Exercise Physiology EXAM 1 Energy The Capacity for Work o The anaerobic and aerobic breakdown of ingested food nutrients provides the energy source for synthesizing the chemical fuel that powers all forms of biological work o Extracting energy from the stored macronutrients and transferring it to the contractile proteins of skeletal muscle greatly influences exercise performance o ATP represents the energy currency that powers all forms of biologic work First Law of Thermodynamics o Conservation of energy o Dictates that the body does not produce consume or use up energy rather it transforms energy from one form into another as physiologic systems undergo continual change Three Types of Energy o Potential Energy o Kinetic Energy o Heat Energy Energy Releasing and Energy Conserving reactions o Exergonic reactions o Endergonic reactions chemical processes that release energy to its surroundings e g Breakdown of ADP or ATP Food intake in the form of Carbohydrates fats and proteins are stored for future use chemical processes that store or absorb energy e g Second Law of Thermodynamics o The tendency of potential energy to degrade to kinetic energy of motion with a lower capacity for work o Flashlight battery o Sunlight when strikes and becomes absorbed by a surface o Food during the oxidative processes Energy Conversions o Photosynthesis endergonic light co2 and water carbs and oxygen Examples of Biologic Work o Mechanical work o Muscle contraction o Chemical work o Synthesis of macromolecules o Transport work fluids Biological Work within the Human Body o Cellular Respiration Exergonic o Concentration of various substances in intracellular and extracellular Key Point o The limits of exercise intensity ultimately depend on the rate that cells extract conserve and transfer chemical energy in the food nutrients to the contractile filaments of skeletal muscle Factors Affecting Bioenergetics o Enzymes are highly specific protein catalysts accelerate the forward and reverse reactions are neither consumed nor changed in the reaction o Reaction rates o Mode of action interaction o Coenzymes complex non protein organic substances facilitate enzyme action by binding the substrate with its specific enzyme How Do enzymes work their magic o 1 Substrate matches the active site of enzyme o 2 Enzyme substrate complex splits to yield product o 3 Enzyme now available for interaction with other substrate Coenzymes reaction o require less specificity than enzymes because it acts to help not initiate the o These can be vitamins minerals or other non protein molecules Enzyme Inhibitors Hinderers o Competitive inhibitors are particles that resemble normal substrate and bind to the enzyme blocking its active site o Non competitive inhibiters bind to a site other than the active site altering enzyme structure Phosphate Bond Energy o ATP energy currency o Storage form of energy o Powers all cellular reactions o Energy stored within a phosphate bond o Chemical reaction Chemical Bonds Transfer Energy Phosphorylation ATP H2O w ATPase ADP Pi o Bond splitting releases potential energy o Energy conservation occurs by new bond formation o In the body biological work takes place when compounds relatively low in potential energy juice up from the transfer of energy via high energy phosphate bonds ATP is ideal o Phosphorylation refers to energy transfer through phosphate bonds Anabolic and Catabolic Reactions o Anabolic reactions require energy for glycogen triacylhlycerol and protein synthesis o Glucose glucose w Energy glycogen o Glycerol fatty acid tracylglycerol o Amino acids amino acids protein o Catabolic reactions release energy in glucose glycerol fatty acid and amino ATP is Limited but can be re synthesized by both aerobic and anaerobic processes acid breakdown o Glycogen glucose energy o Tracylglycerol glycerol fatty acids o Protein amino acids energy o Mitochondrion o Citric Acid Cyle Respiratory Chain Aerobic Fatty acids Pyruvate from glucose Some deaminated amino acids o Cytosol o Glycolysis anaerobic Phosphocreatine Glucose glyogen Glycerol Some deaminated amino acids PCr Energy Reservoir Creatine Kinase CK o PCr ADP w creatine kinase Cr ATP o Also known as creatine phosphokinase CPK o ADP in the cell stimulates the CK activity level o CK facilitates PCr breakdown to Cr and ATP for rapidly forming ATP from high energy phosphates known as CK reaction Adenylate Kinase ADK o Also known as myokinase o Another single enzyme mediated reaction for ATP regenereation o The reaction uses two ADP molecules to produce one molecule of ATP and o 2 ADP ATP AMP o in muscle ATP is typically 7 10x that of ADP and usually 100 x that of AMP AMP CK ADK o CK and ADk reaction not only augment how well the muscles rapidly increase energy output i e increase ATP availability o They also produce the molecular byproducts AMP Pi ADP that activate the initial stages of glycogen and glucose catabolism and the respiration pathways of the mitochondrion Intramuscular High Energy Phosphates o The energy released from ATP and PCr breakdown within muscle can sustain all out running cycling or swimming for 5 to 8 seconds o E g in the 100 m spring the body cannot maintain maximum speed for longer than this duration During the last few sec runners actually slow down with the winner slowing the least most effectively use this system ATP PCr Immediate Energy System o Plays an important role in success or failure of some phase of performance o If all out effort continues beyond 8 sec or if moderate exercise continues for much longer period ATP resynthesis requires an additional energy source o w o this additional ATP resynthesis the fuel supply diminishes and high intensity movement ceases Food cellular ATP PCr supplies Energy Source Important body o A 72 kg person will have about 120 grams of creatine sorted naturally in his o Creatine food sources meat fish poultry cranberries o Almost 1 g of creatine is provided per half pound of meet Raw o Methionine arginine and glycine o To get 20 g of Cr one would have to consume roughly 16 18 steaks Muscle Creatine Concentration o Shown the consuming a 21 day lacto vegetarian LOV diet was an effective procedure to decrease muscle creatine concentration in individual hwo normally consume meat and fish in their diet Anaerobic ATP Re synthesis PCr Phosphocreatine o Another high energy phosphate o Reaction works in both direction o Cells store roughly 6 times more PCr than ATp due to its free energy o
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