PHYL2730

PHYL2730

1. Fuel Production / Metabolism

   • Fats
     • Fatty Acids
       • Lipolysis
       • Lipogenesis
   • Carbs
     • Glucose
       • Glycogenolysis (Glycogen stores to Glucose Pools)
       • Glycogenesis (Glucose pools to Glycogen stores
       • Gluconeogenesis
         • During prolonged exercise- Liver producing glucose through the use of amino acids
       • Stored in: Liver, Muscle (more in muscle than liver) and Body fluids (Narrow limits due to high reactivity)
   • Proteins
     • Amino acids

2. Energy

   • Energy Balance
     • Energy in (food) = Energy out (Work) + Energy out (heat) ± Energy stored (fat)
       • Energy out (heat) = 60 - 70%
         • Heat causes cardiovascular stress
   • Energy Systems
     • Aerobic
       • Substrates include: Glucose, Glycogen, Fat (Mainly), Amino Acids
         • Fat needs to be burnt in oxygen
         • Glycogen can be used anaerobically and aerobically
       • The Oxidative System: Aerobic ATP production, Oxidative Phosporylation
         • Oxidation of Fat: Breakdown of fat - Lipolysis
           • FFA transported in the blood
             • FFA activation (attached to CoA) - need ATP
               • Beta Oxidation - converting fatty acids to Acetyl CoA
                 • Krebs Cycle
                   • Complete the oxidation of CHO, fats and proteins using NAD and FAD as hydrogen carriers
                     • Hydrogens removed for ETC
                       • ETC
                   • Citrate Synthase and Succinate Dehydrogenase are more active in endurance athletes
                     • Peripheral adaptations to training - in specific muscles trained
     • Anaerobic
       • Immediate Energy Source: ATP/ Pcr
         • ATP
           • ATP resting conc. doesn't change
           • Rate of ATP resynthesis contributes to fatigue - Training improves rate
           • Small amount of ATP maintained to avoid 0 ATP for energy pumps
         • CP
           • CP can be supplemented
             • 50% of people can supplement - good for resistance or high intensity exercise
           • CP doesn't resynthesis until rest or low intensity exercise (Active recovery) - Aerobic process
           • Used to maintain muscle ATP levels
       • Non Oxidative Energy Source: The Glycolytic System
         • Glycogenolysis
           • Substrate: Glycogen
           • Occurs in the cytosol/cytoplasm of the muscle cell
           • Process involves series of enzymatically catalysed coupled reactions
         • Glycolysis
           • Breakdown of glucose to form Pyruvic acid + 2 ATP and Lactic Acid
             • Lactic Acid
               • Anaerobic Threshold
                 • Ventilation Threshold
                 • OPLA
                 • OBLA (Onset of Blood Lactate Accumulation)
                   • Lactate inflection point at 4mmol - Historically relevant
                 • Lactate Threshold
                   • Coincidence that ventilation threshold and lactate threshold match up
                   • Sped up by mass action
                 • Defined as; Production = Removal
                   • Highest sustainable work rate
                     • Accumulates first in muscle, then in blood
               • Oxygen required for removal
                 • Reconverted to pyruvate → enters the TCA cycle → broken down into CO2 and Water
             • Pyruvate
               • Low intensity exercise
                 • Converted to Acetyl CoA → Mitochondria → Krebs Cycle
               • High intensity exercise
                 • Large amount of pyruvate converted to lactic acid
   • Use of Energy Sources
     • Rest: Primarily Fat
     • Light - Moderate: High Fat use
     • High Intensity (Sprint): 95% Glycogen contribution
     • High Intensity (Endurance): Mainly glycogen but a small contribution of fat if oxygen is present

3. Muscle Fibre Type

   • Type 1 - Oxidative (Red Fibres)
     • Aerobic Capacity
       • Redness from Myoglobin
     • Small Diameter
       • Low force generation
       • Small Mitochondria
         • Only location where aerobic metabolism can occur
   • Type 2a - Fast Oxidative Glycolytic
     • Endurance Training increases amount of these fibres
   • Type 2b - Fast Glycolytic
     • Large diameter
     • Fast to contract - Fatigue quickly
       • Rely on anaerobic glycolysis - therefore accumulate lactic acid
     • Sprint training doesn't allow the change from Type 2a → Type 2b due to limited recovery time
   • Recruitment Order: Type 1 → Type 2a → Type 2b

4. Oxygen Consumption

   • Fick Principle
     • Product of Cardiac Output x (a-v) O2 diff
       • (a-v)O2 diff → How much O2 a muscle has used (O2 going in - O2 leaving muscle
   • VO2 Max
     • Test of central adaptation
       • High VO2 = reduced risk of CVD
     • EPO - Blood doping
       • Death due to increased viscosity
     • Decrease with age due to Max HR
   • RER - Respiratory Exchange Ratio
     • CO2 produced and O2 Consumed
       • Starts from 0.7 - 1.0
         • At 1.0 (VO2 Max) Carbs are exclusively being burnt
         • At rest 0.7 Fats are primarily being burnt
         • 0.7 - 1.0 mixture of substrates being burnt
   • EPOC: Excess Post exercise Oxygen Consumption
     • Excess caused by adrenaline circulating → driving up metabolic rate - removal of lactic acid

5. Responses to Training

   • Resting
     • Increased Capillarisation
       • Greater increase in Type 1 fibres - Aerobic metabolism
         • Increased (a-v)O2 diff
     • Increased Mitochondrial Density
       • More efficient O2 use
     • Decreased Heart Rate
     • Increased Stroke Volume
     • Glycogen super compensation. After exercise more receptive to taking up glucose due to enzyme - Glycogen-Synthase
     • Increased blood volume
       • Increased Plasma volume
         • Decreased viscosity
           • Prolonged period before heart stress
         • Buffer against dehydration
         • Dilutes catecholamine response - less mass action effect
           • Delayed recruitment
     • Increased RBC number
   • Exercising
     • Adaptations
       • Central
         • VO2 Max
           • Measure of endurance capacity
             • Not a good predictor of performance - Plateaus as performance increases
       • Peripheral
         • Trained muscle has less blood submaximally, more blood maximally
           • Less disruption to blood flow (submaximally)
         • More effective O2 uptake
         • Enzyme activity
           • Less stress response (Less catecholamines)
             • Increased heart filling time
               • Increased SV
         • Mitochondria measure of endurance capacity
           • More closely related to performance
     • Endurance training
       • Capable of greater fat use
         • Delayed stress response
           • Delayed recruitment of Type 2b fibres

6. Cardiovascular System

   • Cardiovascular Disease
     • Cholesterol
       • LDL
         • Prone to oxidation
           • Leads to plaque build up (atherosclerosis)
         • Increased by saturated fat consumption
       • HDL
         • Higher amount = low risk coronary heart disease
           • High HDL has protective effect
             • Removes cholesterol for disposal
               • Exercise increases HDL conc
                 • Aerobic and endurance training increases HDL conc
                 • Resistance training seen to reduce total cholesterol
       • Dietary prevention is fresh fruit and vege
     • Triad
       • Cerebrovascular Disease
         • Haemorrhagic Stroke
           • Bleeding in the brain
         • Ischaemic stroke/ Cerebral Infarction (brain attack)
           • Blockage of blood supply leading to death of that part of the brain
         • Hypertension increases risk of stroke
           • Risk can be reduced by exercise and changes in lifestyle factors
       • Coronary Heart Disease
         • Angina Pectoris
           • Symptom of impaired oxygen to the heart - partial occulsion of blood and oxygen
         • Myocardial Infarction
           • Complete blockage leading to death of the heart (heart attack)
       • Peripheral vascular Disease
         • Peripheral Artery Disease
           • Potential blockage of arteries of the lower limb - "Angina" of the lower limb
           • Stiffness and pain during exercise - due to inability to supply O2 demand of lower limb muscles
           • Management includes exercise, stop smoking, control of diabetes and hypertension
     • Highly influenced by lifestyle factors
       • Metabolic Syndrome: Collective group of risk factors - obesity, high blood pressure, diabetes, high cholesterol
         • All these risk factors can be lowered by exercise
     • RRP = HR x SBP
       • Rate Pressure Product
         • Estimate of how hard the heart is working
   • Cardiovascular Drift
     • Increased heat = Increased stress response = Increased catecholamines
       • Increased HR
     • Q = increased HR x decreased SV
       • Decreased blood volume due to decreased water = decreased venous return = increased heart rate = decreased SV
         • Associated with increased temperature, increased hormone conc. and dehydration
           • Intake of fluid or glucose intake can dampen effect
   • Cardiac Output
     • Q = HR x SV
       • Stroke Volume
         • Frank Starling Mechanism
           • The greater the distension (stretch), the greater the subsequent contraction
         • Preload (amount of blood in the left ventricle) - increases the stretch
           • The greater the pre-stretch, greater the force of contraction
       • Heart Rate
         • Declines with age
         • 208 - (0.7 x age)
         • Highly reproducible
         • Strongly effected by sympathetic and parasympathetic activity
   • Main functions
     • Deliver O2, nutrients
       • Glucose, FFA... Substrates
     • Remove CO2 and other metabolic end products
       • Lactate, H ions
         • Lactic acid → used as a fuel in other parts of the body
     • Transports hormones and other molecules
     • Temperature balance and fluid regulation
     • Acid - Base balance (resting blood pH 7.4)
       • Lactic acid accumulation = acidosis
     • Immune Function

7. Endocrine Responses

   • Glucose / Insulin Response to Exercise
     • High glucose and insulin conc. have an inflammatory response in blood vessels → Micro damage
       • Spikes/ micro damage can be reduced by a low GI, high fibre diet
     • Exercise provides glycaemic control
       • Non insulin dependent glucose uptake
         • Process of contraction → muscle permeability to glucose → GLUT4 receptors; Glucose uptake in absence of insulin
   • Insulin Antagonists
     • Growth Hormone
     • Cortisol
     • Catecholamines (Noradrenaline/ Adrenaline
       • Mass Action
         • Occurs when rate of glycolysis is greater than the rate of the TCA cycle
           • When out of sync the pyruvate is converted to lactic acid instead of going through the electron transport chain
             • Lactic acid can still be produced in the presence of O2 due to the fast rate of the glycolytic pathway (out of sync)
         • Seen in altitude training
         • Can access glycogen of non exercising muscles
           • Cori Cycle
             • Blood Lactate → liver → Glyconeogenesis → Liver releases glucose into the blood
             • Doesn't occur at a high enough rate to be sustainable
       • Can cause vasoconstriction in some areas leading to increased lactate accumulation
       • McArdles Paitents get catecholamine response but no mass action
       • Curve similar to lactate threshold
     • Glucagon
   • Types of Hormones
     • Steroid
       • Can enter the cell directly
         • Lipid soluble
     • Non Steroid
       • Can't enter the cell; require second messenger