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SportsPerformance MeasurementandAnalytics TheScienceofAssessingPerformance, PredictingFutureOutcomes, InterpretingStatisticalModels, andEvaluatingtheMarketValueofAthletes
LORENA MARTIN
Publisher:PaulBoger
Editor-in-Chief:AmyNeidlinger
ExecutiveEditor:JeanneGlasserLevine
CoverDesigner:AlanClements
ManagingEditor:KristyHart
ProjectEditor:AndyBeaster
ManufacturingBuyer:DanUhrig
ConsultingEditor:ThomasW.Miller
c 2016byLorenaMartin
PublishedbyPearsonEducation,Inc.
OldTappan,NewJersey07675
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PrintedintheUnitedStatesofAmerica
FirstPrintingFebruary2016
ISBN-10:0-13-419330-X
ISBN-13:978-0-13-419330-4
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Preface “Impossibleisjustabigwordthrownaroundbysmallmenwhofindit easiertoliveintheworldthey’vebeengiventhantoexplorethepowerthey havetochangeit.Impossibleisnotafact.It’sanopinion.Impossibleisnot adeclaration.It’sadare.Impossibleispotential.Impossibleistemporary. Impossibleisnothing.”
MUHAMMAD ALI
Ihaveplayedsportsmyentirelife.Ibeganplayingthesportoftennisatthe ageofthirteen,toolateintheeyesofmanytennisexpertstobecomeatop professionaltennisplayer.ItrainedsixhoursadayfromthefirstdaythatI wonamatchagainstaboyataneighborhoodtenniscourt.Inaninstant,I wasaddictedtothesport.
Idreamedofbecomingaprofessionaltennisplayer.Ispentcountlesshours onthecourt,skippinghangouts,holidays,anddatesjusttohittennisballs. Iwentontoplayhighschoolandcollegetennis.Idroppedoutofcollege toplayprofessionaltennis.IworkedforanairlinesoIcouldtravelinexpensivelytocompeteinprofessionaltennistournamentsaroundtheworld. Tournamentswere(andstillare)scatteredacrosstheglobe,givingaperson oflowersocioeconomicstatusaveryslimchanceofmakingit.Through mytennistrainingandcompetition,IreachedaFloridastaterankingof numberthreeandatop200women’sprofessionalrankingintheUSA.
Asanundergraduate,Imajoredinpsychology.Iwantedtolearnaboutthe psychologicalandbehavioralprofilesofsuccessfulprofessionalathletes.I wentontogetamaster’sdegreeinpsychology.
SportsPerformanceMeasurementandAnalytics Afterstudyingpsychology,Iwantedtoobtainadeeperunderstandingof theimportanceofphysiologyandphysicalfitnessvariablesinsports,such asmuscularstrength,power,endurance,anaerobicpower,cardiorespiratoryendurance,andflexibility.Ifeltitwasessentialtolearnasmuchas possibleabouttheprocessesgoingoninsideaneliteathlete’smindand body.IearnedadoctorateinexercisephysiologyfromtheUniversityof Miamiandwasrecruitedtoconductpostdoctoralresearchinbehavioral medicineattheUniversityofCalifornia,SanDiego.
Ihavealwaysbeendriventolearnaboutstatistics,aboutwhatisandisnot beingsaidbythenumbers.Iwantedtoseewhichvariablescouldbeusedto predictsportperformanceandtoanswerasimplequestion:“Whatarethe qualitiesapersonmusthavetobecomeaworldclassathlete?”Thisquestionandmanymoremaybeansweredthroughresearch,measurement, statistics,andanalytics.
IwentontoteachresearchmethodsandstatisticaldesignatFloridaInternationalUniversity.LaterIjoinedNorthwesternUniversity,whereI currentlyteachintroductiontostatisticalanalysisaswellassportsperformanceanalytics.
Asateacherofsportsperformanceanalytics,Itriedtofindabookthatencompassedsports-relevantanatomyandphysiologyanddescribedathletic performancemeasures.Iwantedabookthatincludedstatisticalanalyses andmodelsusedinvariousindividualandteamsports,alongwithstatisticsadoptedbythesportsindustry.ButIfoundnosuchbook.
Ichosetowritethisbooktogiveathletes,coaches,andmanagersabetter understandingofmeasurementandanalyticsastheyrelatetosportperformance.Todevelopaccuratemeasures,weneedtoknowwhatwewant tomeasureandwhy.Thisbookprovidesnewinsightsintoconstructsand variablesthathaveoftenbeenneglectedinsportstothisday.Italsoreviews fundamentalsofsportsanatomyandphysiology,sportmeasurement,and performanceanalytics.
Thisbookservesmanyreaders.Peopleinvolvedwithsports,including players,coaches,andtrainers,willgainanappreciationforperformance measuresandanalytics.Peopleinvolvedwithanalyticswillgainnewinsightsintosportsperformanceandseewhatittakestobecomeacompetitiveathlete.Andstudentseagertolearnaboutsportsanalyticswillhavea
Preface vii
practicalintroductiontothefield.Datasetsandprogramsinthebookare availablefromthebook’swebsite http://www.ftpress.com/martin/.
ManythankstoThomasW.Miller,myconsultingeditor,formakingthis bookhappen,asitwouldnothavebeenpossibletocompletewithouthim. Andspecialthanksgotomyeditor,JeanneGlasserLevine,andpublisher, Pearson/FTPress,forgivingmetheopportunitytopublishmyfirstbook. Ofcourse,anywritingissues,errors,oritemsofunfinishedbusinessare myresponsibilityalone.
Iwanttogiveaspecialthankyoutomybrotherandprofessionaltennis player,JuanJ.MartinJr.,whoconstantlyprovidesmewithinsightfulinformationbasedonhisexperienceinprofessionalsportsandexercisephysiology.IwouldalsoliketothanktheDallasCowboys’DirectorofFootballResearch,TomRobinson,forhisinstrumentalremarksandcomments.Thanks toRoySanford,aleadfacultymemberinNorthwesternUniversity’sMaster’sPrograminPredictiveAnalytics,whoprovidedconstructivecritiques onstatisticalmethods.Iwanttothankmymother,EstelaMartin,forbeing theredayandnightandofferingcontinuedsupport. Tambien,graciasami padre, JuanJ.MartinSr.,forprovidingmewithasports-likemotivation,impellingmetocompletethisbook.Inaddition,Iwouldliketomentionmy dogs,whicharealwaysthereformeandbroughtasmiletomyfacewhile workingonthisbook.
Mostofall,IwanttothankGodformakingthispossible.
LorenaMartin
SanDiego,California December2015
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Figures 5.1Three-ConeAgilityDrillbyPlayerPosition(NFL) 79
5.220-YardShuttlebyPlayerPosition(NFL) 79
5.3VerticalJumpbyPlayerPosition(NFL) 80
5.440-YardDashbyPlayerPosition(NFL) 80
5.5BroadJumpbyPlayerPosition(NFL) 81
5.6BenchPressbyPlayerPosition(NFL) 81
6.1LaneAgilityDrillbyPlayerPosition(NBA)
6.2BenchPressbyPlayerPosition(NBA)
6.3MaxVerticalLeapbyPlayerPosition(NBA)
6.4StandingVerticalLeapbyPlayerPosition(NBA) 105
6.5ThreeQuarterSprintbyPlayerPosition(NBA) 106
6.6ShuttleRunbyPlayerPosition(NBA) 106
6.7StealsbyPlayerPosition(NBA) 107
6.8DefensiveReboundsbyPlayerPosition(NBA) 107
6.9OffensiveReboundsbyPlayerPosition(NBA) 108
6.10AssistsbyPlayerPosition(NBA) 108
6.11ShootingPercentagebyPlayerPosition(NBA) 109
6.12PlayerEfficiencyRatingbyPlayerPosition(NBA) 109
7.1HitsbyPlayerPosition(MLB) 126
7.2RBIsbyPlayerPosition(MLB) 126
7.3RunsbyPlayerPosition(MLB) 127
7.4HomeRunsbyPlayerPosition(MLB) 127
8.1NumberofAssistsbyPlayerPosition(UEFA) 149
8.2NumberofGoalsScoredbyPlayerPosition(UEFA) 149
8.3NumberofPassesAttemptedbyPlayerPosition(UEFA) 150
8.4NumberofPassesCompletedbyPlayerPosition(UEFA) 150
9.1ProfessionalTennisPlayerEarningsbyNationality(ATP,WTA) 167
9.2ProfessionalTennisPlayerEarningsbyRankandSex(ATP,WTA) 168
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5.1AnalyzingNFLCombineMeasures(R)
6.2AnalyzingNBAGameTimePerformanceData(R)
7.1AnalyzingMLBPlayerPerformance(R)
7.2AnalyzingMLBGameTimeBattingPerformance(R)
8.1AnalyzingUEFAAssistsandGoalsScored(R)
8.2AnalyzingUEFAPassesAttemptedandCompleted(R)
9.1AnalyzingATPandWTAPlayerEarningsbyCountry(R)
9.2AnalyzingATPandWTAPlayerEarningsbyRankandSex(R)
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1 AnatomyandPhysiology “Amuscleislikeacar.Ifyouwantittorunwellearlyinthemorning,you havetowarmitup.”
FLORENCE GRIFFITH JOYNER
Understandingthebasicsofanatomyandphysiologyisfundamentaltoobtainingamorecomprehensiveknowledgeofwhatitmeanstobeanathlete. Letusstartbyansweringthequestion,“Whatisanathlete?”Wecanthink ofanathleteasapersonwhoisskilledatasport,trains,andpossesses physicalattributessuchasmuscularstrength,power,endurance,speed, andagility,tonameafew.
Thephysicalattributesandvariablesofanathletewillbedetailedandexplainedinchapter2.Thischapterfocusesonthefundamentalanatomyand physiologyofanathlete.Theobjectiveofthischapteristohelpthesports dataanalyst,aswellasathletesthemselves,understandthehumanbody andhowitsmachineryfunctionsduringathleticeventsinordertocomprehendhowperformanceisaffectedbyphysiology.Thischapterwillopen youreyestonewwaysofthinkingaboutnumbercrunchingandsportsanalytics.Knowledgeofthemainphysiologicalmechanismswillmakeyoua morecompetitiveandinsightfulsportsdatascientist.
Type of Bone
Table1.1.
TypesofBones Example of Bone
Long bones Femur, Humerus, Tibia
Short bones Tarsals of the foot, Carpals of the hand and wrist
Flat bones Scapula, Sternum, Cranium
Irregular bones Vertebrae, Sacrum, Mandible
Sesamoid bones Knee Cap, there are four sesamoid bones in the hand, there are two sesamoid bones in the foot
Letusreviewthebasicbonestructureandanatomicalinformationyou shouldbeawareof.Thehumanbodyismadeupof206bonesandmore than430skeletalmuscles.Thetopicofanatomyalonecouldtakeseveral bookstodoitjustice.Wewillcoverthepartofhumananatomyandphysiologymostrelevanttosportsperformance.
Thestudyofbonesiscalledosteology.Osteologistsdedicatetheirlivesto understandinghowbonesfunction.Bonesareresponsibleforproviding constantrenewalofredandwhitebloodcells,andarevitalnotonlytoour organs,buttogainingacompetitiveedgeinsportsperformance.Thereare severaltypesofbones:longbones,shortbones,flatbones,irregularbones, andsesamoidbones.Longbonesareassociatedwithgreatermovement duetotheleverlength,comparedtoshortboneswhichhavelimitedmobility,butareknowntobestronger.Pleaserefertotable1.1forexamplesof eachtypeofbone.
Themusculoskeletalsystemisintegraltohumanmovement,asitiscomprisedofligamentsthatconnectbonetoboneandtendonsthatconnect musclestobone.Consequently,whenthemusclepullsonthebone,motion occurs.Dependingonthemethodofclassificationorgrouping,estimates ofthenumberofmusclesinthebodyrangebetween430toover900.In fact,eachskeletalmuscleisconsideredanorganthatcontainsmuscletissue,connectivetissue,nerves,andbloodvessels.Muchofthedebateisa matterofdefinitionintermsofhowthemusclesarequantified.
Likebones,musclesmaybeclassifiedbytype:smoothmuscleisfound inthebloodvesselsandorgans,cardiacmuscleisfoundintheheart,and skeletalmuscleisabundantthroughoutthehumanbodyandisresponsible forourdailymovement.
Upperbodymusclesandmusclegroupstobecomefamiliarwithinclude thelatissimusdorsi,trapezius,deltoids,rotatorcuff,pectorals,biceps,triceps,andbrachioradialis.Midsectionmusclesinvolvedinsportsperformanceincludetherectusabdominus,externalandinternalobliques,and thetransversusabdominis.Lowerbodymusclesvitalformanysportsincludethequadriceps,hamstrings,gluteus(maximus,minimus,medius), gastrocnemius,andthesoleus.Pleaserefertotable1.2forthelocationsof thesemusclesandtheirfunctioninsports.
Manyofyouhaveheardoffasttwitchandslowtwitchmusclefibers.Most peopleareonlyawareoftwofibertypes,fastandslow,orwhiteandred. However,itismuchmoreaccuratetosaythattherearehybridfibertypes thatliewithinthespectrumofTypeIandTypeIImusclefibers.Morerecently,thescientificfieldrevealedthreedistinctcategoriesofmusclefibers. TheseareTypeI,TypeIIa,andTypeIIxmusclefibers.TypeIfibersare commonlyreferredtoasslow-twitchwhilebothTypeIIaandTypeIIxare recognizedasfast-twitchmusclefibers.
Tofacilitateunderstanding,wewillfocusonthedifferencesbetweenType IandTypeIIbecausetheyareinherentlydifferentastheyrelatetothefollowingcharacteristics:abilitytoutilizeoxygenandglycogenasdetermined byaerobicenzymecontent,myoglobincontent,capillarydensity,andmitochondriasizeanddensity.
Typically,slow-twitchmusclefiberstendtobehighinallthecriteriamentionedabove.Incomparison,fast-twitchmusclefiberstendtobelowin thesecharacteristics,whilehavinggreaternerveconductionvelocity,speed ofmusclecontractility,anaerobicenzymecontent,andpoweroutput.Fast twitchfibersareknowntohavehighglycolyticactivity,meaningtheyutilizeglycogen(thestorageformofglucose,whichmanycallsugar)athigh levels,whereasslow-twitchmusclefibersrelyontheiroxidativecapacity. Pleaserefertotable1.3foradditionalmusclefibertypecharacteristics.
SportsPerformanceMeasurementandAnalytics Name of Muscle
Upper Body Muscles
Latissimus dorsi
Table1.2. MusclesinSport Location of Muscle
located in the posterior part of the body, largest muscle group in the upper body, also called the back
Rhomboids located in the upper back underneath the trapezius and consists of two muscles; rhomboid major and minor
Trapezius located above and superficial to rhomboids extends from shoulders to neck muscles
Function
in Sport involved in extension and adduction of the shoulder as well as pulling motions; relevant for all sports
involved in retraction of shoulder blades relevant for all sports
involved in distributing loads away from the neck and keeping the shoulders stabilized
Deltoids commonly referred to as the shoulders involved in throwing motions used extensively in overhead athletes
Rotator Cuff located in the shoulder area deep under the deltoids, muscles that hold the shoulder in place involved in throwing motions; quarterbacks, pitchers, and tennis players when serving
Pectorals commonly referred to as the chest includes pectoralis major and minor
Biceps located in anterior part of the arm and called biceps because of the two heads of the muscle
Triceps located in posterior part of the arm and called triceps because of the three heads of the muscle
Brachioradialis and Pronator Teres
Core and Midsection Muscles
forearm muscles
Rectus Abdominus located in the anterior part of the body under the abdomen
External Obliques located above and superficial to the internal obliques on each side of the trunk
Internal Obliques located underneath the external abdominal oblique on each side of the trunk
Transversus Abdominis located in the deepest layer of abdominal muscles that wraps around the torso
Lower Body Muscles
involved in chest press strength, and abduction of the shoulder and pushing movements
involved in swinging motion; tennis players forehand and baseball swings; also involved in bending of the elbow and for picking up motions
extension of elbow; used to straighten the elbow; used in stiff-arm movement in football players
utilized in sports using the wrist
utilized for flexion of the spine and core stabilization; relevant for all sports
utilized for sideways bending and rotation of the torso; integral for tennis strokes
utilized for flexion of the spine, sideways bending, trunk rotation and compression of the abdomen; relevant for all sports
utilized for respiration and core stabilization; relevant for all sports
Quadriceps located in anterior part of thigh consisting of four muscles responsible for extension of the knee; major source of strength for soccer players; relevant for all sports
Hamstrings located in posterior part of thigh consisting of three muscles
responsible for flexion and bending of the knee; relevant for all sports
Gluteus Maximus, Gluteus Medius, and Gluteus Minimus located in the area usually called the buttocks utilized in explosive first step movements; integral for lower body strength and power
Gastrocnemius located in the lower leg area and typically referred to as part of the calf muscle
Soleus located in the lower leg area and typically referred to as part of the calf muscle
utilized in jumping and tip-toe motions including being on the ball of your feet
utilized in jumping and tip-toe motions including being on the ball of your feet
Table1.3. CharacteristicsofFiberTypes
Characteristics
Motor neuron size SmallLarge Large
Nerve conduction velocitySlowFast Fast
Contraction speed SlowFast Fast
Relaxation speed SlowFast Fast
Fatigue resistance
Force production
Power output
Endurance
HighIntermediate/LowLow
LowIntermediateHigh
LowIntermediate/HighHigh
HighIntermediate/LowLow
Aerobic enzyme contentHighIntermediate/LowLow
Anaerobic enzyme contentLow High High
Capillary density
HighIntermediateLow
Myoglobin content High Low Low
Mitochondria size/densityHigh IntermediateLow
Fiber diameter SmallIntermediateLarge
Color RedWhite/RedWhite
AdaptedfromBaechleandEarle(2008).
Table1.4.
MuscleFiberTypesandSports and LinemenLow
AdaptedfromBaechleandEarle(2008).
Itisevidentthatanatomyandphysiologyplayamajorroleinsportsperformance.Asprintermaybenefitfromagreaternumberoffasttwitchmuscle fibers,whereasalong-distancerunnerwillbenefitmuchmorefromhaving agreaterdistributionofslowtwitchmusclefibers.Refertotable1.4for TypeIandTypeIImusclefibercontributioninavarietyofsports.
Inadditiontothecontroversyoverthenumberofmusclefibertypes,there alsoremainsthequestionofwhetheronecantrainandmodifyone’sown fibertypethroughconditioning.Severalanimalstudieshaveshownthat enzymesthatwouldotherwisebedormantareactivatedthroughphysical training,implyingthatthereisapossibilityofchangingthefibertypetoa certaindegree.
Nowthatwehavethebasicsoftheskeletalandmuscularsystem,letus considerthephysiologyofsportsperformance.First,wemustrealizethat humanmetabolismincludesbothanabolicandcatabolicprocessesthatare ongoinginourbodies.Anabolicprocessesinvolvethesynthesisoflarger moleculesfromsmallermolecules.Conversely,catabolicprocessesinvolve thebreakdownoflargermoleculesintosmallerones,andareassociated withthereleaseofenergy.Energyreleasedinabiologicalreactionisquantifiedbytheamountofheatthatisgenerated.Theamountofheatrequired toraiseonekilogramofwateronedegreeCelsiusiscalledakilocalorie. Thiscorrespondstotheenergyfoundinfoodthatisbrokendownwithin ourbodiesandstoredintheformofadenosinetriphosphate(ATP).
Inthebody,energysystemsareresponsibleforprovidingtheATP(energy) thatisutilizedundervaryingintensitiesanddurationsofsportperformance.Therearethreemainenergysystemsatplayduringsportsperformance.Theyarethephosphagen(ATP-PCr)system,theglycolyticsystem, andtheoxidativephosphorylationsystem.Allthreesystemsareconstantly atworkandinteractingwitheachother,functioningonsomelevelasthey arenot“allornothing”systems.Thepredominanceofonesystemislargely determinedbytheintensityanddurationofthesportingactivity,aswellas thesubstrate(foodsource)thattheathletehasconsumed.Substrateutilizationisafancytermforthefoodthatisbeingconsumedbytheathlete. Correspondingly,thesethreeenergysystemsarealsosometimesreferredto asbioenergeticssystems.
Theathlete’sabilitytoperformisbasedonhisorhermuscles’capacity tofunctionanddependsontheoxygenorglucose(substrate)availability. Whatdoesthismean?Well,ifanathleteissprinting,muscleswithinthe bodydonotnecessarilyhavethetimerequiredtobeabletoutilizeoxygen, asabodyatrestdoes.Thiscausesthebodytoshiftintoananaerobicstate inwhichitcanextractenergyintheformofATP,withouttheuseofoxygen.However,whenthehumanmachineisrunningataslowerpace,the standardmetabolicprocessesthatutilizeoxygenareallowedtooccurinthe mitochondria(theengineofthecell).Somemightsaythatthehumanbody isinherentlyintelligentandcanbecomparedtoacomputer,inthatafter theprogramisbuiltandalgorithmestablished,itknowswhattodoonits own.
Tosimplify,thethreeenergysystemswillbereferredtoasthephosphagen, glycolytic,andoxidativesystems.ThesesystemsproduceATPandreplenishATPstoreswithinthehumanbody.ThebodynaturallystoresATPsufficientforbasiccellularfunctions,nottheamountnecessaryforsports.The phosphagensystemutilizesanenzyme,creatinekinase,tomaintainATP levelsduringintense,explosivemovementsofshortduration,allowingfor thereleaseofonemoleofATPortheequivalentof0.6kilocalories.The phosphagensystemisheavilyinvolvedinsportsthatconsistofhighintensity,short-termexplosivemovements.Thissystemisusedinallsportsat thepointofinitiationofactivity—attheshiftfromsedentarytoactive.
Table1.5. Rate/CapacityofAdenosineTriphosphate(ATP)
Note: 1 = fastest/greatest; 5 = slowest/least
AdaptedfromBaechleandEarle(2008).
Theglycolyticsystemisresponsibleforcontrollingglycolysis(breakdown ofglycogen)forenergyproduction,aswellastheonsetoflactateformation. Glycolysisisthetermfortheprocessesthatbreakdownglycogenstored inthemusclestoglucose,ultimatelyyieldingATP.Remarkably,intensity anddurationofthesportalsodictatesthetypeofglycolysisthatoccurs. Therearetwopossiblepathways:Theshorterpath,termedanaerobic(fast) glycolysis,consistsoffewerstepsthatleadtolactate;theotherpath,aerobic(slow)glycolysis,hasalongertrajectoryandyieldstwotothreemoles ofATPortheequivalentof1.2to1.8kilocalories.Aerobicglycolysisisa slowerprocess.Itrequiressufficientquantitiesofoxygentooperate,comparedtoanaerobicglycolysiswhichcanfunctionwithlimitedamountsof oxygen.
Finally,theoxidativesystemisresponsibleforbreakingdownglycogen, fat,andprotein.ItisalsoresponsibleforproducingATPwhenthebodyis atrestorduringlonglasting,lowintensitysportingactivities.Itisacommonlyheldbeliefthatwhentrainingatlowintensity,thebodyutilizesmore fatthanothersources(carbohydratesorprotein)ofenergy.Thisconceptis theresultofasimplifiedinterpretationofthisthirdsystem.
Theoxidativesystem’sprimarysourceoffuelisfat,sinceitinitiatesthe releaseoftriglyceridesfromfatcells.Thisleadstotheroamingoffreefatty acidsintheblood,whicharetransportedtothemusclefibersforoxidation (burnedforenergy).Thebreakdownoffattoglucoseiscalledlipolysisand yieldsbetweenthirty-sixtofortymolesofATPortheequivalentof21.6to 24kilocalories.
Additionally,thissystemisabletooxidizeprotein,however,proteinisnot itsfavoredsourceoffuel.Themechanismofbreakingdownproteinintoenergyislessthanefficient.Proteolysisrequiresseveralstepstobreakdown proteinintoaminoacids,andeventuallyconvertstheproductstoglucose throughanotherprocesscalledgluconeogenesis.Agreaterspanoftimeis neededtosynthesizeATP.Therefore,fatandcarbohydratearethepreferred fuelsforsport,becausetheyyieldenergyatamuchfasterrateoverlonger periods.Pleaserefertotable1.5fortherateandcapacityofATPproduction foreachenergysystem.
Theathlete’spredominantenergysystemdiffersnotonlybysport,butalso byplayerpositionorstyleofplaywithinaparticularsport.Forinstance, whenatennisplayersprintstohitaforehand,abasketballplayerjumps explosivelytoslamdunk,abaseballplayersprintstogetonbase,aquarterbackthrowsthefootball,orastrikershootstoscoreagoal,theirbodies areusingthephosphagensystemastheprimaryenergymechanism.If,on theotherhand,awidereceiverissprintingdownthefieldformorethan sixseconds,hisbodyhasshiftedfromusingthephosphagensystemtoa hybridstateconsistingofboththephosphagenandglycolytic(anaerobic glycolysis)systems.
Asoccermidfielderrunningnon-stop,backandforthatafastpaceforthe durationofonetotwominutesisinatruestateofanaerobicglycolysis. Ifthesoccerplayerweretocontinuerunningforalongerperiodoftime, rangingfromtwotothreeminutes,theyarelikelytobeinahybridstate offastglycolysisandoxidativephosphorylation.Finally,alongdistance runnerwhorunsforprolongedperiodsoftimeataslowerrateisusing theoxidativesystemastheprimarymechanismforproducingATP.Refer totable1.6fortherangesofintensityanddurationtypicalofeachenergy system.
Insummary,thephosphagenenergysystemprimarilysuppliesATPfor high-intensityactivitiesofshortduration.Theglycolyticsystemisassociatedwithmoderate-tohigh-intensityactivitiesofshorttomediumduration.Andtheoxidativesystemistheprimarysystematworkduring low-intensityactivitiesoflongduration.
SportsPerformanceMeasurementandAnalytics Table1.6. PrimaryEnergySystemDurationandIntensity Duration IntensityPrimary Energy System
0-6 seconds
Extremely HighPhosphagen
6-30 seconds Very HighPhosphagen and Fast Glycolysis
30 seconds to 2 minutesHigh Fast Glycolysis
2-3 minutes ModerateFast Glycolysis and Oxidative System
>3 minutes Low Oxidative System
AdaptedfromBaechleandEarle(2008).
Table1.7.
LimitingFactorsforEnergySystems Note: 1 = Least Probable Limiting Factor; 5= Most Probable Limiting Factor
AdaptedfromBaechleandEarle(2008).
Table1.7describesthelimitingfactorsofthebioenergeticssystems.Itshows howathletes,dependingonthesporttheyplay,involuntarilyutilizebioenergeticssystems.Ifwetakealookatthediscusthrower,itisimportantfor theirperformancetohaveenoughATPandcreatinephosphateinorderto throwthediscusinapowerfulmanner.Ontheotherhand,ifwetakea lookatmarathonrunners,theyaremuchmorelimitedbytheamountsof glycogen(largeamountsofglucosegroupedtogether)storedinthemuscles andliverbecauseofitsroleinglycolysisandoxidativephosphorylation. Thereby,iftheyarelimitedinmuscleorliverglycogentheirperformance willbehinderedgreatly.
Table1.8describestheprimarysystemthatwillbeutilizedbypercentmaximumpoweranddurationofexercise(sport).Withthisinformationwecan learntotrainourbodiestoutilizedifferentsystems.Forexample,ifyouare anathletethatwantstoimproveutilizationofthephosphagensystem,then youwouldtrainonetime(sprint)at90percentintensityforfivesecondsin
Table1.8. AthleticTrainingandEnergySystems
Percent
90-100Phosphagen 5-10 seconds1:12 to 1:20
75-90Fast Glycolysis 15-30 seconds1:3 to 1:5
30-75Fast Glycolysis and Oxidative1-3 minutes1:3 to 1:4
20-30Oxidative > 3 minutes1:1 to 1:3
AdaptedfromBaechleandEarle(2008).
durationataworktorestratioofonetotwenty,meaningyouwouldrest (5 × 20)100seconds,oraminuteforty.Ifhowever,youwouldwanttoimproveyourcardiorespiratoryendurance,youwouldtrainat20–30percent forlongerdurationataworktorestratioofonetothreeatmost.
Table1.9detailsphysiologicalmarkersofperformanceoutcomes.Itiswell documentedintheliteraturethattestosterone,growthhormone,andIGF-1 arestronglyrelatedtomusclemassdevelopmentandmaintenanceaswell asbonedensity.Lactatelevelsarecommonlyusedtoassesswhetherthe athleteisfatigued.Trainingthatrequireshighleveloftechniqueorskill shouldnotbeperformedsincecoordinationissignificantlydecreasedand riskofinjuryisincreasedwhenhighamountsoflactatearepresentinthe blood.Additionally,thehormonecortisolisknowntobeextremelyelevatedwhenanathleteisovertrainingcausinginflammationandstressin thebody,whichchronically,mayleadtoinjury.
Morerecentlytherehasbeenextensiveresearchondelayingaging.TelomeresarelocatedattheendofourchromosomeswithinourDNA.Youmay ask,“Whyisthisrelevanttosport?”Professionalathletesareinterestedin prolongingtheirathleticcareersandsincetelomereshavebeenshowntobe stronglyrelatedtophysicalaging,thisisarelevantmarkerofhavinganextendedathleticcareer.Manystudieshavealreadyshownthatlongertelomeresareassociatedwithhealthierandlongerlifespansinbothanimaland humanmodels.AnewermethodofassessingagingisMethylomeanalysis. Ithasbeenshowntohaveanevenstrongercorrelationtophysicalaging thantelomerelength.Itisnowrecognizedasameasureofbiologicalage andcanhavemajorimplicationsforinjurypreventionandtheextensionof athleticcareers.
