Carbohydrates and Fats Flashcards
(22 cards)
Basic carbohydrate functions
- Provide energy
- Fuel the central nervous system (brain = high requirement for glucose)
- Physical activity
- Provides health benefits surrounding fibre
Glucose and glycogen stores in the liver, blood and muscle?
Liver = 80-110g glycogen
Blood = 4-6g glucose
Muscle = 300-600g glycogen
Influence of exercise intensity on metabolic responses?
At rest: Energy source is predominantly plasma glucose and plasma FFA
At moderate: Increased contribution from plasma FFA, other fats and muscle glycogen, relatively low plasma glucose contribution.
At high: Very dependant on muscle glycogen, less fat contribution and slight increase in plasma glucose usage.
Hepatic glucose output and blood glucose (exercise effects?)(2 points)
Exercise increases hepatic (liver) glucose output, dependant on intensities.
Very close matching with muscle glucose uptake and liver glucose output
What happens to blood glucose during increasing exercise intensities?
There is an average net gain towards 80% VO2 max, however, overall it stays relatively well matched between uptake (muscle) and output (liver)
What happens to glycogen stores in a fasted state during prolonged exercise?
In the liver
Liver glycogen stores will eventually run out due to lack of fuelling - potentially going lower than 3g - create weakness and potentially fatigue.
What happens to glycogen stores in a fed state during a prolonged exercise state?
Plasma glucose levels are relatively well conserved over the duration of the exercise bout.
Muscle glycogen stores during exercise
During the first 20 mins of exercise, muscle glycogen stores see a steep decline.
After that, there is an exponential decay.
Glycogen stores in exercising muscle is a decisive factor for maximal work time (T or F)
True = at high relative workloads, glycogen stores is a decisive factor
What occurs during a low carbohydrate diet?
Pre-exercise glycogen content is low and exercise capacity is also very low
What happens during a mixed diet?
There is a double in glycogen stores compared to low CHO diet, as well as a double in exercise capacity
What occurs during a high CHO diet?
Shows an increase in exercise compacity and glycogen muscle content compared to that found in the mixed and low CHO diet
What is the relationship between dietary CHO intake and glycogen storage and exercise capacity?
Positive, almost linear, correlation.
As diet CHO increases, so does exercise capacity and muscle glycogen storage to an extent.
What does carbohydrate feeding do? (3)
During exercise
Increases blood plasma glucose levels
Effects total carbohydrate oxidation rates
However, has no effect on at the muscle level
Signals for fatigue?
Muscle glycogen depletion; send signals of pain and discomfort in the muscle.
Hypoglycaemia; signal fatigue in regions such as the brain
Fatigue is strongly correlated with carbohydrate depletion; explain to factors!
> Muscle glycogen depletion
Hypoglycaemia reflecting liver glycogen depletion (reduced glycogen stores resulting in inability to regulate blood glucose levels)
Blood glucose use in soccer
Blood glucose concentration showed no change (unaffected)
What occurs during carbohydrate feeding during exercise (fasted, low and high CHO)?
Fasted: total glucose output was contributed solely from the liver.
Low-CHO: More glucose seen in circulation, which is so effective that the liver does not need to contribute to the glucose output as much (30:70)
High-CHO 22% solution: contribution from the liver is almost none.
Muscle glycogen use during soccer
Muscle glycogen stores will reduced by 42% reduction from first half to second half.
Muscle glycogen use in soccer (specific fibre usage)
47% of fibres were empty or almost empty by the end of the game.
Therefore, important for individuals to supplement CHO in order for sprints to still be efficient to the end of the game (reduce mistakes and fouls etc..)
Muscle glycogen use in soccer in women (20 elite)
Also showed an reduction in muscle glycogen of 42% from before the game to the second half
Decrease in repeated sprint ability Vs reduction in muscle glycogen?
Not a very strong correlation, but a correlation none the less; cases showed that at the highest drop in muscle glycogen showed the highest drop in repeated sprint ability.
