Nutrition is rapidly becoming the next frontier that many scientists, coaches and athletes are exploring and manipulating for improved distance running performance.

This article will discuss the basic principles of good nutrition with a detailed examination of the primary nutrients (carbohydrates, fats, proteins and water) as well as the recommendations made by exercise scientists and nutritionists as to the proper amounts of each nutrient that should be included in your diet. I note right up front that nutrition, like training, is very individual. You need to experiment and listen to your body to find the right mix of nutrients and the timing of your nutrient intake to see what best fuels your running.

Vital to the improvement of your diet is evaluating (1) the amount of calories that you obtain per day (called your total daily caloric intake), (2) the proportion of these daily calories that are supplied by carbohydrates, fats and proteins. Armed with this information, you can evaluate your nutrient intake and even adjust your caloric intake to acheive your weight loss goals. This evaluation will also reveal your dietary strengths and weaknesses, enabling you to compare your diet to what the diets recommended by various experts. To help you, we've created the Runner's Nutrition Calculator.

And finally, you’ll learn how to use your calculated nutritional needs to analyze your diet. This analysis will allow you to correct your nutritional weaknesses to ensure that you are eating properly, thus optimizing your chances at distance running success.

The Primary Nutrients

There are four substances that the body requires in large quantities in order to function properly. These four substances are called the primary nutrients and include (1) carbohydrates, (2) fats, (3) proteins and (4) water.

Carbohydrates

Carbohydrates, also known as sugars, are the primary nutrient and dietary source of quick energy for distance runners. Experts recommend that runners’ diets consist of 50 to 70 percent carbohydrate. The zone diet recommends 40 percent and a low-carb diet reduces this even further.

The sole purpose of carbohydrates in the body is to provide energy. The standard unit for the energy our bodies use is called a calorie. Each gram of carbohydrate provides four calories.

The carbohydrates that we eat can be classified as either simple or complex. Simple carbohydrates are the most basic form of sugar and consist of only one or two molecules. These simple sugars include among others, glucose, fructose and sucrose. Examples of foods containing this type of carbohydrate include candy, fruit, milk, sports drinks and energy gels.

Since simple carbohydrates consist of only one or two molecules, they are rapidly absorbed into the bloodstream. While this fast absorption is great for providing a quick “shot” of energy during periods when the blood sugar level is low, it also induces what exercise scientists call an insulin response.

Insulin, a hormone produced by the pancreas, facilitates the removal of sugar from the bloodstream and places it in the cells. As a result, the blood sugar level is returned to a low level resulting in both decreased energy and performance. Athletes have to be careful with their intake of simply sugars to avoid this spike and fall in blood sugar. The typical American diet is full of simple sugars which may be a contributing factor in the epidemic in diabetes. We’ve all experienced a “sugar crash” so you’re well aware of the potential for this to interfere with your everyday life and your running.

The second type of carbohydrate is the complex carbohydrate. Complex carbohydrates, unlike the simple sugars, are composed of several glucose molecules linked together. As a result of their more complex structure, they are absorbed more slowly into the bloodstream, providing a more favorable slow and steady supply of energy, thus avoiding the pitfalls of the insulin response.

Since complex carbohydrates maintain a more consistent blood sugar level than do simple carbohydrates, experts recommend that the majority of the calories obtained from carbohydrates be in the form of the complex carbohydrates. Examples of foods that are high in complex carbohydrates include cereals, pasta, breads, rice, potatoes, and vegetables.

营养已经很快成为了科学家、教练和运动员用以提高耐力跑能力而探索和摆弄的下一个前沿。

这篇文章将讨论良好营养的基本原则，其中将有对基本应邀要素（碳水化合物，脂肪，蛋白质和水）的详细的实验，以及实验科学家和营养学家对你饮食中每种营养要素应当包含多少才合适的建议。我最近注意到营养和训练一样都是很个人化的。你需要实验和倾听自己的身体来找到合适的营养搭配以及摄取营养的时间，以发现如何才能为你跑步最好的加油。

改善你的饮食的重要性在于评价（1）你每天摄入的热量（称之为你每日摄入总热量）；（2）每日热量中分别由碳水化合物、脂肪、和蛋白质提供的比例。有了这些信息，你就可以评价你摄入的营养和调整你的热量摄取以达到减轻体重的目的。这个评估同样反应了你的饮食重点和薄弱环节，让你可以将你的饮食和很多专家推荐的饮食做个比较，为了帮助你，我们开发了跑步者营养计算器 。

最终你会学会使用你计算出的必需的营养来分析你的饮食，这样的分析可以让你弥补你饮食中的薄弱环节，从而保证你吃的合适，提高你在耐力长跑比赛中获胜的机会。

主要营养素

有四种营养素是人体大量需要以维持功能正常的，它们被称为主要营养素，包括（1）碳水化合物（2）脂肪（3）蛋白质和（4）水。

碳水化合物

第一种主要营养素是碳水化合物。碳水化合物也就是通常说的糖，是长跑运动员的基础营养以及快速补充能量的饮食来源。专家建议跑步者的饮食应当包含50-70%的碳水化合物。而推荐的区间减肥法只包含40%的碳水化合物，而一种低能减肥饮食甚至更低。

身体中碳水化合物的唯一用处就是提供能量。身体中能量的标准单位是卡，每克碳水化合物可以提供4卡能量。

我们摄入的碳水化合物可以分为简单的和复杂的。简单的碳水化合物就是糖的最基本形式，只由1-2个分子组成，包括葡萄糖、果糖和蔗糖。包含这类碳水化合物的食物包括糖果、水果、牛奶、运动饮料和能量棒。

由于简单的碳水化合物只包含1-2个分子，因此可以迅速的被血液吸收。这种快速吸收可以在你血糖浓度很低的时候快速而短暂的提供能量，那同时也意味着运动医学家所说的血糖效应。

胰岛素是一种胰脏分泌的激素，用于将糖从血液中转移到细胞中。这样血液中的糖浓度又会回到一个较低水平，从而降低能量和运动水平。运动员需要谨慎摄入单糖以避免血糖的忽上忽下。典型的美国饮食包含了很多单糖，这是其流行的一个因素。我们都经历过这样的“糖崩”因此我们能很好得了解其对我们每日生活和跑步的潜在影响。

第二种碳水化合物是多糖。多糖和单糖的不同在于其有多个葡萄糖分子结合而成。由于其复杂的结构，被血液吸收的速度要慢得多，也能提供更加缓慢和稳定的能量供应，因此可以避免血糖效应。

因此多糖比单糖更能保持稳定的血糖浓度，专家建议从碳水化合物中摄取的大部分能量应当是以多糖的形式获得。富含多糖的食物包括粗粮、面、面包、米饭、土豆和蔬菜。