Energy Systems EDU2EXP Exercise & Performance

Types of energy Chemical Mechanical Heat Light Electric Nuclear Start with some bioenergetics Many types All around us EDU2EXP Exercise & Performance

Laws of Thermodynamics energy transfer always proceeds in the direction of increased entropy and the release of free energy 1- Energy cannot be created or destroyed Chemical energy  mechanical energy First law of thermodynamics  Dictates that the body does not produce, consume, or use up energy; rather, it transforms it from one form into another as physiologic systems undergo continual change And this is the same for energy outside of our bodies as well Conservation of energy always the priority 2nd law is that energy transfer always proceeds in the direction of increased entropy and the release of free energy Science that studies how energy is converted from one form to another in the body = bioenergetics EDU2EXP Exercise & Performance

Definitions Enzymes Coenzymes Highly specific protein catalysts Accelerate the forward and reverse reactions Are neither consumed nor changed in the reaction Coenzymes Complex nonprotein organic substances facilitate enzyme action by binding the substrate with its specific enzyme transport chemical groups from one enzyme to another. EDU2EXP Exercise & Performance

Catabolism and Anabolism Metabolic pathways that break down molecules into smaller units and release energy Girl crying cos she ran over her cat? Or her name is Catherine, she breaks down EDU2EXP Exercise & Performance

Overview of Catabolism Electron Transport Chain Figure 3.4, simplified Overview of Catabolism FFA’s Glucose Amino acids glycolysis deamination NH 2 Acetyl CoA  - oxidation TCA Cycle Electron Transport Chain + NADH + H CO 2 + FADH + H mitochondria EDU2EXP Exercise & Performance

Anabolism Covalent bonding of electrons, protons and small molecules to produce larger molecules  building up Anna - the free energy cost of building new and/or larger molecules occurs at the expense of the increased heat and entropy released from catabolism. Many anabolic processes are powered by adenosine triphosphate (ATP). Anabolic processes tend toward "building up" organs and tissues. These processes produce growth and differentiation of cells and increase in body size, a process that involves synthesis of complex molecules. Examples of anabolic processes include growth and mineralization of bone and increase of muscle mass. Catabolism and anabolism function in a dynamic balance.  Anabolism is powered by catabolism  Greater stimulation for catabolism increases catabolism and reduces anabolism Q: What are examples? Catabolism is used to break down glucose  ATP  energy for activity Anabolism is used to build up muscles  hypertrophy/ increased strength - Catabolism and anabolism function in a dynamic balance. EDU2EXP Exercise & Performance

More definitions Exergonic is a spontaneous reaction that releases energy. Endergonic is an anabolic reaction that consumes energy. EDU2EXP Exercise & Performance

Energy systems Generate ATP under different conditions ATP-PC Lactic acid/ glycolysis Aerobic/ Oxidative EDU2EXP Exercise & Performance

ATP- Adenosine Triphosphate Powers all of cell’s energy-requiring processes Potential energy extracted from food Energy is stored in bonds of ATP 80-100g is stored Anaerobic energy source- possible (but not advisable) to swim underwater for about 15 metres while holding your breath Hold breath, do as many star jumps as possible until your body tells you that you need to breathe 80-100 g of ATP is stored in the body- used within 2 seconds of activity beginning yet a sedentary person uses 75% BW in ATP per day; that is a sedentary person who weights 80 kg uses 60 kg of ATP Per day. THEREFORE it must be resynthesised EDU2EXP Exercise & Performance

Energy Systems Immediate energy  8 seconds Short-term energy ATP-PC Short-term energy  1 or 2 minutes Lactic acid system Glycolytic system Anaerobic glcolysis Long-term energy >3 minutes Aerobic system You should already know about 3 main energy systems – VCE PE, refreshers, text Those time limits are probabley what was presented to you in high school What isn’t obvious and what might sometimes is the fact that there is an interplay between the systems to allow us to perform. When you are running you don’t stop and ‘change gears’ after 8 seconds into lactic and then at 3 minutes into aerobic- That is why this graph is important, it shows the percentage of energy that is being produced by each. So they all have their time being the main source ATP/PCR system = rapid, immediate- just the reconstruction of ADP to ATP using PCR Anaerobic without oxygen. Called many things- lactic acid as it involves pyruvate or glycolytic because it involves glycolysis (breakdown of glucose) EDU2EXP Exercise & Performance

http://www.online-stopwatch.com/full-screen-stopwatch/ Get a person out the front to ‘be’ each of the energy systems. Have an ‘athlete’ running around them. Audience has to help each of the energy systems to act out the graph. EDU2EXP Exercise & Performance

ATP All gone after 2 seconds maximal intensity EDU2EXP Exercise & Performance

ATP-PC system Anaerobic resynthesis of ATP- 5-8 seconds of energy Hydrolyzed by the enzyme, creatine kinase ADP is phosphorylated to ATP Creatine may be phosphorylated back to PCr Anaerobic resynthesis of ATP- 5-8 seconds of all out energy it’s why in a 100m sprint, the athletes always slow down towards the end Anaerobic resynthesis of ATP only provides about 10% of energy the majority is oxidative phosphorylation EDU2EXP Exercise & Performance

Adenosine Diphosphate ADP is ATP minus one phosphate group 14 calories of energy is released each time ATP  ADP 80-100 g of ATP is stored in the body, yet a sedentary person uses 75% BW in ATP per day; that is a sedentary person who weights 80 kg uses 60 kg of ATP Per day. THEREFORE it must be resynthesised EDU2EXP Exercise & Performance

Remember the Spare Phosphate?? The Spare P that was released from ATP  ADP hooks up with Creatine to form … Creatine Phosphate (CrP) Cells store ~ 4 – 6 times more PCr than ATP EDU2EXP Exercise & Performance

Get 6 volunteers to act it out 3 phosphates Person to indicate when it is called ATP Person for ADP Creatine EDU2EXP Exercise & Performance

Creatine Supplementation If Phosphocreatine (PCr) is depleted, it cannot regenerate ATP Ingestion Creatine monohydrate (20 g per day) over 5 days  increased stores PC Therefore improves performance short intense exercise in non weight bearing exercise Also enhanced physiologic adaptation to resistance training  Increased dynamic muscular strength and muscle mass Beware of side effects  long term still unknown Therefore improves performance- lab setting- wingate test in non weight bearing exercise- Creatine supplementation results in increased weight gain that is due to water retention around muscle fibres  weight bearing exercises such as running this would be a disadvantage EDU2EXP Exercise & Performance

Glycolysis During performances of short duration and high intensity that require rapid energy transfer that exceeds that supplied by phosphagens 400-m sprint 100-m swim Multi-sprint sports Anything up to 3 minutes Lactate is the by product “Lactic acid system’ Multi-sprint sports Ice hockey Field hockey Soccer Glycogen stored in muscles provides energy to phosphorylate ADP during glycogenolysis As we showed in our demo- anaerobic system is working, even at rest, it is just that the by product, or pyruvate is sent to Cori cycle rather than accumulating as lactic acid in the blood. EDU2EXP Exercise & Performance

Glycolysis Breakdown of glucose or glycogen to form 2 molecules pyruvate and 4 ATP Requires 2 molecules ATP for the process to occur = Net gain 2 molecules ATP EDU2EXP Exercise & Performance

Lactic acid? Lactate? Not the same Lactate that accumulates during anaerobic metabolism does not cause acidosis Lactate  Pyruvate  Acetyl CoA  Kreb’s cycle & Aerobic production ATP Related but technically different Lactic acid produces and then ionises to lactate produces hydrogen ion ATP hydrolised- releases hydrogen rapid accumulation hydrogen ions = lower Ph = acidosis. The acidosis that is associated with increases in lactate concentration during heavy exercise arises from a separate reaction. When ATP is hydrolysed, a hydrogen ion is released. ATP-derived hydrogen ions are primarily responsible for the decrease in pH. EDU2EXP Exercise & Performance

Lactic Acid System Blood lactate @ rest is usually 1-2 mmol/L but can rise to over 20 mmol/L during intense exertion. Lactate accumulation rate of lactate production exceeds the rate of lactate removal Lactate removal Gluconeogenesis- conversion to glucose through Cori cycle in the liver If oxygen present: Oxidation to pyruvate Fuels citric acid cycle During power-intensive exercises such as sprinting, when the rate of demand for energy is high, lactate is produced faster than the ability of the tissues to remove it and lactate concentration begins to rise. The increased lactate produced can be removed in a number of ways including: oxidation to pyruvate by well-oxygenated muscle cells which is then directly used to fuel the citric acid cycle conversion to glucose via the Cori cycle in the liver through the process of gluconeogenesis. EDU2EXP Exercise & Performance

Lactate Inflexion Point- LIP Intensity of exercise above which anaerobic energy system is required to meet energy demands. Lactate accumulates as removal cannot exceed production Measurable as blood lactate levels increase substantially Page 109 of text Previously referred to as Anaerobic threshold. LIP reading in back of lab manuals- terminology changed since VCE PE Now recognised that there is no exact point, but more of a general region or lactate inflexion Just as it takes time to explain aerobic metabolism, it takes time to do it- anaerobic is much faster and can therefore allow a quicker generation of energy EDU2EXP Exercise & Performance

Aerobic Oxidative Phosphorylation Lipids Carbs Lipolysis Beta oxidation Kreb’s cycle Carbs Glycolysis Pyruvate  Acetyl CoA Krebs cycle (citric acid cycle or tricarboxylic acid cycle) Electron transport chain Real deal- provides the most, especially when exercise duration extends beyond 2 to 3 minutes Where oxygen is present, oxidation of carbs (glucose) or FFA occurs through the citric Slow glycolysis (aerobic glycolysis)  oxidation glucose to form ATP Krebs cycle (citric acid cycle or tricarboxylic acid cycle) Electron transport chain Beta oxidation Krebs Cycle The Krebs cycle is a complex series of chemical reactions that continues the oxidization of glucose that was started during glycolysis. Acetyl coenzyme A enters the Krebs cycle and is broken down in to carbon dioxide and hydrogen allowing more two more ATPs to be formed. However, the hydrogen produced in the Krebs cycle plus the hydrogen produced during glycolysis, left unchecked would cause cells to become too acidic (2). So hydrogen combines with two enzymes called NAD and FAD and is transported to the… Electron Transport Chain Hydrogen is carried to the electron transport chain, another series of chemical reactions, and here it combines with oxygen to form water thus preventing acidification. This chain, which requires the presence of oxygen, also results in 34 ATPs being formed (2). Beta Oxidation Unlike glycolysis, the Krebs cycle and electron transport chain can metabolise fat as well as carbohydrate to produce ATP. Lipolysis is the term used to describe the breakdown of fat (triglycerides) into the more basic units of glycerol and free fatty acids (2). Before these free fatty acids can enter the Krebs cycle they must undergo a process of beta oxidation - a series of reactions to further reduce free fatty acids to acetyl coenzyme A and hydrogen. Acetyl coenzyme A can now enter the Krebs cycle and from this point on, fat metabolism follows the same path as carbohydrate metabolism (5). Fat Metabolism So to recap, the oxidative system can produce ATP through either fat (fatty acids) or carbohydrate (glucose). The key difference is that complete combustion of a fatty acid molecule produces significantly more acetyl coenzyme A and hydrogen (and hence ATP) compared to a glucose molecule. However, because fatty acids consist of more carbon atoms than glucose, they require more oxygen for their combustion (2). So if your body is to use fat for fuel it must have sufficient oxygen supply to meet the demands of exercise. If exercise is intense and the cardiovascular system is unable to supply cells with oxygen quickly enough, carbohydrate must be used to produce ATP. Put another way, if you run out of carbohydrate stores (as in long duration events), exercise intensity must reduce as the body switches to fat as its primary source of fuel. Protein Metabolism Protein is thought to make only a small contribution (usually no more 5%) to energy production and is often overlooked. However, amino acids, the building blocks of protein, can be either converted into glucose or into other intermediates used by the Krebs cycle such as acetyl coenzyme A. Protein may make a more significant contribution during very prolonged activity, perhaps as much as 18% of total energy requirements (1). The oxidative system as a whole is used primarily during rest and low-intensity exercise. At the start of exercise it takes about 90 seconds for the oxidative system to produce its maximal power output and training can help to make this transition earlier (1). Beyond this point the Krebs cycle supplies the majority of energy requirements but slow glycolysis still makes a significant contribution. In fact, slow glycolysis is an important metabolic pathway even during events lasting several hours or more (2). EDU2EXP Exercise & Performance

Krebs Cycle Also known as the TCA cycle, or citric acid cycle Continues oxidation of Carbohydrates following glycolysis Fatty acids following beta oxidation Some amino acids following deamination The citric acid cycle (TCA cycle, the Krebs cycle, or Szent-Györgyi-Krebs cycle (after Hans Adolf Krebs and Albert Szent-Györgyi who first determined the chemical intermediates and reaction sequence of the cycle) is a series of enzyme-catalysed chemical reactions of central importance in all living cells that use oxygen as part of cellular respiration. citric acid cycle is part of a metabolic pathway involved in the chemical conversion of carbohydrates, fats and proteins into carbon dioxide and water to generate a form of usable energy. It is the third of four metabolic pathways that are involved in carbohydrate catabolism and ATP production, the other three being glycolysis and pyruvate oxidation before it, and respiratory chain after it. EDU2EXP Exercise & Performance

The citric acid cycle is the third step in carbohydrate catabolism (the breakdown of sugars). Glycolysis breaks glucose (a six-carbon-molecule) down into pyruvate (a three-carbon molecule). pyruvate moves into the mitochondria and is converted into acetyl-CoA by decarboxylation and then enters the citric acid cycle. The citric acid cycle is always followed by oxidative phosphorylation. This process extracts the energy (as electrons) from NADH and FADH2, oxidizing them to NAD+ and FAD, respectively, so that the cycle can continue. The citric acid cycle itself does not use oxygen, but oxidative phosphorylation does. Coenzyme A is a derivative of B1- it’s why they say that B vitamins give you energy! They don’t, but are crucial to the whole process The total energy gained from the complete breakdown of one molecule of glucose by glycolysis, the citric acid cycle and oxidative phosphorylation equals about 36 ATP molecules. worth the effort! All controlled by a negative feedback loop  won’t happen when there are high concentrations of ATP in cells  therefore limits production of too much ATP http://www.youtube.com/watch?v=1aYPo5xNVIA EDU2EXP Exercise & Performance

Anaerobic/ aerobic systems 12 chemical reactions to convert carbohydrate (either stored glycogen or circulating blood glucose) to pyruvate Oxygen Pyruvate enters Krebs cycle and is used to generate ATP Produces 38-39 mol ATP No Oxygen Pyruvate converted to Lactate Produces 2-3 mol ATP No oxygen because in first few minutes of exercise or requiring fast burst to breakaway to get the ball. During intense exercise, aerobic metabolism cannot produce ATP quickly enough to supply the demands of the muscle. As a result, anaerobic metabolism becomes the dominant energy producing pathway as it can form ATP at high rates. http://www.youtube.com/watch?v=1aYPo5xNVIA Cellular Respiration Overview Animation with Glycolysis, Krebs EDU2EXP Exercise & Performance

What you need to know: 3 different systems Predominant energy systems used for different sorts of activities ATP-PC system- how is energy generated and ATP regenerated? Anaerobic- diagram- net gain of energy Aerobic- terms- 3 stages- net gain energy EDU2EXP Exercise & Performance

Transition to Exercise O2 consumption O2 consumption increases rapidly, but not instantaneously Oxygen deficit is the lag in O2 uptake, the difference between what is required and what is available at during the first few minutes of exercise untill a steady state is reached Time to reach steady state is shorter in trained as opposed to untrained subjects  trained have lower O2 deficit - Next 3 slides not in handouts so will give time to make notes EDU2EXP Exercise & Performance

Recovery -EPOC O2 consumption remains elevated O2 Dept = payment for O2 deficit Pg 118 text Increased intensity of exercise = increased deficit and therefore increased debt Volume of oxygen consumed that is above that normally consumed at rest Also termed EPOC – Excess post exercise consumption Respiration also increased- mostly to clear out Co2 that is accumulated in the cells as it is a byproduct of metabolism. During this period – ATP and PCr resynthesised and blood and muscle O2 levels restored --. Completed within 2-3 minutes EDU2EXP Exercise & Performance

Vo2 Max Determines cardiovascular fitness O2 uptake increases with intensity of exercise up until a certain point ml/kg/minute Factors influencing: Delivery uptake Once uptake reaches Vo2 max, an increase in power does not result in an increase in oxygen uptake. Therefore it is the physiological ‘ceiling’ for the ability of the o2 transport system to deliver o2 to connecting muscles Measured in ml of oxygen / per kg of body weight /per minute Factors influencing: Delivery- Ability of cardiorespiratory system to deliver oxygen to contracting muscles Uptake- muscles’ abiility to take up oxygen and produce ATP aerobically Factors influencing both of those = genetics and training EDU2EXP Exercise & Performance

Yield: 1g = 4.1 Cal Yield: 1g = 9.4 Cal Yield: 1g = 4.1 Cal Another summary Glucose conversion to fat Lipogenesis Citrate diverted to cytosol Fatty acids are synthesized. Protein conversion to fat Excess amino acids deaminated Converted to acetyl-CoA Fatty acids are synthesized Yield: 1g = 4.1 Cal Yield: 1g = 9.4 Cal Yield: 1g = 4.1 Cal EDU2EXP Exercise & Performance

Chronic Adaptations to Training Chronic adaptations in the energy systems Increased number and size of mitochondria means that a greater mitochondrial surface area is exposed to cytosol which allows for better exchange of metabolites. May have noticed that the kreb’s cycle and formation ATP takes place in the mitochondria Basically the body is better able to catabolise CHO and lipid fuels Increased Lactate threshold- so can exercise at a higher intensity while still being at a steady state therefore able to maintain a faster pace for a longer period of time resulting in decreased finishing time and increased performance Hurley et al, 1986 trained 9 subjects for 12 weeks sic times per week at 75-100% Vo2 max 5-40 min in duration After the 12 week training period subjects could perform a bout of exercise using less muscle glycogen and more muscle trygliceride than prior to training- therefore more efficient use of energy Endurance training  increased capillary density in working muscles therefore greater availability oxygen. EDU2EXP Exercise & Performance

Implications EDU2EXP Exercise & Performance

Sources of Fatigue- p 113 text PCr depletion Muscle glycogen depletion Neuromuscular- nerve impulses CNS- muscle recruitment Metabolic by-products Lactate Hydrogen ions low ph Buffers- bicarbonate Not in handout- make notes- PCr depletion- reduces capacity to replenish ATP quickly Muscle glycogen depletion- Remember glycogen stores are about 1% muscle mass? Say 280 g in total- but there is less contained in each muscle group. Lactate not necessarily only cause of fatigue- it only accumulates when production exceeds removal- marathon runners can have near resting levels at the end of a race despite the fact that they are extremely fatigued!! When lactic acid does accumulate, and is not dispersed, it dissociates, or ionises, and hydrogen ions accumulate- which causes acidosis- a reduction in ph. Luckily the body has buffers- bicarbonate- which neutralise the ph levels by EDU2EXP Exercise & Performance

Muscle Fibre Types Type 1 = Slow twitch Type 2 = fast twitch Generates energy aerobically For endurance exercise Type 2 = fast twitch 2a- some aerobic power / anaerobic 2b-predominantly anaerobic Generates energy anaerobically For short intense exercise High in slow twitch = endurance athletes  therefore generally have a high lactate threshold Type 2 = fast twitch Generates energy anaerobically. Both subtypes have rapid contraction speed and capacity for anaerobic ATP production in glycolysis Fast twitch muscle fibres don't use oxygen to make energy, so they don't need such a rich blood supply. This is why fast twitch muscles are lighter in colour Type 1 Slow Twitch are red, because they contain lots of blood vessels. Slow twitch muscle fibres rely on a rich supply of oxygenated blood as they use oxygen to produce energy for muscle contraction. Dark and white meat Chickens have fast and slow twitch muscle, too. Dark meat, like in chicken legs, is mainly made up of slow twitch fibres. for walking and standing, which they do most of the time White meat, like in chicken wings and breasts, is largely made up of fast twitch muscle fibres. wings for brief bursts of flight. EDU2EXP Exercise & Performance

Recovery from exercise Remove lactate Re-oxygenation muscle myoglobin Replace Muscle glycogen PCr Lipid levels In recovery, generally concerned about removal of lactate and Co2 from skeletal muscle, and replacing everything that was consumed during exercise, ie; creatine phosphate, glycogen, lipid EDU2EXP Exercise & Performance

Active recovery Movement at a lower intensity/ submax performed immediately after exercise Assists with oxidation of lactate (Lactate shuttling) But as is aerobic may impair glycogen synthesis May impair glycogen synthesis as active recovery still requires glucose for fuel EDU2EXP Exercise & Performance

Passive recovery Lie down  complete inactivity Theory is that this ‘frees’ oxygen for the recovery process Downfall no lactate shuttling EDU2EXP Exercise & Performance

Which is best? Research inconclusive Depends on exercise to recover from Steady rate exercise PCr stores not depleted Lactate levels not increased Depends on post exercise glucose intake Intense/Non-Steady rate exercise Large O2 deficit In recovery, generally concerned about removal of lactate and Co2 from skeletal muscle, and replacing everything that was consumed during exercise, ie; creatine phosphate, glycogen, lipid Nutrition is important Steady rate exercise- What energy systems are predominant?? AEROBIC therefore PCr stores not depleted Lactate levels not increased But glycogen synthesis must take place, and glucose/ CHO required for this If steady rate exercise was for a long period of time, muscle glycogen stores will be severely compromised and post exercise glucose intake is required Even more if there was muscle damage If damage, glycogen synthesis cannot occur unti 12 hours after, as the influx of macrophages and leukocytes need glucose to help fix the muscles too Non steady rate exercise ANAEROBIC EDU2EXP Exercise & Performance

Lactate Removal Exercise Recovery Active Passive Passive Performing exercise 35%-50% Vo2 max during recovery from exercise increases lactate removal from the blood Not always positive Lactate =/= acidosis Creatine phosphate recovery and acidosis are more closely related Passive EDU2EXP Exercise & Performance

Ice baths proposed for many reasons Bulldogs- NRL Ice baths proposed for many reasons Vasoconstriction BV in lower extremities mean blood shunted to heart and lungs for greater reoxygenation Reduced intramuscular swelling therefore reduced soreness and better ability to train next day EDU2EXP Exercise & Performance

Summary Energy is never created nor destroyed. Complex chemical process synthesize glucose/ glycogen from our foods Immediate energyATP-PC Short-term energy Lactic acid system Long-term energy Aerobic system Dynamic balance Training Recovery Energy is never created nor destroyed. Q: WHAT HAPPENS TO IT? It is transferred EDU2EXP Exercise & Performance