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.

營養(yǎng)已經(jīng)很快成為了科學家、教練和運動員用以提高耐力跑能力而探索和擺弄的下一個前沿。

這篇文章將討論良好營養(yǎng)的基本原則，其中將有對基本應邀要素（碳水化合物，脂肪，蛋白質(zhì)和水）的詳細的實驗，以及實驗科學家和營養(yǎng)學家對你飲食中每種營養(yǎng)要素應當包含多少才合適的建議。我最近注意到營養(yǎng)和訓練一樣都是很個人化的。你需要實驗和傾聽自己的身體來找到合適的營養(yǎng)搭配以及攝取營養(yǎng)的時間，以發(fā)現(xiàn)如何才能為你跑步最好的加油。

改善你的飲食的重要性在于評價（1）你每天攝入的熱量（稱之為你每日攝入總熱量）；（2）每日熱量中分別由碳水化合物、脂肪、和蛋白質(zhì)提供的比例。有了這些信息，你就可以評價你攝入的營養(yǎng)和調(diào)整你的熱量攝取以達到減輕體重的目的。這個評估同樣反應了你的飲食重點和薄弱環(huán)節(jié)，讓你可以將你的飲食和很多專家推薦的飲食做個比較，為了幫助你，我們開發(fā)了跑步者營養(yǎng)計算器 。

最終你會學會使用你計算出的必需的營養(yǎng)來分析你的飲食，這樣的分析可以讓你彌補你飲食中的薄弱環(huán)節(jié)，從而保證你吃的合適，提高你在耐力長跑比賽中獲勝的機會。

主要營養(yǎng)素

有四種營養(yǎng)素是人體大量需要以維持功能正常的，它們被稱為主要營養(yǎng)素，包括（1）碳水化合物（2）脂肪（3）蛋白質(zhì)和（4）水。

碳水化合物

第一種主要營養(yǎng)素是碳水化合物。碳水化合物也就是通常說的糖，是長跑運動員的基礎(chǔ)營養(yǎng)以及快速補充能量的飲食來源。專家建議跑步者的飲食應當包含50-70%的碳水化合物。而推薦的區(qū)間減肥法只包含40%的碳水化合物，而一種低能減肥飲食甚至更低。

身體中碳水化合物的唯一用處就是提供能量。身體中能量的標準單位是卡，每克碳水化合物可以提供4卡能量。

我們攝入的碳水化合物可以分為簡單的和復雜的。簡單的碳水化合物就是糖的最基本形式，只由1-2個分子組成，包括葡萄糖、果糖和蔗糖。包含這類碳水化合物的食物包括糖果、水果、牛奶、運動飲料和能量棒。

由于簡單的碳水化合物只包含1-2個分子，因此可以迅速的被血液吸收。這種快速吸收可以在你血糖濃度很低的時候快速而短暫的提供能量，那同時也意味著運動醫(yī)學家所說的血糖效應。

胰島素是一種胰臟分泌的激素，用于將糖從血液中轉(zhuǎn)移到細胞中。這樣血液中的糖濃度又會回到一個較低水平，從而降低能量和運動水平。運動員需要謹慎攝入單糖以避免血糖的忽上忽下。典型的美國飲食包含了很多單糖，這是其流行的一個因素。我們都經(jīng)歷過這樣的“糖崩”因此我們能很好得了解其對我們每日生活和跑步的潛在影響。

第二種碳水化合物是多糖。多糖和單糖的不同在于其有多個葡萄糖分子結(jié)合而成。由于其復雜的結(jié)構(gòu)，被血液吸收的速度要慢得多，也能提供更加緩慢和穩(wěn)定的能量供應，因此可以避免血糖效應。

因此多糖比單糖更能保持穩(wěn)定的血糖濃度，專家建議從碳水化合物中攝取的大部分能量應當是以多糖的形式獲得。富含多糖的食物包括粗糧、面、面包、米飯、土豆和蔬菜。