Caffeine

Question 1

When does peak blood caffeine concentrations typically occur?

Answer 1

~60 mins after ingestion in a dose-dependent way.

However, benefits from caffein can occur soon after intake (before reaching peak blood concentrations).

Question 2

Where is caffeine metabolised?

Answer 2

Liver

Question 3

What are the effects of caffeine?

Answer 3

• Improved vigilance and alertness
• Reduced perception of effort
• Reduced fatigue and pain
  = IMPROVED PERFORMANCE

Question 4

What are the 3 proposed mechanisms of caffeine?

Answer 4

1) Adenosine blocker
2) Stimulates lipolysis
3) Stimulation of Ca2+ release

Question 5

How does caffeine directly and indirectly stimulate fat metabolism?

Answer 5

Directly - increase TG breakdown
Indirectly - increase epinephrine

Only occurs at high doses

Question 6

Does addition of carbohydrate (with caffeine) have an effect on carb/fat metabolism?

Answer 6

No - the combination of glucose + caffeine has no effect on metabolism.

Caffeine only increases fat/carb metabolism in a FASTED STATE.

When carbs are consumed, the insulin response is GREATER than that of caffeine.

Question 7

What is the ‘central effect’ (main mechanism) of caffeine?

Answer 7

Blocking adenosine - caffeine has similar chemical structure to a molecule called adenosine (responsible for feelings of tiredness, fatigue + pain).

Caffeine can stop adenosine from binding to its receptors in the brain, reducing sensations of tiredness and pain.

This can occur at very small doses.

Question 8

What is the recommended way of consuming caffeine?

Answer 8

For exact caffeine content, supplements (batch tested) are recommended.

Question 9

What is the best way of getting faster caffeine absorption?

Answer 9

Caffeinated gum - 30 mins faster.
- Most of caffeine bypasses the gut (↑absorption, ↓GI distress).

Question 10

What is the optimal dose for enhancing athletic performance?

Answer 10

~3mg/kg BM (same as the optimal dose for enhancing cognitive function)

Question 11

Timing - when is the best time to consume caffeine?

Answer 11

Usually ~40-60 mins before the event/exercise
- also throughout event at lower doses (~1.5 mg/kg).

Question 12

Are the effects of acute caffeine ingestion influenced by the level of habitual caffeine consumption?

Answer 12

No - acute caffeine supplementation (irrespective of past consumption) = performance benefit

Question 13

Is caffeine a diuretic?

Answer 13

It can be - however caffeine sports drinks contain elements which increase fluid retention (sodium etc)

Question 14

How should you approach caffeine consumption with regards to genetics?

Answer 14

Self-experimentation and practise in training.

Question 15

What are the risks of caffeine?

Answer 15

Sleep - caffeine has a half-life of ~5 hours.
Hydration - small-moderate doses have minimal effects on urine losses or overall hydration.
- At mod-high doses (>6-9mg/kg) other side effects can occur: anxiety, jitters, insomnia, inability to focus, GI unrest.

Question 16

What are some of the safety issues associated with caffeine?

Answer 16

• <400mg/day
• pure/highly concentrated caffeine can be lethal
• children <18 years old suggests to limit caffeine intake to <2.5 mg/kg/day
• All supplements have a doping risk of some kind. Some supplements are riskier than others. Athletes should aim to only use batch-tested supplements.