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Carbohydrate and fat utilization during exercise 24 july 16
Carbohydrates and fats provide energy through exercise, with carbohydrates being the preferred fuel for intense exercise. The type of fuel utilized depends on exercise intensity and duration. At low intensities, fat is the primary fuel from peripheral and intramuscular stores. At medium intensities, intramuscular triglycerides supplement fat. High intensities exceed fat utilization rates, requiring carbohydrates from glycogen and glucose. Very high intensities exceed aerobic capacity, relying on anaerobic carbohydrate breakdown. Fuel utilization shifts between fat and carbohydrate stores over different exercise phases and intensities.
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Carbohydrate and fat utilization during exercise 24 july 16
- 1. 1 Carbohydrate and Fat UtilizationDuring Exercise Developed by: AQ Khan
- 2. 2 Key Terms CARBOHYDRATESthey contain carbon and water, and are the perfered fuel source during intense exercise. ATP supplies the enegy for all forms of biologic work. TCA CYCLE fats and carbohydrates are burned in the mitochondria.
- 3. 3 Terms Continued FATa molecule that has the same structural elements as a carbohydrate except that it differs in its linkage of atoms. fats are commonly known as lipids. CLYCOGEN stored in active muscle supplies almost all of the energy in the translation from rest to moderate, submaximal exercise, just as it does in intense exercise.
- 4. 4 Terms Continued GLYCOGENPHOSPHORYLASE augments glycogen breakdown in the liver and active muscle. GLUCOSE can also be called dextrose, or blood sugar, occurs naturally in food. the digestion of complex carbohydrates can produce glucose. TRIGLYCERIDES the simple lipids, or neutral fats. they are the most plentiful fats of the body. they constitute the major storage form of fat in the adipose (fat) cells.
- 5. 5 Energy Substrate Comesin Two Varieties Carbohydrates Fats In Two Sources Intramuscular Blood
- 6. 6 Exercise Intensity andDuration For all energy substrates, carbs and fats, ultimately ATP is generated in the muscle cell as the high energy substrate for moving muscle. Energy can be generated aerobically or anaerobically Fats and carbs get burned in mitochondria by the TCA cycle Carbs can also be broken down in the absence of oxygen for limited energy production
- 7. 7 FAT SOURCES Fatfor fuel is in the form of free fatty acids Two sources of these fats are Peripheral fat stores • Rolls of fat on the belly Intramuscular fat • Triglyceride stored in the actual muscle
- 8. 8 CARBOHYDRATE SOURCES Carbohydratescome in two sources Simple sugar glucose Storage form of glucose –glycogen Glycogen is stored in • Muscles • Liver • Blood (smallest percent in blood) The liver is the only tissue that can release stored glycogen in the form of glucose A function of the liver is to maintain blood sugar levels by releasing glucose through gluconeogenesis and glycogenolysis
- 9. 9 Fuel Utilization isDetermined by Energy Output or Intensity Level Primarily first thing in the morning before you eat breakfast your energy demands are very low and can be met mainly by fat derived from blood free fatty acids Free fatty acids are released at a low rate by peripheral fat stores This allows the muscles to preserve both intramuscular fat and glycogen stores
- 10. 10 Fuel Utilization -Intensity low-medium-high-very high Low intensity Walking – energy output can be generated entirely by peripheral fat stores releasing free fatty acids The removal rate of free fatty acids by muscle cells is faster than at rest and after 20-30 minutes, there will be a stimulus to increase free fatty acid release to maintain sufficient blood concentrations of free fatty acids for efficient removal by the working muscles
- 11. 11 Medium Intensity Atmedium intensity levels, you exceed the capacity of peripheral fat stores to supply enough free fatty acids to meet energy output rates Intramuscular triglyceride is broken down to provide more fat Peripheral fat release and uptake does not stop – it plateaus and another source is provided to makeup the needed generation rate
- 12. 12 Medium Intensity Amedium intensity pace can be maintained until either your instramuscular fat stores are depleted or you run out of glycogen When the glycogen is depleted then protein is degraded for three reasons Amino acids can be burned for energy much like carbs Some amino acids (branched chain ones) can supply TCA cycle intermediates to maintain aerobic energy production derived from fat burning Some amino acids (like alanine) are secreted into the bloodstream, picked up by the liver and converted into glucose
- 13. 13 High Intensity HighIntensity exercise goes above the limits of energy production rates that fats can supply and requires additional energy derived from sugar The reason for this is that sugar requires less oxygen per unit of energy At lower intensities, the energy production rate is low enough that oxygen is plentiful enough for fat burning
- 14. 14 Very High Intensity At very high intensities the aerobic system reaches its limitations for energy generation (fat or sugar) The anaerobic system takes over Only a little of the potential energy of glucose is released but it is done so in a very rapid manner to meet short duration and very high energy production rates
- 15. 15 The Benefits ofExercise At Any Intensity Low intensity exercise is not the best form for weight loss Intramuscular stores (fat or glycogen) are depleted During the recovery phase (post exercise) fats and carbs from the diet will go to restoring those levels High intensity exercise can lead to fat loss because with depletion of glycogen those glycogen stores must be replenished with dietary carbs that would otherwise be burned for energy While that storage process is occurring, the body will burn extra fat to supply current energy needs
- 16. 16 To Sum ItAll Up High intensity exercise has its limitations because that pace cannot be maintained for a long period of time Total calories burned will be limited Consuming some form of glucose during the exercise to maintain energy may be necessary for performance consideration only It is unnecessary to consume any form of glucose during an exercise workout with a duration of two hours at a moderate intensity if weight loss is your goal Aerobic exercise improves the body’s ability to burn fats for energy Therefore no additional supply of fuel is needed at the time
- 17. Liver Glycogen Blood Glucose Muscle Glycogen Carbohydrate Stores afteran Overnight Fast Sedentary 4 grams 100 grams 400 grams
- 18. Liver Glycogen Blood Glucose Muscle Glycogen Carbohydrate Stores afteran Overnight Fast 1 hr of Exercise 4 grams 100 grams 400 grams
- 19. Liver Glycogen Blood Glucose Muscle Glycogen Carbohydrate Stores afteran Overnight Fast 2 hr of Exercise 4 grams 100 grams 400 grams
- 20. Liver Glycogen Blood Glucose Muscle Glycogen Carbohydrate Stores afteran Overnight Fast 3 hr of Exercise 4 grams 100 grams 400 grams
- 21. Liver Glycogen Blood Glucose Muscle Glycogen Carbohydrate Stores afteran Overnight Fast 4 hr of Exercise 4 grams 100 grams 400 grams !!!
- 22. The Most EfficientFuel depends on Exercise Intensity and Duration Metabolic Efficiency CHO is preferred during high intensity exercise because its metabolism yields more energy per liter of O2 than fatmetabolism. kcal/l of O2 CHO 5.05 Fat 4.74 CHO can also produce energy without O2!!! Storage Efficiency Fat is preferred during prolonged exercise because its metabolism provides more energy per unit mass than CHO metabolism. kcal/g of fuel CHO 4.10 Fat 9.45 Fats are stored in the absence of H2O.
- 23.
Editor's Notes
- #18 Blood glucose is preserved at the expense of glycogen reservoirs. This is illustrated by the response to exercise. In the normal postabsorptive state. There are about 100 g of glycogen in the liver and 400 g of glycogen in muscle. With exercise CHO oxidation by the working muscle can go up by tenfold and yet after 1 h, 4 grams of glucose is maintained in the blood at the expense of liver and muscle glycogen stores. Even after 2 h the amount of glucose in the blood is constant. Even after glycogen stores get criticallly low liver gng willl kick in and limit the fall in glucose. Only after extremely long duration exercise will the blood glucose levels fall to critically low levels.
- #19 Blood glucose is preserved at the expense of glycogen reservoirs. This is illustrated by the response to exercise. In the normal postabsorptive state. There are about 100 g of glycogen in the liver and 400 g of glycogen in muscle. With exercise CHO oxidation by the working muscle can go up by tenfold and yet after 1 h, 4 grams of glucose is maintained in the blood at the expense of liver and muscle glycogen stores. Even after 2 h the amount of glucose in the blood is constant. Even after glycogen stores get criticallly low liver gng willl kick in and limit the fall in glucose. Only after extremely long duration exercise will the blood glucose levels fall to critically low levels.
- #20 Blood glucose is preserved at the expense of glycogen reservoirs. This is illustrated by the response to exercise. In the normal postabsorptive state. There are about 100 g of glycogen in the liver and 400 g of glycogen in muscle. With exercise CHO oxidation by the working muscle can go up by tenfold and yet after 1 h, 4 grams of glucose is maintained in the blood at the expense of liver and muscle glycogen stores. Even after 2 h the amount of glucose in the blood is constant. Even after glycogen stores get criticallly low liver gng willl kick in and limit the fall in glucose. Only after extremely long duration exercise will the blood glucose levels fall to critically low levels.
- #21 Blood glucose is preserved at the expense of glycogen reservoirs. This is illustrated by the response to exercise. In the normal postabsorptive state. There are about 100 g of glycogen in the liver and 400 g of glycogen in muscle. With exercise CHO oxidation by the working muscle can go up by tenfold and yet after 1 h, 4 grams of glucose is maintained in the blood at the expense of liver and muscle glycogen stores. Even after 2 h the amount of glucose in the blood is constant. Even after glycogen stores get criticallly low liver gng willl kick in and limit the fall in glucose. Only after extremely long duration exercise will the blood glucose levels fall to critically low levels.
- #22 Blood glucose is preserved at the expense of glycogen reservoirs. This is illustrated by the response to exercise. In the normal postabsorptive state. There are about 100 g of glycogen in the liver and 400 g of glycogen in muscle. With exercise CHO oxidation by the working muscle can go up by tenfold and yet after 1 h, 4 grams of glucose is maintained in the blood at the expense of liver and muscle glycogen stores. Even after 2 h the amount of glucose in the blood is constant. Even after glycogen stores get criticallly low liver gng willl kick in and limit the fall in glucose. Only after extremely long duration exercise will the blood glucose levels fall to critically low levels.