范围内提高您的运动整体表现”。红牛则宣称“红牛饮料无数次被证明能提高运动成绩”。

Science behind the claims

Caffeine has long been used to enhance sports performance, and energy supplements containing caffeine, in addition to other compounds, are purported to be uniquely performance enhancing when taken together. These include taurine, a sulphonic amino acid that is thought to increase skeletal muscle contractility while decreasing systemic vascular resistance; and guarana, which contains caffeine and related xanthines. Caffeine acts as a competitive inhibitor of adenosine on central nervous system receptors, and an inhibitor of phosphodiesterase. It increases heart rate and induces glycogen sparing, and is believed to enhance available energy stores.

长久以来，我们使用咖啡因用来提高运动成绩，并且相信使用含有咖啡因和其他兴奋制剂的能量补充品能提高运动成绩。其他兴奋剂包括牛磺酸（一种被认为能增加骨骼肌收缩力并能降低全身血管阻力的磺酸氨基酸）和瓜拉那（含有咖啡因和三甲基黄嘌呤）。咖啡因是一种中枢神经腺苷的竞争性抑制剂，同时也是磷酸二酯酶的抑制剂，它加快心率，加快动员肝糖原分解（sy603注：可快速升高血糖，有时作用比肾上腺皮质激素更强），被认为可更好的利用储存的能量。

What the evidence says

One systematic review of adding caffeine to carbohydrate and several other reviews of caffeine alone suggest that it enhances endurance performance, with these effects being most marked after at least seven days’ abstinance from caffeine.

一篇综述发现，咖啡因加糖可增加运动耐力，其它一些综述报道，单用咖啡因也可增加耐力，但这些起效的前提是使用者7天内未服用过咖啡因。

We found nine randomised controlled trials investigating the effects of caffeine energy drinks. Four trials recruited the general public and five trained athletes. Seven tested a caffeine energy drink in addition to guarana and/or taurine.

我们分析了有关咖啡因功能饮料的9项随机对照试验。4项试验基于普通人群，5项基于运动员。7项试验测试了含牛磺酸和/或瓜拉那的咖啡因饮料。

Four studies reported positive effects: a study of 15 “healthy young adults” reported an energy drink increased mean bench press repetitions, but not anaerobic peak or average power during a cycling test. Aerobic and anaerobic endurance was increased in 14 habitual caffeine users and two trials demonstrated improved endurance in trained athletes.

4项研究报道了阳性结果：一项15人的“健康青年成人”的研究报道了一种功能饮料可增加仰卧举重次数，但在循环测试周期内并不能增加无氧峰值或平均推举力。另一项研究中，14名经常服用咖啡因者的有氧耐力和无氧耐力有所提高，还有2项研究显示，咖啡因可提高运动员的耐力。

Three studies found energy drinks did not improve sports performance: for running time to exhaustion among physically active university students, mean sprint time among female collegiate soccer players engaged in repeated running trials, and sprint performance or anaerobic power in American college football players.

3项研究发现能量饮料并不能提高运动成绩：包括在校大学生的持续跑步时间、大学女子足球队员在重复冲刺跑中的平均冲刺时间，以及美国大学生足球运动员的冲刺成绩或无氧运动能力。

Two studies tested the effect of a caffeine-only energy drink and did not include other supposedly performance enhancing compounds. One study of a caffeine-taurine energy drink reported its effect on echocardiographic findings and did not report sports outcomes. We did not find any research comparing the effectiveness of energy drinks versus caffeine alone on sports performance.

2项研究测试了仅含咖啡因的饮料（不包含其它可能提高运动成绩的成分）的作用。其中1项研究测试了一种咖啡因-牛磺酸饮料对运动前后超声心动图（心超）的 影响，结果呈阴性（无影响）。我们并没有检索到任何比较仅含咖啡因饮料与其他复合成分饮料对运动成绩的影响的报道。

On the negative side, effects of caffeine consumption can include insomnia, headache, and gastrointestinal bleeding. The harms of energy supplements include nausea and vomiting, tachycardia, tremors, seizures, and sleep disturbances, particularly in adolescents. There are several reports of cardiac arrhythmia and death, as well as reports of adolescents requiring hospital admission as a result of consuming energy drinks.

咖啡因的不良反应包括失眠、头痛和胃肠出血。而能量补充剂的损害包括恶心、呕吐、心动过速、震颤（sy603注：帕金森病的表现之一）、慢性病的急性发作（sy603注：也有可能是癫痫的突然发作）和睡眠障碍，损害在青少年人群中尤为明显。有数篇在饮用能量饮料后出现心率失常甚至死亡文献报道，还有一些研究报告青少年因饮用能量饮料而住院。

We could not identify any research that assesses the additional benefit energy drinks provide in addition to moderate caffeine doses, and we found no systematic reviews of these products and sports performance.

我们未检索到任何文献报道饮用功能饮料可以获得其他的（除了由摄取适量咖啡因可获得一定的益处）额外益处，并且，我们未检索到系统性的文献综述功能饮料与运动表现之间的关系。（拗口啊，意思是，运动饮料中除了咖啡因以外，其他成分毫无用处）

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专题４

Carbohydrate and protein combinations improve post-workout performance and recovery

碳水化合物和蛋白质联用促进运动后的恢复

“The combination of protein and carbohydrates has been shown to stimulate increased uptake of glucose by the cells, resulting in faster glycogen storage compared to carbohydrates or proteins alone (www.myprotein.com/uk/products/recovery_evo).”

Myprotein公司宣称，“联用蛋白质和碳水化合物被证实可促进细胞对葡萄糖的吸收，相较单纯补充蛋白质或碳水化合物，联合补充可更快的促进肝糖原储存。”

Science behind the claims

科学理论它说……

After exercise, hours of rest are usually sufficient to replenish glycogen stores alongside a regular diet. Ingesting carbohydrate during recovery from exercise may improve subsequent sports performance by increasing the rate of glycogen synthesis. However, combined ingestion of both protein and carbohydrate has been shown to synergistically influence the release of insulin, increase the rate of muscle glycogen storage, and reduce markers of exercise induced muscle damage.

运动后，运动者除了常规饮食外，需要数小时的休息储存糖原。在训练的恢复期间摄入碳水化合物可促进糖原合成，提高后续的运动成绩同时补充蛋白质和碳水化合物可能产生协同作用，影响胰岛素的释放，从而增加肌糖原的存储，降低肌肉损伤。

What the evidence says

循证医学证据如是说……

We identified 21 trials (15 randomised with 322 participants), of which fewer than half reported an overall benefit of combined protein and carbohydrate compared with carbohydrate alone. One systematic review concluded that the available evidence fails to show a relation between increased muscle glycogen synthesis and improved sports performance.

我们分析了21项研究（包括15项研究，涵盖322名参试者），其中不到一半的研究显示同时补充蛋白质和碳水化合物优于单纯补充碳水化合物。一篇系统性回顾文献认为现有循证医学证据无法证实肌糖原与运动表现有关。

Studies varied considerably in the outcomes and the ratio of carbohydrate to protein used: from 2:1 up to 6:1. Four studies that evaluated the effects of a 2:1 ratio on cycling performance were inconclusive. A 2006 study reported no difference in total distance cycled with supplementation, but two years later the same group reported the effect was significant. Similarly, another group found added protein improved sprint cycling performance in men 60 hours after exercise but not at 15 hours after exercise.

在不同研究中，碳水化合物/蛋白质摄入的比例不同（比例从2:1到6:1不等），效果也不同。有四项基于自行车成绩的研究采用2:1碳水化合物/蛋白质摄入的比例，结果不尽相同。一项2006年的研究称补充碳水化合物和蛋白质并不能提高自行车训练中的骑行距离，但2年后同一研究小组的研究结果与2006年相反（即补充碳水化合物和蛋白质可提高自行车训练中的骑行距离）。与此类似，另一研究小组发现在碳水化合物之外额外摄取蛋白质可提升男子自行车追逐赛后60小时的运动质量，但无法提升运动后15小时的运动质量。

The five studies evaluating a 4:1 protein to carbohydrate ratio had contrasting results. Only one study evaluated performance in a competition and reported no change in cross-country race times.

有5项对比研究采用4:1碳水化合物/蛋白质摄入的比例，只有一项研究评估了运动员在竞赛中（一项越野跑赛事）的表现，且该研究未发现有意义的结果。

Four of six studies evaluating a 3:1 ratio, used an isocaloric control, enabling comparison between two products of the same caloric content. Two reported improved cycling performance while the other two reported no change in running time to exhaustion or performance tests for football players. The improvement reported in the most recent study was trivial: a small increase in mean sprint cycling power of 2.5% with overlapping confidence intervals.

有6项研究采用3:1碳水化合物/蛋白质摄入的比例，其中4项研究控制了参试者的能量摄入，使研究者得以在参试者能量消耗相同的前提下比较碳水化合物和蛋白质的作用。在这4项研究中，2项针对自行车运动的研究得出同时补充碳水化合物和蛋白质可以提升运动成绩，而1项针对延缓跑步极点出现时间和1项提升足球运动员表现的研究未发现有阳性结果。一项近期研究（2011年）显示，使用亮氨酸-蛋白质可提升专业自行车追逐赛运动员2.5%的力量（99%可信区间； ±2.6%；p = 0.013）。

One study evaluated a 6:1 ratio and found no change in running time to exhaustion in 16 recreationally active men.

1项聚焦于积极参加运动人群（样本量：16）研究采用6:1碳水化合物/蛋白质摄入的比例，结果未发现碳水化合物和蛋白质摄入可延缓参试者跑步极点出现时间。

Experts have suggested there is little additional benefit of protein in supplements when carbohydrate is ingested in adequate quantities (≥1 g/kg/hour). If carbohydrate content reduces to below 1 g/kg/hour, then adding protein will produce similar results to carbohydrate alone. We found little consistent evidence across all included studies to support this claim.

专家建议，在摄入足量碳水化合物后（≥1 克/公斤/小时），再补充蛋白质效果有限。在摄入碳水化合物不足的情况下（<1 克/公斤/小时），补充蛋白质的效果与补充碳水化合物的效果类似。我们在少量研究中发现了支持这一专家观点的循证医学证据。

Six studies looked at whether carbohydrate and protein improved muscle recovery. Only one found that carbohydrate and protein after exercise induced muscle damage resulted in smaller decreases in muscle performance (such as. knee flexion repetitions) compared with carbohydrate alone. However, the main findings were post hoc analyses, and two follow-up studies failed to definitively replicate the findings. Three further studies looking at similar measures found no effects on muscle recovery.

6项研究分析了联合补充碳水化合物和蛋白质是否能加快肌肉恢复。其中，仅有1项研究发现，联合补充碳水化合物和蛋白质比单纯补充碳水化合物可以减少运动后由肌肉损伤引起的肌肉性能下降（如：膝关节反复屈曲能力）。然而，此项研究的结果是针对运动后肌肉的分析，且此研究后类似的2项研究重复出与此研究一致的结果。另外3项采用类似方法、更深入的研究也未能发现连用碳水化合物和蛋白质可加快肌肉恢复。

The lack of benefit from protein supplements on performance or muscle is probably due to the fact that most athletes consume adequate amounts of protein in their diets.

可能由于大多数运动员在日常饮食中摄入了足量的蛋白质，导致运动中额外补充蛋白质对提升运动成绩和改善肌肉恢复效果不佳。

sy603

专题5
Branched chain amino acids improve performance or recovery after exercise

支链氨基酸可提高运动成绩、加快运动恢复

Pure branch chain amino acids are claimed to help hard training athletes recover faster after intense exercise, combat muscle damage during exercise, and support peak endurance performance (www.maxifuel.com/bcaas). Manufacturers also maintain that they can “help to sustain a healthy immune system during periods of intense training and play an important role in fatigue and performance” (www.maximuscle.com/viper).

据Maxifuel公司（终于搞清楚这家公司的来头了，原来是gsk葛兰素史克公司的子公司，于2010年被gsk收购）称，支链氨基酸可帮助刻苦训练的运动员们在剧烈运动后快速恢复，战胜训练中产生的肌肉损伤，维持运动耐力的巅峰（说得花好稻好，药厂都是奸商啊）。而制造商Maximuscle则声称支链氨基酸“有助于在高强度运动时维持健康的免疫系统，在抗疲劳、提成绩方面亦有举足轻重的作用”。

Science behind the claims

科学理论依据

Branched chain amino acids (leucine, isoleucine and valine) are termed essential amino acids because they cannot be synthesised by humans and therefore have to obtained from the diet. They are incorporated into all protein structures and are an essential precursor for muscle protein. Muscle fibres are disrupted during exercise and essential amino acids are therefore required for repair, remodelling, and synthesis. Ingesting excess branch chain amino acids around the time of exercise is proposed to ensure maximum availability for synthesis of muscle. High blood levels of amino acids stimulate insulin release, which also promotes muscle synthesis. They also increase the activity of the mTOR (mammalian target of rapamycin) pathway, which regulates muscle cell growth and protein synthesis.

支链氨基酸（如亮氨酸、异亮氨酸和缬氨酸）亦称必需氨基酸，它们无法人工合成，只能从饮食中获取。（sy603注：必需氨基酸一共有8种，sy603读书时老师教大家用一句话来记忆：“借一两本带色书来”，即借(缬氨酸)、一(异亮氨酸)、两(亮氨酸)、本(苯丙氨酸)、带(蛋氨酸)、色(色氨酸)、书(苏氨酸)、来(赖氨酸)）。必需氨基酸是所有蛋白质必不可少的组成结构，自然是合成肌肉蛋白的重要原料。肌纤维在运动过程中被破坏，因此必需氨基酸起到修复、重构和合成纤维的作用。在运动过程中吸收额外的支链氨基酸被认为能在最大程度上确保肌肉（sy603注：似乎应该是肌蛋白）的合成。高浓度的氨基酸刺激胰岛素释放，同时促进肌蛋白合成。必需氨基酸也激活雷帕霉素靶蛋白（mTOR）旁路，后者调节肌细胞生长和肌蛋白合成。

What the evidence says

循证医学它说……
We found two systematic reviews; one did not report the inclusion criteria and the search strategy was poor quality, and the other concluded that any performance improvement was due to the energy value of the amino acids rather than muscle protein metabolism. We identified 27 randomised controlled trials, of which 20 (with 6-41 participants) measured athletic performance or recovery. There was no consistent use of objective measures for athletic performance or recovery and adverse effects of amino acid administration were not recorded across studies.

我们检索到2篇荟萃分析：一篇未说明文献入选标准，且文献收集方法不科学，另一篇分析得出的结论是氨基酸对提高运动成绩与氨基酸本身提供的能量有关，而与肌蛋白的代谢无关。我们检索到27项随机对照研究，其中20项（受试者人数6~41名）测定了运动成绩或恢复情况。遗憾的是，这些研究中均未采用一致、客观的方法评估运动成绩或运动恢复，也没有有关支链氨基酸应用的记录。

Crossover studies, which used a single dose of amino acids at the time of exercise testing, found no effect on work done during cycling sprints, distance travelled in a cycling time trial, maximum oxygen consumption, or time to exertion during cycling, and no effect was seen in parallel group studies on running to exhaustion or strength during squat weight lifting.
交叉研究（在运动时使用单一剂量的氨基酸）未发现氨基酸可以在自行车追逐实验中增加骑行距离，在自行车训练中也未能提升最大耗氧量或缩短骑行时间。平行对照研究也未发现氨基酸可减少跑步疲劳或增加蹲举力量。

Trial designs with longer durations of amino acid supplementation showed variable effects. One trial showed no effect over the course of a 32 hour yachting race on hand grip strength and vertical jump height. Studies using amino acid supplementation of up to one week reported no effect on cycling sprint power but found small increases in maximum oxygen consumption, increased time to exhaustion, and increased hand grip strength. Supplmentation for more than three weeks alongside regular weight training had no effect compared with standard protein on maximum leg and bench presses, but compared with placebo increased leg strength, upper body strength, and rowing time to exhaustion.
针对长时间运动时补充氨基酸的临床实验结果各异。一项实验在32小时赛艇比赛中测试参赛者的握力和纵跳高度，结果显示补充氨基酸并无影响。数项研究显示，在连续补充一周氨基酸后，自行车追逐赛中受试者的（冲刺）力量并未有所提升，但发现受试者的最大耗氧量、握力有些许增加，极点出现时间略有推迟。在常规举重训练之外，连续补充氨基酸三周以上并不能增加最大蹲举力量和最大推举力量，但相比使用安慰剂的受试者，补充氨基酸者的腿部力量、上身力量有所加强，推举疲劳有所缓解。

Short term ingestion of branched chain amino acids reduced perceived exhaustion at the time of testing independently of changes in performance. Significant reductions in fatigue have been reported in studies over the first hour of exercise, a reduction of 2.9 points on a 16 point exertion scale at 90 minutes and a 2.6 point difference on a 20 point scale at 120 minutes after exercise. Studies of longer term supplementation also showed subjective mean improvements on a 0 to 10 cm visual analogue scale (VAS) of 1.1 cm, small improvements on arbitrary indices from a VAS 12, and a difference of 2 points between BCAA and placebo on a 15 point scale. Amino acids significantly attenuated the reduction in leg flexion torque and maximal isometric leg muscle contraction observed in the placebo groups.
单因素统计显示，短期摄入支链氨基酸可减少视疲劳。此外，一些研究报道，补充氨基酸可降低运动第一小时内、一个半小时内（减少几率为2.9分，评分范围0~16分）、两小时内（减少几率为2.6分，评分范围0~20分）晕厥发生的几率。一些聚焦于长期摄入氨基酸的研究显示，摄入氨基酸者在基于主观评价的视觉模拟评分法（VAS）中可以增加1.1cm的分数（评分范围0~10cm），较服用安慰剂者，摄入氨基酸者可增加2分的评分（评分范围0~12分）。相较于安慰剂组，补充氨基酸者屈腿能力和腿部肌肉最大等长收缩力均有所增加。

Three trials reported the effect of amino acids on delayed onset muscle soreness after exercise. Amino acids significantly reduced muscle soreness by 1.2 points on a 10 point scale at 24 hours after endurance training but had inconsistent effects after intensive squats, with one trial showing no effect over 72 hours and another showing a reduction of 2 points on a 10 point scale at 24 hours.
3项临床实验报道证实了氨基酸有助于缓解迟发性运动后肌肉酸痛。其中一项研究表明，氨基酸可以大幅降低耐力训练24小时后发生的肌肉酸痛（以满分10分计算，缓解效果为1.2分）。但对高强度的蹲举式举重训练后肌肉酸痛的缓解效果，不同的研究给出不同的结果：一项研究认为训练72小时之后仍无缓解效果，而另一项研究显示，以满分10分计算，24小时后缓解效果为2分。

Trials with a high risk of bias that use longer term supplementation report improved athletic performance under laboratory conditions. All trials reporting subjective measures of endurance showed positive effects, irrespective of objective measures of performance.
一些临床实验中，受试者长时间使用氨基酸，结果显示在实验室环境中补充氨基酸可以提高运动成绩，但这些实验可能存在偏倚。且所有针对运动耐力的阳性结果报道均基于主观评判，缺乏客观的氨基酸与运动成绩之间的衡量方法和标准。

sy603

专题６

Compression garments improve performance or enhance recovery

压缩衣提高运动质量，加速运动恢复

“This ultra-tight, second-skin fit delivers a locked-in feel that keeps your muscles fresh and your recovery time fast” (www.underarmour.com/shop/uk/en/m ... -legging/pid1000525).

Under Armour公司在其公司网页上宣称：“这件超级紧身的‘第二层皮肤’牢固锁定您的肌肉，使您的肌肉外形焕然一新，并加速您的运动恢复”。

Science behind the claims

Sports compression garments are made of body hugging fabric that exerts various degrees of pressure and are designed to be worn next to the skin. They can cover the entire body or only the lower or upper halves.

运动压缩衣采用契合身体、具包裹性的材料制成，它直接穿着于皮肤之外，对身体产生不同的压缩力。它们可以贴合整个身体，也可以仅穿着于上半身或下半身。

Wearing compression garments during exercise is thought to improve venous return and increase removal of metabolites such as lactic acid. Additionally the garments are claimed to work by reducing the oscillation (or “wobble”) of muscles and tendons that occurs during repetitive exercise, thus reducing muscle pain and fatigue. By reducing damage the garments may reduce the predisposition to serious injury later. Finally, for contact sports such as rugby or American football, compression garments may cushion direct trauma to the body.

压缩衣被认为可以促进静脉血液回流，促进乳酸等代谢产物的清除，此外厂商声称压缩衣可以减少重复运动中肌肉、肌腱的震动（或称“晃动”），进而可以减少肌肉疼痛和肌肉疲劳。运动中减少肌肉的损伤意味着减少运动后严重受伤的几率。此外，压缩衣在接触性运动中（如橄榄球、美式足球）可以缓冲对人体的直接损伤。

What the evidence says

循证医学证据如是说……

We identified three trials that examined the effect of compression garments on actual sporting performance measures, all of which had negative results. One study of cyclists found no difference in 1 hour time trial performance, and two studies of runners found no significant difference in 10 km time trial performance or lactic acid levels.

我们查阅了3篇临床实验以验证压缩衣在实际运动中的作用，遗憾的是，所有报道均未发现压缩衣有任何益处。其中，1项对自行车手的。

A further 10 studies found no benefit from compression garments on various exercise protocols in controlled or laboratory settings. This included treadmill running or sprinting performance, performance in a netball specific circuit, cricket players’ sprinting performance and ball throwing distance, sprinting performance or lactate levels in hockey players, and tests on speed, aerobic endurance, agility, or power. Finally, a small study of cycling on ergometers found participants wearing compression stockings had significantly higher blood lactate levels at the end of exercise period and during the recovery period.

另有其他10项研究表明，无论是在不同种类的运动或在实验室环境中，穿着压缩衣的运动者运动成绩均未有所提高。这些研究的观察指标包括参试者在跑步机上进行长跑、短跑冲刺的表现，投球命中率，板球运动员的冲刺和掷球距离，曲棍球运动员的冲刺能力和血乳酸水平，传统的速度、有氧耐力、敏捷和力量测试。一项样本量较小的自行车测力计试验发现穿着压缩袜者在运动结束时和恢复期乳酸水平反而显著增加（不好的结果）。

Four studies reported improvements in exercise performance and reduced lactic acid levels in participants wearing compression garments; however, effects sizes were generally small.

4项研究表明，穿着压缩衣可以提升锻炼表现，降低乳酸水平，然而，这些研究的样本量均较小。

In terms of recovery from exercise, one study found compression substantially improved performance in a 40 km cycling time trial by a mean of 1.2%.

1项基于锻炼后恢复的研究表明，压缩衣可能提升40公里循环测试中1.2%的平均成绩。

Six studies reported a beneficial effect of compression garments (worn during or after exercise) on muscle soreness in runners, cricket players, weight lifters, general sprinting and jumping exercise session, untrained women doing arm exercises, and rugby players. Of these, three reported significantly lower levels of creatine kinase in the compression groups, a surrogate marker of muscle damage.

6项研究指出，运动时或运动后穿着压缩衣可以减轻长跑运动员、板球运动员、举重运动员、短跑跳高运动员的肌肉酸痛感，未经训练的妇女和橄榄球运动员在进行手臂训练时穿着压缩衣亦可减轻肌肉酸痛。在这6项研究中，3项研究中穿着压缩衣者肌肉损伤的指标肌酸激酶显著降低.

Finally, three studies that compared recovery using compression garments to other forms of recovery treatment (such as massage, hot and icy cold water therapy, low intensity exercise) found that all strategies were better than nothing but that compression garments had similar effects to those of these other treatments.

3项研究比较了穿着压缩衣和采用其他恢复手段（如按摩、冰水热水治疗、低强度的运动）对于运动恢复的影响，结果发现无论采取那种手段恢复速度均无差异。

Several studies have found that compression garments increased skin temperature compared with normal clothing. Although the single study that examined core temperature was done in cool conditions, it found no effect on core temperature. But for exercise in hot or humid environments, the alteration of normal skin thermoregulation could be important. One study of compression garments noted a reduced range of motion of the hips during exercise.

一些研究发现相对于穿着普通运动衣，压缩衣穿着者皮温更高。但炎热潮湿的运动环境中，皮肤自身的温度调节功能尤为重要。另一项研究发现，压缩衣可减少运动中髋关节的活动。

（本段漏译一句，容我三思）。

lijun

抢个沙发！

心有一抹蓝

太强悍了~
群里人才真多，欢迎多多分享

Dr.funk

等更新 搬个板凳慢慢看~~~

my201

总之一句话 人体结构不是为大运动量设计的 诸多运动后的辅助手段终究只会有很有限的改善作用

暴躁的豆腐

搬个板凳慢慢看

大白鲨笑江湖

占个板凳，然后飘过

小细

听专家给讲解，占位

leedior0101

这也太专业了，高深啊

sy603

欢迎论坛里运动专家、三甲医院医生、高年资医生及SCI专家拍砖。

TTHH2358

多数情况下，我们都不需要。理想的运动饮料是清水，平淡且简单，价格也合适。

如果你不是连续数个小时进行运动，运动饮料便不是必须的，相反，饮用可能会影响你的运动成绩。运动饮料的问题在于他们含有糖(不管什么形式的糖，糖总是糖)，当运动时你喝了含糖饮料，你必须在以后的运动中不断地通过喝糖饮料来维持血糖，否则更会遭受低血糖。

TTHH2358

一旦你开始摄入含糖的运动饮料，你就要连续服用，否则你便会顶不住。

sy603

多数情况下，我们都不需要。理想的运动饮料是清水，平淡且简单，价格也合适。

如果你不是连续数个小时进行运动，运动饮料便不是必须的，相反，饮用可能会影响你的运动成绩。运动饮料的问题在于他们含有糖(不管什么 ...
TTHH2358 发表于 2012-7-26 13:08

                               
登录/注册后可看大图

糖是个问题~~~~~~

iyomi

看着肝颤~~~~~~~~~~~~~~~