Energy Systems and Muscle Fibre Types

Three Key Nutrients Proteins: amino acids (4.3cal/gram) Fats: fatty acids (9.3cal/gram) Carbohydrates: glucose/glycogen (4.1 cal/gram) Calorie : the amount of heat require to raise 1 gram of water by 1 deg. Celsius

Bioenergetic conversion - the process of breaking down the three key nutrients in digestion thus enabling us to carry out physical activity. Metabolism - process by which the body energy is supplied and broken down by the body

Carbohydrates 4.1 calories per gram Most abundant organic substance in nature vegetables, fruits, grains Formed via photosynthesis

PLANTS & PHOTOSYNTEHSIS: Carbon dioxoide (CO2) + water (H2O) + sunlight = carbohydrates (CHO) + oxygen (O2)

ANIMAL KINGDOM: O2 + CHO  energy + release carbon dioxide (CO2)

Glycogen (gk. ‘sweet’) - important carbohydrate - originates as glucose - stored in liver and skeletal muscle - carried via blood

ADENOSINE TRIPHOSPHATE - ATP ATP = Adenosine + 3 Phosphate (Pi) Usable fuel for muscle contraction and other cellular processes within the body Made in the mitochondria Energy is released when (Pi) is broken from ATP…..results in ADP (adenosine diphosphate) and energy or…. ATP  ADP + Pi + energy Used up quickly…… how can we keep up?

Two Energy Systems (resynthesizing ATP) Aerobically With O2 mitochondria Requires breakdown on carbs then fats, and proteins Used for endurance activities Anaerobically Without O2 Uses chemicals and enzymes that are readily available for short term powerful physical actions High intensity & short run activities These systems work together- -- coexist, overlap and interact 

Metabolic Pathways Within the 2 systems there are 3 metabolic pathways… 1. ATP-PC pathway 2. Lactic Acid pathway 3. Cellular Respiration so here we go…….

ATP-PC Pathway Anaerobic Alactic - lasts 10-15 seconds - uses stored ATP and stored creatine phosphate - No by products PC (phosphocreatine) + ADP = 1 ATP + creatine - 50m dash, high jump, weight lifting - limited because muscles can only store a small amount of PC and ATP

Lactic Acid Pathway Anaerobic Lactic - lasts 15 seconds to 3 minutes - uses glucose and glycogen to make ATP - by product is lactic acid and pyruvate C(6)H(12)O(6) + 2ADP + 2Pi = 2 C(3)H(6)O(3) + 2ATP + 2H(2)0 (glucose) (lactic acid) - 400m sprint, 800m sprint, hockey shift

PYRUVATE When inadequate O2 is present pyruvate is converted to lactic acid Lactic acid slows glucose breakdown Contractibility of muscles is limited 30-60 minutes of exercise recovery/1-2 hours rest recovery to rid

Aerobic (Cellular Respiration) - activity longer than 90 seconds - in mitochondria - uses fats, proteins, glucose, glycogen to make ATP - fats are used in exercise > 20 minutes - proteins are used during energy shortages C(6)H(12)O(6) + 6O(2) + 36ADP + 36Pi = 6CO(2) + 36ATP + 6H(2)0 - complete breakdowns of glucose - marathon running, soccer match, swimming

Cellular Respiration (3 Sub Pathways) Glycolysis Similar to Lactic Aicd pathway Difference is O2, sopyruvate becomes acetyl CoA Acetyl CoA is used in Kreb Cycle 2 ATP Kreb (Citric Acid Cycle) Metabolizes fats and proteins 8 reactions Produces 2 ATP and new compounds Compounds are high energy and sent to ETC Electron Transport Chain In mitochondria Produces H2O + CO2 + 32 ATP Free radicals (highly reactive electrons) and by products and may result in long term muscle fatigue

To raise, train both anaerobically and aerobically LACTIC ACID Blood-Lactate Threshold/Anerobic Threshold: lactate levels in the blood increase abruptly beyond resting levels Untrained person accumulates lactate in blood at lower exercise intensity and in a shorter time than an elite athlete To raise, train both anaerobically and aerobically Anerobically: to extend the point at which lactate build up occurs Aerobically: increase concentration of mitochondria and myoglobin (oxygen carrier in blood) in muscle fibre

CORI CYCLE Uses lactic acid by transporting it from muscle fibre mitochondria to the liver Converted back to glucose Glyconeogenesis: glycogen in formed Available as an energy source

Fats Recall fats contain a large quantity of stored energy (9.3 cal/gram) Fatty acids are available energy source Lipolysis: triglycerides (stored fatty acids) are broken into energy source Beta-Oxidations: chemical reactions in mitochondria that convert fatty acids to acetyl CoA Used in Kreb cycle to make ATP balance

Proteins No protein reserves in the body 20 amino acids 9 essential cannot be synthesized by body Used in absence of other energy sources

Muscle Fibre Types Type I - slow twitch - red - aerobic system - high concentration of myoglobin - ATP producing reactions to be sustained over long periods of time

Type II A - fast twitch - reddish/whitish - contraction is moderately fast - moderate myoglobin - predominantly used in anaerobic glycolysis

Type II B - fast twitch - white - fastest contraction speed - low myoglobin - predominantly used in anaerobic alactic system