C1 Ex Phys A

• energy is the ability to perform work • comes from the breakdown of ATP • key roles: 1. muscle contraction, 2. repair tissues, 3. nerve conduction, 4. hormone manufacturing • typical person uses their own body weight + over in ATP per day

• powers all metabolic reactions • stored as glycogen or fat ATP splitting 1. ATP molecule - 1 adenosine, 3 phosphates (Pi) 2. ADP molecule - 3rd Pi breaks off, releases energy, cause muscle contraction 3. ATP molecule - fuel used to resynthesise 3rd Pi to ADP • ATP splitting/resynthesis must occur on an ongoing basis to generate constant energy • this is the role of energy systems - breakdown fuel and use the energy to resynthesise ATP

• known as: phosphocreatine, PC, CP, PCr • storage: muscle + brain cells • sources: half from food, half resynthesised by the body (in liver, kidneys, pancreas) • usage: produces energy by splitting (used to regenerate ATP)

• includes sugars + starches, simple or complex Transport: • broken down by digestive system into glucose • transported in blood • also, glucose is released from liver into blood to control blood glucose lvls Storage: • in blood (GLUCOSE) • in muscles + liver (GLYCOGEN) • as fat (ADIPOSE TISSUE) GLYCEMIC INDEX - high GI - 70-100: quickly broken down, rapid energy release (jelly beans, sports drinks, fruit juice) - medium GI - 55-70: (bread, couscous, sweet potato) - low GI - 0-55: slow, sustained long term energy release (lentils, milk, carrots)

• high energy molecules • made up of: triglycerides + fatty acids • sources: food (oils, butter, avo, dairy, meat), and produced from storage of excess carbs • transport: in blood as free fatty acids (FFAs) Storage: • mostly as adipose tissue • in muscles + liver (triglycerides) • in blood (FFAs) Important: • energy from fat breakdown mostly used during rest + periods of low int, sub max exercise • produces most energy/gram than other fuels • provides up to half of body’s everyday energy • provides protection for organs • production of cell membranes, hormones, cholestrol • primary fuel source when carbs are depleted (long periods of exercise)

• made from AAs Roles: • formation + growth of body tissues (esp muscles) • repair + recovery of damaged tissues • production of RBCs, hormones, enzymes • emergency fuel source • usage: event of extremity, after carbs/fats depleted (eg. ultra marathon, starvation) • transport: in blood (AAs) to sites where needed Storage: • not technically ‘stored’ • in blood/body fluids (AAs) • in skeletal muscle (AAs) • excess AAs converted to adipose tissue

• occurs when liver + muscle glycogen stores are depleted • fats must be used as primary energy source • breakdown of fat is slow compared to carbs (requires more energy) • ATP production is slowed • results in sudden fatigue, decreased power output • only occurs after extended period of exercise

• glycogen stores are not used early on in exercise due to body’s increased ability to use triglycerides as fuel • aerobic system can metabolise fats efficiently, preserving glycogen stores for later • this delays glycogen depletion, allowing athlete to access them at a later point • = delayed exhaustion

• energy requirement = low (not under physical stress) • all energy supplied aerobically due to abundant O2 supply • occurs in mitochondria Fuel sources - mostly fats (2/3), stored w/i muscle + body adipose tissue - glucose/glycogen (1/3), breakdown in muscles + liver - fat is richer source of energy, however requires abuandance of O2 to breakdown. therefore it is used at rest

• energy requirement = high • body under physical stress = increased O2 demand to working muscles • respiratory + circulatory systems unable to meet this • body starts producing energy anaerobically • if the activity is sub max, aerobic can be used

Anaerobic - provides energy quickly + powerfully in absence of O2 - only operate for short period - small ATP yield - produce toxic byproducts with cause fatigue Aerobic - produce ATP for sustained period of time (at rest or sub max) - slow, sustained release, not rapid - large ATP yield - no toxic byproducts

• aerobic = effecient at producing ATP (large yield, long period of time, sustained release) • however, anaerobic is essential as O2 transportation is not efficient enough to sustain ATP production during higher int exercise • limited speed by circ + resp systems • CO2/O2 exchange is often not rapid enough to sustain the body’s ATP supplies • need to be able to produce energy w/o O2!!!!

• When: power/explosive efforts (sprint, throw, weight lift, jump) • anaerobic (no O2) Fuel - phosphocreatine (PC) - stores located w/i muscle - ATP produced through PC breakdown in muscle - splitting of PC allows a phosphate to synthesise to an ADP molecule = ATP - this occurs until PC stores are depleted Duration - two parts of the system - ATP stores w/i muscle (0-2 sec) - PC stores (2-10 sec) - overall, ATP-PC system dominant for first 10 sec of max effort exercise - takes 3-5 min to restore ATP/PC stores w/i muscles during rest Effectiveness - speed is fast: produces ATP almost instantly - however: produces a limited quantity of ATP, depleted quickly

• dominant during high int (still sub max) exercise (400m sprint, 500m row, team game) • anaerobic (no O2) • Fuel: glycogen/glucose, the incomplete breakdown of glucose (anaerobic glycolysis) • Duration: dominant from 10-30 sec until 2-3 min of high int (after which aerobic takes over) PROCESS - glycogen (stored in liver + skeletal muscle) - broken down to glucose - converted via GLYCOLYSIS to - pyruvic acid (small ATP yield) when insufficent O2 (too much pyruvate for aerobic system to use), converted to - = LACTIC ACID, H+ ions

• lactic acid is produced by body constantly • during rest + most exercise (not max), lactic acid production = the rate at which it is removed • = no accumulation AT HIGH INT: - lactic acid & H+ ion production increases, rate of removal increases - athlete will reach their lactate threshold - if continued, LA + H continue to increase expotentially - increase in muscle acidity, fatigue, - cannot physically continue, must slow or stop

• the point at which the production of lactate is greater than the rate of its removal • once reached, LA + H increase expotentially • also referred to as OBLA

• rate of removal (muscle to blood stream) determined by rate of blood flow thru muscles) FATES - a little taken up by heart + skeletal muscle, converted to pyruvic acid, used for ATP - MAJORITY converted by the liver to: - 65% resynthesised to CO2 + H2O - 20-25% to glycogen - 10% to protein - 5% to glucose

• dominant during sub-max efforts from 2-5 min onwards • most efficient system, produces most ATP overall • slow ATP production, large yield • CO2, H2O + heat byproducts GLYCOLYSIS - occurs in muscle cell - glycogen -> glucose -> pyruvic acid - anaerobic breakdown of glycogen/glucose - occurs in both aerobic + anaerobic systems (in LA system, P is converted to lactate instead) - only needed when carbs are used as the fuel source (fats + proteins go straight to next stage) CITRIC ACID CYCLE - occurs in mitochondria - fuel: pyruvic acid / fats (lipolysis) /prtoteins - aerobic, fuel combines with O2 - byproducts: CO2 (released via lungs), H+ ions (used in next stage) - ATP yield: small ELECTRON TRANSPORT CHAIN - occurs in mitochondria - byproducts: H2O (diffuses into tissues/blood), heat (released) - aerobic - ATP yield: LARGE (majority)

• glycogen • glucose • broken down via GLYCOLYSIS (small ATP yield) to: • pyruvate (or fats/proteins used instead) • if O2 present: • CITRIC ACID CYCLE (byproducts: CO2 - released, H+ ions - used) + small ATP yield • E TRANSPORT CHAIN (byproducts: H2O - diffuses into body, heat - released) + large ATP yield • total: 30-38 ATP

• H: TRANSPORTS O2 in the blood to capillary beds of muscles • M: ATTRACTS O2 from bloodstream into muscle cells + STORES O2 within muscle cells

• red oxygen binding protein in skeletal muscle cells • when O2 diffusion from blood -> muscle is too slow for O2 demands, myoglobin will release O2 • ROLES: ATTRACTS O2 to muscles, STORES O2 in muscles, RELEASES O2 when needed • usually during intermittent exercise

enhances the body’s ability to attract O2 into muscle cells = performance increase: - increased size + number of mitochondria - increased myoglobin stores

• skeletal muscle fibre makeup is determined by genetics • all muscles contain varying proportions of fibres w/i them • fibre makeup varies w/i diff muscles of same indv. eg. slow dom leg, vs fast dom arm SLOW TWITCH (1A) - aerobic - high fatigue resistant - red - small fibre diameter - contract slowly, low force - high mitochondria - endurance exercise (repeated contractions) FAST TWITCH (2A) - anaerobic + aerobic - medium fatigue resistant - pink - medium fibre diameter - contract rapidly, medium force - medium mitochondria - medium distance/efforts (repeated contractions) FAST TWITCH (2B) - anaerobic - low fatigue resistant - white - large fibre diameter - contract rapidly, high force - low mitochondria - short, rapid, intense efforts

the ongoing and continual overlapping contribution of the 3 energy systems during exercise