Fats and performance Flashcards
After what time are carbohydrates a limiting factor in exercise?
> 90 mins
Which is an alternative to delay fatigue?
to increase the capacity to oxidise fat
What are some advantages of lipids over CHO?
- Greater energy density
- Most efficient way of storing energy in limited space
- More ATP per molecule (147 vs 38)
What is the primary function of white fat (WAT)?
energy storage (triglycerides)
What are the two different WAT depots?
- Subcutaneous (scWAT)
- Visceral (vWAT)
Explain brown fat (BAT)
Metabolically active tissue, oxidises CHO and lipids to generate heat.
Central nucleus and a high density of mitochondria
Explain beige fat (brite)
- Only found in scWAT
- Generate energy in the form of heat, contributing to thermogenesis
- High degree of spasticity, revert to WAT in the absence of stimuli
True or False
Lower-body adipocytes (scWAT) tend to expand via hyperplasia
True
True of False
Upper-body adipocytes (vWAT anterior abdominal wall region) expand via hypertrophy
True
What is hyperplasia?
Increase in the number of fat cells
What is hypertrophy?
Increase in size of cells
What are some differences in MFO and fatmax between groups?
- MFO was greater in trained groups
- Absolute MFO were greater in males than females
- Fatmax was greater in females compared to males
- Prior CHO feeding tends to reduce MFO and Fatmax
Increases in vWAT are correlated with:
- Impaired glucose tolerance
- Increased insulin resistance
Increases in scWAT are correlated with:
- Decreased metabolic risk
True or False
Long term exercise increases fatty acid oxidation in human WAT
True
which exercise intensity oxidise the most fat?
65% VO2max in trained
55-72% VO2max well conditioned cyclist
43-61% VO2max in obese individuals
Where are the intramuscular triglycerides (IMTG) located?
adjacent to mitochondria in trained muscle
What is associated with insulin resistance in obese/sedentary individuals?
Intramuscular triglycerides (IMTG)
What is the main source of fat oxidation at moderate to high exercise intensities?
Intramuscular triglycerides (IMTG)
What is the difference between maximal fat oxidation and Fatmax?
- Maximal rate of fat oxidation (MFO) (g.min-1) is the point at which the body’s use of fatty acids (FAs) for energy is at its highest.
- Fatmax: exercise intensity at which MFO occurs (% VO2max)
What are the main differences in exercise-induced adaptations in WAT compared with BAT in man?
- long term exercise increases fatty acid oxidation in human WAT
- Glucose uptake: Exercise increases glucose uptake in WAT, but does not affect glucose uptake in BAT.
- Endocrine activity: Exercise increases endocrine activity in both WAT and BAT.
Where does ketogenesis occurs?
In mitochondria of liver cells
Briefly outline the factors that affect IMTG use for fuel during exercise
Exercise duration
Training status
Diet
Hormones
What are the 3 ketone bodies synthesised in ketogenesis?
- acetoacetate (AcAc)
- beta-hydroxybutyrate (BOHB)
- acetone
Explain some facts about Keto Diet (KD)
- <50g CHO/day 60-80% kcal from fats and 1.2g.kg/d protein
- keto adaptation may take 2-4 weeks
- increased fat oxidation but impairs glycolytic pathways
- no performance benefit
- may be effective to reduce body weight and fat mass (in the short term)
Explain fat adaptation
- may result in metabolic alterations favouring fat oxidation
- not improved exercise performance
What is ketogenesis?
A catabolic pathway of metabolism. Fatty acids and certain ketogenic amino acids are broken down to derive energy by alternative means. Ketone bodies are produced in the process.
Reason for why endurance training results in increased capacity to oxidise fats during mild-moderate intensity exercise
Regular aerobic exercise promotes training induced adaptations such as increased activity of lipoprotein lipase an increased capillarisation in trained muscle
