Energy Systems & Sports Nutrition Diploma

• This study guide covers energy systems applied to exercise within the virtual diploma in sports nutrition.
• Module 1 aims to help students grasp the basics of metabolism and energy expenditure in relation to sports nutrition.
• Key topics in this module include carbohydrate, fat, and protein metabolism, and energy expenditure.

Carbohydrate Metabolism

• Carbohydrates are a primary energy source for the body, comprising 50-60% of caloric intake and are found in grains, vegetables, fruits, and dairy.
• Monosaccharides like glucose, fructose, and galactose form the basic units of carbohydrates.
• Oligosaccharides (2-10 monosaccharides) include lactose, sucrose, and maltose and polysaccharides (>10 monosaccharides) are classified based on the number of units.
• Simple carbohydrates (monosaccharides and disaccharides) raise blood sugar levels faster than polysaccharides.
• The glycemic index (GI) determines how quickly carbohydrates affect blood sugar and carbs with a GI of 1-50 increase blood sugar slowly, resulting in lower insulin levels.
• Carbohydrates with a high GI cause a rapid increase in blood sugar, leading to high insulin levels, hypoglycemia, and increased appetite.
• General advice for athletes is to consume 6-10g of carbs per kilogram of body mass daily, depending on body mass, training intensity, and goals.
• Eating carbs before, during, and after workouts is essential to matching carb intake with training intensity.
• Ingesting 4g/kg four hours before exercise and 1g/kg one hour before exercise is recommended.
• During exercise lasting over an hour, consuming 0.7g/kg per hour helps maintain blood glucose levels.
• After exercise, a carb-rich meal is sufficient if recovery time exceeds 24 hours.
• Consuming 1 to 1.5 g/kg during the first 30 minutes and 0.75 g/kg every 2 hours when the recovery time is less than 12 hours.
• Consistent carb intake is determining for athletic performance, and human bodies have limited carb storage compared to other energy sources.
• Intense training utilizes glycogen rapidly, potentially depleting this energy source quickly and those who are well trained can use fats better than glycogen.

Fat Metabolism

• Fats provide 9 calories per gram and are mainly composed of carbon, hydrogen, and oxygen.
• Fats help absorb vitamins A, D, E, and K and, excessive fat intake can lead to health problems regardless of the source.
• Lipids function as a concentrated energy source, providing 9 Kcal per gram compared to 4 Kcal per gram from carbohydrates or proteins.
• Subcutaneous and visceral fat maintain body temperature for those exposed to climatic changes, especially cold conditions.
• Lipids prolong satiety by slowing gastric emptying, that helps manage food consumption and prevent overeating.
• Fatty acids have a carbon-hydrogen chain of 12-28 atoms, with some containing 8-10 atoms.
• Fatty acids are categorized as saturated, monounsaturated, or polyunsaturated, and they combine with glycerol to form triglycerides.
• Saturated fatty acids lack double bonds, remain high in blood longer, and increase atherosclerosis risk.
• The body tolerates monounsaturated fatty acids, having one double bond well, such as those found in olive oil.
• Polyunsaturated fatty acids contain two or more double bonds, are easily digested, quickly removed from the blood, and reduce atherosclerosis risk; omega-3 is an example of these.
• Triglyceride catabolism yields twice the energy of carbohydrates and proteins but requires oxygen and is used during aerobic exercise.
• Low-intensity exercise are preferred to metabolize fat, as higher intensities increase carb metabolism to meet energy needs, reducing fat use.
• Type 1 muscle fibers have a higher fat storage capacity, while type 2 fibers have a much lower capacity and exercise stimulates the sympathetic nervous system, releasing adrenaline, which aids fat transport into muscles.

Protein Metabolism

• Proteins provide amino acids for muscle protein synthesis (MPS) and are essential for body functions.
• Proteins enable tissue repair, cellular growth, and homeostasis and are essential substances.
• Proteins are an energy substrate for adenosine triphosphate (ATP) production and have other essential functions.
• Physically active people require more protein, but excessive consumption can hinder its utilization for anabolic needs and lead to the inefficient utilization of proteins.
• When proteins aren't used properly, nitrogen is removed, and proteins are converted into fat for storage or fuel.
• Athletes need more nutrients but must focus on the form and source of essential foods.
• Proteins convert into individual amino acids, which interact to create available amino acids.
• Muscles need amino acids for repair and tissues vary in requirements to complete all functions.
• Proteins help in antibody production to fight viruses and bacteria, provide cell and tissue structure, including muscles and skin, and act as messengers to control functions.
• Protein intake recommendations depend on age, sex, and activity level and should be distributed evenly throughout the day in servings of 20-30 g.
• Adults need 0.80 g / kg / day, adolescents need 0.85 g / kg / day, children aged 4-13 need 0.95 g / kg / day and kids aged 1-3 need 1.10 g / kg / day.
• Active individuals requires 1.2-1.7 g kg body weight (BW) per day, depending activity type, duration, and age.
• Resistance athletes need 1.2-1.4g/BW, and strength athletes need 1.6-1.7/BW.
• Some athlete diets are justified such as, those with muscle growth phases need to eat energy and protein foods.
• Restricting food for reduce weight leads athletes to consume high protein to prevent muscle loss, while vegetarian and vegan athletes need to consume animal protein by raising their biological value.
• Sufficient carb consumption prevents proteins from being used for energy.
• Chronic protein overconsumption (more than 2.0 g/BW) can elevate the risk of kidney damage, as studies show signs of impaired kidney function after high intake without enough carbs for two years.

Energy Expenditure

• Adequate energy is vital for exercise performance and recovery, making calorie control key.
• A person’s energy inputs vary with several of variables like weight, age, sex, ambient temperature, and physical activity type.
• Energy requirements differ between a light 30-minute jog and a marathon, and this section explores the following topics: basal metabolism, energy requirements, and ATP & energy stores.
• Basal metabolism refers to the minimum required kilocalories (Kcal) to sustain life. As a value that cells need to survive and perform chemical reactions and tasks such as breathing and pumping blood/
• The following is what each nutrient provides: 1g protein is 4 Kcal, 1g carbohydrate is 4 Kcal, 1g fat is 9 Kcal and 1g alcohol is 7 Kcal.
• The Harris Benedict formula, developed in 1919 and altered by Mifflin-St. Jeor in 1990, can calculate basal metabolic rate (BMR).
• The following is how to calculate the BMR for men: (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5
• To calculate the BMR for women: (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161
• The number of kilocalories can be determined based on the level of training: light is 1-3 day per week equaling BMR x 1.375 , moderate is 305 days per week equaling BMR x 1.55, strong is 6 days per week equaling BMR x 1.725 ad professional is BMR x 1.9.

ATP and energy reserves

• Energy is accumulated using molecules that synthesize and break down which is stored as adenosine triphosphate ATP comprised of adenosine and three phosphate molecules.
• Constant synthesis of ATP is necessary because only small amounts of ATP are stored in our body.
• Various energy substrates are used for ATP synthesis, including ATP proprio, phosphocreatine, amino acids, glucogen and glucose, and fatty acids.
• ATP and phosphocreatine are stored in small amounts in muscle fibres, used in short bursts and glucos and glycol are created from carbs.
• Fats turn into triglycerides to give energy in the muscles.
• Finally proteins may give energy is the other food sources are depleted.