fat metabolism and energy production during exercise.pptx

Fat metabolism and energy production during exercise status.

1. Fat Metabolism During Exercise

2. Contents  Introduction  Digestion and Absorption Transport and storage Fats and exercise Fats vs carbohydrates 8/2/2025 2

3. INTRODUCTION Fat and carbohydrate (CHO) are the primary fuels for the generation of energy during aerobic exercise in well fed individuals. The relative contribution of these pathways is determined primarily by the exercise intensity and duration of exercise, but is also affected by training status, preceding diet, sex and environmental conditions. 8/2/2025 3

4. Digestion & Absorption * Fats emulsified by bile salts in the small intestine * Broken down by pancreatic lipase → FFAs + monoglycerides * Absorbed by enterocytes, re-esterified to triglycerides * Packaged into chylomicrons → lymph → bloodstream 8/2/2025 4

5. Transport & Storage * Chylomicrons deliver triglycerides to tissues * Lipoprotein lipase (LPL) breaks TG → FFAs for uptake * Excess stored as triglycerides in: * Adipose tissue * Skeletal muscle (IMTG) 8/2/2025 5

6. Fats and exercise Fat is a great fuel for survival but it is not adequate for high intensity exercise therefore fat is essential for longer, slower, lower intensity and endurance exercise such as cycling and walking. If exercising at a low intensity and enough stored fat available to fuel activity for hours or even days as long as there is sufficient oxygen to allow fat metabolism to occur. 8/2/2025 6

7. As exercise strength increases, carbohydrate metabolism takes over. It is more efficient than fat metabolism, but has limited energy stores. This stored carbohydrate (glycogen) can fuel about 2 hours of moderate to high level exercise. After that, glycogen depletion occurs (stored carbohydrates are used up) and if that fuel isn't replaced athletes performance may impaired When carbohydrate intake is depleted, oxidation of fatty acids accelerate to provide energy through the production of acetyl CoA (TCA substrate) 8/2/2025 7

8. Using fat for fuel for exercise Some factors might affect using fat as fueling intense exercise 1-Fat is slow to digest and be converted into a usable form of energy but it can take up to 6 hours. 2-Converting stored body fat into energy takes time. The body needs to breakdown fat and transport it to the working muscles before it can be used as energy. 3-Converting stored body fat into energy takes a great deal of oxygen, -For these reasons, athletes need to carefully time when they eat fat, how much they eat and the type of fat they eat. In general, it's not a great idea to eat fat immediately before or during intense exercise 8/2/2025 8

9. Fat metabolism during exercise People store large amounts of body fat in the form of triglyceride within adipose tissue as well as within muscle fibers. These stores fat must be metabolize into FFA and transported to muscle mitochondria for oxidation during exercise. 8/2/2025 9

10. Muscle Uptake & Mitochondrial Entry FFAs enter muscles via FAT/CD36 transporters Activated to fatty acyl-CoA Enters mitochondria via carnitine shuttle (CPT-I) 8/2/2025 10

11. Beta-Oxidation & Energy In mitochondria: Fatty acyl-CoA → Acetyl-CoA + NADH + FADH2 Acetyl-CoA enters Krebs cycle NADH/FADH2 enter Electron Transport Chain (ETC) → ATP 1 Palmitate = >100 ATP 8/2/2025 11

12. Hormonal Regulation Increases Fat Use: - Catecholamines - Glucagon - Cortisol - Growth hormone Decreases Fat Use: - Insulin (post-meal, promotes storage) 8/2/2025 12

13.  Influencing Factors Factor Effect on Fat Metabolism Intensity Low/moderate ↑, high ↓ Duration Longer = more fat use Fitness Trained = more efficient Gender Females use more fat Diet Low-carb ↑ fat oxidation 8/2/2025 13

14. Fat vs. Carbohydrates Parameter Fat Carbohydrate Energy (kcal/g) 9 4 Availability Slow fast O2 Requirement high low Use in exercise Low/mod intensity High intensity Storage Abundant Limited 8/2/2025 14