Thursday, June 4, 2009

Sports Nutrition - Protein Needs for Athletes



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.

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.

Wednesday, June 3, 2009

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Sports Nutrition - Protein Needs for Athletes

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Sports Nutrition - How Carbohydrate Provides Energy for Exercise


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.