Dietary supplements (year 2) Flashcards
Caffeine?
- C8H10N4O2
- Trimethylxanthine
- Natural vs. Synthetic
- Found in seeds, nuts and leaves
- Rapid absorption
- Peak plasma 30-60 min
- Half-life 3-5 hours
Adenosine?
- C10H13N5O4
- Regulated by ATP metabolism
- Backbone of ATP
- increase during muscular work and during sleep
- decrease in brain during wakefulness
- ATP breakdown = Adenosine
- Similar chemical structure to caffeine…
Adenosine effects
- ‘Modulates’ release of most brain neurotransmitters such as:
- Dopamine
- Serotonin
- Acetylcholine
- Norepinephrine
- This results in:
- decreased arousal •increased sleepiness •decreased spontaneous motor activity
Adenosine Receptor Antagonism
•CNS stimulation•
increase Excitatory neurotransmitter release
- Caffeine
- Potent adenosine antagonist (opposing)
- Can also cross blood brain barrier
•Adenosine Receptors
•Located throughout the body:•
4 types
•A1, A2A, A2B, A3
Increased lipolysis
•A2A receptor has additional roles: Inhibit phosphodiesterase (PDE)
= ↑ in cyclic AMP (cAMP)
Sym. Nervous System (SNS)↑ Adrenaline (CA or NA)
Calcium handling?
- Calcium mobilisation •increase capacity for muscle contraction
- Caffeine reduces the threshold for ryanodine receptors
Summary of caffeine’s effect on endurance performance?
- increase time to exhaustion (20 -50%)
- decrease fatigue
- increase performance (middle and long-distance)
Beetroot (nitrate)
to get Nitro oxide you need to have enough L-citrulline which leads to L-arginine plus oxygen to allow for nitro oxide (natrual)
using beetroot shots to increase Nitrate to nitrite to nitro oxide after reduction.
What does Nitrate Allow?
reduces energy cost of sprinting and allows the athlete to reach the steady state quicker with less energy needed.
what dose has the largest effect?
8.4 mmol nitrate has the largest time until exhaustion.
Mechanisms of nitrate?
vasodilates the blood vessels, more o2 supply
allows for reduced use of ATP, more ATP available.
ATP / Oxygen ratio(mitochondrial efficiency)
