Sports Nutrition - Carbohydrate - Carbs

Carbohydrate is arguably the most important source of energy for athletes. No matter what sport you play, carbs provide the energy that fuels muscle contractions. Once eaten, carbohydrates breakdown into smaller sugars (glucose, fructose and galactose) that get absorbed and used as energy. Any glucose not needed right away gets stored in the muscles and the liver in the form of glycogen. Once these glycogen stores are filled up, any extra gets stored as fat.

Glycogen is the source of energy most often used for exercise. It is needed for any short, intense bouts of exercise from sprinting to weight lifting because it is immediately accessible. Glycogen also supplies energy during the first few minutes of any sport. During long, slow duration exercise, fat can help fuel activity, but glycogen is still needed to help breakdown the fat into something the muscles can use.

Adequate carbohydrate intake also helps prevent protein from being used as energy. If the body doesn’t have enough carbohydrate, protein is broken down to make glucose for energy. Because the primary role of protein is as the building blocks for muscles, bone, skin, hair, and other tissues, relying on protein for energy (by failing to take in adequate carbohydrate) can limit your ability to build and maintain tissues. Additionally, this stresses the kidneys because they have to work harder to eliminate the byproducts of this protein breakdown.

Carbohydrate has other specific functions in the body including fueling the central nervous system (CNS) and brain.

Storing Carbohydrate
One gram of carbohydrate provides four calories of energy. Athletes often talk about carbohydrate loading and carbohydrate depletion which refers to the amount of carbohydrate energy we can store in our muscles. This is generally around 2,000 carbohydrate calories, but we can change this number through depletion and loading. During depletion (from diet, exercise or a combination) we use up the stored carbohydrate.

If we don’t replenish these stores, we can run out of fuel for immediate exercise. Athletes often refer to this as "bonking" or "hitting the wall." In the same way, eating large amounts of carbohydrates can increase these stores. This is often referred to as carbohydrate loading or carbo-loading. Our maximal carbohydrate storage is approximately 15 grams per kilogram of body weight [15 grams per 2.2 pounds]. So a 175-pound athlete could store up to 1200 grams of carbohydrate [4,800 calories]; enough energy to fuel high intensity exercise for quite some time.

How Carbohydrate Fuels Exercise
Carbohydrate stored as glycogen is an easily accessible source of energy for exercise. How long this energy supply lasts depends on the length and intensity of exercise and can range anywhere from 30 to 90 minutes or more. To avoid running out of energy during exercise, start with full glycogen stores, replenish them during exercise and refill them after exercise to be ready for the next workout.

Types of Carbohydrate
Carbohydrates are also divided into simple and complex forms. Simple sugars (carbs) are absorbed and converted to energy very quickly and provide a rapid source of energy. Fruit and energy drinks are a good source of simple carbohydrates.

Complex carbohydrates take a bit longer to be digested and absorbed into the body. They also take longer to breakdown and therefore provide energy at a slower rate than simple sugars. Examples of complex carbohydrates are breads, rice and pasta. Starch and fiber are also considered complex carbohydrates but fiber can not be digested or used for energy. Starch is probably the most important energy source in an athlete’s diet because it is broken down and stored as glycogen. Foods high in starch include whole grain breads, cereals, pasta, and grains.

Sports Nutrition - Fat
Dietary fat is often blamed for many health problems; however, fat is an essential nutrient for optimal health. Adipose tissue (stored fat) provides cushion and insulation to internal organs, covers the nerves, moves vitamins (A, D, E, and K) throughout the body and is the largest reserve of stored energy available for activity. Fat is stored when we consume more calories then we use. There is an optimal level of body fat for health and for athletic activity. When that optimal level is exceeded, too much dietary fat can lead to problems with health as well as athletic performance.

Types of Dietary Fat

• Saturated fats are found primarily in animal sources like meat, egg yolks, yogurt, cheese, butter, milk. This type of fat is often solid at room temperature. Too much saturated fat has been linked to health problems such as high cholesterol and heart disease. Because of this, saturated fat should be limited to no more than 10% of total daily calorie intake.
• Unsaturated fats include monounsaturated and polyunsaturated fats, which are typically found in plant food sources and are usually liquid at room temperature. Unsaturated fats have health benefits such as lowering cholesterol and reducing the risk of heart disease. Common food sources include olive and canola oil, avocados, fish, almonds, soybeans and flaxseed.
• Trans fat has recently been added to the nutrition labels of most products. Trans fatty acids are created (naturally or man-made) when an unsaturated fat is made into a solid. Trans fats, like saturated fat, should be limited because they increase cholesterol levels and the risk of heart disease.

How Fat Provides Energy for Sports
Fat provides the highest concentration of energy of all the nutrients. One gram of fat equals nine calories. This calorie density, along with our seemingly unlimited storage capacity for fat, makes fat our largest reserve of energy. One pound of stored fat provides approximately 3,600 calories of energy. While these calories are less accessible to athletes performing quick, intense efforts like sprinting or weight lifting, fat is essential for longer, slower lower intensity and endurance exercise such as easy cycling and walking.

Fat provides the main fuel source for long duration, low to moderate intensity exercise (endurance sports such as marathons, and ultra marathons). Even during high intensity exercise, where carbohydrate is the main fuel source, fat is needed to help access the stored carbohydrate (glycogen).

Using fat for fuel for exercise, however, is dependent upon these important factors:

• Fat is slow to digest and be converted into a usable form of energy (it can take up to 6 hours).
• Converting stored body fat into energy takes time. The body needs to breakdown fat and transport it to the working muscles before it can be used as energy.
• Converting stored body fat into energy takes a great deal of oxygen, so exercise intensity must decrease for this process to occur.

For these reasons, athletes need to carefully time when they eat fat, how much they eat and the type of fat they eat. In general, it’s not a great idea to eat fat immediately before or during intense exercise.

Sports Nutrition - Protein

Proteins are often called the building blocks of the body. Protein consists of combinations of structures called amino acids that combine in various ways to make muscles, bone, tendons, skin, hair, and other tissues. They serve other functions as well including nutrient transportation and enzyme production. In fact, over 10,000 different proteins are in the body.

Adequate, regular protein intake is essential because it isn’t easily stored by the body. Various foods supply protein in varying amounts with complete proteins (those containing 8 essential amino acids) coming mostly from animal products such as meat, fish, and eggs and incomplete protein (lacking one or more essential amino acid) coming from sources like vegetables, fruit and nuts. Vegetarian athletes may have trouble getting adequate protein if they aren’t aware of how to combine foods.

Learn More:
Tips for Vegetarian Athletes

Protein Needs for Athletes

Athletes need protein primarily to repair and rebuild muscle that is broken down during exercise and to help optimizes carbohydrate storage in the form of glycogen. Protein isn’t an ideal source of fuel for exercise, but can be used when the diet lacks adequate carbohydrate. This is detrimental, though, because if used for fuel, there isn’t enough available to repair and rebuild body tissues, including muscle.

Recommended Daly Protein Intake

• The average adult needs 0.8 grams per kilogram (2.2lbs) of body weight per day.
• Strength training athletes need about 1.4 to 1.8 grams per kilogram (2.2lbs) of body weight per day
• Endurance athletes need about 1.2 to 1.4 grams per kilogram (2.2lbs) of body weight per day

How Much Protein is That?
Not much, as it turns out. Here is a list of some high protein foods.

Food, Amount, Protein

Fish, 3 oz, 21 grams
Chicken, 3 oz, 21 grams
Turkey, 3 oz, 21 grams
Meat, 3 oz, 21 grams
Milk, 8 oz, 8 grams
Tofu, 3 oz, 15 grams
Yogurt, 8 oz, 8 grams
Cheese, 3 oz, 21 grams
Peanut butter, 2 tbsp, 8 grams
Eggs, 2 large, 13 grams

Strength athletes believe more protein is important to build muscle. It turns out that strength athletes actually require high carbohydrate intake and adequate glycogen stores to fuel their workouts. It is the strength training workout that leads to increased muscle mass and strength. This is because all high intensity, powerful muscle contractions (such as weight lifting) are fueled with carbohydrate. Neither fat nor protein can be oxidized rapidly enough to meet the demands of high-intensity exercise. Adequate dietary carbohydrate must be consumed daily to restore glycogen levels.

If you don’t eat meat, it can take a bit more planning to get adequate protein for muscle building and sports training. Vegetarians must take extra care to avoid deficiencies of iron, zinc, and B12, which can hurt exercise and strength training performance.

Nutrition Tips for Vegetarian Athletes

The following tips will help vegetarians who want to get the most from strength training programs.

 

How to Get Adequate Protein in Your Diet

The current protein recommendations for optimal muscle building in a strength athlete is 1.6 to 1.7 gram protein per kilogram of body weight (0.73 grams per pound). For a 200-pound athlete, that is a total of 145 to 154 grams of protein a day. There is no scientific evidence that more than 2.0 grams of protein per kg of body weight has any additional benefit in muscle strength or size.

You can get enough protein by including plenty of low-fat dairy products and protein-rich plant sources, like soy, in your diet. The following protein sources may work for vegetarians:

• Milk, 8 oz, 8 grams
• Tofu, 3 oz, 15 grams
• Yogurt, 8 oz, 8 grams
• Cheese, 3 oz, 21 grams
• Peanut butter, 2 tbsp, 8 grams

 

How to Get Adequate Iron in Your Diet

Heme iron is a type of easily absorbed iron that is found in animal protein. If you eat fish or chicken, you will get this type of iron, but if you eat no meat, you will need to find other sources of iron. Our bodies don't absorb non-heme iron –- the kind found in vegetables -– as easily as the iron that comes from animal foods. Non-meat eaters, especially female athletes, must pay attention to their dietary iron needs. Good sources of non-heme include wholegrain cereals, leafy green vegetables, figs, lentils and kidney beans, and some dried fruits.

How to Get Adequate Vitamin C in Your Diet

Vitamin C in fruits, vegetables, and other foods help vegetarians absorb non-heme iron from other foods, so it’s a good idea to eat a combination of foods at each meal. Consider eating citrus fruits with an iron-fortified wholegrain cereal or have a citrus fruit juice with beans.

How to Get Adequate B12

Because vitamin B12 is available only from animal products, it is one of the most common nutrients missing from the diets of vegetarian athletes. To get enough B12 (you require only a small amount-2.4 micrograms-per day) try to eat B12-fortified foods like soymilk, and cereal. You can also get enough B12 if you consume eggs, cheese, milk or yogurt.

Avoid Foods That Interfere with Iron Absorption

Some foods contain substances that block the absorption of iron in the intestine. Coffee, whole grains, bran, legumes, and spinach all interfere with iron absorption and should be combined with vitamin C to increase iron absorption.

Talk To Your Doctor About Supplements

Although dietary supplements should not be used to make up for a poor diet, there are times when they can help prevent some deficiencies. Ideally, you should discuss the use of any supplements with your healthcare team.

All athletes are encouraged to eat a balanced diet that includes a wide variety of foods, but vegetarian athletes can rest assured that they don’t have to eat meat in order to get adequate nutrition for strength building. If you have concerns about your nutritional status, is is recommended that you talk with your doctor or a registered sports nutritionist to review you eating plan and make recommendations.