Chapter 11- Aerobic Athletes Flashcards
When exercise intensity becomes moderate or high and we can’t wait for other processes, what does it trigger?
glucose and FFAs to be taken from muscle stores
At maximal intensity, over what percent of substrates comes within the muscle?
90%
95-98% of fuels for endurance exercise is from?
glucose and fatty acids
the higher the intensity of exercise, the more activation of what?
the sympathetic nervous system, which leads to enhanced oxygen delivery
2 ways to boost macronutrients for endurance athletes
give the body a constant supply of glucose during exercise and maximize amount of glycogen in muscle before the event begins
How much of endurance athlete’s energy intake should come from fats?
20-35% or 1-2 g/kg BW
What is the carb loading theory?
if athletes deplete glycogen with exercise followed by repletion with a high-carb diet, then more glycogen will be stored than if they maintained exercise routine and consumed a steady amount of carbs
When can carb loading be effective?
for endurance events lasting 90+ minutes or if implemented a week before the event
Important things to remember about carb loading?
carb intake should include foods low in dietary fiber, and athletes should experiment with this strategy during practice rather than the event
Ideally, athletes will begin endurance events…
with full glycogen stores
What is relative hypoglycemia?
when insulin spikes and glucose plummets after eating certain foods which results in fatigue and lightheadedness
How many carbs should you consume during endurance events lasting longer than an hour?
30-90 g per hour
Is there evidence that a high-fat pre-exercise meal enhances performance?
No there is not, but some studies show a result in increased fatty acids and fatty acid oxidation
What is the #1 priority for macronutrient intake post-event?
refilling glycogen stores, especially with multiple practices in a day
Can glycogen stores replenish with normal eating habits?
yes, but it might take more time and not maximize the stores
What are needed to replenish glycogen?
glucose and insulin
What is the first phase of glycogen replenishment?
insulin-indepenent (30-60 minutes post-exercise) glycogen depletion is a stimulus for glycogen resynthesis and is important to take advantage of the cell signaling
What is the second phase of glycogen replenishment?
Insulin-dependent (1-2 hours post exercise, up to 48 hours) a period of enhanced insulin sensitivity
What is the recommendation for carb consumption in post-exercise window?
1-1.5 (1.2) g/kg BW and a mixture of carbs
Sugar intake should be below what percentage of calories each day?
25%
What is the theory of “training low, competing high”?
training in a glycogen-depleted state, the body will learn to prefer fatty acids over glucose as fuel, but then load up on carbs and have both stores available
What are the impacts of endurance training on metabolism?
trained athletes have 20-30% higher levels of muscle glycogen stores than sedentary individuals
