Caffeine Flashcards
(27 cards)
What is caffeine?
1,3,7-trimethylxanthine -> Metabolised in the liver
Its the worlds most commonly consumed drug (T or F)
T
What year was it removed from the WADA list and its previous limit?
Removed from WADA list in 2004 (previous limit 12 ug/mL)
What are some common sources of caffeine?
Coffee
Tea
Dark chocolate
Coke
RedBull (energy drinks)
Supplements
When are peak bioavailable caffeine contents found after consumption?
Approximately 60 mins after ingestion in a dose dependant way
However, benefits from caffeine can occur soon after ingestion (prior to reaching peak blood conc.)
What is the half-life of caffeine?
~5 hours
What areas of the body does caffeine interact with?
All body cells and crosses the blood brain barrier
What are the benefits of caffeine?
Improved vigilance and alertness
Reduced perception of effort
Reduced fatigue and pain
Therefore, improved performance
Explain the mechanistic process on the brain bringing about a positive response to caffeine.
The neurotransmitter adenosine is responsible for feeling of fatigue and tiredness due to hyperpolarisation of the target tissue.
Caffeine is an antagonist neurotransmitter to adenosine which puts them in competition.
Caffeine binds to the receptors in place of the adenosine, causing the resting potential to be closer to the threshold, which thereby delays fatigue.
Explain how caffeine may have a metabolic effect.
Caffeine may stimulate lipolysis (breakdown of triglycerides).
Possibly directly and also due to its effect on the adrenal medulla which increases release of adrenaline resulting in increased lipolysis.
This therefore may spare muscle glycogen for longer, allowing for reduction in fatigue.
However, effects are very minimal and would not be classified as a performance benefit.
Explain the possible peripheral effect of caffeine.
Caffeine may have direct effects on the skeletal muscle, however, needs very high consumption.
Caffeine has been shown to stimulate calcium release from the sarcoplasmic reticulum.
Therefore, more efficient activation of the excitation coupling reaction and improved force output.
What is the most important mechanism?
Effects on the brain
Provide a list of caffeine sources from lowest to highest
Coke
Espresso
250 ml redbull
Cappuccino
Brewed coffee
5hr energy shot
Rockstar 2X energy drink
Does the form you consume caffeine in effect its effects?
No - Caffeine in the form of a supplement or coffee will improve performance.
Slight advantage of using caffeinated gum is that most of the caffeine bypasses the gut (increases absorption and decreases GI distress), appears in the blood stream slightly quicker.
What is the optimal dosage for enhancing athletic performance (and improved cognitive function)?
3-6 mg/kg BM
Larger amounts do not provide an extra benefit and may increase side effects
When is the recommended time to consume caffeine prior to exercise?
Typically 40-60 mins before (allows time to peak); important to consider if there is an important stage in the event.
What are the recommendations for caffeine consumption during exercise?
1.5 mg/kg (lower dose; as long as sufficient time is considered)
If it is an endurance event, what is recommended for late into the event or an important stage of an event?
100 - 200 mg
Does caffeine still work to its optimal effect if you are a habitual consumer?
General view is that the habitual caffeine consumers will not have a reduced effect. No reason to taper off caffeine to boost its effect when you next consume.
However, there is some evidence to suggest that habitual may effect, but this is very on the fence.
Habitual caffeine consumption showed no effect on the improved strength endurance and jumping performance gained when consuming caffeine (T or F)
T
Does co-ingestion of CHO and caffeine show an enhanced performance effect?
NO - A study tested this hypothesis and the presence of caffeine was the major reason for improved performance.
When would you consider consuming caffeine?
Endurance sports (>60min)
Sustained high-intensity sports (1-60 min)
Team and intermittent sports (work rate, skills and concentration)
Single efforts involving strength or power
Pre-training energy boost if carrying fatigue into a session
What are the effect of genetics on caffeine?
Gene variants:
CYP1A2 (AA) form = increased ergogenic effect (standard guidelines); increased caffeine metabolism speed
CYP1A2 (C) form = Smaller ergogenic effect (higher caffeine dose or allow greater time); Slower caffeine metabolism speed
ADORA2A (TT) form = Increased ergogenic effect, increased anxiety (lower dose before competitions of high anxiety); nervous system excitability
ADORA2A (C) form = Smaller ergogenic effect, reduced sleep (lower dosage post exercise when sleep is important); nervous system excitability
What are the sleep risks?
Caffein can affect sleep onset and quality
It is a stimulant
Can therefore effect recovery between sessions, or multi-day competitions.
The caffeine intake in relation to need for sleep must be considered (5 hr half life)
