Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22EXERCISE PHYSIOLOGY [Ch. 25]•Source of energy for muscle contraction depends upon 1) duration and 2) intensity of effortEnergy Stores•Ready reserve•Long-term ATPTriacylglycerolsecondsminutes-month(s)ProteinType of metabolism rapidly changes -- [pp. 836-8]CP stores used up within secondsOnce CP gone, fuel use depends on intensityAnaerobic -- rapid but limited•Glucose stores: as glycogen in muscle sarcoplasm and in liver; blood glucose•If no O2, cannot regenerate NAD+ needed for GAPDH rxn, since e.t.c. not running•Conversion of pyruvatelactate can regenerate NAD+ in absence of O2, which keeps glycolysis goingAt low-medium intensity, fuel use switches to fat.But as intensity increases, fuel usage switches back to glucoseFuel/Pathway Max Sustainable MR (µmol ATP/g/min)FA oxidation 20.4Glucose oxidation 30.0Glucose fermentation 60.0P-creatine/ATP hydrolysis 96-360[Fig. 25.2, p. 837]Crossover point coincides with “lactate threshold,” which can be shifted to the right with training (this is goal of endurance + interval training)•Extends use of vast fat reserves to very high power outputs•Spares glucose for brain, and for highest intensity effort toward end of event> 65 km/h even after almost 200 km of racingHormonal environment during exercise [p. 838]•Catabolic hormones predominate—glucagon, cortisol, catecholamines—acts to promote glycogenglucose to maintain blood glucose•Insulin secretion is suppressed via sympathetic input to pancreas—acts to limit glucose use by tissues other than muscle & brainPossible factors limiting exercise [p. 839]•Ability of CV system to deliver oxygen to muscles—cardiac fxn•Ability of pulmonary system to deliver oxygen to bloodVentilation is only at 65% of maximum when CO is at 90%CVfxn is more limiting than ventilation•Ability of muscles to use oxygen—number/activity of mitochondria Endurance training increases mitochondrial capacity ↑ biogenesis (as can certain drugs, e.g. AICAR—high potential for abuse)Tour de France samples to be tested for AICAR By: Cycling NewsPublished: December 16, 2013, 20:45, Updated: December 16, 2013, 21:59Edition: First Edition Cycling News, Tuesday, December 17, 2013Re:gw 501516 and AICAR Wednesday, August 15, 2012 10:06 PM (permalink) Just get GW or Aicar mate .. combo is not what you want AICAR is good with MYO not my experience so cant 100% say for future trials Dont know the chemistry mate and unfortunately haven't time to research it for youVentilatory response to exercise [pp. 839-40]•Muscle movement triggers reflexes mediated by motor cortex respiratory control center in medulla which increase breathing•↑ ventilation mantained by input from central, carotid, & aortic chemoreceptors which monitor PCO2, PO2, pHAdjustments in ventilation, cardiac output act to maintain blood gases and pHCardiovascular response to exercise—C.O., muscle blood flowincrease – [pp. 840-43]•Reflex: working musclesmotor cortexCV control center in medulla cardiac contractility & heart rate↑ S.V. + ↑ H.R. = ↑C.O.•Vasodilation in muscle + vasoconstriction in other tissues  diversion of up to 90% of C.O. to the working muscleBlood pressure rises slightly despite huge overall drop in peripheral resistance—mainly due to ↑↑ C.O. BP = C.O. x P.R.[p. 843]•Baroreceptor-mediatedregulation of B.P. is altered;precise mechanism(s) unclear--∆ baroreceptor setpoint--afferent signals from baroreceptors blocked at level of spinal cord--override of signals from baroreceptors by other factors, e.g. H+ Mean arterialpressureAnticipatory “feedforward” responses [p. 843]•Start of exertion triggers ventilatory/CV increases even before see changes in pO2, pCO2, other blood metabolites•Probably due to reflexes beginning with stretch receptors in working muscle tissueTemperature regulation in exercise [pp. 843-44]•↑↑ heat generation due to increased metabolic rateRegulatory response to increased core temperature•↑ sweating to promote evaporative cooling – sweat is hypotonic, salt loss can be further decreased with acclimization•↑ blood flow to skin to transfer heat from core to periphery•As duration of exercise ↑, must replace fluids lost or risk heat strokeMetabolic system biased toward storage of energy during times of energy abundance for use during times of scarcityAdvent of agriculture ~ 8000 B.C.E. led to significant decreasein energy expenditure required to obtain foodExercise and HealthBeneficial effects of exercise [pp. 844-46]•↓ rates of all-cause mortality, CV disease, hypertension, stroke, metabolic syndrome, type 2 diabetes, breast & colon cancer, depression and accidental falling•Rates of moderate-vigorous activity > 150 min/wk (minimum WHO recommendations) associated with higher life expectancy•Training improves endothelial function (e.g. prevents age-assoc- iated decrease in endothelial-dependent vasodilation)•↓ B.P., ↓ plasma TG, LDL, ↑ plasma HDL recall criteria for metabolic syndrome (slide # 21, 4/23)•↑ IN sensitivity, ↑ IN-independent glucose usage•↓ age-induced autonomic dysfunctionSkeletal muscle as an endocrine organ—exercise stimulatesrelease of myokines which may mediate many of the beneficialeffects of physical activityExercise-induced adipose tissue browning through PGC-1α and irisin. Castillo-Quan J I Dis. Model. Mech. 2012;5:293-295©2012 by The Company of Biologists LimitedExercise is anti-inflammatory –precise mechanism(s)not yet clarifiedElite athlete paradox—hard training appears to increase susceptibility to infection [Fig. 25.10, p. 846] – may be due to extreme anti-inflammatory effects producing