Carbs

Question 1

What are the most common carbs in sport supplements?

Answer 1

Sucrose

Maltodextrin-Fructose mix

Question 2

Why are carbs important for performance?

Answer 2

At exhaustion we see almost complete depletion of muscle glycogen, therefore, some is required for continued motion.

Question 3

How does ingestion of carbs prior to or during exercise benefit performance?
- references

Answer 3

keeps levels of euglycaemia, maintaining CHO oxidation rates through increase of exogenous CHO oxidation, sparing muscle and liver glycogen and delaying fatigue.
- Coyle et al (1986); Tsintzas et al (1996).

Question 4

How does ingestion of Fru+Glu benefit exogenous CHO oxidation and performance compared with Glu only?
- references

Answer 4

• fructose uses seperate transporter pathway than glucose, so more can be absorbed together. Then it’s converted to lactate and oxidised
• Fru has lower GI than Glu, so lower insulin response and less chance of rebound hypoglycaemia if taken directly before exercise.
• Lower GI carbs associated with higher fat oxidation rates (Wu & Williams, 2006)

Question 5

What are the performance benefits of CHO supplementation (specifically Suc)?

Answer 5

• Decreased fatigue
• increased TTE
• Suc exhibits lower GI discomfort than Glu

Question 6

How strong is the evidence into CHO’s benefits on performance?
-reference and study type (why’s this good?)

Answer 6

extremely strong.

Confirmed by many meta-analyses (Wallis, 2013) observing RCTs, the strongest form of study design in this area.

Question 7

What are the potential risks of CHO supplementation?

a) chronic use
b) acute use

Answer 7

A)
- high levels for a long period can lead to diabetes
- weight gain (if energy balance isn’t considered)
- dental issues
B)
- GI issues if lots are taken at once
- rebound hypoglycaemia if lots of high GI CHO ingested close to exercise.

Question 8

What is the optimal ingestion rate of multiple transportable CHOs during prolonged exercise?
- reference

Answer 8

~1.5 g/min

- Jeukendrup (2014)

Question 9

What benefits are there to acute CHO supplementation?

Answer 9

• Benefits found to performance for CHO supplementation during exercise as it maintain CHO oxidation rates, delaying fatigue

Question 10

What benefits are there to chronic CHO supplementation?

Answer 10

Better training quality and volume lead to superior adaptations.

Question 11

What should the frequency and amount (not specific) of CHO feeding be during prolonged exercise (if possible) and during recovery?
Why?

Answer 11

small and often.

• minimises GI discomfort
• Keeps insulin levels high, keeping GLUT 4 on plasma membrane of muscles and glucose movement into cells high.