Kine 1020 notes exam PDF

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January 6th, 2020Importance of energy expenditure/ the metabolic engine Healthy muscles are required for increased expenditure and associate impact on:  Body composition o Increasing muscle mass results in relatively lower fat mass – body tone o Delay of the loss of muscle with aging  Systems- ske...

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January 6 , 2020 th

Importance of energy expenditure/ the metabolic engine Healthy muscles are required for increased expenditure and associate impact on:  Body composition o Increasing muscle mass results in relatively lower fat mass – body tone o Delay of the loss of muscle with aging  Systems- skeletal, CV and metabolic o Retard osteoporosis o Reducing blood pressure o Improve glucose metabolism o Increased HDL and lowering LDL Reciprocal relationship exists between muscle’s functionality and energy expenditure  They can work together or in opposition to each other o Ex. Muscle fatigue impacts the muscle’s functionality Interrelated factors, between functionality and energy expenditure, that limit movement  Difficulty with locomotion  Poor performance in work related tasks/activities (limits scope of activity) Categories of muscle with specialized actions, functions or outputs  Skeletal muscle o Striated and voluntary o Functions are locomotion, breathing, posture, heat production through shivering  Cardiac muscle o Electrically coupled cells that stimulate nearby cells  Smooth muscle o Non-striated

Relationship types of skeletal muscle actions and functions or outputs  Static o Isometric contractions: force but no movement  Dynamic o Shortening contractions: greater the force the slower the velocity o Lengthening contractions- greater the force stretching a muscle, the greater the velocity A variety of skeletal muscle outputs or functions are necessary to support functionality and energy expenditure  Strength: ability to exert maximum force against a resistance- mass x acceleration (kilograms (kg); Newtons (N)); work is force x distance (kg. metres or N. metres) o Handgrip, lat pulldown, arm curl, leg curl, bench press  Speed: perform voluntary muscle contractions as rapidly as possible- velocity (degrees/sec; joules/sec; km/hr or time for specific distance) o 30m, 50m run times  Endurance: sustain voluntary muscle contractions or performance- time (seconds, minutes and/or hours) o Chest raise, curl up, sit-ups, side leg raise, flexed arm hang  Power: the rate of performing work- – includes force x velocity (watts) (joules/sec) or work x time (kg. m/min) o Standing long jump, vertical jump, standing 3-hop Structure of skeletal muscle

Each fiber has myofibrils: 2500-5000 running along length of fibre/cell

Muscle cell (fiber) membrane systems

January 8 , 2020  Actin (thin filament) and myosin (thick filament) are in an orchestrated manner not just random  Sarcomere is the base contractile unit of muscle o Force generation for strength, power, speed etc. of the muscle th

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I band and A band are differentiated by their ability to transmit light A band has more protein and also contains the thick myosin protein Actin is associated with the Z line/ Z disc o This is here the active fore generation is going to happen  More light transmission means the filament is thicker (myosin)

The areas that stick out are the myosin head regions are the cross bridges  The active binding site on the cross bridge region likes to bind with the actin filament  Tropomyosin runs in the groove between the actin-actin filament Interaction of sarcomere proteins  Actin: G-actin monomers, f-actin filaments o Myosin-binding site blocked by tropomyosin o Troponin (3 units) moves tropomyosin  Myosin: head and tail regions contain binding sites for actin, ATP dependent, enzymatic  Actin-myosin interaction: contraction � force Changes in sarcomere organization with different types of contractions 

Sliding filament mechanism  Sequence of events that occurs between the time a cross bridge binds to a thin filament, moves and then is set to repeat, there are 4 steps: 1. Attachment of the cross bridge to a thin filament

2. Movement of the cross bridge, producing tension in the thin filament also known as the power stroke 3. Detachment pf the cross bridge from the thin filament 4. Energizing the cross bridge so it can attach to a thin filament and repeat the cycle Actin and myosin cross bridge cycling Cycle has 4 phases with the sarcomere shortening: 1. Energized 2. Resting or bound 3. Power stroke (movement or rigor) 4. Detachment Requirements: energy (ATP) and Calcium Role of ATP  myosin is also an enzyme and it interacts with ATP  ATP becomes hydrolyzed by the myosin enzyme ATPase o ATP is responsible for the dissociation of actin and myosin interaction o Heat is also produced which is why when we exercise we heat up and feel warm  If we had no ATP then actin wouldn’t dissociate Role of calcium  Most of the calcium isn’t available to actin and myosin right away  Calcium is stored in the sarcoplasmic reticulum o Must be released so it can move the tropomyosin rod so then the cross bridges  You don’t want too much calcium inside the muscle sarcoplasm because it can cause muscle death  Actin molecules form coiled chains and tropomyosin molecules run along actin, blocking cross bridge biding sites  Troponin hold tropomyosin in place  Calcium bind troponin on actin, change its conformation which pulls tropomyosin away from the cross-bridge binding sites o This allows for actin-myosin interaction to occur by exposing actin to myosin  When calcium is removed, tropomyosin moves back to block cross-bridge binding sites (no actin-myosin interaction) Muscle fibre excitation-contraction coupling  Α-motor neuron connects and innervates muscle fibres  Contraction is triggered by an action potential (from the brain/spinal cord to α-MN)  The AP travels down the axon terminals into myofibrils via t-terminals o Calcium released om sarcoplasmic reticulum  An AP must be generated before the muscle can contract January 10 , 2020 th

Classification System for Identifying Types of Muscle Cells or Fibre

Types Characteristics: Functional  Speed of contraction  Fatigue resistance  Slow contraction means max force can be maintained longer  Fast contraction means max force won’t be maintained long ad it will be fatigued faster Metabolic  Oxidative capacity (mitochondria) Anatomical  Colour o Lots of hemoglobin means the muscle is more red  Size � fibre diameter Slow Twitch (I)  Slow oxidative (in producing and releasing the energy but it lasts longer) o Heavy reliance eon mitochondria  Red  Fatigue resistant fibres (Max tension ↑)  Muscle fibres used to maintain posture Fast Twitch (IIa)  Fast oxidative glycolytic o Heavy reliance on mitochondria, also high glycolytic capacity  red

fatiguing fibres (Max tension ↑↑)  muscle fibres used for non-exertive movement (walking) Fats Twitch (IIx or IIb)  Fast glycolytic o Heavy reliance on glycolysis  White  Fast fatigue fibres (Max tension ↑↑↑)  Muscle fibres sued for powerful movements (jumping and sprinting) (look at features of muscle cells table) Organizational components Features of motor units:  All muscle fibres within a MU are the same cell/fibre types  All muscle fibres within a MU contract at the same time when stimulated  A muscle can contain many MU Time dependent relationship for stimulus (AP) – Response (contraction)  Latent period can be 1-5 msec  Contraction time – ranges from 40-120 msec  Relaxation time – ranges from 50-200 msec Demand (Load) Dependent Relationship for Contraction Times  Latent period is longer  Duration of contraction time is less (ex. Twitch is shorter)  Velocity of shortening is lower  Distance shortened is less  (lighter loads are the opposite) Muscle S � R Characteristics are Dependent on the Type of Muscle Cell/Fiber and/or Motor Unit  Contraction time o Depends on type of myosin present  Relaxation time o Dissociation of calcium from troponin o Speed of relaxation tends to match speed of contraction What else determines force generated by muscle? 1. Optimal length of contracting muscle fibre  Compressed o A-M filaments overlap and less tension is produced  Optimal o Optimal tension when stimulated o Optimal A-M interaction and cross-bridges available  Stretched o A-M filaments barely touch o Decreased amount of tension 2. Action potential frequency/frequency summation  Unfused Tetanus o partial dissipation of tension between subsequent stimuli 

Fused Tetanus o No time for dissipation of tension between rapidly occurring stimuli 3. Number of fibres per motor unit and cross sectional area  The total tension a muscle can develop depends on two factors: o The amount of tension developed by each fibre o The number f fibres contracting at a given time, which is a function of:  The number of fibres in each motor unit (motor unit size)  The number of active motor units (MU recruitment) Features of motor unit recruitment  When activated, all muscle fibres within a MU contract  With only 1 MU activated- weak contraction  Stronger contractions – need more MU recruited: o MU quantity: more MU the greater the tension o MU fibre number: more fibres in one MU, the greater the tension o MU type: fast fatiguing vs. fatigue resistant 

All MU types are present in skeletal muscle: how do they work together (recruited)  MU are recruited according to the size principle (SO, FOG, FG)  The number of MU recruited depends on the tension required to perform the task  Smaller units are recruited fist and the larger units are recruited last Motor unit recruitment  MU size varies form one muscle to another o Few fibres vs many hundreds/thousands fibres  Force produced by a. single fibre depends on fibre diameter- the greater the diameter, the greater the force o 100 FG fibres produce ire force than 100 SO fibres Muscle tension: contractile and series-elastic components Tension/force generation  Contractile component: A-M (Cross-bridge) interaction Tension/force transmission  Parallel elastic (inside myofibril- intermediate filaments)  Series elastic component (tendons/ligaments at origins/insertions) January 13 , 2020 Bioenergetics and energy metabolism  Nutrients from ingested foods are provided and stored as carbs, fats and proteins o these 3 substrates are a source if chemical energy  chemical pathways (enzymes) convert substrates to energy  all of the nutrient and chemical reactions in the body are referred to as metabolism Bioenergetics and muscle metabolism  Bioenergetics: flow of energy in a biological system resulting in the ability to do work, heat, etc.  Thermodynamics (energy is neither created or destroyed) th

Types of energy including thermal, chemical, mechanical, electrical, radiant and atomic/nuclear  Exergonic reactions: energy releasing reactions (Negative G)  Endergonic reactions: energy consuming reactions (Positive G) Metabolic pathway – Metabolism  Total of all the catabolic/exergonic and anabolic/endergonic reactions in a system  Regulated by mass-action and/or allosteric enzymes o Catabolic - breakdown of larger molecules into smaller molecules o Anabolic - synthesis of larger molecules from smaller molecules  ATP is the metabolic currency o Intermediate high energy phosphate containing molecule (negative G of -7.3 kcal/mol) o Allows the transfer of energy form exergonic to endergonic enzyme catalyzed/facilitated chemical reactions  When we look at ATP concentrations in muscle, they do not change drastically* o Skeletal muscle wants to keep ATP at a relatively constant level* Muscle Metabolism (Look a slide with picture)  Approximate rates of ATP turnover in types of muscle fibres o

 Rate location capacity are important when talking about metabolic pathways Energy systems used to replenish ATP: Muscle metabolic pathways (look at pictures on slides) 1. Phosphagen System (Phosphocreatine)  Phosphocreatine (PCr: uses creatine phosphate as substrate) o Reduced levels or lower supply (can be depleted ~80%)  Increased Pi and H+ conc. From ATP breakdown  Rate: immediate and fast (enzyme is creatine kinase)  Location: in the sarcomere (adjacent to myosin ATPases in the M line)  Capacity: only lasts seconds to few minutes and doesn’t require O2 2. Oxidative phosphorylation: Kreb’s cycle + Electron Transport Chain

Uses glucose, lipids and proteins  Rate: takes 3-5 mins and relatively slower (2 pathways)  Location: in the mitochondria throughout the cell  Capacity: >3 hours (aerobic) 3. Glycolysis  Uses glucose from different sources; aerobic glycolysis and anaerobic glycolysis (muscle glycogen)  Fatigue is associated with anaerobic glycolysis o lower supply- reduced glycogen concentrations o Lower pH- build up muscle H+ ion but not from lactic acid o lower supply or reduced glycogen concentrations  Rate: takes 90 seconds and relatively fast (can vary rate)  Location: bound with actin and involves several enzymes  Capacity: muscle glycogen (1-2 hours and anaerobic); blood glucose (hours and aerobic) January 15 , 2020 ATP- Phosphocreatine 

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Reaction is bi-directional depending on substrate level concentration During skeletal muscle contraction, there is a ↑ in the concentration of ADP and H+ and a ↓ in ATP  If PCr is available, the reaction will work to restore ATP  Only involves 1 reaction: fast and simple, but only good for a few contractions  After exhaustive exercise, PCr replenishment can take up to 15 mins  Creatine kinase is a near equilibrium enzyme** o Can shift the reaction left or right depending on the amount of product or concentration** Oxidative phosphorylation 

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Glycolysis #1. When exercise continues for more than a few seconds, ATP regeneration is derived from blood glucose and muscle glycogen stores #3. Phosphofructokinase (PFK) is known as the rate limiting enzyme: regulates the interaction between F6P and F1,6- biphosphate #4/5. 1 x 6C is converted to 2 x 3C molecules to step #10 (pyruvate), each 3C produces 4 ATP but 2 ATP is used up so the yield is 2 ATP (substrate level phosphorylation) #6. Ratio: NAD/NADH (redox potential), requires cofactors (NAD) #10. The end product, PYRUVATE can be converted to lactate (anaerobic) or acetyl CoA oxidative (aerobic) systems to produce additional energy Anaerobic and Aerobic Glycolysis  At the end of glycolysis pyruvate can go in 2 directions: o If oxygen is present, Acetyl CoA is produced using pyruvate dehydrogenase and it enters the Kreb’s cycle o Oxidation of acetyl-CoA leads to the formation of 2ATP, CO2 and H2O o In anaerobic conditions, pyruvate is converted to lactate by lactate dehydrogenase Kreb’s cycle  Citrate synthase uses Pyruvate (3C) and oxaloacetate to (3C) form citrate (6C) o Citrate synthase has a feedback system for glycolysis directly to phosphofructokinase o If there is too much citrate, glycolysis will slow down and vice versa

2ATP formed here  Succinate dehydrogenase has a feed forward letting the ETC know what’s coming  Hydrogen formed in glycolysis and Kreb’s cycle reduce NAD and FAD o 3NADH and 1FADH are formed per pyruvate in the kerbs cycle and passed to the ETC and used as electron donors Electron transport chain  NADH and FADH are oxidized releasing electrons that help form a concentration gradient  When he gradient is formed, the electrons go down their concentration gradient and drive ATP synthase to form ATP by reducing ADP through oxidative phosphorylation  Glycolysis (2ATP) + Kreb’s Cycle (2ATP) + ETC (34 ATP) = 38 ATP  Net 34 ATP since 4 is used up in glycolysis January 22 , 2020 Physiology of fatigue Selected definitions  Rate limiting adjustments in central and peripheral processes that limit human performance  Exercise induced reduction in the maximum capacity to generate force or power output  Fatigue was distinct from sensations of weakness, tiredness and pain  Newest definition: symptom in which physical and cognitive function is limited by interactions between performance fatigability and perceived fatigability Human performance  Performance fatigability: decline in an objective measure of performance over a discrete period of time (contractile function, muscle activation)  Perceived fatigability: changes in the sensations that regulate the integrity of the performer (homeostasis, psychological state) Performance fatigability: Quantifying and Assessing  NM fatigue definition: condition in which there is loss in the capacity for developing force/velocity of muscle resulting from muscle activity under a demand/load which is reversible by rest  NM characteristics: focuses on changes in processes responsible for o Force generation/muscle function (peripheral) o nature of coordinated movement – integration of muscle mass, fibre types and movements  NM fatigue traits: specificity and reversible with rest Physiology indices of Performance (not perceived) fatigue Direct muscle outputs: voluntary and/or electrical stimulation (individually or in combination are used to identify NM fatigue)  Used to assess impact of task  Voluntary o Maximal voluntary contraction (MVC), either isometric or isotonic contractions o Peak (maximal) and/or mean power output (PPO, MPO)  Stimulation o Maximal evocable force (MEF) – supramaximal (twitch; tetanic) 

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Tetanic force (submaximal and/or maximal- using low (50Hz) frequency stimulation o Twitch/tetanic stimulation to assess low frequency fatigue Indirect muscle characteristics/traits – associated with NM fatigue:  Provide information about impact of a task on metabolic system  Twitch interpolation: a supramaximal twitch during a maximal voluntary contraction (either isometric/dynamic)  Endurance time: sustained contractions (exhaustion) o Generally consider metabolic parameters (PCr, glycogen, lactate, oxygen, etc.)  lactate increases while blood glucose and glycogen drops w/ exhaustion  Increased power output=increased oxygen consumption=increased HR=increased lactate  Electromyography: EMG Assessment of muscle fatigue: Human  Electrical stimulation o MEF- stimulated isometric force (supramaximal stimulus)  With MVC: voluntary isometric force  Tetanic force (maximal and/or submaximal) – high frequency stimulation for isometric or dynamic  Central fatigue  If more force with ES than MVC (i.e. lower MVC/MEF ratio)  Difference between MVC and tetanic force  With higher MVC > lower tetanic force (central fatigue)  With lower MVC = lower tetanic force (not central fatigue) o

January 24 , 2020  There’s a relationship between functionality, metabolic engine and assessment measures for measuring NM fatigue Concerns w/ using cardio-metabolic variables and thresholds for intensity domains in fatigue  Only uses systemic data (metabolic variables) to classify or drive exercise intensity (%VO2max; %HR) or exercise domains (classified as moderate, heavy, severe – generally using [lactate]; VE or GET ventilatory thresholds)  minimal information on the muscle/muscle group output (force, power, speed, torque…) is doing  therefore it is important to classify exercise intensity and/or domains with CV system variables and capacity for muscular variables/response/outputs Critical power  unifies the relationship between systemic-metabolic parameters (%VO2 max; LaT) and muscle outputs (power; velocity)  CP is regarded as a “Fatigue Threshold“ and can separate exercise intensity domains where physiological/metabolic responses are stable (CP where they are not stable (>CP)  Critical power is assessed through a 3 minute all-out effort bicycle test th

Power- duration relationship- intensity domains for critical power (CP) and metabolic

responses  Above CP (fatigue is evident) o Extreme: highest work rates where task failure (time limit) occurs before VO2 reaches VO2max o Severe: relatively high work rates with no steady-state possible and VO2 continues to rise to VO2max o Maximal power generating capacity of the muscle is reduced which is why its fatigue  Below CP (exhaustion is evident) o Heavy: work rates with a steady- state obtained ~10-20min due to a slow rise in VO2 (VO2max not obtained) o Moderate: work rates with a steady- state obtained ~2-3min Relevancy of critical power  Critical power represents a functional level where the greatest metabolic rate occurs with oxidative energy sources  Differences in the cardio-metabolic respons...