Energy Systems & Metabolism

Question 1

ATP System

Answer 1

• Powers exercise for 1-2 secs
• Maximal intensity
• 100% anaerobic

Question 2

Phosphagen System

Answer 2

• Fuel - PCr
• Powers exercise for 10-15 secs
• Very high intensity
• 85% anaerobic, 15% aerobic
• PCr recycles ATP for further contractions

Question 3

Glycolysis

Answer 3

• Partly catabolises carbohydrates
• Convert 6C molecule into 2 molecules of pyruvate
• Occurs in cytoplasm
• Net gain of 2 ATP molecules
• Powers exercise for 3-5 mins
• Moderately high intensity
  * Pyruvate passed onto next energy system
  * 30% anaerobic, 70% aerobic
• High intensity
  * Hydrogen binds to pyruvate forming lactate
  * 70% anaerobic, 30% aerobic

Question 4

Citric Acid Cycle

Answer 4

• Fuel - glycogen, fat
• Pyruvate converted to Acetyl CoA
• Acetyl joins with oxaloacetate to form citrate
• 2 molecules of ATP produced
• H+ ions, H atoms, NADH, FADH2, CO2 produced
• Powers exercise for more than 2-3 minutes
• Low to moderate intensity
• <3% anaerobic, >97% aerobic

Question 5

Electron Transport Chain

Answer 5

• Fuel - glycogen, fat
• NADH and FADH2 release H+ ions and electrons
• H+ ions actively pumped across membrane
• Electrons passed down series of complexes
• H+ ions diffuse back across membrane via ATP synthase
  * 30-34 molecules of ATP
• Electrons coupled with H+ ions and oxygen to form water
• Powers exercise for more than 2-3 minutes
• Low to moderate intensity
• <3% anaerobic, >97% aerobic

Question 6

Creatine Supplementation

Answer 6

• Creatine monohydrate sold in capsules, powder, liquid
• Creatine found in meat, fish, poultry
• High dose of creatine monohydrate increases creatine up to 30%
• Remains elevated for a few weeks
• May improve performance in HIT

Question 7

Carbohydrate & Bicarbonate Supplementation

Answer 7

• Increased lactate production
• Improve performance at middle distance due to increased work output
• Changes intracellular pH - cause of fatigue during HIT
• Reduces sensitivity of contractile apparatus to Ca2+ ions
• Bicarbonate enters muscle cells, increases extracellular pH, allowing H+ ions to leave
• CO2 produced, GI distress

Question 8

Carbohydrate Supplementation

Answer 8

• Energy demands of endurance events, 6-10g CHO/kg body mass/day
• Athletes eat 50-100g of CHO after training
• Carbohydrate loading delays glycogen depletion
• During exercise, 30-60g of CHO are recommended after 1 hour of exercise