Three Metabolic Pathways. PSK 4U Unit 5: Energy Systems Days 2-3

Transcription

1 Three Metabolic Pathways PSK 4U Unit 5: Energy Systems Days 2-3

2 The Energy Systems The ability to move, work or play sports is dependant on supplying sufficient energy at the required rate for the duration of the activity. All energy in the human body comes from the breakdown of complex nutrients like carbohydrates, fats and proteins.

3 Biologic Energy Cycle Energy can neither be created or destroyed but merely transformed. Sun = Solar Energy. CO2 H2O Plants Carbohydrates Proteins Chemical Energy O2 Humans Carbohydrates, Proteins, Fats, ATP PC. Animals Carbohydrates Proteins Fats Chemical / Mechanical Energy Chemical / Mechanical Energy

4 Bioenergetic Conversion The breakdown of energy nutrients for energy to carry out physical activity. Carbohydrates Fats Proteins 4.1 cal/gram 9.3 cal/gram 4.3 cal/gram Glycogen Triglycerides Amino Acids Glycolysis Lipolysis Glucose Fatty acids Not stored; excreted through urine

5 Review Carbohydrates are the most abundant substances in nature they come to us from foods that originate from plants (fruits and vegetables) and grain based products (such as bread and pasta). Glycogen = Stored form of glucose within skeletal muscle and the liver.

6 Adenosine Triphosphate (ATP) The end result of nutrient breakdown is the production of various amounts of adenosine triphosphate (ATP). ATP is the immediate energy source for muscular contraction. An ATP molecule consists of an adenosine molecule bonded to three phosphate groups. Adenosine P P P Adenosine Triphospate (ATP) ATP molecules are supplied by chemical reactions that take place in the mitochondria found in muscle cells.

7 To release the energy, a phosphate molecule breaks away from the phosphate group through hydrolysis to form adenosine diphosphate (ADP) HEAT Adenosine P P P Hydrolysis Adenosine P P P Breaking ATP into ADP releases energy and allows cross bridge formation to occur between the myosin and actin filaments inside the muscle. ENERGY

8 ATP is a renewable resource that can be regenerated by the recombination of ADP with a free phosphate. The following reaction describes the regeneration process. Adenosine + + P P P Adenosine P P P ENERGY To accomplish this synthesis, energy must be available; Energy is supplied through the breakdown of complex food molecules, such as fats and carbohydrates.

9 The 3 Energy Pathways The production of ATP involves three energy pathways, each producing ATP at a distinct rate and duration: 1. The Immediate or High Energy Phosphate system (Anaerobic Alactic or ATP- PC system) 2. The Short-Term or Glycolytic system (Anaerobic Lactic or Lactic Acid system) 3. The Long-Term or Oxygen system (Aerobic) The three energy pathways are designated as anaerobic or aerobic, depending on whether oxygen is needed by the system in the production of energy.

10 1.Anaerobic Two Systems = Three Pathways Energy systems that do not rely on the immediate use of oxygen. There are two types of anaerobic energy systems. Anaerobic Alactic (ATP-CP) A short term energy of both fast and slow twitch muscle fibres that does not require oxygen and does not produce lactic acid. Anaerobic Lactic (glycolysis) A fast twitch muscle energy system which does not require the immediate use of oxygen but does produce lactic acid. 2.Aerobic (cellular respiration) A slow twitch muscle energy system which is used in prolonged continuous activity in the presence of oxygen and does not produce lactic acid.

11 ATP-PC (Anaerobic Alactic) An immediate - high energy phosphate system Adenosine P P HEAT ENERGY P Involves high power output activities that require an immediate high rate of energy production for a short period of time. Involves activities such as weight lifting, high jump, long jump, shot put, discus 50 metre sprint, 25 metre swim.

12 As muscle contraction begin, the body s metabolism may not be able to supply ATP to the contracting muscle cells as rapidly as required The body must then make use of creatine phosphate (phosphocreatine). Creatine phosphate serves as a quick available energy reserve for muscles as it is broken down into creatine and phosphate. + Adenosine P P P PC PC PC PC PC PC Creatine ATP ENERGY The free phosphate ions bonds with ADP to produce ATP and leaves behind creatine. The new ATP molecule is stored as potential energy.

13 Anaerobic Alactic Characteristics Only a small amount of ATP and PC is stored in muscle fibres; Uses very large amounts of energy in a short period of time; The rate of recovery is relatively rapid. After a brief rest (2 minutes or so), the system is recharged and ready for the next sprint; Oxygen is not required; Glucose is not used; Lactic acid is not produced; The system can only provide energy for muscles for the first seconds of high intense activity; Uses both fast and slow twitch muscles; Work output is relatively high.

14 Glycolysis (Anaerobic Lactic) In all out sprint, which requires a great deal of power output in a short period of time, (15-60 or 120 seconds) ATP cannot be supplied rapidly enough to meet the needs of the muscle cells. Energy is quickly available, but the anaerobic pathways are not very efficient short term energy stores are rapidly depleted, lactic acid builds up exercise soon comes to a halt.

15 If an athlete must continue vigorous work a second energy system uses a complex biochemical process which breaks down carbohydrates into glucose and glycogen to release energy. Lactic Acid Carbs Glucose/glycogen ENERGY ADP + P ATP One molecule of glucose yields: two molecules of ATP and pyruvate, which is converted to lactic acid in the absence of oxygen.

16 The Effects of Lactic Acid During intense exercise, lactic acid builds up in the blood faster than it can be removed. Lactic acid hampers the breakdown of glucose As lactic acid build up an athlete will reach their Anaerobic Threshold. Anaerobic threshold is the point where a person begins to feel discomfort and a burning sensation in their muscles. At the anaerobic threshold the muscle loses it ability to contract resulting in muscle fatigue.

17 As work increases, the body reaches the Anaerobic Threshold At this point the anaerobic system can no longer keep pace with the increasing requirements of the muscles. The anaerobic threshold is the highest intensity of workload at which lactate clearance still keeps pace with lactate production. Low Slow twitch fibres dominate Exercise Intensity Moderate Fast-twitch type A fibres are recruited Once this level is reached the intensity level must decrease to reduce the amount of lactic acid buildup High Fast-twitch Type B fibres dominate

18 The Effects of Lactic Acid Lactic acid causes ph changes in the muscle fibres and they can no longer respond to stimulation. Lactic acid interferes with cross- bridge bonding by limiting the strength of the fibre contraction. A high production of lactic acid ultimately limits continued performance in intense activities When lactic acid accumulates, extreme fatigue sets in and oxygen debt develops. Oxygen debt is the reason you must breathe rapidly and deeply for a few minutes after strenuous exercise. After you stop anaerobic exercise, your body needs extra oxygen to burn up the excess lactic acid and return your energy reserves to normal. Lactic acid cannot be removed until extra oxygen is supplied to convert it to harmless, re-usable products.

19 Oxygen Debt Oxygen debt refers to post exercise oxygen consumption where the body needs to pay back its debt incurred above after the exercise is over You will notice that even after you are done racing you will continue to breath hard. At this point your body is still trying to repay the oxygen debt that was created when you were working hard.

20 Characteristics of the Lactic Acid System The energy source is entirely carbohydrate; Oxygen is not required Energy is provided for or 120 seconds depending on conditioning Uses predominately fast twitch muscle fibres Work output is moderate Used in sports such as football, basketball and hockey. The Effect of Training on the Lactic Acid System At any level of work, the rate of lactic acid build-up is decreased through training. The anaerobic threshold rises. The individual is able to handle a higher level of lactic acid. Trained individuals are able to remove lactic acid faster from exercising muscles. Improvements in the cardiovascular system deliver an increased blood flow to the working muscle.

21 Raising Your Anaerobic Threshold Since it is not possible to convert fast twitch fibres to slow twitch fibres, raising your anaerobic threshold depends on improving the condition of the fast twitch muscle fibres. This occurs when effort intensifies. How do you know if your workouts are pushing your AT? Pay attention to how your running feels. After several workouts, you'll notice the feeling when you are in the anaerobic zone. Elite athletes use the Conconi test which requires a handheld device that directly measures blood lactate concentration. The corresponding heart rate at the AT gives you a convenient way of monitoring your workouts.

22 End of Day 2

23 Long-Term Energy: Aerobic System As the length of an exercise session continues the athlete requires a steady power output over a long period of time Exercise performed at a lower intensity level relies almost exclusively on the aerobic system for energy production and requires the athlete to use oxygen as its source of energy. o Most daily activities use energy provided by the aerobic energy system o The oxygen energy system is the most important energy system in the body. While this pathway cannot generate the speed of the anaerobic, it does provide a great deal more efficiency and endurance.

24 The Cori Cycle The process by which lactic acid is concerted to pyruvate for future conversion to glucose and glycogen This gets rid of lactic acid in our system and helps to contribute to future energy production.

25 Aerobic System Cellular Respiration The aerobic system energy requires the metabolism of Glucose (stored in muscles) Fats Proteins Oxygen Combine to produce ADP + P ATP ENERGY CO 2 Using energy produces Water

26 Characteristics of the Aerobic System The oxygen system is highly efficient. When oxygen is used in muscle cells: it prevents the build-up of lactic acid an individual can work out longer before lactic acid build-up begins it is able to remove lactic acid from muscles allowing the muscle to continue to contract allowing exercise to continue it promotes the re-synthesis of ATP for energy when work output is low. As the duration of activity increases, the contribution of the aerobic system to the total energy requirement increases. Due to this, there are two limitations to the aerobic system: The system requires a continuous supply of oxygen and fuel sources necessary for the aerobic metabolism. The use of ATP must be relatively slow to allow the process to meet the energy demands

27 Aerobic System Oxygen uptake The power of the aerobic system is generally evaluated by measuring the maximum volume of oxygen that can be consumed in a given amount of time. This can be measured by determining the amount of oxygen exhaled as compared to the amount inhaled. As the intensity of work increases the capacity of aerobic system reaches a maximum. The greatest rate at which oxygen can be taken in and used during exercise is referred to maximal oxygen consumption or (VO2max)

28 Aerobic Power VO2 Max Each person has his or her own maximal rate of oxygen consumption (VO 2 max) The maximal rate at which oxygen can be used is genetically determined. A normal VO 2 max for most high school athletes would fall somewhere between 45 and 60 range. The VO 2 max values of trained athletes will reach for males and for females The more active we are the higher the VO 2 max.

29 Maximal O2 Consumption (VO2 Max) in ml / kg / min. for the 2.4km Run Time Max Time Max VO 2 VO 2 8: : : : : : : : : : : : : : : : : : :

30 Oxygen Deficit While exercising intensely the body is sometimes unable to meet all of its energy needs. Specifically, it is unable to take in and absorb enough oxygen to adequately 'feed' the muscles the amounts of energy needed to adequately perform the tasks the athlete is requesting from the body. In order to make up the difference without sacrificing output, the body must tap into its anaerobic metabolism. This is where the body uses both aerobic and anaerobic energy production. While not hugely detrimental, oxygen deficits can grow to a level that the anaerobic energy system cannot cover. This can cause performance to deteriorate.

31 Effect of Training on the Aerobic System The performance of any activity requires a certain rate of oxygen consumption. A person s ability to perform an activity is limited by their maximal rate of oxygen consumption. Therefore, the most efficient method for improving the aerobic energy system is endurance training/exercise. Long, slow distance training or exercise at the low end of your target heart rate tends to use slow twitch fibres. Walking, jogging or any other light exercise, uses mainly slowtwitch fibres to do the work. ST fibres are slower to fatigue and are well suited for endurance activities.

32 Effect of Training on the Aerobic System Endurance exercise consists of repeated, sustained effort of long duration several times per week. Generally, the higher the intensity, the greater the oxygen consumption. When exercising the target heart rate (THR) should be raised to 70% of max. Examples include: running, swimming or biking for 40 minutes or more at a heart rate of bpm Notes: A highly trained or elite athlete should be able to sustain a heart rate of 85% of their VO2 max. This type of training does not raise your anaerobic threshold. Endurance training has four major effects on the aerobic system: Improved delivery of oxygen and nutrients to the muscles Increase the size and number of mitochondria in muscle fibres Increased activity of enzymes involved in the aerobic pathway Preferential use of fats over glucose during exercise which saves the muscles limited store of glycogen

33 Using All 3 Pathways While running at a comfortable pace you use both systems, but the anaerobic: aerobic ratio is low enough that the lactate generated is easily removed, and doesn't build up. As the pace is increased, eventually a point is reached where the production of lactate, by the anaerobic system, is greater than its removal. The anaerobic threshold is the point where lactate (lactic acid) begins to accumulate in the bloodstream. Note: Depending upon the distance, and effort, the body can use different proportions of both of these systems. For example, the 800 m race is too long to be a sprint, but too short to be a distance race. Therefore, it is run at the cross-over between the aerobic and anaerobic systems.

34 Training the Pathways The best method to train all of the systems together is interval training. Interval work consists of repeating a series of short, high intensity, runs alternating with rest (recovery) periods. Whichever method is used, the athlete must continually push themselves into a lactate burdened state which makes their body adapt. Regardless of the race distance you are training for, 5k or marathon, interval work will help you run faster. Pushing the body past the 'comfortable' speed of running increases aerobic capacity, trains the fast twitch muscles to operate at a higher /faster level and makes the athlete more tolerant of lactic acid build up. The result of interval training is that a runner who can comfortably run at eight-minute/ mile pace and runs their intervals at a seven-minute/mile pace will be able to increase their steady comfortable pace under an eightminute/mile pace.

35 Summary of the Systems Energy for muscular activity depends on a supply of ATP that can be broken down into ADP and phosphate All of the body s biochemical processes and the three energy systems require ATP Trained individuals are able to use ATP and remove lactic acid more efficiently than untrained individuals Endurance training can significantly improve the aerobic system

36 Comparing the Systems Energy system Anaerobic Alactic Anaerobic Lactic Aerobic Type of Activity short sprints used in games such as football, long distance running baseball, pole vault Basketball, Hockey cross country skiing long jump triple jump swimming Range of Maximum Work Times 0 15 seconds 15 to 60 or 120 seconds (depending on conditioning) 120 seconds plus Oxygen Required None None or very little Yes Lactic Acid Produced None Yes, accumulated faster than it can be removed Depends on intensity Energy Source Chemical energy stored in muscles, ATP and CP Entirely carbohydrate (glycogen) Mixture of fat, protein and carbohydrate End Products of Fuel Breakdown Adenosine Diphosphate Creatine Phosphate plus energy Lactic Acid CO 2 and H 2 O Muscle Fibre Recruited Work Output per Unit of Time Fast and slow twitch Predominately fast twitch Slow twitch and some fast twitch High Medium Low

37 Roles of 3 Pathways in Sports Primary Energy Source Anaerobic Pathways ATP produced without the presence of oxygen Aerobic Pathways ATP produced with the presence of oxygen Energy System Immediate Alactic Short-term Lactic Long-term Oxygen Fuel ATP and CP Glycogen + glucose Glycogen, glucose, fat and protein Duration 0s 10s 40s 70s 2 min 6 min 25 min 1 hr 2hr 3hr Sprinting Track 100 m Swim Middle Long Distance 100 m dash m, 800 m track distance track, Track,swimming, Sport Event Throwing Jumping 500m Speedskating Gymnastic floor exercise swimming, speedskating canoeing, speedskating Weightlifting Most Alpine skiing 1000 m canoe Cycling road racing Ski jumping gymnastics Cycling 1000m Boxing, Marathon Diving Events, pursuit Wrestling Triathlon Vaulting in Cycling(track) Rowing Gymastics 50 m swim Figure skating Cycling pursuit Most team Sports/Racquet Sports

38 When the systems are used ATP - CP System Glycolytic System Aerobic System Feel the burn!

39 Picture All 3 Pathways

40 End of Day 3