1. What is Energy? Energy is defined as the capacity to do work One of the more common ways to express energy is Calorie A calorie is a measure of heat There are 1000 calories in a kilocalorie A kilocalorie is commonly referred to as a Calorie

2. What is Energy? 1 gram of carbohydrate = 4 C 1 gram of fat = 9 C 1 gram protein = 4 C The calories in food represent a form of potential energy

3. How is energy stored in the body? Energy is stored in the body in the form of adenosine triphosphate (ATP) ATP is a complex molecule that contains a pair of high energy bonds When the bond is split by enzymes, energy is quickly released This energy is used to fuel body processes (eg. muscle contraction)

5. ATP ATP can be regenerated from ADP in three ways: 1.Interaction of ADP with CP 2.Anaerobic metabolism 3.Aerobic metabolism

6. Creatine Phosphate CP is another high-energy compound stored in the muscles ADP + CP → C + ATP CP donates its P to regenerate ATP Process lasts around 10 seconds

7. Creatine Phosphate Recent creatine supp. studies have shown: –increases muscle total creatine (20 g/day for 5 days) –the extent of the increase that is normally observed is inversely related to the presupplementation level (e.g. vegetarians) –increased performance in situations where the availability of creatine phosphate is important (high intensity activity with short recovery)

8. Carbohydrate (CHO) Metabolism We will continue our discussion of ATP production with CHO metabolism Why CHO? –Only food that can create energy anaerobically –Preferred fuel (requires less O 2 ) –If you understand CHO metabolism, it’s easy to understand fat and protein metabolism

9. Carbohydrates (CHO) Monosaccharides, disaccharides, polysaccharides Most come from plants (exception is lactose found in animal and human milk) Most common monosaccharides are glucose and fructose Complex CHO are polysaccharides: starch, glycogen, and cellulose

12. Carbohydrate (CHO) Metabolism All CHO must be broken down into glucose before it can continue through the metabolic pathways The complete breakdown of glucose is a four-step process

13. Carbohydrate (CHO) Metabolism Imagine the four stages as the four quarters of a football game Each step of the is like a single football play String the series of plays (steps) together to form an offensive drive (metabolic pathway) Two differences –Plays must follow the same order –The final score is predetermined

14. Carbohydrate (CHO) Metabolism First Quarter = Glycolysis Second Quarter = Formation of Acetyl CoA Third Quarter = Krebs Cycle Fourth Quarter = Oxidative Phosphorylation

15. First Quarter: Glycolysis Prepares glucose to enter the next stage of metabolism Glucose  Pyruvate (Lactate) ATP is also produced

16. First Quarter: Glycolysis Glucose 2 Pyruvate 2 ATP 4 ATP 2 NAD + 2 NADH

17. Second Quarter: Acetyl CoA 2 Pyruvate 2 Acetic Acid 2 Acetyl coenzyme A 2 CO 2 2 NADH

18. Third Quarter: Krebs Cycle Krebs cycle begins and ends with the same substance No ATP used Forms –2 ATP –6 NADH –2 FADH –4 CO 2

19. Fourth Quarter: Oxidative Phosphorylation Series of reactions where ATP is created from the hydrogen atoms that we have accumulated Produces 3 ATP for every NADH & 2 ATP for every FADH

20. The Final Score QuarterProcessProduct# ATP 1 st Glycolysis2 ATP 2 nd Pyruvate  Acetyl CoA 2 NADH + H + 3 rd Krebs Cycle2 ATP 6 NADH + H + 2 FADH 2 2 ATP 4thOxidative Phosphorylation2 NADH + H + 8 NADH + H + 2 FADH 2 4 ATP * 24 ATP 4 ATP Final Score36 ATP

21. Lipids 95% of lipids in our diet are triglycerides Triglycerides are divided into: –Saturated fats –Unsaturated fats Monounsaturated fats (olive and peanut oils) Polyunsaturated fats (fish, safflower, sunflower, corn oil) The more saturated the product, the harder it is at room temperature

24. Lipids How is percentage of fat in food calculated? –One gram of fat= 9 Calories –Multiply number of grams of fat by 9 and represent the number of Calories as a percentage of the total Calories per serving. –e.g. Calories per serving = 120 Calories Total fat = 7 grams 7 x 9 = 63 Calories → 63 / 120 = 52.5% fat

25. Lipids

26. Lipids

27. Lipids

28. Lipids: An Important Energy Source Lipids as an energy source –The part of the lipid molecule that is used for energy production is the free fatty acid (FFA) –FFA are metabolized by a process called beta- oxidation –Acetyl-CoA is formed from beta-oxidation

29. Lipids: An Important Energy Source Lipids as an energy source –Most of the acetyl-CoA enters the mitochondria and the Krebs cycle –During rest, nearly 60% of the energy supply is provided by the metabolism of fats

30. Protein Chains of amino acids 20 different amino acids –Essential amino acids (9) –Non-essential amino acids Used to synthesize protein in the body Also used as a source of energy Excess amino acids stored as glycogen or fat

32. Cellular Respiration Cellular respiration can be either anaerobic or aerobic Not an “either/or” situation – both systems work concurrently When we describe muscular exercise, aerobic and anaerobic refer to which system predominates

33. The Energy Continuum ATP-PC system predominates in activities lasting 10 seconds or less Continues to provide at least 8% for maximal activities up to 2 minutes

34. The Energy Continuum Anaerobic metabolism (ATP-PC & LA) predominates in supplying energy for exercises lasting less than 2 minutes Continues to provide up to 15% energy requirements for exercise as long as 10 minutes

35. The Energy Continuum The O 2 system is the dominant system five minutes into exercise The longer the exercise, the more important it becomes

36. The Energy Continuum

37. Lactic Acid / Lactate Production Lactic acid is produced in muscle cells NADH + H + transfers its hydrogen to pyruvate which forms lactic acid The amount of lactic acid present depends on the balance between its production and its removal

38. Lactic Acid / Lactate Production What conditions lead to lactic acid production? –Muscle contraction results in lactic acid production –Fast twitch fibers produce lactic acid when they contract –Insufficient amounts of oxygen

40. Why is Lactic Acid a Problem? It is the H + that comes from the lactic acid that is the problem Normally we can buffer the H + to maintain pH When the amount of H + exceeds the capacity to buffer, the pH becomes acidic At this point, pain is perceived and performance suffers

41. Why is Lactic Acid a Problem? Pain sources: –Activities that rely on the ATP-PC and LA systems –H + ions accumulate and stimulate pain nerve endings located in the muscle Performance –Metabolic fatigue –Muscular fatigue

42. Lactate Removal Lactate is removed from the bloodstream relatively quickly following exercise There are wide interindividual differences, but generally half of the lactate is removed in about 15 - 25 minutes (half-life) Near-resting levels can be achieved in 30 - 60 minutes

43. Lactate Removal Evidence suggests that lactate removal occurs more quickly when individual exercises during recovery Intensity of the exercise peaks at about 40% VO 2max Careful! Active recovery can deplete glycogen stores and delay glycogen resynthesis

44. Lactate Threshold (LT) The LT represents an exercise level where the production of lactic acid exceeds its removal Function of LT –Indicator of aerobic training status –Predicts endurance performance –Establishes effective training intensity

45. Aerobic Metabolism The aerobic system provides long-term energy Occurs in mitochondria Includes Krebs cycle and oxidative phosphorylation (3 rd & 4 th quarters)

46. Aerobic Metabolism Exercise time (min) Oxygen Consumption ml/kg/min Steady State Rest

47. Steady State Lactic acid does not accumulate in the blood under steady state conditions Steady state is different for different people Depends on –The capacity to deliver oxygen to the muscles –The ability of the muscles to use the oxygen

48. Training the Anaerobic System Anaerobic training (sprint/power training) –Increases in resting levels of ATP, CP, creatine & glycogen and increases in strength –Increases in the quantity of enzymes that control glycolysis –Increased capacity to generate high levels of blood lactate

49. Training the Aerobic System Aerobic training –Larger, more numerous mitochondria in muscle –Enhanced breakdown of fat (conserves glyocgen) –Enhanced ability to breakdown CHO during max exercise –Delay the onset of blood lactate during exercise of progressively increasing intensity –Body composition changes

50. Training the Aerobic System Aerobic training –Performance changes –Psychologic benefits

51. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness 2.Training intensity 3.Training frequency 4.Training duration

52. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness Great improvements can be made if aerobic fitness is low to start Aerobic fitness improvements generally range between 5 & 20% with endurance training

53. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness 2.Training intensity Adaptations depend on the intensity of the overload %HR is commonly used to set intensity Aerobic capacity will improve if intensity regularly maintains heart rate between 55 and 70% of max “Conversational pace”

54. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness 2.Training intensity Relationship between %HR max and %VO 2max %HR max %VO 2max 5028 6040 7058 8070 9083 100

55. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness 2.Training intensity 3.Training frequency Number of days/week varies Some studies report that frequency influences cardiovascular improvement Others report that intensity and duration is more important and frequency is less important

56. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness 2.Training intensity 3.Training frequency Increased frequency is important when weight loss is desired To effect meaningful weight loss, exercise session should be at least 60 min. at an intensity to expend 300 kCal or more

57. Factors That Influence Aerobic Training 1.Initial level of aerobic fitness 2.Training intensity 3.Training frequency 4.Training duration No magic number (depends on exercise intensity) Duration needs to increase if intensity is lower e.g. 60 min at exercise intensities < 70% HR max

58. Factors That Influence Aerobic Training ACSM Recommendations –Cardiovascular function Exercise has an additive effect (3 x 10 min nearly equals 1 x 30 min) Intensity = 40-50 to 85% VO 2max (55-65 to 90% HR max ) Duration = at least 20 to 60 minutes Frequency = more than 2 days weekly