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Kin 310 Exercise/Work Physiology

Kin 310 Exercise/Work Physiology. Office hours - K8629 Mondays and Wednesday 10-11 am or by appointment through email class email list announcements, questions and responses inform me of a preferred email account class notes will be posted on the web site in power point each week

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Kin 310 Exercise/Work Physiology

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  1. Kin 310Exercise/Work Physiology • Office hours - K8629 • Mondays and Wednesday 10-11 am • or by appointment through email • class email list • announcements, questions and responses • inform me of a preferred email account • class notes will be posted on the web site in power point each week • can be printed up to six per page • lecture schedule along with reading assignment on web site • www.sfu.ca/~ryand/kin310.htm

  2. Energy Sources and Recovery from Exercise • Ch 2 Foss and Keteyian - Fox’s Physiological basis for Exercise and Sport- 6th edition • all human activity centers around the capability to provide energy on a continuous basis • without energy cellular activity would cease - organism would die • Main sources of energy • biomolecules - carbohydrate and fat • protein small contribution • lecture will review metabolic processes with an emphasis on regulation and recovery

  3. Energy • Energy - capacity or ability to perform work • Work - application of a force through a distance • Power - amount work performed over a specific time • forms of energy can be converted from one form to another • transformation of energy • chemical energy in food to mechanical energy of movement • Biological energy cycle

  4. ATP - adenosine tri-phosphate • Energy liberated from food - • used to manufacture ATP - Fig 2.2 • only energy released from ATP can be utilized to perform cellular work • represents immediate source of energy available to muscle • bonds between phosphate groups • high energy bonds • broken by hydrolysis in presence of water • reaction reversible • phosphocreatine (PC) • and at points in metabolic pathways • oxidation reduction • oxidative phophorylation

  5. Sources of ATP • Limited quantity of ATP available • constant turnover - requires energy • 3 processes - use coupled reactions • ATP-PC system (phosphagen) • energy for re-synthesis from PC • Anaerobic Glycolysis • ATP from partial degeneratoin of glucose • absence of oxygen • generates lactate • Aerobic System • requires oxygen • oxidation of carbohydrates, fatty acisds and protein • Krebs cycle and Electron Transport

  6. Anaerobic sources • ATP -PC system • high energy phosphates • energy in PC bond is immediately available • as ATP is broken down • it is continuously reformed from • ADP and PC • enzyme - Creatine Kinase • also - ADP + ADP can form ATP • enzyme - myokinase • PC reformed during recovery when ATP formed through other pathways • Table 2.1 - most rapidly available fuel source - very limited quantity

  7. Anaerobic Glycolysis • Incomplete breakdown of glucose or glycogen to lactate • 12 separate, sequential chemical reactions • breakdown molecular bonds • couple reaction to synthesis of ATP • yields 2 (glucose) or 3 (glycogen) ATP • very rapid but limited production • lactate accumulates - fatigue • PFK - phosphofructokinase • rate limiting enzyme- slow step in reaction - further held back • Table 2.2

  8. Anaerobic Glycolysis • Lactate produced when low O2 • pyruvate converted to lactate • enzyme LDH - lactate dehydrogenase Fig 2.6 • frees up NAD+ required in glycolysis • continued rapid production of ATP • summary fig 2.7 • glycogen vs. glucose

  9. Aerobic Sources of ATP • Acetyl groups - 2 carbon units • formed from pyruvate and from Beta oxidation of free fatty acids • NAD and FAD - electron carriers • become reduced when molecules are oxidized forming NADH, FADH2 • carry these hydrogen atoms to the electron transport chain • donated and passed down chain of carriers to form ATPs • oxygen is final acceptor of hydrogen's forming H2O • occurs in mitochonrial membrane system - cristae

  10. Aerobic Glycolysis • Sufficient oxygen • Pyruvate diverted into mitochondia • law of mass action • 1 mole glycogen • 2 moles pyruvate • 3 moles ATP • 2 moles NADH (6 ATP) • Fig 2.12 - Krebs Cycle • Key regulatory enzymes • PDH, CS, SDH • CO2 produced as molecule breaks down and H are removed • oxidation - removal of electrons • reduction - addition of electrons

  11. Krebs Cycle • Krebs - 2 GTP produced • 6 NADH and 2 FADH2 • Electron Transport System • H passed down series of electron carriers by enzymatic reactions coupled to production of ATP • oxidative phosphorylation • each NADH - 3 ATP • each FADH2 - 2 ATP • total 36 ATP from Krebs and ETS • glucose (38) glycogen (39) • for process to continue, must liberate NAD+ and FAD+ requires oxygen • high energy state= high ratio of NAD+/NADH

  12. Fat Metabolism • Fat and Protein only oxidized in presence on oxygen • Fatty acids - 16-18 carbon units • broken down into acyl groups • Beta oxidation Fig. 2.15 • uses 1 ATP • produces 1 NADH and 1 FADH2 • same through Krebs as acetyl co-a • 12 ATP • total of 16 ATP for first acyl • 17 for remainder • last only 12 - does not go through beta oxidation • requires 15% more oxygen to produce a mole of ATP

  13. Comparing the Energy Systems • Table 2.5 • energy capacity - amount of ATP able to be produced independent of time • power - rate - in given amount of time • *aerobic - represents availability from glycogen only - fat unlimited • Rest • aerobic - supplies all ATP • mainly carbs and fats • some lactate ~10 mg/dl • does not accumulate, but LDH effective

  14. Exercise • Both anaerobic and aerobic • relative roles depends on • intensity • state of training • diet of athlete • Two types of exercise investigated • near max - short duration • sub max - long duration • Fig 2.18 glycogen depletion • activities below 60 % and above 90% - little glycogen depletion • 75% significant depletion - exhaustion • 2.18b - rate of depletion dependant on demand • total depletion related to duration

  15. Short duration • 2-3 minutes high output exercise • fig 2.19 - major energy source CH2O • ATP and PC will drop rapidly • restored in recovery • Aerobic limited by power output • also takes 2-3 to increase • oxygen deficit - period during which level of O2 consumption is below that necessary to supply all ATP required by exercise demands • ATP supplied by anaerobic systems • rapid accumulation of lactate • 200 mg/dl

  16. Prolonged Exercise • 10 minutes or longer • fats and carbs • carbs dominate up to about 20 min • fats minor but supportive • after 1 hr fat dominant - also at lower intensities • fig. 2.20 • fatigue not associated with lactate, other factors - discussed later in semester • Fig 2-22 activites require blend of anaerobic and aerobic systems • energy continuum

  17. Control and Regulation • Matching provision of energy to demand so performer does not experience early or undue fatigue • Enzymes, hormones, substrates interact to modify flow through pathways and reactions of each system • Fig 2.7 factors • high vs low energy state of cell • Hormone levels • “amplification” of hormone effects • modification of key enzymes • power output requirements relative to aerobic power • adequacy of oxygen supply • competition for ADP

  18. Regulation • Simply • regulation within muscle cell • influences from outside • both serve to modify regulatory enzymes • Fig 2.23 • Energy State regulation • ADP/ATP ratio • very quick - tightly linked to rate of energy expenditure • Hormone Amplification • cAMP 2nd messenger systems - amplification • Ep and Glucagon - activate phosphorylase - glycogen breakdown • lipase - fat breakdown

  19. Regulation • Substrates - • eg. NADH - buildup • stimulates LDH - frees up NAD+ • occurs when ETS is maximized • can not oxidize NADH fast enough • eg. Inc Pyruvate • stimulates PDH - entry into Krebs • Oxidative State Regulation • O2 and ADP availability • stimulates cytochrome oxidase • final step in ETS • low O2 - inhibits CO - build up NADH, FADH2 • key factor oxygen availability

  20. Recovery from Exercise • Ch. 3 • process of recovery from exercise involves transition from catabolic to anabolic state • breakdown of glycogen to rebuilding of stores • breakdown of protein to protein synthesis for muscle growth • looking at all the processes that return the exerciser to resting state • oxygen consumption post exercise • energy stores • lactate • oxygen stores • intensity and activity specifics • guidelines for recovery

  21. Recovery Oxygen • Net amount of oxygen consumed during recovery from exercise • excess above rest in Litres • Fast and Slow components • first 2-3 min of recovery - O2 consumption declines very rapidly • then slowly to resting • Fig 3.1 • Fast Component • restore myoglobin and blood oxygen • energy cost of elevated ventilation • energy cost of elevate heart activity • replensihment of phosphagens • volume = area under curve • related to intensity not duration

  22. Recovery Oxygen • Slow Component • elevated body temperature • Q10 effect - inc metabolic activity • cost of ventilatoin and heart activity • ion redistribution Na+/K+ pump • glycogen re-synthesis • effect of catecholamines • oxidation of lactate • duration and intensity do not modify slow component until threshold of combined duration and intensity • 20 min and 80% 5 fold increase

  23. Energy Stores • Both phosphagens and glycogen depleted during exercise • ATP/PC - fast component • measured by sterile biopsy, MRS • study of ATP production • 20-25 mmol/L/min glycogen • rate of PC recovery indicative of net oxidative ATP synthesis • during exercise • PC down to 20%, ATP down to 70 % • PC lowest at fatigue, rises immediately with recovery • Fig 3.2 - very rapid recovery • 30 sec 70%, 3-5 min 100%

  24. Phosphagen Recovery • Fig 3.3 • occlusion of blood flow - no recovery • estimate 1.5 L of oxygen for ATP-PC recovery • Energetics of Recovery • Fig 3.4 • breakdown carbs, fats some lactate • produce ATP which reforms PC • high degree of correlation between phosphagen depletion and volume of fast component oxygen • Fig. 3.5 • power in athlete related to phosphagen potential - Wingate test

  25. Glycogen Re-synthesis • Requires 1-2 days and depends on • type of exercise • amount of dietary carbs consumed • Two types of exercise investigated • continuous endurance(low intensity) • intermittent exhaustive (high intensity) • Continuous • Fig 3.6 - diet effect • minor recovery in 1-2 hours, does not continue with fasting • complete resynthesis • requires high carb diet - 2 days • does not occur without carb diet • depletion related to fatigue • Fig 3.7 - heavy training

  26. Glycogen Re-synthesis • Intermittent, short duration exercise • Fig 3.8 • significant re-synth in 30 min-2 hrs • did not require food • complete resynth did not require high carbs • only 24 hrs for 100 % recovery’ • rapid in first few hours • continuos vs intermittent • amount depleted • precursor availability • lactate, pyruvate, glucose • fiber type involved • re-synthesis faster in type II fibers

  27. Lactate Reduction • Increasing intensity no change in lactate until threshold • large inc in [ lactate ] • influenced by duration and rest interval • Speed of lactate removal • fig 3.10 - intermittent activity • Fig 3-11 active vs passive • Active recovery - light activity • passive recovery - no activity • Fig 3-12 intensity of recovery • untrained 30-45% VO2 Max • trained 50-60% - some studies • glycogen re-synthesis slowed with high intensity active recovery

  28. Lactate and the Slow Component of O2 • fig. 3.13 • Fig 3.14 • close association between slow recovery component of O2 and removal of lactate • restoration of O2 stores • fast component - 10-80 seconds • Ion concentrations • pH - rapid return after light exercise • heavy exercise dec. From 7-6.4 • ~20 min for recovery • close correlation to lactate and fatigue • Max Contraction correlated with H+ and Pi (restored within 5 min)

  29. Performance Recovery • Regain performance - force, power • med intensity 60-80% • fast recovery - one minute • higher intensity bout - • longer recovery • Aerobic fitness (high VO2 max) important influence • good correlation between fast recovery of muscle function and VO2 max • why? • Fast component requires O2 • Guidelines Table 3.2

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