1 SPORT AND METABOLISM HENDRA WIJAYA

Sport Books Publisher2 Learning Objectives: To develop an awareness of the basic chemical process that the body uses to produce energy in the muscles To develop an understanding of the body’s three main energy systems To introduce the energy requirements and source of energy for skeletal muscle ( Resting vs. Working) To introduce the effect of training and exercise on the energy systems

Sport Books Publisher3 The Chemistry of Energy Production Energy in the human body is derived from the breakdown of complex nutrients like carbohydrates, fats, and proteins. The end result of this breakdown is production of the adenosine triphosphate (ATP) molecule. ATP provides energy necessary for body functions Carbohydrates Fats Proteins ATP Muscular Work Digesting Food Thermoregulation Breakdown ofEnergy currencyBiochemical processes

Sport Books Publisher4 ATP Cycle Overview a) ATP breakdown b) Phosphorylation c) ATP resynthesis

Sport Books Publisher5 1. Hydrolysis of the unstable phosphate groups of ATP molecule by H 2 O 3. Energy is released (38-42 kJ, or 9-10kcal/ mol ATP) ATP H2OH2O+Energy+P+ 2. Phosphate molecule (P) is released from ATP (ATP ADP) ADP a) ATP breakdown (ATP turnover)

Sport Books Publisher6 1. Energy released by ATP turnover can be used by body when a free P group is transferred to another molecule (phosphorylation) Energy for muscle contraction Molecule P+ b) Phosphorylation

Sport Books Publisher7 1.Initial stores of ATP in the muscles are used up very quickly and ATP must be regenerated 2. ATP is formed by recombination of ADP and P ATP ADP Energy+P+ 3. Regeneration of ATP requires energy (from breakdown of food molecules) c) ATP resynthesis

Human Energy Systems ATP-PC System –adenosine triphosphate –phosphocreatine Lactic Acid System –anaerobic glycolytic pathway Oxygen System –aerobic metabolic pathways

Sport Books Publisher9 The Energy Systems a)the high energy phosphate system (ATP-PC) 1.Adenosintriphosphate 2.Phosphocreatine b)the anaerobic glycolytic system (Lactic acid system) c) the aerobic oxidative system

Sport Books Publisher10 The Roles of the Three Energy Systems in Competitive Sport

Sport Books Publisher11

Sport Books Publisher12 The High Energy Phosphate System Overview Primary energy source: Duration of activity: Sporting events: Advantages: Limiting factors: Stored ATP, CP 7-12 s Weight lifting, high jump, long jump, 100m run, 25m swim Produce very large amount of energy in a short amount of time Initial concentration of high energy phosphates (ATP, PC)

ATP-PC Energy System ATP – Energy for muscle contraction

Sport Books Publisher15 Training the High Energy Phosphate System a) Interval training: - 20% increase in CP (creatine phosphate) stores - no change in ATP stores - increase in ATPase function (ATP -> ADP+P) - increase in CPK (creatine phosphokinase) function (CPK breaks down CP molecule and allows ATP resynthesis) b) Sprint training: - increase in CP stores up to 40% - 100% increase in resting ATP stores

Sport Books Publisher17 The Anaerobic Glycolytic System Overview Primary energy source: Duration of activity: Sporting events: Advantages: Limiting factors: Stored glycogen, blood glucose 12 s – 3 min Lactic acid build up, H+ ions build up (decrease of pH) 800m run, 200m swim, downhill ski racing, 1500 speed skating Ability to produce energy under conditions of inadequate oxygen

Sport Books Publisher20 The Anaerobic Glycolytic System ADP + P i  ATP ENERGY Lactic Acid Glycogen

Sport Books Publisher21 Glycolysis A biochemical process that releases energy in the form of ATP from glycogen and glucose anaerobic process (in the absence of oxygen) The products of glycolysis (per molecule of glycogen): - 2 molecules of ATP - 2 molecules of pyruvic acid The by-product of glycolysis (per molecule of glycogen): - 2 molecules of lactic acid

Sport Books Publisher22 Anaerobic Threshold The exercise intensity at which lactic acid begins to accumulate within the blood The point during exercise where the person begins to feel discomfort and burning sensations in their muscles Lactic acid is used to store pyruvate and hydrogen ions until they can be processed by the aerobic system

Sport Books Publisher23 The Anaerobic Glycolytic System cont. Starts when: –the reserves of high energy phosphate compounds fall to a low level –the rate of glycolysis is high and there is a buildup of pyruvic acid

Sport Books Publisher24 Substrates for the anaerobic energy system The primary source of substrates is carbohydrate Carbohydrates: –primary dietary source of glucose –primary energy fuels for brain, muscles, heart, liver

Sport Books Publisher25 Glucose stored in blood Glycogen stored in muscle or liver Complex Carbohydrates Digestive system Glycogen Gluconeogenesis Circulation of glucose around body Glucose Blood Stream Carbohydrate breakdown and storage

Sport Books Publisher26 Effect of Training on the Anaerobic Glycolytic System Rate of lactic acid accumulation is increased in the trained individual This rate can be decreased by: a) reducing the rate of lactate production - increase in the effectiveness of the aerobic oxidative system b) increasing the rate of lactate elimination - increased rate of lactic acid diffusion from active muscles - increased muscle blood flow - increased ability to metabolize lactate in the heart, liver and in non-working muscle

Oxygen Energy System

Sport Books Publisher29 Primary energy source: Duration of activity: Sporting events: Advantages: Limiting factors: Glycogen, glucose, fats, proteins > 3 min Lung function, max.blood flow, oxygen availability, excess. energy demands Walking, jogging, swimming, walking up stairs Large output of energy over a long period of time, removal of lactic acid The Aerobic Oxidative System Overview

Sport Books Publisher30 Aerobic Oxidative System ADP + P i  ATP ENERGY Carbon Dioxide Carbon Dioxide Water Glycogen O2O2 O2O2 Protein Fat

Sport Books Publisher31 The Aerobic Oxidative System The most important energy system in the human body Blood lactate levels remain relatively low (3-6mmol/L bl) Primary source of energy (70-95%) for exercise lasting longer than 10 minutes provided that: a) working muscles have sufficient mitochondria to meet energy requirements b) sufficient oxygen is supplied to the mitochondria c) enzymes or intermediate products do not limit the Kreb’s cycle Primary source of energy for the exercise that is performed at an intensity lower than that of the anaerobic oxidative system

Glucose Plasma membrane Extracellular fluid Aerobic Respiration Overview Slide number: 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mitochondrion Cytoplasm PyruvateGlycolysis ATP NADH ATP H2OH2O O2O2 Electron transport system ATP NADH CO 2 Krebs cycle NADH Acetyl-CoA

Sport Books Publisher33 The Oxidative Phosphorylation System Two Pathways: Krebs Cycle & Electron Transport Chain Biochemical process used to resynthesize ATP by combining ADP and P in the presence of oxygen Takes place in mitochondrion (contains enzymes, co-enzymes) Energy yield from 1 molecule of glucose is 36 ATP molecules Energy yield from 1 molecule of fat up to 169 ATP molecules By-products of this reaction: carbon dioxide, water

INTERACTION OF ENERGY SYSTEMS ImmediateShort-termLong-term

Energy Systems for Exercise Energy Systems Mole of ATP/min Time to Fatigue Immediate: ATP - PCr (ATP & phosphocreatine) 4 5 to 10 sec Short Term: Glycolytic (Glycogen-Lactic Acid) to 2 min Long Term: Oxidative 1 Unlimited time

Sport Books Publisher39 Summary of the three energy systems

Sport Books Publisher40 The Role of Three Energy Systems During an All-out Exercise Activity of Different Duration

Sport Books Publisher41 Factors Affecting Physical Performance

ENERGY REQUIREMENTS AND SOURCE OF ENERGY FOR SKELETAL MUSCLE ( Resting vs. Working)

ATP Use in the Resting Muscle Cell ATP is necessary for cellular housekeeping duties, e.g.: glycogenesis –ATP is used for glycogenesis (storage form of glucose) creatine phosphate –ATP is used to create another energy storage compound called creatine phosphate

Resting Muscle and the Krebs Cycle Resting muscle fibers typically takes up fatty acids from the blood stream. mitochondriaAcetyl-CoA Inside the muscle fiber, the FA’s are oxidized (in the mitochondria) to produce Acetyl-CoA & several molecules of NADH and FADH2 Krebs cycle mitochondria ATP, Acetyl-CoA will then enter the Krebs cycle (in the mitochondria)  CO 2, ATP, NADH, FADH2, and oxaloacetate the Electron Transport Chain. mitochondrial ATP NADH and FADH2 will enter the Electron Transport Chain. (in the inner mitochondrial membrane)  synthesis of ATP

Figure 10–20a

ATP use in Working Muscle As we begin to exercise, we almost immediately use our stored ATP next 15 seconds For the next 15 seconds or so, we turn to the creatine-phosphate. This system dominates in events such as the 100m dash or lifting weights.

Working Muscle After the phosphagen system is depleted, the muscles must find another ATP source. * anaerobic metabolism about 45-60s. * The process of anaerobic metabolism can maintain ATP supply for about 45-60s. pyruvic acid Glycogen  Glucose  2 pyruvic acid (2 ATP + 2 NADH) lactic acid 2 Pyruvic acid  2 lactic acid (2 NAD + ) Lactic acid diffuses out of muscles  blood  taken by the liver  Glucose (by gluconeogenesis)  blood  taken by the muscle again * * It usually takes a little time for the respiratory and cardiovascular systems to catch up with the muscles and supply O 2 for aerobic metabolism.

Muscle Metabolism Figure 10–20c

Anaerobic Metabolism, continued… Anaerobic metabolism is inefficient… Why? –Large amounts of glucose are used for very small ATP returns. –Lactic acid is produced whose presence contributes to muscle fatigue Which type of sports uses anaerobic metabolism? –Sports that requires bursts of speed and activity, e.g., basketball.

Aerobic Metabolism Occurs when the respiratory and cardiovascular systems have “caught up with” the working muscles. myoglobin –Prior to this, some aerobic respiration will occur thanks to the muscle protein, myoglobin, which binds and stores oxygen. restlight to moderate During rest and light to moderate exercise, aerobic metabolism contributes 95% of the necessary ATP. Compounds which can be aerobically metabolized include: –Fatty acids, –Fatty acids, Pyruvic acid (made via glycolysis), and amino acids.

Sport Books Publisher52 Cori Cycle Lactic acid is taken to the liver to be metabolized back into pyruvic acid and then glucose Glucose Glycogen Lactate Glucose Glycogen Lactate Blood Glucose Blood Lactate

Glucose alanine cycle

Sport Books Publisher55 The Power Of The Aerobic System Evaluated by measuring the maximal volume of oxygen that can be consumed per kilogram of mass in a given amount of time This measure is called aerobic power or VO2 max (ml/min/kg) Factors that contribute to a high aerobic power: a) arterial oxygen content (CaO 2 ) - depends on adequate ventilation and the O 2 -carrying capacity of blood b) cardiac output (Q = HR x stroke volume) - increased by elevation of the work of heart and increased peripheral blood flow c) tissue oxygen extraction (a-vO 2 diff) - depends upon the rate of O 2 diffusion from capillaries and the rate of O 2 utilization

Sport Books Publisher56 The Substrates for the Aerobic System Carbohydrates ( glycogen and glucose) and fats (triglycerides and fatty acids) Fats: –found in dairy products, meats, table fats, nuts, and some vegetables –body’s largest store of energy, cushion the vital organs, protect the body from cold, and serve to transport vitamins –each gram of fat contains 9 calories of energy

Sport Books Publisher57 Effect of Training on Aerobic Systems Endurance training is the most effective method (long duration several times per week): - increases vascularization within muscles - increases number and size of mitochondria within the muscle fibres - increases the activity of enzymes (Krebs cycle) - preferential use of fats over glycogen during exercise Endurance training increases the max aerobic power of a sedentary individual by 15-25% regardless of age An older individual adapts more slowly

Aerobic or Anaerobic?

Sport Books Publisher64 Discussion Questions: 1. What are the differences between the 3 energy systems? 2. List one advantage and one disadvantage of each of the 3 energy systems. 3. Give an example of three activities or sports that use each of (a) the high energy phosphate system, (b) the anaerobic glycolytic system, and (c) the aerobic oxidative system as their primary source of energy (one sport for each energy system). 4. What is the most important source of fuel in the body for all types of energy production - a substance also known as the energy currency of the body? 5. Define ATP turnover and ATP resynthesis.

Sport Books Publisher65