Energy systems and sources (Lactate and aerobic systems) and the energy continuum

when does the break down of glycogen occur?

when energy demands are increases and oxygen is not required to function

what is the first stage of the lactate system?

glycogen is stored in muscles and liver and converted into glucose by the enzyme glycogen phosphorylase

what is the enzyme that converts glycogen into glucose?

glycogen phosphorylase

describe step 2 of the lactate system

glucose is broken down by the enzyme phosphofructokinase (PFK)

what enzyme is glucose broken down by?

phosphofructokinase

what is anaerobic glycolysis?

the break down of glucose when oxygen is absent to release energy

what is stage 3 of the lactate system?

energy is released and 2 ATP molecules are resynthesised

what is stage 4 of the lactate system?

due to the lack of oxygen pyruvic acid is converted by the enzyme lactose dehydrogenase (LHD) into lactic acid

what converts pyruvic acid into lactic acid?

dehydrogenase

what are the advantages of the lactate system?

• no delay waiting for oxygen to be supplied from lungs for glycogen breakdown as oxygen isn’t required

• large amounts of glycogen stored in our bodies and so can provide more ATP than PC system

• few chemical reactions so ATP can be provided for high intensity activities

what are the disadvantages of the lactate system?

the by-product, lactic acid reduces the pH of the muscle making it more acidic preventing the enzyme from functioning properly, leading to muscle fatigue

how long does physical activity normally last whilst using the lactate system?

15-90 seconds

what happens to glycogen stores during endurance exercise?

they decrease but have high levels of glycogen in their muscle tissue

what happens to skeletal muscle glycogen content as a result of resistance training?

it increases and blood glucose levels do not decrease either

what are the advantages of the aerobic system?

• large amount of ATP can be resynthesised (34 + 2)

• system can apply ATP for long duration at submaximal intensity

• no harmful by products from the chemical reactions

what are the disadvantages of the aerobic system?

• system can’t resynthesise ATP immediately during exercise due to a delay in oxygen being transported to muscles

• system can’t provide ATP while working at high intensities as o2 is not delivered in time to the working muscles

what is the krebs cycle?

begins where the acetyl CoA combines with oxaloacetic acid to form citric acid and is converted into CO2 and hydrogen which are removed forming 2 ATP

what are the energy sources for maximal activity?

ATP, PC, blood glucose or glycogen

what are the energy sources during submaximal activity?

carbohydrates, fatty acids or protein

where is ATP stored?

within the sarcoplasm of muscle

what is ATP?

an energy source for muscle activation and the energy currency of the body

where is pc stored?

in the sarcoplasm

what is pc used for

resistance exercises such as: short duration, high power and high force

what are the stages of the ATP-PC system?

1. eat food

2. energy stored in muscle as ATP

3. atpase breaks phosphate bond

4. ADP + P + energy released for use

5. CP stored in sarcoplasm

6. creatine kinase is activated

7. creatine kinase breaks creatine and phosphate bond

8. energy released for reforming ATP

9. end equation = P + ADP = ATP + C

how do we improve our ATP system?

high intensity and short duration exercise

what are the advantages of the ATP - PC system?

• energy is immediately available for use by the muscle

• has a large power capacity

• supplies large amounts of energy per second to support muscular contraction

what are the disadvantages of the ATP - PC system?

• as exercise continues there is an imbalance between use and resynthesis of ATP, leading to fatigue

• stores must be fully replenished to continue further intense amounts of training

how long can the ATP-PC system last for during exercise?

up to 0-15 seconds

how long does it take for the ATP-PC system to recover?

aprox 180-240 seconds

how long can the anaerobic system last for during exercise?

up to 15-90 seconds

how long does it take for the lactate system to recover?

2-10 minutes

how long can the aerobic system last for during exercise?

2 hours

how long does it take for the aerobic system to recover?

up to 24 hours

what is the energy continuum?

• describes the collaboration of the three energy systems in the provision of energy and resynthesis

• demonstrates the predominant system or usage of each system relative to the intensity and duration of the exercise

how long is ATP used for?

up to 3 seconds

what does OBLA stand for?

• onset blood lactate accumulation

• the point at which lactate begins to pool as the muscle is unable to remove it, it can then move to the blood stream which can be felt as a burning sensation

what does obla prevent?

it prevents o2 from binding to haemoglobin which decreases availability for energy production, leading to lactate build up, fatigue and failure

what factors affect OBLA?

• intensity of exercise

• muscle fibre type

• ability of body to remove and use lactate

• training adaptations