1.3 Energy For Exercise

ATP

Body’s universal energy currency - broken down to release energy

Exothermic

A reaction which produces energy and releases heat

Endothermic

A reaction which uses energy

Coupled Reaction

The product from one reaction is used as a reactant in another reaction

Sarcoplasm

Located in muscles - the site of the ATP/PC system and the lactic acid system

Mitochondria

The site of aerobic respiration

Lactic Acid

A harmful by-product which causes muscle pain and fatigue

Enzyme

An organism that catalyses a reaction

Resynthesis

Builds back up

Energy Continuum

The relative contribution of each energy system to overall energy production

Intermittent exercise

Exercise which varie

Adenosine Triphosphate

• one adenosine molecule and 3 phosphate molecules

• the energy stored in the phosphate bonds is released to cause muscular contractions

ATP breakdown

• The chemical reaction which causes the molecules to split - enzyme ATPase

• Exothermic (releases energy to the muscles) - 2/3 seconds

• ATP = ADP + P + energy

• ADP = Adenosine diphosphate (1 mol adenosine and 2 mol phosphate )

ATP resynthesis

• ADP + P + energy = ATP (endothermic)

• To replace the bond between two molecules, an energy is required from an alternative source - endothermic

• COUPLED REACTION – continual breakdown and resynthesis of ATP

ATP/PC system

Phosphocreatine(PC) - stored in the sarcoplasm - broken down with the enzyme Creatine Kinase - makes creatine and phosphate – this phosphate is the P in the reaction

The phosphate lost in the breakdown goes back into the phosphocreatine stores

• High intensity (under 10 second)

• Immediately available

• No harmful by-products

• Type 2b – Fast Glycolytic – high phosphocreatine stores

Glycolytic system

• Used when the ATP/PC system is exhausted

• Glucose is the next source of energy available to resynthesis ATP

• Triggered by the rise of ADP in muscle cells

• GPP = Glucose Phosphorylase

• Glycogen breaks down to glucose - enzyme GPP

• Glucose breaks down to pyruvic acid/ pyruvate - enzyme PFK - releases 2mol energy (pyruvate)

• In high intensity exercise and during the early phases of ATP resynthesis, oxygen is not available

• Lactate Dehydrogenase only appears without oxygen (anaerobic respiration)

• Pyruvic acid combines with the enzyme LDH - produces lactic acid

• Lasts for around 3 minutes at moderate intensity

Impact of lactic acid

• inhibits the release of enzymes and causes pain receptors in the muscles to be stimulated

Aerobic system

• Aerobic Glycolysis

• Krebs cycle

• Electron Transfer Chain

• At rest the main system is the aerobic system – plentiful supply of oxygen

Aerobic glycolysis

• Glucose breaks down to glycogen - enzyme GPP

• Glycogen breaks down to pyruvic acid/ pyruvate - enzyme PFK

Krebs cycle

• Pyruvate breaks down to acetyl COA - enzyme Coenzyme A

• This combines with oxaloacetic acid to create citric acid

• Citric acid gets oxidised – carbon dioxide is released as a bi-product

• The resynthesis of 2 ATP moles can then happen

• This occurs in the matrix of the mitochondria

• Hydrogen atoms are removed and transported to the cristae of the mitochondria

• By the hydrogen carriers NAD and FAD

Electron transport chain

• Cristae of the mitochondria

• Hydrogen atoms are split into ions and electrons

• Some ions are oxidised and released as H2O

• Pairs of hydrogen ions carried by NAD release enough energy to resynthesis 30 ATP

• FAD carries enough pairs to resynthesis another 4 molecules of ATP

• = 38 moles of ATP are produced from 1 mole of glucose

ATP/PC advantages

• No oxygen 

• Quick energy supply 

•Good for powerful/ explosive work

 • Quick recovery

Glycolytic advantages

• Large glycogen store 

• 2 ATP produced per molecule 

• Fewer reactions 

• Good for intense work

Aerobic advantages

• Large glycogen and fat stores 

• 38 ATP per molecule 

• No fatigue 

• Good for endurance

ATP/PC disadvantages

• Small energy yield – 1 mole

• Limited duration 

• Only a small amount is stored

Glycolytic disadvantages

• Slower than ATP/PC 

• Produces lactic acid 

• Stimulates pain receptors 

• Early fatigue 

• Slow recovery

Aerobic disadvantages

• Slow to metabolise 

• Complex reactions 

• Slow to engage – requires oxygen 

• No use for explosive movement 

• Complexed recovery

ATP/PC facts

• ATP/PC

• Sarcoplasm

• High intensity

• 1:1 yield

• ATPase/ Creatine Kinase

Glycolytic facts

• Glycogen/ Glucose

• Sarcoplasm

• High - moderate intensity

• 2:1 yield

• PFK/LDH

LDH facts

• Glycogen/ Fat

• Mitochondria - matrix for Krebs and cristae for ETC

• Moderate - low intensity

• 38:1 yield

• PFK/ GPP

EPOC

• Excess Post-Exercise Oxygen Consumption

Alactacid component

• PC stores are restored 

  • 3 minutes to recover fully, 30 seconds for 50%, and 60 seconds for 75%

  • Requires 1-4L of oxygen

• Replenishment of blood and muscle oxygen

  • Within 1 minute, oxygen resaturates the bloodstream - associates with haemoglobin

  • Within 3 minutes, the oxygen link to muscle cells is restored

Alactacid component

• PC stores are restored 

  • 3 minutes to recover fully, 30 seconds for 50%, and 60 seconds for 75%

  • Requires 1-4L of oxygen

• Replenishment of blood and muscle oxygen

  • Within 1 minute, oxygen resaturates the bloodstream - associates with haemoglobin

  • Within 3 minutes, the oxygen link to muscle cells is restored

Lactacid component

• needs 5-8 litres of O2

• takes hours to complete

• Elevated ventilation and circulation

  • Respiratory rate, depth, and HR remain elevated - gradually decrease to maximise O2 delivery, and bi-product removal

• Elevated body temperature

  • Increases metabolic rate - 60-70% of the slow lactacid component

• Removal of lactic acid

  • 50-75% is converted back into pyruvic acid and used in the Krebs Cycle

  • 10-25% is converted back to glucose

  • Can be converted to proteins by the Cori Cycle

  • Can be removed via sweating and in urine

Maximising recovery

• Warm Up = minimise time spent using anaerobic aerobic system - reduces oxygen deficit

• Active Recovery = maintains respiratory rate, and HR -  speeds up the removal of lactic acid

• Cooling Aids = used post-event to speed up the removal of lactic acid and to reduce muscle soreness and DOMS - ice baths

• Intensity of Training = high intensity training will increase ATP/PC storage - boosts efficiency of the fast component, increases tolerance of lactic acid and buffering capacity, and delays OBLA - reduces demand on the slow component. Low intensity exercise will increase aerobic capacity - delays OBLA - maximises oxygen delivery to working muscles - higher intensity takes longer to recover, and low intensity allows for a faster recovery

• Work:Relief Ratios = can maximise recovery - 1:1 /1:2 / 1:3

• Strategies and Tactics = using time-outs and substitutions - delays OBLA and fatigue

• Nutrition = maximise fuel stores - delays fatigue - reduces lactic acid - speeds up recovery - creatine supplements