Pre/During/Post recomendations for CHO intake Flashcards
Why use low GI pre exercise?
High GI will create rebound hypoglycaemia because of the sharp blood glucose spike, and potentially decrease performance.
Strategy for 3-5 hours before?
Eat a large meal to replenish glycogen stores after overnight fast.
Strategy for 1 hour before exercise?
Easily digestible foods to top off liver glycogen and increase blood glucose levels, to be used as a substrate during exercise.
Proof of it improving performance?
Balmer et al. (1995):
1 hour cycle after CHO ingestion (8% concentration) improved performance compared to control.
Glycogen loading use?
This tries to maximise muscle glycogen stores.
Involves phase of glycogen depletion, followed by 3 days of low carb diet whilst training, then 3 days of very high carb diet with inactivity.
Study about glycogen loading?
Madsen et al. (1990):
CHO supercompensation did not appear to improve endurance capacity of highly trained individuals (n=6).
Liver glycogen utilised more, but muscle utilisation identical compared to control.
The loading procedure can cause athletes to become irritabl, hypoglycaemic and unable to train.
What influences CHO utilisation during exercise?
Exercise intensity, exercise duration, gender, age.
Why intake CHO during exercise?
By upkeeping blood glucose concentration, liver glycogen is spared because CHO is contributed more for oxidation.
What does Kerksick et al. (2008) recommend for CHO ingestion during exercise?
CHO should be consumed at a rate of 10-15g every 10-15 minutes in a 6-8% CHO solution.
Mixing different forms of CHO shown to increase muscle CHO oxidation to aid time-trial performance.
Addition of protein to CHO (3:1 CHO:PRO) has been shown to increase endurance performance by aiding glycogen resynthesis.
Describe study on use of CHO for intermittent performance?
Gomes et al. (2014):
12 tennis players ingested 0.5g/kg bodyweight/hour during 3 hours of play.
Ingestion helped maintain glycaemia and attenuate increase in salivary cortisol concentration.
Also muscle glycogen in type II muscle fibres were spared.
Goal of post CHO ingestion?
Replenish glycogen stores.
Coyle (1991) recommendation?
7-10g/kg bodyweight optimal quantity.
Why best to ingest CHO within 1 hour of finishing exercise?
Because during and after exercise, cells permeability to glucose increases and muscle sensitivity to insulin.
Consequences of not enough CHO in diet?
Will cause dehydration as glycogen carries a lot of water = lower ability to train intensely.
Bilsborough (2003) states what happens with low CHO?
Osteoporosis, kidney damage, impairment of physical activity, and even death.
