Metabolic Aspects of Nutrition and Fitness

2. Lecture 11b-2 April 2019 This lecture is based largely onCHAPTER 23 IN KRAUSE'S FOOD NUTRITION AND DIET THERAPY (ON RESERVE IN LIBRARY) AND CHAPTERS 7,8,9 IN ROLFES ET AL.

3. Final exam-120 multiple choice-120 marks from vitamins to end of course -4 short answer questions-15 points each for a total of 60 points covers whole course -3 hours- 180 marks

4. Lecture 11 Outline Metabolic aspects of Nutrition and fitness/Sports Nutrition Energy production ATP             Anaerobic pathway             Aerobic pathway             Energy continuum             Sources of fuel

5. Outline of lecture 11 Energy production Substrate choice Intensity Duration Effect of training Diet

6. Outline of lecture 11 Nutritional Requirements             Fluid                  Fluid Balance                  Fluid Absorption Factors affecting fluid absorption                  Requirements                          Short duration                          Endurance

7. Outline of lecture 11 Nutritional Requirements            Carbohydrate Types of carbohydrate                         Pre-event                         During event                         Post-event

8. Outline of lecture 11 Nutritional Requirements            Protein Endurance                 Resistance Exercise Amino acid supplementation

9. Outline of lecture 11 Nutritional Requirements             Lipid             Minerals   Iron                         Calcium             Vitamins Anti-oxidant vitamins and B-carotene C                         E                         B vitamins

10. Outline of lecture 11 Regulation of metabolism

11. Energy production Energy continuum All pathways can produce ATP At the beginning of any exercise whatsoever anaerobic metabolism is in place to produce ATP If the person continues to exercise at a moderate level for a prolonged period then the aerobic pathway will become the predominant pathway for energy production (eg marathon run)

12. Energy production Energy continuum If the person continues to exercise for a short period of high power and high intensity then the anaerobic pathway will become the predominant pathway for ATP energy production(eg 100 metre sprint) Production of ATP is therefore a continuum that depends on the:             -availability of oxygen             -the capacity for intensity of the exercise             -the capacity for the duration of the exercise

13. Energy production Energy continuum There is an inverse relation between the capacity for intensity and the capacity for the duration of the exercise -one cannot perform high intensity exercise over a long period of time -the duration increases as the intensity drops and as the intensity of the exercise increases the duration of that exercise drops

14. Energy production Energy continuum -the aerobic pathway cannot tolerate the same level of intensity as the duration increases due to the decreased availability of oxygen and the production of lactic acid

17. Energy production Sources of fuel as the duration increases more energy is obtained from fat (fatty acids) and as the duration decreases and the intensity increases more energy is obtained from carbohydrate carbohydrate is obtained from dietary carbohydrate, glycogen or amino acids (amino acids can be synthesized to glucose-this process is known as gluconeogenesis)

18. Energy production Sources of fuel Kreb’s cycle-alanine is the main amino acid contributing to the Krebs cycle -3 carbon units of glucose contributing to the Krebs cycle -2 unit carbons of fatty acids contributing to the Kreb’s cycle

19. Energy production Sources of fuel Kreb’s cycle -all of these substrates are used most of the time however the intensity and duration of the exercise dictates the relative rates of substrate utilisation

20. Energy production Substrate choice Intensity- high intensity must rely on carbohydrate Because oxygen is not available for high intensity exercise glycogen must be utilized Glycogen catabolism is much higher than with aerobic activity- 18-19 times faster (2 ATP versus 36-38 ATP)

21. Energy production Substrate choice Intensity-Hockey, basketball for eg favour higher glycogen utilization rates than marathon running while moderate intensity exercise favours 50/50 split of (glycogen)/(glucose-lipid) use

22. Energy production Substrate choice Low intensity exercise like walking is entirely aerobic and most of the ATP comes from lipid Fat yields 4.65 kcal / L of oxygen consumed vs  for carbohydrate a yield of 5.01 kcal/L of oxygen consumed -thus in longer term exercise carbohydrate use is favoured relative to low intensity exercise However, once the glycogen stores are depleted then that is the end of the high intensity exercise as carbohydrate utilisation is critical to lipid utilisation

23. Energy production Substrate choice Duration-the longer the event the greater the proportion of lipid used to produce ATP                           -consequently the lower the amount of lactate produced Effect of aerobic training-increase number of mitochondria and activity of ATP producing enzymes-this impacts efficiency of both carbohydrate and lipid utilisation which ever is chosen

24. Energy production Substrate choice Diet-dictated by fuel utilization for a particular event -high intensity requires more carbohydrate in the diet -lower intensity requires more lipid in the diet however do not consume a high fat diet- crowd out carbs and run the risk of heart disease

25. Class exercise Explain the effects of exercise intensity, duration and training on substrate utilisation.                         

26. Break 

27. Nutritional Requirements     Fluid         Fluid Balance Important for maintaining blood flow which in turn is important for supplying blood to skin and hence temperature control 75 percent of energy goes out as heat-therefore must sweat regulated by kidney, sweat loss, feces, respiration and fluid intake important to consume sodium and water to replace water lost as sweat-thus blood sodium is maintained and therefore so are hormone levels which limit the rate of urine production

28. Nutritional Requirements Fluid Absorption          Factors affecting fluid absorption                    -glucose and sodium travel across intestine on same carrier

29. Nutritional Requirements Fluid Requirements       Short duration -if several heats before actual race this can be problem for hydration - plain water dilutes the blood, increases urination and results in dehydration        Endurance -plain water lowers blood glucose concentrations thus increasing the demand on muscle glycogen

30. Nutritional Requirements Carbohydrate       Types of carbohydrate After glycogen runs out must use gluconeogenesis to maintain blood glucose levels Glycogen loading is important-eg pasta diet some have suggested complex carbs are better at glycogen loading in muscle than are simple carbs but this is debatable

31. Nutritional Requirements Carbohydrate Pre-event              Takes care of hunger              Maintains adequate blood glucose levels for event           During event               Maintains blood glucose and delays fatigue           Post-event               Builds glycogen up in muscle after depletion

32. Nutritional Requirements Protein        Endurance                Less required than for resistance events        Resistance Exercise                  More required than for endurance events                                                 -muscle mass issue

33. Nutritional Requirements Protein Amino acid supplementation A waste of time- eat more calories in accordance with Canada’s food guide to meet increased energy demands and this will easily meet added protein/amino acid requirements Can lead to dehydration, loss of urinary calcium, weight gain and stress on the kidney and liver

34. Nutritional Requirements Lipid          -supplies essential fatty acids          -important energy source during endurance exercise           -less important as an energy source for high intensity exercise

35. Class exercise How do the 6 nutrient classes work together to allow: • Aerobic exercise • Anaerobic exercise

36. Break                           

37. Nutritional Requirements Minerals           Iron               -oxygen carrying-hemoglobin and myoglobin               -part of electron transport chain-ATP           Calcium                -bone mass

38. Nutritional Requirements Vitamins     Anti-oxidant vitamins and b-carotene, vitamin C and E -exercise produces increased amount of  lipid peroxides and free radicals-damage muscle -supplements are not required-no evidence that they improve performance B vitamins             -important co-enzymes in energy production            -B12-supplement required in strict vegans

39. Regulation of Metabolism Oxygen supply As intensity of exercise increases the oxygen supply becomes limiting-with training one can supply more oxygen Substrate supply Availability of co-enzymes Hydration Mechanisms described for each of the nutrient classes

40. Class exercise What is the major direction of metabolism during exercise? after exercise?    Why ?