KNS 480 Bioenergetics I Guided Notes PDF

KNS 480 Guided Notes Hormones I Hormones _____________________: hormones chemical messengers produced in one tissue that signal changes in other organs or tissues throughout the body o Transported via ________________________________...

KNS 480 Guided Notes Hormones I Hormones _____________________: hormones chemical messengers produced in one tissue that signal changes in other organs or tissues throughout the body o Transported via ________________________________ bloodstream o Interact with _______________________________ cellular receptors Goals of Hormonal Control During Exercise 1. Regulation of ________________________________________ macronutrient fuel stores 2. Control “________________________________” fight or flight responses 3. Allow for __________________________ adaptive responses to exercise and maturation Classes of Hormones hormone =polar Classes of Hormones fats nonpolar = o Amino acid derivatives o ________________________________ Peptides o Proteins o ______________________________________ steroids ______________________________ hormone structure determines how it travels through the bloodstream and interacts with cellular receptors Hormone-Receptor Interactions Hormones only affect tissue with Specific receptors  instructions fro DNA ribosome ______________________ Magnitude of effect dependent on: o _______________________ concentration of the hormone o __________________________ number of receptors on the cell o __________________________ affinity of the receptor for the hormone Hormones work by altering _________________________________________ cellular activity ____________________________: Down regulation Decrease in receptor number in response to high concentration of hormone o Example: _________________________________ TIDM _________________________: upregulation Increase in receptor number ozempic : in response to low concentration of hormone altering sensitivity o Example: Testosterone with building-mass into sells, ___________________________________ Strength Training men 1-10 Testoster x. ___________________________: Primary Messengers hormones that can pass directly through cell membranes to influence cellular activity o ________________ Steroid bases are non-polar and allow for the direct movement through the cellular membrane o Are slow-acting, but have long lasting effects ______________________________- Secondary Messengers due to their structure, these hormones must activate a G-protein on the cellular surface, which in turn activates secondary messenger pathways, which then influence cellular activities o All polar hormone types Endocrine Glands and Associated Hormones Hypothalamus and Pituitary Gland  o The hypothalamus and pituitary gland are referred to as the “___________________________” master glands due to their influence over other endocrine tissues o Neurons from the hypothalamus activate hormone release from the pituitary gland o Anterior Pituitary ▪ Adrenocorticotropic Hormone (ACTH) ▪ Follicle Stimulating Hormone (FSH) ▪ Luteinizing Hormone (LH) ▪ _____________________________ Growth Hormone (HGH or GH) ▪ Prolactin (PL) ▪ Thyroid Stimulating Hormone (TSH) o Posterior Pituitary ▪ Oxytocin ▪ ____________________________/Antidiuretic Vasopressin Hormone (ADH) Growth Hormone o Released from the anterior pituitary gland. o Stimulates release of  ___________________________________________ Insulin-like growth factors (IGFs) ▪ IGF-1 in muscle responsible for muscle growth o Stimulated by ____________________________________________ Growth hormone regulating hormone ____ (GHRH) most active night o Inhibited by ____________________________________________ Somatostatin SST _____ o Essential growth of all tissues ▪ Amino acid uptake and ______________________________________ Protein Synthesis ▪ _____________________________ Long bone growth o Spares plasma glucose ▪ Opposed ____________________ insulin action to reduce the use of plasma glucose ▪ Increases ___________________________________ gluconeogenesis ▪ Mobilizes ___________________________ fatty acids from adipose tissue o GH increases with exercise to help maintain plasma glucose concentration o Also stimulates protein synthesis following exercise o ________________________________ is associated with large increases in GH release and total GH secretion  S read Growth Hormone and Performance ant. Pituitary o GH increases _______________________ protein Synthesis in muscle and long bone growth ▪ Used to treat childhood dwarfism ▪ Also used by athletes and elderly o More adverse effects than benefits * o No evidence that GH promotes _________________________________ strength gains ▪ Minimal strength gains compared to resistance training alone o Questionable benefits as anti-aging therapy Antidiuretic Hormone (ADH) Post. Pituitary  o Reduces _______________________ water loss from the body to maintain plasma volume ▪ Favors reabsorption of water from kidney tubules to capillaries o Release stimulated by _________________________________________ high plasma osmolarity and low plasma volume ▪ Due to sweat loss without water replacement o Increases during exercise >60% VO max 2 ▪ To maintain ______________________________________ plasma volume o Change in Plasma ADH Concentration During Exercise ↳ not as if strong water supplement. drink e-lytes coconut water Salt hyponatremia water poisoning Adrenal Glands o Endocrine gland that sits ____________________to superior the kidneys o Made up of two parts ▪ Adrenal ________________________ Medulla Epinephrine  Norepinephrine ▪ Adrenal ______________________________ cortex Mineralocorticoids Glucocorticoids Androgens Adrenal Medulla-Catecholamines o Epinephrine (E) and norepinephrine (NE) ▪ ______________________ fast acting hormones ▪ Part of “______________________” fight or flight response o Bind to adrenergic receptors ▪ Alpha (a) a fast acting ▪ Beta (b) B o Effects depend on hormone used and receptor type Epinephrine and Norepinephrine o Fast-acting hormones o Maintain blood glucose during exercise ▪ ________________________ muscle glycogen mobilization ▪ Increasing ____________________ liver glucose mobilization ▪ Increasing ______________mobilization FFA free fatty acid  ▪ Interfere with ______________________________________ glucose uptake o Plasma E and NE increase during exercise ▪ Also related to increased _________________________ to inc HR. and ________________ BP during exercise o Decreased plasma E and NE following training responds to inhaler - Cortisol stress hormone o Maintenance of ______________________________ Plasma glucose ▪ Promotes ___________________________ Protein breakdown for gluconeogenesis ▪ Stimulates ________________ FFA mobilization ▪ Stimulates ___________________________________ glucose Synthesis ▪ Blocks uptake of glucose into cells Promotes the use of ___________________ free fatty acids as fuel o Stimulated by: ▪ __________________, Stress via ACTH Part of General Adaptation Syndrome (GAS) ▪ Exercise Pancreas ↑ Both endocrine and exocrine organ Exocrine functions Releases digestive enzymes and bicarbonate Endocrine functions Releases Insulin Glucagon Somatostatin This Photo by Unknown Author is licensed under CC BY Insulin and Glucagon Fast-acting hormones * Insulin Insulin Uptake and storage of glucose and FFA Plasma concentration decreases during exercise Decreased insulin response following training Glucagon GIUCAGOH : opposite action of insulin Mobilization of glucose and FFA fuels Plasma concentration increases during exercise Decreased response following training Insulin and glucagon secretion influenced by catecholamines S Blood Glucose Homeostasis During Exercise Plasma glucose maintained through four processes: ① Mobilization of glucose from liver glycogen stores ② Mobilization of FFA from adipose tissue Spares blood glucose ③ Gluconeogenesis from amino acids, lactic acid, /lactate and glycerol beta oxidation ⑨ Blocking the entry of glucose into cells Thyroxine , - Forces use of FFA as a fuel Cortisol Controlled by hormones catabolic protein - break down glucose Permissive or slow-acting Thyroxine, cortisol, and growth hormone Fast-acting Me Epinephrine, norepinephrine, insulin, and glucagon Influence of insulin and glucagon utilize glucose : put into bloodstream  Testes and Ovaries Mainly associated with sexual reproduction and the hormonal regulation of testosterone (testes) and estrogen (ovaries) we are * up until 8 weeks This Photo by Unknown Author is licensed under CC BY-SA-NC all female. Testosterone Secreted by the interstitial cells in testes in males and adrenal glands and ovaries in females pituitary gland Controlled by LH : anterior Both an anabolic and androgenic hormone Testosterone & exercise Circulating plasma testosterone increases 10-37% during prolonged submaximal work, maximal effort exercise, and endurance/strength training workouts Post-exercise, testosterone production is elevated producing : extra testosterone Exercise-induced increases in testosterone leads to Increased protein synthesis and hypertrophy Varies person to person and only accounts for ~10% of response a sensitivity maturation · testosterone response depends on Estrogen and Progesterone follicular Luteal : : estrogen dom. Progesterone dom to produce egg. Estrogen- primarily responsible for female Me secondary sex characteristics, breast development and female fat deposition patterns Menstrual cycle regulation ↳ Follicular phase- day day 28.. estrogen produced, regulated by FSH Luteal Phase- estrogen and progesterone produced-controlled by This Photo by Unknown Author is licensed under CC BY-SA LH Exercise and the Menstrual Cycle Uncertainty about the direct influence of exercise and the menstrual cycle No anaerobic performance differences Mixed results in endurance and ultra-endurance performance Notes on the luteal phase: Glucose metabolism is lower with high intensity exercise Eliminated if glucose is supplemented or in fed state Increased protein catabolism at rest and during exercise Progesterone effect Chronic Exercise and Amenorrhea Chronic heavy exercise may influence menstrual cycles and lead to amenorrhea Primary amenorrhea- no menarche before age 15 Secondary amenorrhea- loss of cycle or 9 or less cycles in a year Most prevalent in ascetic, endurance and weight class sports biggest % strength , : in : endurance based class sports Young ages are more influenced by high training volumes and lower body weight Q high training notes + low body weight = Female Athlete Triad/RED-S Spiral of bad endocrine hormone Summary of the Hormonal Responses to Exercise ilicites exercise hormonal response to rest elevated until we go increase in : remain : S Plateau ~ ↑  A: matching -STUDY on ?? exam S : ↑ ↑ y I 3  KNS 480 Guided Notes Nervous System 1: Neurological Control of Movement Functions of the Nervous System ] 1. Control the ____________________________________________ internal environment a. Coordinated with the ______________________________________ endocrine system 2. _____________________ voluntary control of movement 3. Spinal cord reflexes 4. Assimilation of experiences necessary for ___________________ Memory and _____________________ learning I Organization of the Nervous System Central Nervous System (CNS) o _________________________________ brain+ Spinal cord Peripheral Nervous System (PNS) o Neurons outside CNS o Sensory Division ▪ _______________________________ Afferent fibers transfer impulses from receptors to CNS o Motor Division ▪ _________________________________ Efferent fibers transmit impulses from CNS to _____________________________________ effector organs  Anatomical divisions of the nervous system body organs balance Skeletal muscle auto' Structural and functional organization of the nervous system... what are I components of nervous system 2 motor system composed... of Nervous System Organization Neuron I 3 Regions – o _____________________________ body (somal o _____________________________ dendrites o _____________________________ axons At ends of axons are branches called ______________________ axon terminals o Their tips have synaptic knobs, which house _____________________________ NT's neurotransmitters Neurons communicate via _____________________________________. electrical impulses  Clinical Application: Exercise training benefits multiple sclerosis (MS) patients MS is a neurological disease that destroys _________________________ myelin sheaths of axons Occurs due to immune attack on myelin Exact cause not known- defects in several genes MS results in progressive loss of nervous system function Fatigue, muscle weakness, poor motor control, loss of balance, mental depression Exercise training improves both functional ___________________ capacity and + help (not cure) but , slow disease.  ________________________ quality of life Synaptic transmission Electrical activity in neurons Neurons are an “excitable cells” o ________________________ Irritability ▪ Ability to respond to a stimulus and trigger a neural impulse o _________________________ conductivity ▪ Transmission of the impulse along the axon Resting membrane potential _______________________ negative charge inside cells at rest o -5 to -100 mv across all cell types o -40 to -75 mv in neurons Charge determined by: o _______________________ permeability of plasma membrane to ions o Difference in ion concentrations across membrane ▪ Na , K , and Cl play most important role + + – Maintained by sodium-potassium pump o _________________________ potassium tends to diffuse out of  cell o Na /K pump moves 2 K in and 3 Na out + + + + Illustration of resting membrane potential in cells Concentration of ions across a cell membrane Channels regulate ion passage across cell membranes Exchange of sodium and potassium across cell membrane Neurons transmit messages via the action potential Occurs when a stimulus of sufficient strength _________________________ depolarizes the neuron o Opens Na channels, and Na diffuses into cell + + o Inside becomes more _____________________________ Positive Repolarization ▪ Return to __________________membrane resting potential K leaves the cell rapidly + Na channels close + __________________________________________ All-or-none Law/principal - o Once a nerve impulse is initiated, it will travel the length of the neuron  ?? Action potential shorter explaing action potential or putting them "sYeps Depolarization and repolarization * steps + why its happening Neurotransmitters and synaptic transmission _________________________________ synapse o Small gap between presynaptic neuron and postsynaptic neuron  ___________________________________ Neurotransmitter o Chemical messenger released from presynaptic membrane o Binds to receptor on postsynaptic membrane o Causes __________________________of depolarization postsynaptic membrane Structure of a synapse Neurotransmitters and synaptic transmission Excitatory postsynaptic potentials (EPSP) o EPSPs can _________________ promote neural depolarization in two ways:  ▪ 1) temporal summation; and/or ▪ 2) spatial summation o Temporal summation ▪ Summing several EPSPs from one presynaptic neuron o Spatial summation ▪ Summing EPSPs from several different presynaptic neurons Inhibitory postsynaptic potentials (IPSP) neg= harder o Causes ______________________ hyperpolarization (more negative to reach resting membrane potential) threshold o Neurons with a more negative membrane potential resist depolarization Neurotransmitters of Interest for PA and Exercise 1. Epinephrine and Norepinephrine 2. _____________________________ Dopamine Y excitatory j · or 3. ______________________________ Serotonin In inhibitory 4. Acetylcholine (AcH) - activating or inhibiting duringexeras cased - exercise Serotonin Schizophrenia ADHD  KNS 480 Guided Notes Nervous System 2: Receptors and Reflexes Review What are the two major anatomical divisions of the Nervous System? CNS + PNS What is the difference between Afferent and Efferent -CNs transf impulses receptors : Pathways? afferent fibers : - efferent fibers transmit impulse CNS Morgans : ; o How can we further subdivide our Efferent Pathways? How do neurons send signals? symatic autonomic us symp parasym o Within the neuron action potential : princ invol. Controlled by gated channels on rol : all or none. o Between neurons neurotransmitters : calm smooth muscle converts electrical signal to chemical Signal muscles Sensory Receptors 4) main classes Nocireceptor thermoreceptor Chemoreceptor Mechanoreceptor  fall wh arms in shoulder to 'roll' out of it falling 'Correctly' : on * Sensory information and reflexes ______________________________________ Proprioceptors o Receptors that provide CNS with information about body position o Located in _____________ joints and ________________________ muscles ________________________________________ Kinesthesia o Conscious recognition of the position of body parts o Recognition of speed of limb movement Mc ToJoint proprioceptors beable to __________________________________________ free Merve endings discuss o Most abundant type of joint proprioceptors differences ! o Sensitive to touch and pressure o Initially strongly stimulated, then adapt Golgi-Type receptors ________________________________________________ ____ o Found in ligaments and around joints o Functionally similar to free nerve endings Pacinian Corpuscles ________________________________________________ __ o Located in tissues around joints o Detect rate of joint rotation Muscle proprioceptors Two primary proprioceptors provide sensory feedback to nervous system about: o Changes in muscle ___________________________ length  o _____________________________________ Force development by by muscle fibers muscle fibers _________________________________________ MuscleSpindle o Provides information about muscle length and rate of shortening _________________________________________ holgi tendon organ o Provides information about muscle force production Muscle spindle Responds to changes in muscle ______________________ length and consists of: o ___________________________________________ Intrafusal fiber ▪ Run parallel to normal muscle fibers (extrafusal fibers) o Gamma motor neurons ▪ Stimulate intrafusal fibers to contract in concert with extrafusal fibers Responsible for ________________________________ Stretch reflex o Stretch on muscle stimulates muscle spindles and promotes a _________________________________________ reflex contraction ▪ Knee-jerk reflex Golgi tendon organ (GTO) Monitors ___________________________________ force development in muscle o Can prevent muscle injury during excessive force generation Stimulation results in reflex _________________________ relaxation of muscle o Inhibitory neurons send IPSPs to muscle alpha motor neurons Big question: Do training-induced reduction in GTO inhibition responsible for gains in muscular strength? Will be discussed in more detail within chapter 14 E Skeletal muscle chemoreceptors Sensitive to changes in the chemical environment surrounding muscle fibers o It ions CO2 and Ke ____________________________________________ , , ____________ CHHETC : make more energy (CO2) by product , of Krebs cycle/ET, Provide CNS with information about muscle ___________________ metabolism during exercise o Important in control of__________________ cardiovascular and ___________________ pulmonary responses to exercise Somatic motor function Efferent Motor neurons are located within ___________________________________ the Spinal cord o Responsible for carrying neural messages from spinal cord to skeletal muscles ______________________________________________ Motor unit o Motor neuron and all the muscle fibers it innervates Innervation ratio o Number of muscle fibers per motor neuron  o ___________ Low ratio in muscles involved in fine motor control (e.g., 23/1 in extraocular muscles) o ____________ Higher ratio in muscles that do not require fine motor control (e.g., 1,000/1 or greater in large limb muscles) Structure of a motor unit Motor unit recruitment and the size principle Motor unit recruitment o Recruitment of additional muscle fibers by ____________ more motor units g activatintriple The ___________________-the orderly recruitment of motor units during exercise o Smallest motor units recruited first during exercise Types of motor units o Type S (slow) or type I fibers [smallest] o Type FR (fast, fatigue resistant) or type IIa fibers [intermediate] o Type FF (fast, fatigable) or type IIx fibers [largest]  Recruitment pattern during incremental exercise o Type S à type FR à type FF & Vestibular apparatus-important for maintaining _______________________________ equilibrium Located within the ______________________________ inner ear Responsible for maintaining general equilibrium and balance o Maintains head position Sensitive to changes in linear and angular acceleration o Stimulated by _________________________________ head movement. Also controls head and eye movement during exercise Motor functions of spinal cord _________________________ Spinal Tuning refers to neural networks within spinal cord that refine voluntary movement after receiving messages from higher brain centers Withdrawal reflex o Means of removing limb from source of pain Withdrawal Reflex  1 e.. Stepping on thumbtack knee bend twist ACL : Slight + Smenisci injury Control of voluntary movement Control of voluntary movement involves cooperation of many areas of brain along with subcortical areas o ____________________ motor cortex receives inputs from variety of brain areas including basal nuclei, cerebellum, thalamus o Spinal mechanisms (i.e., spinal tuning) results in refinement of _______________________________ motor control o Feedback from proprioceptors allows for further modification in motor control Steps leading to voluntary movement  KNS 480 PNF and Muscular System Guided Notes PNF Activity Proprioceptive neuromuscular facilitation (PNF) is common practice for increasing _______________________________ range of motion for rehabilitation and performance Proposed mechanisms include _____________ autogenic inhibition _____________ reciprocal inhibition stress relaxation gate control theory Review ____________________________ autogenic inhibition- occurs in contracted or stretched muscles; GTOs are activated and trigger a decrease in excitatory signals in the same muscle and causes muscle relaxation _____________________________ Reciprocal inhibition -occurs when the opposing muscle is contracted voluntarily and decreased neural activity is seen in the working muscle due to muscle spindle activation Types of PNF Stretches ____________________________________________ Contract Relax - _: Take muscle into an assisted stretch, hold stretch for 5-10 seconds, isometrically contract the stretched muscle for 5-10 seconds, relax for 2-3 seconds, then stretch again (CRAC) ____________________________________________ Contract Contract Relax-antagonist - - ___________________________ Takes muscle into  an assisted stretch, hold stretch for 5-10 seconds, isometrically contract the antagonist muscle for 5-10 seconds, relax for 2-3 seconds, then stretch again https://forms.office.com/r/ADY3nJrGJ4 Skeletal Muscle Functions Produce _______________________ movement Maintain _______________________ posture Generate _______________________ heat Actions Pull NOT Push Connectiv in9 e Tissue Pablo a O of the Muscle ________ ________ ________ - ________ ________ ________. ________ ________ ________ ________ ________________________________________ Basement membrane  Sarcolemma Microstructure of Muscle Myofibrils ________________________________________ activ (thin filament) ________________________________________ myosin (thick filament) ________________________________________ Sarcomere Z line M line H zone A band I band Sarcoplasmic reticulum Transverse tubules Sarcoplasmic Reticulum : actin + Myosin Sate llite Cell s  KNS 480 Muscle 2 Guided Notes Neuromuscular Junction 1. Neuromuscular junction: Junction between __________________________ and muscle fiber motornevron 2. ___________________________: Motor neuron and all fibers it innervates 3. Motor end plate: Pocket formed around motor neuron by sarcolemma 4. Neuromuscular cleft : Short gap between neuron and muscle fiber 5. _____________________________________ Acetylcholine is released from the motor neuron ▪ Causes an end-plate potential (EPP) ▪ ___________________________ depolarization of muscle fiber Muscular Contraction  The process of muscular contraction is explained by two * interacting theories 1. Excitation-Contraction Coupling 2. Sliding Filament Theory cross bridge formation Relationship between troponin, tropomyosin, actin, and myosin actin-thin myosin-thick Troponinious ar ative block myosin on provin sites binding activ Energy for energy contraction ___________ ATP required for muscle contraction Release of energy from ATP __________________ hydrolysis provides energy required for power stroke o Myosin ATPase breaks down ATP as fiber contracts o ATP ® ADP + P i Sources of ATP ↳ o Phosphocreatine (PC) o Glycolysis o Oxidative phosphorylation Sources of ATP production in muscle Excitation-Contraction Coupling  * * ▪ _____________________ Depolarization of motor end plate (excitation) is coupled to muscular contraction o Action potential travels down ________________ transverse triggers release of Ca tubules and causes release of Ca from SR ++ o Ca binds to _________________________ ++ troponin and causes position change in ___________________ tropomyosin ▪ Exposing myosin binding sites on actin o Strong binding state formed between actin and myosin cross bridge. o Contraction occurs (i.e., ___________________________) power stroke ofa putinorder ! answer short Excitation-Contraction Coupling Steps 1. An action potential travels down an alpha motor neuron *  and arrives at the synaptic knob tailend of exon 2. The synaptic knob releases acetylcholine (ACh) across the neuromuscular synaptic cleft of the neuromuscular junction where it binds to receptors on the sarcolemma of the muscle fiber 3. ACh activation of the sarcolemma opens ion channels, and Na moves into the fiber + 4. Movement of Na ions depolarizes the muscle fiber and + sends a depolarization wave through the T-tubules 5. Depolarization of the T-tubules triggers the release of Ca2+ from the sarcoplasmic reticulum into the sarcoplasm of the muscle fiber 6. Excitation-Contraction Coupling Steps 7. Ca ions bind to troponin, resulting in a shift in position of 2+ tropomyosin, exposing the myosin binding sites on actin 8. Crossbridge cycling occurs between actin and myosin to create muscular force development until neural stimulation stops form cross bridges 9. Neural stimulation ceases, stopping ACh release and repolarizing the cell get ready for next signal 10. During repolarization, Ca ions are returned to the 2+ sarcoplasmic reticulum and troponin and tropomyosin return to their resting positions, blocking the myosin binding sites on actin Events leading to muscle excitation, contraction, and relaxation Sliding filament model of muscle contraction-Huxley Also called the ________________________________________________ swinging lever-arm model Muscle shortening occurs due to the movement of the actin filament over the myosin filament Formation of cross-bridges between actin and myosin  filaments o ____________________________________________ power stroke Reduction in the distance between Z lines of the sarcomere Muscle shortening-big picture mysicas r a order. knowstep rSliding Filament Theory Steps ↑ short *Remember: Myosin binding sites on actin must be exposed for ___________________ crossbridge formation to occur* due to Ca 1. Myosin head with an attached hydrolyzed ATP (ADP + P )i is in a resting state 2. Myosin head binds to actin and forms a crossbridge with actin 3. P is released from the myosin head and alters the shape of i myosin, pulling on actin and creating a “power stroke” 4. After the power stroke, ADP is released from the myosin head 5. A new ATP binds to the myosin head, releasing the myosin head from actin and breaking the crossbridge 6. The new ATP is hydrolyzed, allowing the myosin to return to its original resting state Exercise and muscle fatigue Muscle fatigue: defined as a decline in muscle power output o Decline in muscle power output occurs due to: ▪ Decrease in muscle force production at ___________________ cross bridge level ▪ Decrease in muscle shortening ________________________ velocity  ▪ Cause of muscle fatigue dependent upon exercise _________________ intensity that produced fatigue Domains of exercise intensity Mechanisms responsible for muscle fatigue Mechanisms of fatigue during heavy, very heavy, and severe exercise (1-10 min) o Causes of fatigue are multifactorial-range from decreased Ca release from SR to accumulation of +2 metabolites that inhibit myofilament sensitivity to Ca +2 ▪ Key metabolites that contribute to fatigue include increases in P , H , and i + ________________________________________ free radicals  ___ ▪ H ions bind to Ca binding sites on troponin- + +2 preventing Ca binding and contraction +2 ▪ Both P and radicals modify i ________________________ cross bridge head and reduces number of cross-bridges bound to actin ▪ Collectively, these factors act to promote fatigue Mechanisms of fatigue during moderate intensity exercise (>60 min) o Causes of fatigue during prolonged endurance exercise include increased radical production and __________________ glycogen depletion ▪ Accumulation of P and H in muscle do not i + contribute fatigue during moderate intensity exercise ▪ Radical accumulation in muscle fibers modifies cross-bridge head and reduces number of cross- bridges bound to _______________ activ (force production reduced) ▪ Depletion of muscle glycogen reduces TCA cycle intermediates and decreases ATP production via oxidative phosphorylation Exercise and muscle cramps spasmodic Muscle cramps are ________________, involuntary muscle contractions prolonged Often associated with _______________, high intensity exercise Most exercise-associated cramps not caused by an electrolyte or dehydration balance Exercise-associated cramps likely due to hyperactive motor neurons in the spinal cord o Rigorous exercise can alter muscle spindle and Golgi tendon organ function resulting in increased excitatory  activity of muscle spindles and a reduced inhibitory effect of the Golgi tendon organ o Passive stretching often relieves this type of muscle cramp Help for people with muscle cramps? Scientists reason that a potential treatment or prevention of muscle cramps is to send a strong inhibitory stimulus to the spinal cord to prevent motor neurons from firing Recent studies suggest that activation of ion channels (called transient receptor potential channels) in the mouth/throat can send inhibitory signals to the spinal cord to inhibit over-active motor neurons and prevent cramping Studies are underway to test the hypothesis that oral - ingestion of natural spices can prevent exercise-induced + muscle cramps mouth o ________________, _________________, etc. throat Ginger capsaicin Stay tuned, help to prevent muscle cramps could be on the way food & ginger all , spicy what would impede preventy stop , musc contrac neural activation Stop receiving  KNS 480 Muscle III Guided Notes Exercise and muscle cramps Muscle cramps are spasmodic, ________________ muscle contractions involuntary Often associated with prolonged, ___________ high intensity exercise Most exercise-associated cramps not caused by an electrolyte or dehydration balance Exercise-associated cramps likely due to hyperactive motor neurons in the spinal cord Rigorous exercise can alter muscle spindle and Golgi tendon organ function resulting in increased ______________activity excititom of muscle spindles and a reduced ___________________ inhibitory effect of the Golgi tendon organ Passive stretching often relieves this type of muscle cramp Help for people with muscle cramps? Scientists reason that a potential treatment or prevention of muscle cramps is to send a strong __________________stimulus Inhibitory to the spinal cord to prevent motor neurons from firing Recent studies suggest that _______________of activation ion channels (called transient receptor potential channels) in the mouth/throat can send inhibitory signals to the spinal cord to inhibit over-active motor neurons and prevent cramping Studies are underway to test the hypothesis that oral ingestion of natural spices can prevent exercise-induced muscle cramps  ______________________________________________ ________ Stay tuned, help to prevent muscle cramps could be on the way Muscle Fiber Types ____________________________: Size principle the progressive activation of successive recruitment of additional motor units from smallest to largest motor units Three muscle fiber types exist in human skeletal muscle and differ in their functional properties  Contractile properties Maximal specific force production (labeled specific force production) Speed of contraction (______________) Umax o Regulated by myosin ATPase activity Maximal power output = force x shortening velocity o __________ high force, fast fibers produce high power output Fatigue ____________________ resistance Muscle fiber efficiency o Lower amount of ATP used to generate force Three muscle fiber types Type I => Type IIa · TypeType IIx Type lla Type 11 X sprinting running more force It Pink wht dark pink 19 Biochemical and functional characteristics of human skeletal * N muscle fiber types SA , Mc , wer Datin describeri. e. types characteristics -f tell or a 9) Comparison of maximal shortening velocities between fiber types sprintense soccer cos  Comparison of maximal specific force and power output between muscle fiber types Typical muscle fiber composition of athletes and nonathletes ME from o person person elite : power strength : , Muscle Actions Types of muscle actions Speed of muscle contraction and relaxation _______________________ muscle twitch (Contraction resulting from single stimulus) After stimulation- short latent period exist-corresponds to depolarization of muscle fiber Contraction-calcium released from SR o Tension is developed due to crossbridge binding Relaxation-reuptake of calcium into SR o Crossbridge detachment Speed of shortening is greater in fast fibers SR releases Ca++ at a faster rate Higher ATPase activity Time components associated with a muscle twitch Force regulation in muscle Number and types of motor units recruited ________ more motor units = greater force _________ motor units = greater force fast Muscle length “Ideal” length for force generation Increased _____________ cross-bridge formation Firing rate of motor neurons Frequency of stimulation o Simple twitch o _________________________ Summation o Tetanus Contractile history of muscle Rested muscle versus muscle exposed to fatiguing  exercise Warmup exercise results in “__________________________________” postactivation potentation Impact of neural stimuli (i.e. neural drive) on muscle force production Skeletal muscle length-tension relationship Impact of motor neuron firing rate on muscle force production Diseases and aging can negatively impact muscle function: Aging and muscle loss Age-related muscle loss-_______________________ sarcopenia 10% muscle mass lost between age 25-58 _________ years Additional 40% lost between age ______________ 50-86 years  Also a loss of fast fibers and gain in slow fibers _____________________ resistance training can delay age-related muscle loss Muscle force-velocity relationship At any ________________ force exerted by the muscle, the speed of movement is greater in muscles with a higher percentage of fast-twitch fibers Maximum velocity of shortening is greatest at the lowest force True for both slow and fast fibers Muscle force-power relationship At any given velocity of movement, the peak power generated is _________________ in a muscle with a higher percentage of fast-twitch fibers The peak power increases with _______________ up to movement speed of 200–300 degrees/second  Power ____________________ at higher velocities because force decreases with increasing movement speed