Applied Exercise Applied Exercise PhysiologyPhysiology

Section 5: Body Section 5: Body SystemsSystems

Topic 1: Muscular SystemTopic 1: Muscular System

Prepared byPrepared by

Mr. CernyMr. Cerny

Niagara Wheatfield Senior High SchoolNiagara Wheatfield Senior High School

Types of MuscleTypes of Muscle• CardiacCardiac

HeartHeart

• SmoothSmooth Organ liningOrgan lining

• SkeletalSkeletal MovementMovement 40% of total body mass40% of total body mass

MacrostructureMacrostructure

• It is the number of muscle It is the number of muscle fibers packed into a given fibers packed into a given muscle cross-sectional area muscle cross-sectional area that determine overall that determine overall force-generating capacityforce-generating capacity

Skeletal muscle c.s. 40x

MicrostructureMicrostructureSarcomere:Sarcomere:• basic functional basic functional

unit of muscleunit of muscle• Striated (light Striated (light

& dark bands)& dark bands)• Contains Contains ACTINACTIN

& & MYOSIN MYOSIN filaments that filaments that are responsible are responsible for contractionfor contraction

ActinActin & & MyosinMyosin

Sliding-Filament TheorySliding-Filament Theory• Using the list of “characters” below, Using the list of “characters” below,

create a storyboard showing the create a storyboard showing the many different steps involved with many different steps involved with the sliding-filament theory. Each step the sliding-filament theory. Each step should contain a colored drawing should contain a colored drawing (labeled if necessary) and a short (labeled if necessary) and a short explanation.explanation. ““Characters:”Characters:”

ActinActin MyosinMyosin ATPATP ATPaseATPase

TropomyosiTropomyosinn

TroponinTroponin Calcium Calcium (Ca(Ca++++))

Misc.Misc.• Role of ATPase:Role of ATPase:

Enzyme that allows ATP on the myosin head to Enzyme that allows ATP on the myosin head to release energy (release energy ( ADP + P) so that it can form a ADP + P) so that it can form a cross bridge on actincross bridge on actin

Needed again to detachNeeded again to detach

• Power Stroke:Power Stroke: After myosin head attached and “pulls” on the After myosin head attached and “pulls” on the

actinactin

• What is rigor mortis?What is rigor mortis? In relationship to the sliding-filament theory, In relationship to the sliding-filament theory,

explain how rigor mortis occurs.explain how rigor mortis occurs.

Where did the CaWhere did the Ca++++ come come from?from?

• CaCa++++ is stored and released from the is stored and released from the sarcoplasmic reticulum (SR)sarcoplasmic reticulum (SR)

• SR is a network of tubules within the SR is a network of tubules within the muscle fibermuscle fiber

Sarcoplasmic ReticulumSarcoplasmic Reticulum

Nerves & MusclesNerves & Muscles

• An action potential (signal traveling An action potential (signal traveling along a neuron) causing contraction is along a neuron) causing contraction is termedtermed Excitation-Contraction Coupling Excitation-Contraction Coupling

Excitation-Contraction Excitation-Contraction CouplingCoupling

1.1. Action potential travels along neuron by the temporary Action potential travels along neuron by the temporary changing of chargeschanging of charges

2.2. Nerve impulse causes the release of acetylcholine (ACh).Nerve impulse causes the release of acetylcholine (ACh).3.3. ACh travels across neuromuscular junction, binding to muscle ACh travels across neuromuscular junction, binding to muscle

cell membrane.cell membrane.4.4. ACh binding initiates an electrical impulse which travels across ACh binding initiates an electrical impulse which travels across

membrane and into T tubules.membrane and into T tubules.5.5. Impulse stimulates release of CaImpulse stimulates release of Ca+2+2 from SR. from SR.6.6. CaCa+2+2 binds with t-t complex of the actin filaments, shifting it's binds with t-t complex of the actin filaments, shifting it's

position, exposing myosin binding sites.position, exposing myosin binding sites.7.7. Myosin binds to actin; CaMyosin binds to actin; Ca+2+2 presence also causes enzymatic presence also causes enzymatic

actions of myosin to breakdown ATP into ADP + P + energy.actions of myosin to breakdown ATP into ADP + P + energy.8.8. Energy of ATP degradation causes shape change of myosin Energy of ATP degradation causes shape change of myosin

head, pulling actin molecule toward center of sacromere.head, pulling actin molecule toward center of sacromere.9.9. After sliding, a new ATP binds to myosin, breaking the myosin-After sliding, a new ATP binds to myosin, breaking the myosin-

actin bond, releasing the myosin head.actin bond, releasing the myosin head.10.10. If CaIf Ca+2+2 is still present, the process repeats itself until is still present, the process repeats itself until

sacromere has shortened completely.sacromere has shortened completely.11.11. If a nerve impulse ceases, the CaIf a nerve impulse ceases, the Ca+2+2 is reabsorbed by the SR is reabsorbed by the SR

and the muscle relaxes. and the muscle relaxes.

Muscle FatigueMuscle Fatigue

What is it?What is it? Decline in force-producing capabilities Decline in force-producing capabilities

over timeover time

What’s the point?What’s the point?

1.1. Prevents exhausting of metabolic Prevents exhausting of metabolic (energy-producing) reserve (like (energy-producing) reserve (like enzymes)enzymes)

2.2. Limits the buildup of harmful productsLimits the buildup of harmful products

3.3. Reduces the likelihood of damage to the Reduces the likelihood of damage to the contractile elements (ex.: sarcomeres)contractile elements (ex.: sarcomeres)

Muscle Fatigue Muscle Fatigue 11

What causes it?What causes it?• 1) Reduction in ATP1) Reduction in ATP

Under high stress, ATP utilization reduced Under high stress, ATP utilization reduced faster than ATP productionfaster than ATP production

• 2) Peripheral metabolic bi-products2) Peripheral metabolic bi-products Lactic acidLactic acid H (and other free radicals)H (and other free radicals)

Muscle FatigueMuscle Fatigue• 3) Dehydration3) Dehydration

Increases temp = decreases contractile Increases temp = decreases contractile propertiesproperties

• 4) Decrease nerve signals/action 4) Decrease nerve signals/action potentialspotentials

• 5) Reduction of 5) Reduction of CaCa ““leakage” 1leakage” 1 From decrease nerve connectionFrom decrease nerve connection

Specificity of Muscle Fiber Specificity of Muscle Fiber RecruitmentRecruitment

• Each activity will recruit different Each activity will recruit different groups & different numbers of muscle groups & different numbers of muscle fibersfibers

• Thus…in order to increase force Thus…in order to increase force production for a particular activity, you production for a particular activity, you must train those specific muscle fibers must train those specific muscle fibers used in that activityused in that activity

Specificity of Muscle Fiber Specificity of Muscle Fiber RecruitmentRecruitment

• What does this mean for What does this mean for trainingtraining?? In order for optimum adaptation to occur In order for optimum adaptation to occur

during training, muscles should be trained during training, muscles should be trained in a manner similar to the way they are in a manner similar to the way they are expected to perform during competitionexpected to perform during competition

• What does this mean for What does this mean for rehabilitationrehabilitation?? Return to work in a timely manner requires Return to work in a timely manner requires

you to look at exactly what that worker will you to look at exactly what that worker will be doingbe doing

Muscle TypesMuscle Types• Difference dependant on contraction Difference dependant on contraction

time (rate of cross-bridge cycling) NOT time (rate of cross-bridge cycling) NOT amount of force producedamount of force produced

• ““Twitch”: response of skeletal muscle Twitch”: response of skeletal muscle fiber to a single electrical stimulusfiber to a single electrical stimulus

• Muscle Types:Muscle Types: Slow twitch (Type I)Slow twitch (Type I) Fast twitch (Type II)Fast twitch (Type II)

Muscle TypesMuscle Types

ForceForce SpeedSpeed # mit.# mit. Resistance Resistance to fatigueto fatigue

ActivityActivity # # capillariescapillaries

Oxidative / Oxidative / nonoxidativnonoxidativ

ee

Slow Slow twitchtwitch

(I)(I)SameSame

(slightly (slightly less)less)

SlowSlow ManyMany YesYes EndurancEndurancee

ManyMany OxidativeOxidative

Fast Fast twitchtwitch

(II)(II)SameSame

(slightly (slightly more)more)

FastFast FewFew NoNo Sprinting Sprinting /bursts/bursts

FewFew nonoxidativnonoxidativee

Muscle Muscle InjuryInjury• DOMSDOMS

““Delayed onset muscle soreness”Delayed onset muscle soreness” Damage to sarcomere propertiesDamage to sarcomere properties

• Actual protein molecules in sarcomereActual protein molecules in sarcomere– TitinTitin– NebulinNebulin– CostamereCostamere

Exacerbated by dehydrationExacerbated by dehydration

Recovering faster with steroidsRecovering faster with steroids

Muscle StrengthMuscle Strength““Bigger” muscles:Bigger” muscles:

Usually NOT increase in muscle cells (hyperplasia)Usually NOT increase in muscle cells (hyperplasia) Usually an increase in existing tissue size Usually an increase in existing tissue size

(hypertrophy)(hypertrophy)

Factors contributing:Factors contributing:• GeneticsGenetics• ExerciseExercise• NutritionNutrition• EndocrineEndocrine• EnvironmentalEnvironmental• Nervous Nervous