Wellness Articles

Fuel Sources And The Athlete

Sports Therapy Vancouver

Eating a balanced diet is another key to sports nutrition. The right combination of fuel (calories) from carbohydrates, proteins, and fats gives you energy for optimal performance.

The most important fuel source, carbohydrates come in fruits, vegetables, pastas, breads, cereals, brown rice, and other foods. Carbohydrates should provide about 60-70 percent of daily calories. Your body converts sugars and starches in carbohydrates to energy (glucose) or stores it in the liver and muscle tissues (glycogen), giving you endurance and power for high-intensity, short-duration activities, or non-aerobic activity. If your body runs out of carbohydrate fuel during this type of exercise, it will burn fat and protein for energy, causing your performance level to drop. This can happen if you start exercising without much muscle glycogen, exercise heavily for more than an hour without eating more carbohydrates, do repeated high-intensity, short-duration exercises, or participate in multiple events or training sessions in a single day.

Use a carbohydrate strategy to stay energized and perform at your best
1. Eat carbohydrates for at least several days before exercise/competition, so you start with glycogen-loaded muscles.
2. Eat more carbohydrates during exercise/competition lasting more than an hour to replenish energy and delay fatigue.

Proteins are derived from meats, fish, poultry, eggs, beans, nuts, dairy products, and other foods. Ideally, protein should provide approximately 12-15 percent of total daily caloric intake. Proteins give your body power to build new tissues and fluids, among other vital functions. Your body cannot store extra protein so it burns it for energy or converts it to fat. The amount of protein an athlete needs depends in part upon level of fitness; exercise type, intensity and duration; total calories; and carbohydrate intake.

Level of fitness
Physically active people require more protein as compared with those who don’t exercise. You also require more when you initiate an exercise program.

Exercise type, intensity, and duration
Endurance athletes often burn protein for fuel, as do body builders and others doing intense, strength-building activities.

Total calories
Your body burns more protein if you don’t consume enough calories to maintain body weight. This can happen if you eat too little or exercise too much.

Carbohydrate intake: Your body may use protein for energy if you exercise with low levels of muscle glycogen or if you do repeated training sessions without eating more carbohydrates. When you start with enough muscle glycogen, protein supplies about 5 percent of energy. Otherwise, it may supply up to 10 percent.

Saturated fats are found in animals foods (i.e., meats, eggs, milk, cheese, etc.) and unsaturated fats are found in some vegetable products (i.e., coconut oil, corn oil, etc). To simplify, saturated fats are solid and unsaturated fats are liquid. Fats should provide no more than about 20-30 percent of daily calories. Your body requires a small amount of fat for various critical functions and as an alternative energy source to glucose. Eating too much fat is associated with heart disease, high cholesterol, some cancers, and other major health problems. This can often mean that you don’t consume enough carbohydrates.

How your body uses fat for energy depends upon the intensity and duration of exercise
1. When you rest or exercise at low to moderate intensity, fat is the primary fuel source.
2. As you increase exercise intensity, your body uses more carbohydrates for fuel.
3. If your body uses up its glycogen supply and you keep exercising, your body will burn fat for energy, decreasing exercise intensity.

Which is Better – Carbohydrates or Fats for Exercise?
When it comes to eating for exercise there are several things to consider while meal planning. Carbohydrate, fat, and protein all contribute to the fuel supply needed by working muscles, with carbohydrates and protein providing 4 Calories per gram and fat providing 9 Calories per gram. All nutrients get converted to energy in the form of adenosine triphosphate or ATP. However, each nutrient has unique properties that determine how it gets converted to energy.

Carbohydrate is the main nutrient that fuels exercise of a moderate to high intensity; glycogen for anaerobic and glucose for aerobic exercise. Fat can fuel low intensity exercise for long periods of time (aerobic exercise). Proteins are generally used to maintain and repair body tissues, and are not normally used to power muscle activity. Because the body can not easily store ATP (and what is stored gets used up within a few seconds), it is necessary to continually create ATP during exercise. There are three main pathways to convert nutrients to ATP and it is the intensity and duration of the exercise which determines what method gets implemented. The first path only supplies about 10 seconds worth of energy and is used for short bursts of exercise such as a 100 meter sprint. After this, either aerobic or anaerobic metabolism is used to continue to create ATP. Then major difference between aerobic and anaerobic metabolism is the presence of oxygen to create ATP.

Aerobic metabolism requires oxygen to convert nutrients (carbohydrates, fats, and protein) to ATP. Aerobic metabolism is used primarily during endurance activities.

Anaerobic metabolism (glycolysis), creates ATP exclusively from carbohydrates, with lactic acid and muscle pain, burning and fatigue make it impossible to maintain that intensity. During exercise an athlete will move through these metabolic pathways. As exercise begins, ATP is produced via anaerobic metabolism. With an increase in breathing and heart rate there is more oxygen available and aerobic metabolism begins and continues until VO2Max is reached. If VO2Max it surpassed, the body can not deliver oxygen quickly enough to generate ATP and anaerobic metabolism kicks in again. Since this system is short-lived and lactic acid levels rise, the intensity can not be sustained and the athlete will need to decrease intensity to remove lactic acid build-up. being a by-product. As lactic acid builds up in the muscle it causes physical discomfort and pain that limits performance. Anaerobic metabolism produces energy for short, high-intensity bursts of activity lasting no more than several minutes before the lactic acid build-up reaches a threshold.

Next in the series: Pre-game and post game nutrition

Have a great day,
Dr. Crysta Serné
Vancouver Chiropractor and owner of Vitality Clinic

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