Nutrition and exercise Flashcards
What are the two main determinants of fuel use during exercise?
> intensity
> duration
What is the effect of exercise intensity on fuel use?
Increase intensity = greater muscle glycogen oxidation
- (van Loon et al, 2001)
What is the effect of exercise duration on fuel use?
Increase duration = greater plasma free fatty acid oxidation
- (Romjin et al, 2001)
Roughly how many calories of carbohydrate energy is stored within the human body?
<3,200 kcal
Roughly how many calories of fat energy is stored within the human body?
> 100,000 kcal
The concentration of what in the liver and blood is positively correlated with time to fatigue in endurance exercise?
glycogen
liver glycogen - (Casey et al, 2000)
muscle glycogen - (Bergstrom et al, 1967)
What 2 hormones stimulate gluconeogenesis and glycogenolysis in the liver when the body is in a fasted state or during exercise?
> adrenaline
> glucagon
Adrenaline suppresses the release of what hormone associated with liver glycogen regulation?
insulin
What effect does endurance training have on fasted levels of muscle glycogen?
increases them
- (Gonzalez et al, 2016)
What effect does a high carbohydrate diet have on endurance performance and why?
high CHO diet = increase muscle glycogen = increased time to fatigue
Why may carbohydrate be ingested during endurance exercise?
keeps blood glucose levels steady, preventing hypoglycaemia
So more carbohydrate ingested during exercise the better?
no,
as quantity ingested rises, utilisation rates drop
At what value of CHO ingestion during exercise does utilisation plateau?
~ 1 g per minute
What is the limiting factor for glucose utilisation?
glucose transporters in the intestine
SGLT 1 have a limit of 1.2 g per minute
What effect can glucose build up in the intestinal lumen have on a performer?
creates gut discomfort
How can you solve the problem of SGLT having a limit of 1.2 g per minute?
Ingest sucrose (glucose + fructose) glucose and fructose use different transporters, raising the uptake limit to 1.7 g per minute.
What happens to MUSCLE glycogen pre-post cycling exercise when ingesting water, glucose and sucrose
Water = drop Glucose = drop Sucrose = drop by similar amounts - (Gonzalez et al, 2015)
What happens to LIVER glycogen pre-post cycling exercise when ingesting water, glucose and sucrose
Water = drop Glucose = no change Sucrose = no change
- (Gonzalez et al, 2015)
In the Gonzalez et al 2015 study, what effect did ingesting sucrose have on substrate utilisation and gut discomfort compared with glucose?
Sucrose = increased energy from exogenous CHO utilisation and reduced gut discomfort
When either a placebo, glucose of sucrose drink was consumed 2 hours prior to a 1 hour cycling time trial, which condition resulted in greater average power output?
sucrose > glucose > placebo
- (Currell & Jeukendrup, 2008)
What is the optimal level of CHO ingestion for performance in endurance exercise?
1 - 1.5 g per minute at regular intervals (every 15 mins)
- (Smith et al, 2013)
When in a fed state, which hormone regulates liver glycogen?
Insulin
What effect does insulin have on liver glycogen?
increases stores by stimulating glycogen synthesis and suppressing glycogenolysis and gluconeogenesis.
In the days following exercise, what kind of recovery pattern does muscle glycogen follow?
supercompensation
How does sucrose ingestion effect post exercise LIVER glycogen repletion?
sucrose leads to GREATER repletion of liver glycogen post exercise than glucose
- (Fuchs et al, 2016)
How does sucrose ingestion effect post exercise MUSCLE glycogen repletion?
sucrose does NOT BENEFIT muscle glycogen repletion any more than glucose
- (Fuchs et al, 2016)
How much CHO should be ingested to maximise glycogen repletion rates post exercise?
> 1.2 g/kg/hour
When CHO ingestion is < 1g/kg/hour post exercise, ingestion of what other nutrient can augment muscle glycogen repletion?
brotein
What benefit does sucrose ingestion post exercise have over glucose only ingestion?
Sucrose ingestion augments liver glycogen repletion and lowers GI discomfort
Hey bro,
beach season’s a comin’.
How do i pack on mad muscle?
have greater levels of protein synthesis than protein breakdown
Supplementation of what can stimulate levels of protein synthesis and suppress protein breakdown according to research from Biolo et al (1995-97)
Amino acids
What exercise modality can stimulate greater levels of protein synthesis AND breakdown (but more synthesis)?
resistance training
In the short term, up to what dose of whey protein does muscle protein synthesis continue to rise in rested individuals?
20 g
- (Witard et al, 2014)
Is there a difference in the levels of muscle protein synthesis in exercised individuals when whey protein dose is raised from 20 to 40 g?
not a significant difference, but a difference
- (Witard et al, 2014)
A meta-analysis by Cermak et al (2012) showed supplementing an of average 42 g of protein a day during a, on average, 12 week resistance training protocol, had what effect on muscle mass and muscle function (Leg press 1RM)
increase in muscle mass of ~0.7 kg
increase in muscle function (Leg press 1RM) of ~10 kg
