Carbohydrate and Fat Flashcards
At what intensity is fat mainly used?
Fat was mainly used at low intensity
- More efficient to get energy from glycogen at high intensity
- Consequences of shifting to fat, when carb stores are depleted causes lower performance
Name some:
- monosaccharides
- disaccharides
- oligosaccharides
- polysaccharides
Which of these is most likely to be contained in sports drinks?
- glucose, fructose, galactose
- sucrose, maltose, lactose
- maltodextrin
- amylopectin(starch), amylose
Glucose can be interchanged with maltodextrin as it
Is easy to breakdown, glucose and fructose also found
In sports drinks
* Glucose and galactose are primarily absorbed via active
transport of Na+ by the sodium-dependent
luminal transport protein
How is glucose metabolised in a fasted state?
How is glucose metabolised in a fed state?
- Main store of glucose in the liver
In fasted state glucose is the main source of Brain energy - Pancreas releases insulin to increase uptake at muscle, liver etc
The consumption of easy to digest CHO rich food 3hrs before exercise increases muscle & liver glycogen by 11-15%
What are the types of fats/lipids?
what food sources are they found in?
- Fats, oils, phospholipids and sterols
- Occur naturally in wide variety of foods
- Animal adipose tissue
- Milk and milk products
- Seeds, nuts and oils
- Eggs, fish oils
95% dietary fat intake is from triacylglycerols (TAG)
How are fatty acids classified?
- Number of carbon atoms in the chain
- Number & position of double bonds in the chain
- Saturated (0 C = C) –> Palmitic acid 16:0
○ 16 carbon and NO double bonds - Monounsaturated (1 C = C) –> oleic acid (18:1n-9)
○ 18 carbons, 9th from the right is where double bond is (1 double bond) - Polyunsaturated (2+ C = C) –> Linoleic acid (18:2n-6)
What is the general CHO intake of an athletes with… training load:
- light
- moderate
- high
- very high
- 3-5 g/kg/d
- 5-7 g/kg/d
- 6-10 g/kg/d
- 8- 12 g/kg/d
Describe short term fat loading:
- 3 day high fat (65% fat; 9% CHO) or high carbohydrate (82% CHO; 9% fat) diet
- 70% VO2Max to fatigue in 10oC and 30oC
- Impaired performance with short term high fat diet
- There was very little difference in heat, substrate in the heat is not the primary factor(dehydration is)
What happens during longer fat loading?
What may be a potential benefit of a High fat diet?
- Normal (30±8%) or high (69±1%) fat diet for 15 days
- Increased fat oxidation during submaximal exercise
- Decreased carbohydrate oxidation during submaximal exercise
- No difference in 40 km cycling time trial, May not have benefitted or hindered the performance
- The only benefit of a high fat diet is time to exhaustion at 60% of Vo2max
High CHO group have depleted muscle glycogen by the time they reach 60% Vo2max
Describe the process of diet periodisation:
- Do positives (glycogen sparing) and negatives (lowered CHO stores) cancel each other out?
- If adaptations to metabolism allow increased fat oxidation could this be combined with high CHO stores?
- High fat diet followed by rapid glycogen storage?
- High fat diet decreased muscle glycogen
- 1 d high CHO restored muscle glycogen
- High fat diet decreased rate of muscle glycogen use
Name some benefits of diet periodisation:
- enhanced training quality/intensity with high CHO availability
- enhanced cellular signalling and adaptation with training with low muscle glycogen
- less muscle glycogen is used
What effects were found for a low CHO, high fat diet in elite race walkers?
What benefit was shown?
- LCHF were more efficient, optimum
Approach is periodised CHO intake, leads to mitochondrial biogenesis - Showed higher reductions in economy include observations, from a previous study of a 5 day non-ketogenic LCHF, of an uncoupling of mitochondrial respiration specifically associated with high fat exposure
- Also alters oral microbiome reducing anaerobic bacteria involved in the conversion of dietary-derived nitrate to nitrite - therefore effects all associated NO functions
- These LCHF and endurance performance studies often have flaws of involving the implementation or scientific control.
- CHO intake less than muscle fuel needs while consuming high amounts of dietary fat causes adaptations to increase availability of muscle fats and capacity to oxidise them as muscle fuel
What is the impact of training with low CHO availability?
- Potential to increase molecular adaptations
- Increase in AMPK and PGC1-α leading to increased mitochondrial biogenesis
- Reduced self-regulated training volume à pick the right session/ method
