Exercise Physiology Lecture Notes (30-9-24) PDF

Course Title :Exercise physiology Course Code :FM306 Department :Biochemistry Lecture Title : Nutrition in Exercise Lecturer Name : Dr. Nahla Anas Bashir Nasef FOM-Tanta university Lecture Objectives: Each student at this lecture should be able to: Identi...

Course Title :Exercise physiology Course Code :FM306 Department :Biochemistry Lecture Title : Nutrition in Exercise Lecturer Name : Dr. Nahla Anas Bashir Nasef FOM-Tanta university Lecture Objectives: Each student at this lecture should be able to: Identify the role of carbohydrates, lipids and proteins for athelets Identify the recommended intake of carbohydrates, lipids and proteins during exercise Identify the dynamics and the interplay between carbohydrates, lipids and proteins during exercise Content: The role of carbohydrates, proteins, and lipids in exercise. Recommended daily intake of macronutrients for athletes and physically active individuals. Dynamics of carbohydrates, proteins, and lipids during different types of exercise Recommendation for post-exercise nutrition in recovery and muscle repair. Macronutrient timing to optimize exercise performance and recovery. Nutrition in exercise  Exercise nutrition Exercise nutrition is the study and practice of nutrition and diet to improve the athletic performance. Nutrition is an important part of many sports training regimens in: Strength sports (e.g. weightlifting and bodybuilding) Endurance sports (e.g. cycling, running, swimming).  Exercise nutrition Exercise Nutrition focuses its studies on the type, the quantity of fluids and food taken by an athlete. In addition, it deals with the consumption of nutrients like, minerals, supplements and organic substances that include carbohydrates, proteins and fats. Why study nutrition in exercise? Athletes need to fuel their bodies adequately because exercise degrades the body so the body needs nutrition to repair and recover. This fueling process requires a specialized approach; therefore, athletes should seek out professionals who are experts in sports nutrition and experienced in developing individualized plans. The Body must have: Protein to rebuild muscle. Carbohydrate for energy and to burn fat. Vitamins + Minerals (Electrolyte Balance) Antioxidants to stop Free Radicals (oxidative stress caused by exercise). Benefits of optimal nutrition in exercise: Delay fatigue and enhance energy levels... during exercise and all day long. Lead to better and faster recovery. Reduce soreness and inflammation; enhance immunity. Minimize injury risk... return to play time after injury or surgery. The Nutrient Of Ultimate Performance Carbohydrates Carbohydrates Carbohydrates and Their Role Recommended significance in Exercise intake Carbohydrates Carbohydrate Carbohydrate Dynamics in timing Loading Exercise Carbohydrates and Their Role in Exercise Carbohydrates are the body's preferred energy source, especially during high-intensity exercise. When consumed, carbohydrates are broken down into glucose, which is either used immediately for energy or stored as glycogen in muscles and the liver. During exercise, glycogen is the primary fuel for muscle contraction, particularly in anaerobic and moderate-to-high intensity aerobic exercise  Carbohydrates Recommended intake For the general population: 45-65% of daily caloric intake. Athletes and Active Individuals: 55-65 % of total energy (not less than 55% of daily intake) For moderate exercise: 5-7 grams of carbohydrates /kg/day For intense endurance activities: 8-12 grams /kg/day. Carbohydrates significance Carbohydrate are nutrient-dense rich foods , it contains dietary fiber, vitamins, minerals & various phytochemicals. Main source of Energy especially for Glucose-dependent cells Supply Energy both aerobically and anaerobically Carbohydrates significance Mandatory for cognitive concentration and blood glucose maintenance Carbs have an important role in recovery from high-intensity activity & are essential to replenish muscle fuel stores after hard training or events Protein sparing and ketosis hindering Carbohydrates Dynamics in Exercise Carbohydrates are the primary fuel for high-intensity exercise because they are quickly metabolized for energy through glycolysis and oxidative phosphorylation. Carbohydrate availability directly affects exercise performance, especially in endurance activities  Carbohydrate Dynamics in Exercise Glycogen Utilization: During short bursts of moderate-to-high- intensity exercise, muscle glycogen is the dominant energy source, with depletion rates dependent on intensity and duration. As glycogen stores decline, fatigue sets in, reducing performance, often referred to as "hitting the wall."  Carbohydrate Dynamics in Exercise Blood Glucose Maintenance: For prolonged exercise, liver glycogen is broken down into glucose and released into the bloodstream to maintain energy levels. Once glycogen stores are exhausted, the body starts utilizing alternative energy sources, primarily fats, but at the cost of exercise intensity.  Carbohydrate timing Carbohydrate Intake Before, During, and After Exercise: Pre-Exercise: A meal high in carbohydrates 1 -4 gm/kg about 1 -4 hours before exercise Aim Optimize glycogen stores to ensure an adequate fuel supply Maintain blood sugar Optimize hydration Avoid Hunger  Carbohydrate timing During Exercise: For Brief exercise (< 45 mins) Not needed For activities lasting longer than 90 minutes, consuming 30-60g of carbohydrates per hour (e.g., glucose or maltodextrin) Aim Sparing muscle glycogen Prevent hypoglycemia effect on CNS Better performance & delay fatigue  Carbohydrate timing Post-Exercise: athlete should consume 1 to 1.5 gm carbohydrates /kg immediately after exercise (within 30 minutes) to accelerate recovery. This period, often called the "glycogen window," Aim To replace muscle glycogen stores as trained muscle store more glycogen than untrained one especially in those who trained more than once per day To decrease muscle breakdown  Carbohydrate Loading Carbohydrate Loading is a strategy used by endurance athletes to increase muscle glycogen stores before competition. It is a performance- enhancement strategy ( fights fatigue)  Carbohydrates loading principle Two phases are met : Glycogen depletion phase: the amount of glycogen is depleted to some degree by Dietary manipulation Moderate calorie restriction Increased training. Glycogen replenishment phase : Training intensity is reduced Carb content is greatly increased.  Applying Carbohydrates loading Beginning 6 days before your competition. 1- Carb depletion phase : 3 days Maintaining very high training intensity. Eat 5- 6 meals daily. Caloric ratio: 20% fats 60% protein 20% carbohydrates  Applying Carbohydrates loading 2- Carb loading phase: last 3 days Reduced training during the first 2 days & none on the last day before competition. Rest a lot & keep workouts very high intensity & only 30 minutes duration CHO intake 10- 12 gm/kg /day Caloric ratio: 15% fats 15% protein 70% carbohydrates. The Nutrient of Muscle building The Favorite Nutrient of athletes Proteins and Proteins Their Role in Recommended Exercise Intake Protein Timing and Dynamics in Quality of Exercise Protein Intake Proteins and Their Role in Exercise Proteins are essential for muscle repair, recovery, and growth. During exercise, especially resistance training, muscle fibers are damaged, and protein is necessary to repair and build stronger muscle tissue. Proteins are also involved in the synthesis of enzymes, hormones, and immune function, which are critical for overall health and performance  Proteins Recommended Intake General Population: 0.8 grams of protein /kg/day. Athletes: Endurance athletes: 1.2-1.4 grams /kg/day, particularly during prolonged activities like marathon running. Strength athletes: 1.6-2.0 grams /kg/day as they require more protein for muscle repair and growth as they experience more muscle damage during resistance training.  Protein Dynamics in Exercise Muscle Protein Breakdown and Synthesis (MPB vs. MPS): Exercise, especially resistance training, leads to muscle damage, increasing muscle protein breakdown (MPB). Post-exercise protein consumption promotes muscle protein synthesis (MPS), essential for recovery and hypertrophy. The balance between MPB and MPS determines muscle growth or loss. Protein Dynamics in Exercise: Protein Oxidation During Prolonged Exercise: While not a major energy source, amino acids from protein can be oxidized during prolonged, glycogen-depleting exercise. This occurs particularly when carbohydrate stores are low, forcing the body to rely on alternative substrates.  Timing and Quality of Protein Intake: It is important to Get Enough & Get it on Time The success of achieving a positive muscle protein balance appears to be dependent upon: The amino acid composition of the food ingested The amino acid concentration of the blood supplying the muscle cells The timing of the protein feeding Timing and Quality of Protein Intake: Pre-Exercise: Moderate protein intake before exercise can minimize muscle breakdown. Post-Exercise: A combination of high-quality protein (20-30g) within 30 minutes to 2 hours and carbohydrates post-exercise accelerates recovery and promotes muscle repair. Anabolic window(90-120 min) Whey protein, for example, has an excellent distribution of the essential amino acids and contains leucine, a key amino acid that stimulates muscle protein synthesis. The most misunderstood macronutrient  Lipids and Lipids Their Role in Recommended Exercise Intake Timing and Lipid Dynamics Quality of in Exercise Protein Intake  Lipids and Their Role in Exercise Lipids (fats) serve as a concentrated source of energy They are vital for long-term endurance activities as they provide a stable, long-lasting fuel source when carbohydrate stores are depleted. Lipids are also essential for cell membrane integrity, hormone production, and the absorption of fat-soluble vitamins (A, D, E, and K).  Lipids and Their Role in Exercise Omega 3 fatty acids such as Docosaheaxaenoic acid (DHA) and Eicosapenatenoic acid (EPA) : Have beneficial effects on cardiovascular system act as moderators of inflammation play positive role in improving strength and aerobic performance Lipids Recommended Intake General Population: 20-35% of daily caloric intake (0.5-1.5 g/kg/day) should come from fats, with an emphasis on healthy fats such as monounsaturated and polyunsaturated fats (from sources like nuts, seeds, avocados, and fish). Athletes: Fat intake should generally fall between 20-35% of daily calories, but endurance athletes may consume slightly more to fuel long-duration activities.  Lipid Dynamics During Exercise Triglyceride Storage and Mobilization: Fatty acids stored as triglycerides in adipose tissue are mobilized and broken down into free fatty acids (FFAs) during exercise. FFAs are transported to mitochondria, where they undergo beta-oxidation, producing acetyl-CoA, which enters the Krebs cycle to produce ATP  Lipid Dynamics During Exercise At Rest and Low-Intensity Exercise: Lipids are the primary fuel source During Prolonged Exercise (Long-Term Energy Source): As exercise continues and glycogen stores are depleted, the body increases its reliance on fat oxidation to sustain energy.  Lipids timing Low-fat food are recommended before exercise Avoid high fat intake just before & during sport Small to moderate amounts of fat post exercise is appropriate (Immediately after exercise CHO & Proteins are required) Consuming much lipids just close to exercise time result in GI distress in some athletes  carbs vs. lipids as source of Energy Fat Carbohydrates Much more energy and Sufficient fuel for Less energy and Insufficient fuel for exercise exercise metabolized aerobic only metabolized aerobic and anaerobic Slow source, abundant supply fast source, limited supply the most efficient fuel for resting muscles the most efficient fuel for working active muscles  Interplay Between Carbohydrates, Proteins, and Lipids During Exercise The utilization of carbohydrates, proteins, and lipids during exercise is dynamic and depends on the intensity, duration, and type of activity performed.  Interplay Between Carbohydrates, Proteins, and Lipids During Exercise High-Intensity, Short-Duration Exercise (e.g., sprints, weightlifting): Carbohydrates are the primary energy source, with minimal use of fats. Protein's role is repair and recovery after the exercise. Moderate-Intensity, Long-Duration Exercise (e.g., cycling, running): Carbohydrates provide energy early on, but as exercise continues, fats become more important for sustaining energy. Protein may also be used as an energy source when glycogen is depleted. Recovery: Post-exercise recovery should focus on replenishing glycogen stores through carbohydrate intake, repairing muscle with protein, and maintaining overall health with balanced fat consumption Post-Exercise Nutrition Recommendations Carbohydrates: Aim to consume 1.0-1.5 grams/kg within 30 minutes post- exercise to replenish glycogen.(Glycogen window) Protein: 20-30 grams of high-quality protein immediately post-exercise enhances muscle recovery. Fats: While fat should not be the focus post-exercise, moderate intake is beneficial for overall health and hormonal balance  In summary Carbohydrates are vital for high-intensity activities. Proteins are essential for recovery and muscle growth. Lipids provide long-lasting energy for endurance events Questions 1. Identify carbohydrates loading and how to apply? 2. Compare between carbohydrates and lipids as a source of energy 3. Enumerate significance of lipids Questions During prolonged, moderate-intensity exercise, which of the following macronutrients becomes the predominant energy source? A) Carbohydrates B) Proteins C) Lipids D) Vitamins Questions What is the recommended daily protein intake for strength athletes aiming to optimize muscle growth? A) 0.8 grams per kilogram of body weight B) 1.0 grams per kilogram of body weight C) 1.2-1.4 grams per kilogram of body weight D) 1.6-2.0 grams per kilogram of body weight Questions What is the primary role of proteins post-exercise? A) Providing quick energy for recovery B) Repairing and synthesizing muscle tissue C) Increasing glycogen storage D) Enhancing fat oxidation Questions Which of the following is the primary energy source for high-intensity exercise? A. Proteins B. Lipids C. Carbohydrates D. Vitamins Questions Which strategy is used to maximize glycogen stores before an endurance event? A) Protein loading B) Carbohydrate loading C) Fat adaptation D) Electrolyte replenishment References: 1 Lippincott’s: Illustrated Review Biochemistry. 2 Harpers Illustrated Biochemistry Thank You SUE