Q8 CHO + Triathlon

Question 1

Mechanism

Answer 1

Endurance performance dictated by endogenous carb stores

Fatigue associated with glycogen depletion (hitting the wall)
- study found blood glucose levels to be low at the end of marathon

well-established that carbohydrate ingestion during prolonged (>2 h) moderate-to-high intensity exercise can significantly improve endurance performance

• spares muscle glycogen
• spares liver glycogen
• prevents hypoglycaemia

CHO oxidation as main source of fuel is associated with maintained motor skills and mood state, reduced RPE, delay of fatigue

Question 2

Timing/ dose?

Answer 2

Super compensation effect: glycogen stores can be acutely enhanced following prior glycogen depletion, this is the basis of carb loading

Glycogen depletion followed by up to 12g/kg of CHO prior to competition or when exercise is longer than 4 hours

Eat high carb meal 2-3 hours before to optimize liver glycogen

During event lasting 2-3 hours:
2–3 h, athletes are advised to ingest carbohydrates at a rate of 60 g/hour (~1.0–1.1 g/min)
However well trained athletes can metabolise up to 1.8g/min

• glucose + fructose drinks have 55% increase in carb oxidation rates than glucose alone
• This is due to different receptors
• Also associated with less GIT disturbance
• mouth rinse can confer benefits due to central effects

Question 3

Negative circumstances

Answer 3

Fat is predominant at lower intensities that would be characteristic of a triathlon, but really depends on time frames
- elite would finish much faster than recreational, greater reliance on carbs than fat

Athletes need to be conscious of carb choices
- fructose and galactose oxidised slower than glucose

Train low race high theory:
- training with low glycogen can enhance adaptations by augmented cell signalling and gene expression effecting increases in oxidation of fat