Physiology - Energy for Exercise

Define ATP

- A high energy compound which is the only immediate available source of energy for muscular contraction

Outline ATP as an "energy currency"

- When fuels like glycogen and triglycerides are metabolised and converted into ATP

- When ATP is broken down energy is provided for muscular contractions

Explain how ATP is broken down into ADP

- The enzyme ATPase breaks the high energy bond between the last phosphate group of ATP

- Exothermic reaction

- Provides 1 phosphate for the ATP re-synthesis cycle

Explain how ATP is re-synthesised in the ATP re-synthesis cycle

- Bonding a phosphate group to ADP

- Endothermic reaction

Explain the synthesis of ATP in the ATP-Ps system

- Occurs in the sarcoplasm

- High levels of ADP stimulate creatine kinase

- Creatine kinase breaks down Pc stores to create one phosphate in an exothermic reaction

- Phosphate is then added to the re-synthesis cycle in an endothermic reaction

Outline when the ATP-Pc system would be selected

- High intensity

- Short duration

- 10 seconds of energy provided

- E.g. 100m sprint

Name 2 methods of extending the ATP-Pc system

- Training to extend Pc stores

- Repeated anaerobic training to delay the threshold when Pc stores are used up

Name 3 advantages and 3 disadvantages of the ATP-Pc system

- A = Does not require oxygen

- A = No fatiguing by-products

- A = Pc stores readily available

- D = Only lasts a short duration

- D = Limited Pc stores at the muscle

- D = Not effective for long duration

Define a coupled reaction

- When products are used from one reaction to use in another reaction

Explain the synthesis of ATP in the Lactic Acid system

- High levels of ADP stimulate GP to break down glycogen into glucose in an exothermic reaction

- PFK breaks down glucose into pyruvic acid and 2 phosphates in an exothermic reaction

- The 2 phosphates are used in the ATP re-synthesis cycle

- LDH breaks down pyruvic acid into lactic acid in an exothermic reaction

Outline when the Latic Acid system would be selected

- High intensity

- Short duration

- 30-90 seconds of energy provided

- E.g. 800m

Name 3 advantages and 3 disadvantages of the Lactic Acid system

- A = Re-synthesises 2 molecules of ATP which is more than ATP-Pc

- A = Requires fewer reactions than the aerobic system

- A = Large glycogen stores in muscles

- D = Fatiguing by-product of lactic acid produced

- D = Larger chain of reactions in comparison to ATP-Pc

- D = Not effective for long duration

Define OBLA

- The onset of blood lactate accumulation = 4mmol/l

- When the body cannot clear enough lactate as it is being produced

- Causes muscular fatigue, muscle cramps which stimulate pain receptors and denaturing of enzymes

Explain how the Lactic Acid system can be extended

- Training anaerobically to improve glycogen stores

- Increases lactic acid tolerance

- Delays the OBLA threshold

- Allows athletes to work at high intensities for longer

Outline aerobic glycolysis in the Aerobic system

- High levels of ADP stimulate GP to break down glycogen into glucose in an exothermic reaction

- PFK breaks down glucose into pyruvic acid and 2 phosphates in an exothermic reaction

- The 2 phosphates are used in the ATP re-synthesis cycle

- Pyruvic acid is added to CoenzymeA to create AcetylCoA

Outline aerobic glycolysis without the presence of glyogen

- Occurs in the sarcoplasm

- High levels of ADP stimulate lipase to convert fatty acids into Acetyl CoA in an exothermic reaction

- Lipase system is more efficient but requires 15% more O2 to break fats down

Outline the Kreb's Cycle in the Aerobic system

- Occurs in the matrix

- Acetyl CoA from aerobic glyolysis is combined with oxalocetic acid to form citric acid

- Citric acid moves into the Kreb's cycle producing CO2, hydrogen, oxalocetic acid and 2 phosphates

- The 2 phosphates move into ATP re-synthesis

Outline the Electron Transport Chain in the Aerobic system

- Occurs in the cristae

- Hydrogen combines with NAD + FAD to form NADH + FADH

- NADH + FADH enter the ETC and produce 2 hydrogen ions

- H2O and 34 phosphates are made

Outline when the Aerobic system would be selected

- Low intensity

- Long duration

- 3 mins to 2 hours

- E.g. marathon running

Name 3 advantages and 3 disadvantages of the Aerobic system

- A = Large glycogen and fatty acid stores to be used

- A = Large ATP yield of 38 ATP molecules

- A = No fatiguing by-products

- D = Requires O2 to function

- D = Not effective for explosive actions

- D = Longer chain of reactions compared to ATP-Pc

Define the energy continuum

- The relative contribution of each energy system to overall energy production depending on intensity and duration of the activity

Name the 6 factors affecting the energy continuum

- Exercise intensity and duration

- Energy system threshold

- O2 transport and supply

- Food and fuel available (glycogen and fatty acids)

- Activation of enzymes

- Fitness level of individual

Define intermittent exercise

- Activity where intensity alternates with changes to the work and relief intervals

Name the 4 factors affecting the relative contribution of energy systems in intermittent exercise

- Position played (GK = aerobic but C/WA = LA system)

- Structure of the game (basketball = frequent breaks)

- Coaches strategy (man on man marking VS zonal marking)

- Level of competition (Higher level = more anaerobic)

Define EPOC

- The volume of oxygen consumed post exercise to return the body to a pre-exercise state

Define fast alactic reovery

- Initial fast stage of EPOC where large volumes of O2 are consumed in the first 3 minutes

Outline what happens in the alactic stage of recovery

- Restores ATP and PC stores

- Replenishes myoglobin and haemoglobin

- 3-4 litres of O2 breathed in 3 minutes

- 50% of Pc stores in 30 seconds

Define the slow lactaid stage of recovery

- Lactic acid converted into glycogen via glucogenesis

- Lactic acid converted into proteins

- 5-8 litres of O2 breathed in

- Can last 1-24 hours

Name the 7 implications of recovery on training

- Warm up

- Active recovery

- Cooling aids

- Intensity of training

- Work-relief ratios

- Strategies and tactics

- Nutrition

Outline a warm up as an implication of recovery on training

- Respiratory, heart and metabolic rates increase

- Accelerates the use of the aerobic system

- Reduces use of anaerobic energy system

- Reduces O2 deficit

Outline active recovery as an implication of recovery on training

- Maintains respiratory and heart rates

- Flushes the muscle with oxygenated blood

- Speeds up removal of lactic acid

Outline cooling aids as an implication of recovery on training

- Used post-event to lower muscle and blood temp

- Reduces metabolic rate and demand on slow lactacid component of EPOC

Outline intensity of training as an implication of recovery on training

- Intensity should be monitored using HR

- High intensity training increases muscle mass, ATP and Pc stores, increased tolerance to lactic acid, increased buffering capacity and delays OBLA

- Low intensity training increases aerobic capacity and respiratory and cardiovascular efficiency

Outline work:relief ratios as an implication of recovery on training

- Speed and explosive based performers using the ATP-Pc system need a work:relief ratio of 1:3+

- Muscular endurance performers using the Lactic Acid system need a work:relief ratio of 1:2

- Endurance performers using the Aerobic system need a work:relief ratio of 1:1 to delay OBLA and muscular fatigue

Outline strategies and tatics as an implication of recovery on training

- A coach should use time outs and substitutions to allow 30 second relief for 50% ATP and Pc store replenishment

- Performers can delay play to lower intensity to allow relief intervals to clear lactic acid

- Set plays and marking can lower the intensity to delay OBLA

Outline nutrition as an implication of recovery on training

- Helps to maximise fuel stores, delay fatigue, reduce lactic acid accumulation and speed up recovery

- May load creatine and protein to increase the efficiency of the ATP-Pc system and recovery

- Carb loading and snacks to maximise the efficiency of the glycolytic and aerobic systems

- Bicarbonate helps to enhance buffering when training close to the lactate threshold to speed up recovery