Week 3 - Carbohydrate Flashcards
Describe the difference between fast and slow carbohydrates
Fast and slow carbohydrates refer to the speed at which these carbohydrate types are digested, absorbed, and made available to the body for energy provision
Define multiple transportable carbohydrates
Multiple transportable carbohydrates are sugars that are transported across the intestine by stimulating more than one protein transporter, reducing competition for SGLT1 transport and increasing exogenous carbohydrate oxidation
How does carbohydrate feeding during exercise impact endurance capacity and performance
Maintains blood glucose concentration and high rates of carbohydrate oxidation
Spares liver glycogen which can then be used during later stages of exercise
Spares muscle glycogen in certain situations
Describe the guidelines for carbohydrate intake during exercise
1.0g/min during exercise = 1 litre/h of typical sports drink or 2 gel/h
How does glycogen synthase and branching molecules function in skeletal muscle
Glycogen synthase is used to combine glucose molecules in a line
Branching enzymes creates branching of glucose molecules to increase surface area for quicker oxidation
Explain the metabolic effects of carbohydrate feeding during exercise
- Carbohydrate feeding helps maintain plasma glucose concentration,
- Sustain high rates of carbohydrate oxidation,
- Spare liver glycogen, and
- May spare muscle glycogen, leading to increased exogenous carbohydrate oxidation rates
What are the benefits of post-exercise carbohydrate intake for athlete
Post-exercise carbohydrate intake aids in glycogen repletion, with long-term strategies ensuring repletion on a day-to-day basis and short-term strategies facilitating rapid glycogen repletion within 0-8 hours
How does the regulation of muscle glycogen synthesis change during muscle contraction and food consumption
During muscle contraction, chemical signals:
- Increase GLUT4 translocation
- Increased glycolysis
- Inhibits glycogen synthase
Food consumption, promotes insulin into bloodstream
- Increases GLUT 4 translocation to the membrane
- Increased glycogen synthase activity for storage
How does protein co-ingestion with carbohydrate impact muscle glycogen synthesis
Protein ingestion stimulates insulin secretion when carbohydrate intake is suboptimal
Define the commended carbohydrate intake for the first 4 hours post-exercise
1.2g/kg/bw/h of moderate-to-high glycaemic index carbohydrates for first 4 hours
Early & frequent carbohydrate feeding the first hour, and 30mins intervals 4h thereafter
What are the recommended guidelines for carbohydrates during exercise
30 - 75 mins: small amounts (single or multiple)
1-2 hours: 30g/h (single or multiple)
2-3 hours : 60/h (single or multiple)
>3 hours: 90/h (only multiple)
What are the fast and slow carbohydrates
Fast: Glucose, Sucrose, Maltose, Maltodextrins, Starches in amylopectin
Slow: Fructose alone, Galactose, Isomaltose, Starches in amylose
How can different types of carbohydrates optimise the recovery of whole-body carbohydrate stores
By utilising carbohydrate types with different metabolic fates (liver or muscle) to enhance overall body carbohydrate store recovery
How can multiple transport mechanisms increase exogenous carbohydrate oxidation
Glucose and fructose would stimulate multiple carbohydrate transport mechanisms (more than one transport protein)
Glucose transported by SGLT1
Fructose transported by GLUT5
This increases the amount of carbohydrate that can be absorbed into the circulation and delivered to the muscle
(20-50% above single transported carbohydrates, and improve gut comfort)
What evidence suggests carbohydrate feeding is beneficial
Increases type 1 fibres muscle glycogen
Sparing of liver glycogen
Increased plasma glucose concentration
