Wk 9&10 Lecture 1: Rebuilding Glycogen

Introduction to Sun Yi's Metabolic Responses

• Sun Yi's post-run agenda: shower and breakfast

• Focus on metabolic responses after a healthy breakfast

• Importance of understanding nutrition for metabolism

Sun Yi's Early Morning Run

• Duration: 50 minutes at 200 meters/min

• Energy expenditure: 396 kilocalories

• Fuel use:

  • Depleted glycogen: 79 grams

  • Utilized fat: 8.9 grams

• Initial glycogen stores: 90 grams in liver/muscle; 8 kilograms of fat in tissues

• Comparison of energy content:

  • Fat: 9 kilocalories/gram

  • Carbohydrates: 4 kilocalories/gram

• Thermal response:

  • Body temperature rose to 38 degrees Celsius

  • Fluid loss: approximately 400 ml

Nutrition Basics and Metabolic Switching

• Contrast between metabolic responses:

  • Fasting vs post-meal

• Transition to anabolic mode triggered by rising blood glucose

• Importance of replenishing glycogen stores post-exercise

Sun Yi's Breakfast Priorities

• Goal: replenish depleted glycogen from run and overnight fast

• Avoidance of high glycemic index (GI) foods initially

• Examples of high GI foods:

  • Grape juice → leads to rapid blood sugar rise and insulin release

  • Baked potatoes and white bread

  • Foods high in simple sugars not ideal for initial intake

Components of Sun Yi's Breakfast

• Meal Composition:

  • Omelet: rich in protein and healthy fats

    • Ingredients:

      • Omega-3 enriched eggs

      • Extra egg whites for additional protein

      • Various vegetables (scallions, shiitake mushrooms, tomatoes, orange peppers, garlic, broccoli) rich in antioxidants

  • Smoothie: consisting of berries/yogurt for carbohydrates, fiber, antioxidants, calcium, gut-friendly bacteria

  • Supplementary Foods:

    • Red Delicious apple {

      • Contains antioxidants

    • Freshly ground flaxseed {

      • Rich in lignans believed to show anticancer properties

    • Low-fat tofu {

      • Source of calcium

    • 50 grams of canned salmon {

      • Source of EPA, an anti-inflammatory omega-3 fatty acid

  • Additional foods: precooked pasta, decaffeinated green tea, almonds, pecans

The Role of Antioxidants in Sun Yi's Diet

• Importance of antioxidants:

  • Linked to good cardiovascular health and cancer risk reduction

  • Specific examples of antioxidant-rich foods:

    • Blueberries, cherries, apples, artichokes, nuts, various beans

• Recommended intake: 5-10 servings of fruits/vegetables per day

• Antioxidants mitigate reactive oxygen species (ROS) that are linked to diseases

• Type of beneficial antioxidant compounds:

  • Lutein (retinal health)

  • Lycopene (prostate health)

Dietary Fats and Health

• Classification of dietary fats:

  • Saturated fats: linked to cardiovascular disease (e.g., animal fat, coconut oil)

  • Monounsaturated fats: considered healthy (e.g., olive oil)

  • Polyunsaturated fats: omega-3 (beneficial) and omega-6 (pro-inflammatory potential)

  • Trans fats: associated with higher cardiovascular disease risk, found in processed foods

Transition to Anabolic Metabolism Post-Meal

• Importance of insulin and blood glucose fluctuations:

  • Rising glucose stimulates insulin release from pancreas

  • Insulin effects on metabolism:

    • Suppresses glucagon and adrenaline

    • Triggers glycogen synthesis and fat storage

    • Lowers blood glucose through increased uptake by cells

Mechanism of Insulin Secretion

• Insulin production process:

  • Preproinsulin → Proinsulin → Insulin with disulfide chains

  • Insulin released via exocytosis from pancreatic beta cells

• Insulin receptors activate downstream signaling for metabolic modifications:

  • Phosphorylation and activation of glycogen synthase

Glycogen Metabolism Modulation

• Regulation Overview:

  • Insulin encourages glycogen synthesis while inhibiting breakdown

  • Phosphorylation/dephosphorylation pathways through protein kinases and phosphatases

• Key enzymes in glycogen metabolism:

  • Glycogen phosphorylase (inhibition) and glycogen synthase (activation)

• Glycogen structure and synthesis:

  • Glycogenin provides initial glucose unit for synthesis

  • Branching of glycogen increases solubility and accessibility

Summary of Key Points

• Sun Yi focuses on a balanced post-exercise meal to optimize recovery.

• Importance of nutrient quality regarding glycemic indices and antioxidant-rich foods.

• Comprehensive understanding of metabolic pathways influenced by insulin and dietary components.

• Balance of healthy fats and avoidance of trans fats for long-term health.