This is Part Four of a five-part series on total load, the cumulative training and life stress an athlete experiences while training. ReadPart One,Part Two， 和第三部分获取完整的故事。
There are innumerable articles on sports nutrition on the培训博客还有其他地方，但没有恢复这一基础，而是专注于损害运动员努力训练和迅速康复的能力的营养实践。就像本系列中的其他文章一样，我们将使用heart rate variability (HRV)研究以说明这些实践如何通过在体内产生压力反应来表现。HRV是运动员的宝贵工具，因为它允许每天评估总现金伟德平台压力，该压力可用于评估当前的恢复状态，以及您的身体已准备好哪种训练。
在运动员中造成营养压力的三个最常见因素是：
- 脱水
- 酒精
- 炎
脱水
在温暖的环境中运动超过几个小时的任何人都可能注意到，尽管保持相同的速度或力量，但他们的心率可能会继续增加。乔·弗里尔（Joe Frieldehydration。
Any upward trend in heart rate while maintaining the same load on the body indicates a shift from parasympathetic to sympathetic dominance and an acute increase in stress. If the stress state brought on by dehydration continues, then recovery is delayed relative to an athlete who is adequately hydrated.
2014年，智利大学的研究人员研究了脱水对HRV和HRV代谢率（RMR）的影响。RMR或您的身体在静止状态下消耗能量的速度，众所周知，在强化运动后保持高水平，研究人员想看看这是否也受到脱水的影响。
14名男性大学水平运动员的称重，测量了HRV和静息代谢率，并测试了尿液。要求运动员在32C（90F）环境中进行强化运动，并进行一分钟爆破的电路训练，共有一分钟的休息时间，共45分钟。这样做的目的是使运动员体重的3.5％脱水，或80公斤（176磅）运动员的体重约为2.5千克（5.5磅）。
然后，运动员分为两组，其中一组获得了失去的液体的1.5倍（补液组），而另一组则处于脱水状态（脱水组）。他们发现：
- 心率变异性（HRV）was significantly lower in the dehydration group
- Resting metabolic rate在脱水组中要高得多
The decreased HRV may indicate a delayed return to the “rest and digest” state that we need to rebuild and restore the body’s reserves.
研究人员的建议是，在运动过程中消耗大约150％的液体，以确保完全水合状态并使用电解质补充剂进行扩展锻炼。在热环境中尤其如此，以最大程度地减少脱水贡献total load。
酒精
尽管脱水肌萎缩性侧索硬化症o be the first, and perhaps the only reason, that athletes typically think of for not consuming alcoholic drinks, there are, in fact, several ways in which alcohol adds to the total stress load of the body:
- 水合。酒精是一种利尿剂，即它使您失去的液体比饮料所含的更多。如果未更换该液体，则饮料可能会产生额外的压力并延迟恢复。
- Refueling。糖原（首选的肌肉燃料）的替代是至关重要的，但是研究表明，替换饮酒的运动员需要近两倍。
- 肌肉重建。酒精suppresses the protein synthesis needed to repair and strengthen muscles, impairing your adaptation to training. It also delayed onset muscle soreness (DOMS).
- 睡觉。A drink or two might help you更快入睡如果您的头脑活跃，但酒精也会干扰您的睡眠质量，尤其是REM在晚上睡觉。回忆在REM睡觉期间存储，因此，人们说他们不记得前一天晚上发生的事情的一部分原因。其他后果包括第二天集中精力的能力以及需要精确协调的运动风险增加。
与酒精消耗和心率变异性有关的研究并不多，但是人们仔细研究了全面的SDNN HRV措施。他们表明，随着每周饮酒量的增加，人力资源管理会下降：
This data shows a minimal impact for the recommended two small drinks per day, but by the time research subjects were consuming twice that amount, HRV was reduced by around 10 percent. Doubling consumption again reduces HRV by a very significant 25 percent compared to consuming no alcohol at all.
There are several adjustments that can help minimize the impact of alcohol on recovery:
- Try to leave as much time as possible between finishing training and having an alcoholic drink. Fit in a recovery drink with carbs in between (contrary to popular opinion, beer and wine do not contain useful quantities of carbs for athletes).
- 喝水或软饮料，将有效的酒精浓度降低到三％。这意味着将啤酒与一品脱的水交替，或为每杯酒喝三杯水。
- Eat salty snacks. Studies have found reduced impact of alcohol when taken together with salt, as the salt helps retain water.
- 事前禁欲。您已经花了数周和几个月的时间准备在比赛中尽力而为，因此不要在三到四天的时间里危害性能。
炎
炎is the body’s mechanism for managing repair, and therefore, in principle, a good thing. For example, inflammation is necessary for muscle growth as it participates in protein breakdown, removal of damaged muscle fibres, and production of prostaglandins. However, a lot of the time the body is struggling with low grade chronic inflammation that adds to total load.
炎is a stress response driven by the sympathetic nervous system but regulated or “turned down” by the parasympathetic nervous system that we measure with HRV. What does this have to do with nutrition you may ask? Well, take a look at this example of伊斯莱特HRV readings taken by leading HRV researcher Dr. Andrew Flatt during a week when he relaxed his usual healthy diet in favour of high glycaemic, highly processed, and refined foods known to promote inflammation:
As well as significant daily drops in HRV during the week, his overall baseline also reduced without having done any training.弗拉特博士的结论就是这样：“吃促进体内炎症的食物会产生您的身体必须应对的压力。在应对这种压力时，我们降低了适应和从训练中恢复的能力。”
从营养上讲，驱动慢性炎症的最常见因素之一是omega-3和Omega-6脂肪来源之间的不平衡，后者在促炎性加工食品饮食中都更为常见。答案可能是增加饮食量的omega-3脂肪，最好是来自野生脂肪鱼。养殖脂肪鱼由于饮食的改变而几乎没有omega-3。已知反脂肪是促炎的，并且在糕点，甜甜圈，人造黄油和其他零食食品等食品中发现。
Foods that reduce inflammation include fruits (especially berries) and green vegetables, olive oil, ginger, garlic, turmeric, organic meat and fish, and green tea. Studies have also shown the Mediterranean diet to be associated with higher levels of HRV and overall health.
结论
在本文中，我们回顾了机制和证据，表明年龄段运动员中常见的营养实践会产生压力负荷，除了训练外，身体还必须承担的压力负荷。这种额外的负载延迟了恢复，并阻止运动员尽可能地进行艰苦而有效的训练，以获得最大的适应和表现。
The good news is that all of these factors are relatively easily managed, and that regular HRV monitoring provides an overall health barometer to help identify what is working.
In the final part of this series, we will be looking at how sleep (or more commonly, the lack of it) contributes to total load in the athlete.
The next article in this five-part series will take a closer look at how sleep contributes to total load.
参考：
- IOC共识声明：饮食补充剂和高性能运动员。Maughan RJ，等。Br J Sports Med。, 2018
- Periodized Nutrition for Athletes. Asker E Jeukendrup. Sports Med., 2017
- Heart-rate variability: a biomarker to study the influence of nutrition on physiological and psychological health? Hayley A. Young and David Benton. Behavioural Pharmacology., 201
- 运动后的水合状态会影响静息代谢率和心率
- Variability. Mauricio Castro-Sepúlveda, et al. Nutr Hosp., 2015
- Relations between alcohol consumption, heart rate, and heart rate variability in men. J M Ryan and L G Howes. Heart., 2002
