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Ergometry

answer

measurement of work output

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Ergometer

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Device used to measure work -bench, cycle, arm, treadmill

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Vertical displacement

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% grade X distance

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1 kcal

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4,186 J 1,000 calories

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V02 of 2.0 L x min-1

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10 kcal or 42kj per minute

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Open circuit spirometry

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determines V02 by measuring amount of O2 consumed

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V02

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Volume of oxygen inspired - volume of oxygen expired

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Direct calorimetry

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uses the measurement of heat production as an indication of metabolic rate

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Indirect calorimetry

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estimates metabolic rate via the measurement of oxygen consumption

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Exercise work rate

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efficiency decreases as work rate increases

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Speed of movement

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there is optimum speed of movement and any deviation reduces efficiency

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Running economy

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oxygen cost of running at given speed Lower V02 (ml x kg x min) at same speed indicates better running economy

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Gender difference

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no difference at slow speeds At "race pace" speeds, males may be more economical than females

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Metabolism

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Sum of all chemical reactions in the body Anabolic reactions- synthesis of molecules Catabolic reactions- breakdown of molecules

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Bioenergetics

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Converting food stuffs (fats, proteins, carbohydrates) into energy

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Cell membrane

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AKA sarcolemma Semipermeable membrane that separates the cell from the extracellular environment

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Nucleus

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Contains genes that regulate protein synthesis

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Cytoplasm

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fluid portion of cell contains organelles mitochondria

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Endergonic reactions

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requires energy to be added endothermic

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Exergonic reactions

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release energy (exit) Exothermic

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Coupled reactions

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liberation of energy in an exergonic reaction drives an endergonic reaction oxidation and reduction are always coupled reactions

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Oxidation

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removing an electron

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Reduction

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adding an electron

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NAD oxidized

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NAD+

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NAD reduced

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NADH

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FAD oxidized

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FAD

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FAD reduced

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FADH2

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Enzymes

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catalysts that regulate the speed of reactions -lowers the energy activation factors that regulate enzyme activity -temperature and pH interact with specific substrates -lock and key model

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Kinases

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add a phosphate group

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Dehydrogenases

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remove hydrogen atoms

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Oxidases

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catalyze oxidation-reduction reactions involving oxygen

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Isomerases

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Rearrangement of the structure of molecules

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Carbohydrates

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monosaccharides, disaccharides, and polysaccharides

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Glucose

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blood sugar

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Glycogen

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storage form of glucose in liver and muscle -synthesized by enzyme glycogen synthase Glycogenolysis -breakdown of glycogen to glucose

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Fatty acids

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primary type of fat used by the muscle

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Triglycerides

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storage form of fat in muscle and adipose tissue breaks down into glycerol and fatty acids via lipolysis

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Steroids

answer

derived from cholesterol needed to synthesize sex hormones

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Protein

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composed of amino acids some can be converted to glucose in the liver others can be converted to metabolic intermediates overall protein is not a major energy source during exercise Converted to glucose, pyruvic acid, acetyl-CoA, and Krebs cycle intermediates

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Formation of ATP

answer

phosphocreatine (PC) breakdown degradation of glucose and glycogen oxidative formation of ATP

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Anaerobic pathways

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Do not involve 02 PC breakdown and glycolysis

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Aerobic pathways

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Require 02 Oxidative phosphorylation

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ATP PC system

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Immediate source of ATP

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Glycolysis

answer

Glucose -> 2 pyruvic acid or 2 lactic acid Energy investment phase requires 2 ATP Energy generation phase produces 4 ATP, 2 NADH, and 2 pyruvate or lactate

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creatine monohydrate supplementation

answer

increased muscle pc stores some studies show improved performance in short-term, high intensity exercise increased strength and fat-free mass with resistance training does not appear to pose health risks

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Lactic acid

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lactic acid or lactate interchangeably lactate is the conjugate base of lactic acid produced in glycolysis rapidly disassociates to lactate and H+

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Phosphocreatine

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energy system (PC) PC + ADP -> ATP + C lasts 3-6 seconds

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Production of ATP

answer

ATP-PC system (anaerobic) Glycolysis (anaerobic) Oxidative formation of ATP (3 ways to produce)

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Krebs cycle

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Pyruvic acid (3 C) is converted to acetyl-CoA (2 C) -CO2 is given off Acetyl-CoA combines with oxaloacetate (4 C) to form citrate (6 C) - Citrate is metabolized to oxaloacetate Two CO2 molecules given off - Produces three molecules of NADH and one FADH2 - Also forms one molecule of GTP Produces one ATP

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Fats

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- Triglycerides → glycerol and fatty acids - Fatty acids → acetyl-CoA Beta-oxidation - Glycerol is not an important muscle fuel during exercise

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Electron transport chain

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Oxidative phosphorylation occurs in the mitochondria - Electrons removed from NADH and FADH are passed along a series of carriers (cytochromes) to produce ATP Each NADH produces 2.5 ATP Each FADH produces 1.5 ATP - Called the chemiosmotic hypothesis - H+ from NADH and FADH are accepted by O2 to form water Electron transport chain results in pumping of H+ ions across inner mitochondrial membrane Energy released to form ATP as H+ ions diffuse back across the membrane

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Beta oxidization

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Breakdown of triglycerides releases fatty acids Fatty acids must be converted to acetyl-CoA to be used as a fuel - Activated fatty acid (fatty acyl-CoA) into mitochondrion - Fatty acid "chopped" into 2 carbon fragments forming acetyl-CoA Acetyl-CoA enters Krebs cycle and is used for energy

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Free radicals

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Produced by the passage of electrons along the electron transport chain react with other molecules in the cell Damages the molecule combining with the radical Aerobic exercise promotes the production of free radicals in mitochondria This is not due to oxidative phosphorylation in the mitochondria

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Glucose ATP production

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1 glucose produces 32 ATP 32 moles of ATP are formed from one mole of glucose Potential energy released from one mole of glucose is 686 kcal/mole

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One mole of ATP

answer

energy yield of 7.3kcal

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Aerobic respiration efficiency

answer

Overall is 34% 66% released as heat

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Energy requirements at rest

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Almost 100% of ATP produced by aerobic metabolism Blood lactate levels are low

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Resting O2 consumption

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0.25 L/min 3.5 ml/kg/min

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Rest to exercise transition

answer

ATP production increases almost immediately Oxygen uptake increases rapidly -reaches steady state within 1-4 minutes -After steady state is reached, ATP requirement is met through aerobic ATP production Initial ATP production through anaerobic pathways -ATP-PC system -Glycolysis

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Oxygen deficit

answer

Lag in oxygen uptake at the beginning of exercise

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Trained subject

answer

Have a lower oxygen deficit -better developed aerobic bioenergetic capacity -due to cardiovascular or muscular adaptations -results in less production of lactate and H+

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Oxygen debt

answer

Repayment for 02 deficit at onset of exercise

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EPOC

answer

Excess post-exercise oxygen consumption -terminology reflects that only 20% elevated 02 consumption used to "repay" 02 deficit

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Rapid oxygen debt

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- Resynthesis of stored PC - Replenishing muscle and blood O2 stores

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Slow oxygen debt

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- Elevated heart rate and breathing = ↑ energy need - Elevated body temperature = ↑ metabolic rate - Elevated epinephrine and norepinephrine = ↑ metabolic rate - Conversion of lactic acid to glucose (gluconeogenesis)

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EPOC greater

answer

Following high intensity exercise Higher body temperature Greater depletion of PC Greater blood concentrations of lactic acid Higher levels of blood epinephrine and norepinephrine

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Lactic acid conversion

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70% of lactic acid oxidized -used as substrate by heart and skeletal muscle 20% converted to glucose 10% converted to amino acids Lactic acid is removed more rapidly with light exercise in recovery at about 30-40% of V02 max

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Intense exercise met response

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First 1-5 seconds of exercise -ATP through ATP-PC system Intense exercise longer than 5 seconds -shift to ATP production via glycolysis Events lasting longer than 45 seconds -ATP production through ATP-PC, glycolysis, and aerobic systems -70% anaerobic/30% aerobic at 60 seconds -50% anaerobic/50% aerobic at 2 minutes

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Prolonged exercise met response

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Prolonged exercise (>10 minutes) - ATP production primarily from aerobic metabolism - Steady-state oxygen uptake can generally be maintained during submaximal exercise Prolonged exercise in a hot/humid environment or at high intensity - Upward drift in oxygen uptake over time - Due to body temperature and rising epinephrine and norepinephrine

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Incremental exercise met response

answer

Oxygen uptake increases linearly until maximal oxygen uptake (VO2 max) is reached - No further increase in VO2 with increasing work rate VO2 max - Physiological ceiling for delivery of O2 to muscle - Affected by genetics and training Physiological factors influencing VO2 max - Maximum ability of cardiorespiratory system to deliver oxygen to the muscle - Ability of muscles to use oxygen and produce ATP aerobically

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Lactate threshold

answer

The point at which blood lactic acid rises systematically during incremental exercise - Appears at ~50-60% VO2 max in untrained subjects - At higher work rates (65-80% VO2 max) in trained subjects Also called: - Anaerobic threshold - Onset of blood lactate accumulation (OBLA) - Blood lactate levels reach 4 mmol/L

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Lactate threshold explanation

answer

Low muscle oxygen (hypoxia) Accelerated glycolysis - NADH produced faster than it is shuttled into mitochondria - Excess NADH in cytoplasm converts pyruvic acid to lactic acid Recruitment of fast-twitch muscle fibers - LDH isozyme in fast fibers promotes lactic acid formation Reduced rate of lactate removal from the blood

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Muscle soreness

answer

Lactate production in commonly believed to cause muscle soreness - Delayed-onset muscle soreness (DOMS) - 24-48 hours after exercise Physiological evidence does not support this claim - Lactate removal is rapid (within 60 minutes) following exercise - Power athletes should experience DOMS after every work out Muscle soreness is rare following routine workout What does cause muscle soreness? - Microscopic injury to muscle fibers leads to inflammation

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Low intensity exercise

answer

(<30% V02 max) Fats are primary fuel - High percentage of energy expenditure (~60%) derived from fat - However, total energy expended is low - Total fat oxidation is also low

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High intensity exercise

answer

(>70% V02 max) Carbohydrates are primarily the fuel - Lower percentage of energy (~40%) from fat - Total energy expended is higher - Total fat oxidation is also higher

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Crossover concept

answer

- Describes the shift from fat to CHO metabolism as exercise intensity increases - Due to: Recruitment of fast muscle fibers Increasing blood levels of epinephrine

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Mcardles syndrome

answer

• Cannot synthesize the enzyme phosphorylase - Due to a gene mutation • Inability to break down muscle glycogen • Also prevents lactate production - Blood lactate levels do not rise during high-intensity exercise • Patients complain of exercise in tolerance and muscle pain

question

Muscle glycogen

answer

- Primary source of carbohydrate during high-intensity exercise - Supplies much of the carbohydrate in the first hour of exercise

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Blood glucose

answer

- From liver glycogenolysis - Primary source of carbohydrate during low-intensity exercise - Important during long-duration exercise

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Intramuscular triglycerides

answer

-Primary source of fat during higher intensity exercise

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Plasma FFA

answer

Plasma FFA - From adipose tissue lipolysis Triglycerides → glycerol + FFA - FFA converted to acetyl-CoA and enters Krebs cycle - Primary source of fat during low-intensity exercise - Becomes more important as muscle triglyceride levels decline in long-duration exercise

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Neuroendocrine system

answer

- Endocrine system releases hormones - Nervous system uses neurotransmitters

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Endocrine glands

answer

Releases hormones directly into the blood

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Hormones

answer

- Alter the activity of tissues that possess receptors to which the hormone can bind - Several classes based on chemical makeup § Amino acid derivatives § Peptides/protein § Steroids

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Blood hormone concentration

answer

The effect of a hormone on a tissue is determined by the plasma concentration Determined by: - Rate of secretion of hormone from endocrine gland Magnitude of input Stimulatory versus inhibitory input - Rate of metabolism or excretion of hormone At the receptor and by the liver and kidneys - Quantity of transport protein Steroid hormones - Changes in plasma volume

question

Hypothalamus

answer

Controls secretions from pituitary gland Stimulates release of hormones from anterior pituitary gland Provides hormones for release from posterior pituitary gland

question

Anterior pituitary gland

answer

- Adrenocorticotropic hormone (ACTH) - Follicle-stimulating hormone (FSH) - Luteinizing hormone (LH) - Melanocyte-stimulating hormone (MSH) - Thyroid-stimulating hormone (TSH) - Growth hormone (GH) - Prolactin

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Posterior pituitary gland

answer

- Oxytocin - Antidiuretic hormone (ADH)

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ACTH

answer

Adrenocorticotropic hormone - Stimulates cortisol release form adrenal glands

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LH

answer

Luteinizing hormone -Stimulates production of testosterone and estrogen

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TSH

answer

Thyroid-stimulating hormones - Controls thyroid hormone release from thyroid gland

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GH

answer

Stimulates release of insulin-like growth factors (IGFs) -IGF-1 in muscle responsible for muscle growth Essential growth of all tissues - Amino acid uptake and protein synthesis - Long bone growth Spares plasma glucose - Reduces the use of plasma glucose - Increases gluconeogenesis - Mobilizes fatty acids from adipose tissue

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